Generation Of Batteries Research Articles

Peer-to-Peer trading with Demand Response using proposed smart bidding strategy

The electricity demand is increasing rapidly among residential consumers due to the utilization of many smart appliances. The renewable-based Distributed Generation (DGs) and Electric Vehicles (EV) investment is also rising among residential consumers. Consumers with renewable-based DGs and smart appliances are considered prosumers in this work. The main objective of this work is to reduce the electricity cost of the smart home by scheduling the smart appliances with Demand Response (DR) using Binary Particle Swarm Optimization (BPSO) algorithm and Peer-to-Peer (P2P) trading using a smart bidding strategy. The smart home consists of two prosumers and two consumers with different Distributed Generation (DG) availability, battery, EV, and smart appliances (thermal and electrical loads). The smart appliances are scheduled based on Real-Time Pricing (RTP), DGs and storage devices availability. The available excess power in the prosumers after self-consumption is traded to the neighbouring consumers to reduce the grid dependency. The novelty of this article lies in the trading decision and trading cost determination for P2P trading, which is called the proposed smart bidding strategy in this work. The proposed smart P2P trading algorithm involves the double auction mechanism, where the bidding occurs between the prosumers and consumers based on the supply–demand ratio (SDR) and RTP. The trading cost calculated is beneficial for both prosumers and consumers in reducing their electricity costs. The electricity cost of consumer 1, consumer 2, prosumer 1, and prosumer 2 is reduced by ₹58.073, ₹20.37, ₹51.656, and ₹20.37, respectively, as compared with grid tariff under the category of normal condition. Similarly, the electricity cost of consumer 1, consumer 2, prosumer 1, and prosumer 2 is reduced by ₹63.514, ₹3.208, ₹98.155, and ₹34.049, respectively, as compared with grid tariff under the category of EV uncertainty in both consumer & prosumer premises. The simulation results proved that the proposed smart bidding strategy effectively reduced the electricity cost of the prosumers and consumers under normal and uncertain conditions compared to the grid tariff.

Industrial Perspectives on Innovation: Sustainability, Safety, Scalability, and Advanced Performance

Industry continues to look forward to innovative and to sustainable solutions that can improve battery performance, safety, and manufacturing efficiency. Livent is looking forward to bringing LIOVIX™ to the market as a product to help meeting these growing requirements while opening pathways for the development of next generation battery technology.LIOVIX™, proprietary lithium metal product, is a unique printable formulation of lithium metal and other specialty materials that can improve the performance of lithium-ion batteries, reduce manufacturing costs, and enable the next generation of battery technology, all while enhancing safety and sustainability.LIOVIX™ can be printed on a battery’s anode during electrode manufacturing in a process called pre-lithiation. Pre-lithiation employs an external, sacrificial source of lithium to offset the first cycle loss of lithium due to SEI formation allowing more efficient use of lithium from the cathode and raising the cell energy density. However, pre-lithiation techniques that are scalable at giga-factory throughput speeds have yet to be demonstrated. LIOVIX™ technology is easily scalable using industry standard coating and printing equipment and is adaptable to any anode or cathode chemistry where an independent source of lithium is required. LIOVIX™ can be used in anodes with a range of silicon content, because lithium loading can be accurately controlled based on the applications’ requirements. Incorporation of this technology has led to higher columbic efficiency at the first cycle, better cell capacity, and longer life batteries. In fact, the application of LIOVIX™ has been demonstrated to improve a battery’s output and to extend its useful life for a variety of battery chemistries (Figure 1).LIOVIX™ is an important technology for the development and commercialization of solid-state batteries using lithium metal. These next generation batteries will address many of the challenges and limitations of today’s liquid electrolyte-based battery systems. LIOVIX™ can be directly printed on current collectors and can act as an anode in solid state batteries. It can also be printed on other anode material to improve the first cycle columbic efficiency and cell performance. It can reduce the interface resistance between anode and solid electrolyte layer.Commercialization of battery systems that use metallic lithium anodes is strongly dependent on the industry’s ability to manufacture these anodes cost effectively at scale. Using LIOVIX printable lithium technology thin lithium foils in the range of 10um – 30um have been demonstrated at the desired width. Figure 1

Transfer Learning Enabled Deep Learning Model for the Prediction of Battery Performance from Electrolyte Formulations

Next generation batteries utilizing lithium (Li) metal anode could represent a 10x improvement in anode specific capacity compared to currently used graphite anodes however they still face major challenges associated with their evenness of plating and interfacial stability with the electrolyte. The capability to quickly evaluate and optimize liquid electrolyte formulations that can form stable solid-electrolyte interface (SEI) layers and bring out the best battery performance across a range of relevant performance outcomes will be critical to the realization of these next generation batteries. Integrating AI into battery research and development workflows has the potential to significantly increase the rate of new materials discovery, however, while machine learning models can successfully predict expected specific capacity or cycle life of the battery based on electrode designs, the complexity of liquid electrolytes used in batteries needs more contextual information than a machine or deep learning models can capture from simple structure-performance correlations. The lithium metal anode SEI layer is a formed out of the complex physio-chemical interactions between the lithium metal and the electrolyte and models will likely need to be able to capture those molecular attributes within the electrolyte composition that are decisive in electrolyte-Li interfacial chemistry. For this purpose, we will discuss the scope of two AI approaches that can predict battery performance based on electrolyte composition. The first approach showcases the capability of a deep learning model that is designed specially to represent electrolyte formulation based on structure-to-performance relationship. The second approach improves upon the first by incorporating transfer learning of quantum chemical attributes of electrolyte molecules and building a property-to-performance correlation. We will also discuss how transfer learning of ‘selective’ quantum chemical properties of electrolyte molecules to the capacity predicting deep learning model broadens the scope of the model towards recognizing new beneficial additives to the electrolyte formulation. Using this approach, the model retains impressive predictive accuracies despite limited experimental training data and predictions are validated and improved with experimental feedback for new electrolyte formulations in coin cell tests.

Mechanism of Improved Lithium-Sulfur Battery Performance by Oxidation Treatment to Microporous Carbon as Sulfur Matrix

1. IntroductionLithium-sulfur (Li-S) batteries are rechargeable devices assembled with a sulfur cathode and a lithium metal anode. Li-S batteries have twice the volumetric energy density and 5 times the gravimetric energy density of lithium-ion batteries (LIB). Hence, Li-S batteries are expected to be applied to stationary power sources and EV vehicles [1]. However, Li-S batteries have the following issues:・Sulfur and the final discharge product (Li2S) are insulators.・In the discharge process, sulfur expands up to 1.8 times, so the structure of batteries is unstable.・Intermediate products (Li2Sx (x = 4 – 8)) dissolve in an electrolyte; Li2Sx (x = 4 – 8) diffused to an anode to provide an insulating layer at the anode surface.・In the charge process, Li2Sx (x = 4 – 8) causes redox shuttling.As a result, Li-S batteries cannot charge and discharge stably. In order to deal with this problem, Nazar et al. reported the method that sulfur is confined in porous carbon [2]. This approach provides a cathode realizing good electronic conductivity, restriction of sulfur expansion, and suppression of Li2Sx (x = 4 – 8) dissolution. Although these improved characteristics allow Li-S batteries to operate, The discharge capacity of Li-S batteries is still not high enough and this needs to be addressed.In our previous study, we reported that oxidation treatment to microporous carbon (MC) with HNO3 improves Li-S batteries' discharge capacity [3]. Moreover, we clarified that the discharge capacity of Li-S batteries has an approximate proportional relation with the amount of oxygen-containing functional groups on the MC surface [4].This work attempts to elucidate the mechanism of improved Li-S battery performance by oxidation treatment to MC. Our report would lead to the proposal of a novel strategy to improve the performance of Li-S batteries.2. Method2.1 Preparation of Oxidized MC-Sulfur composite (Ox MC-S)MC was added into 69 wt.% HNO3 and refluxed at 120ºC for 2 h. By vacuum filtration and washing with deionized water, Ox MC was obtained. Ox MC dried in vacuum at 80ºC overnight was mixed with sulfur at a weight ratio of Ox MC: S = 48: 52. The mixture was thermally annealed at 155ºC for 5 h (Ox MC-S). Untreated MC was also composited with sulfur by the same method (MC-S).2.2 Assembling of CellsEach MC-S cathode was prepared by mixing the MC-S, acetylene black, carboxymethyl cellulose, and styrene butadiene rubber at a respective weight ratio of 89: 5: 3: 3 and coating the resulting aqueous slurry on an Al foil current collector. The cells with the MC-S electrode and Li metal foil as an anode were assembled in a glove box filled with Ar. Lithium bis(trifluorosulfonyl)imide (LiTFSI): tetraglyme (G4): hydrofluoroether (HFE) = 10: 8: 40 (by mol) was used as the electrolyte.2.3 Electrochemical Impedance Spectroscopy (EIS)To elucidate the effect of oxidation treatment on the internal resistance of Li-S batteries, EIS was carried out at various potentials (Discharge 2.0 – 1.0 V and Charge 1.0 – 3.0 V). The obtained Nyquist plots were used for the evaluation of solid electrolyte interphase (SEI) resistance (Rsei), charge-transfer resistance (Rct), and Warburg impedance (Rw). Rw was investigated with the calculation of Warburg coefficient (σ).3. Major results and conclusionSince oxidation treatment to MC significantly increased the discharge capacity of Li-S batteries [3][4], it was expected that oxidation treatment would lower the internal resistance of Li-S batteries. EIS of MC-S and Ox MC-S at various potentials showed that oxidation treatment reduced Rsei by an average of 12.2 Ω. This indicates that the SEI thickness was reduced, or the SEI was composed of highly ion-conductive components by the oxidation treatment. Rct decreased only at lower potentials, and the Warburg coefficient decreased except at the end of charge and discharge potential. These results suggest that the oxidation treatment decreases overall resistance, but especially SEI resistance and Warburg impedance, which may improve the discharge capacity of Li-S batteries.We will also report the activation energy of Rsei and Rct and mechanism analysis of decreasing Rsei by oxidation to MC. This work was supported by “Advanced Low Carbon Technology Research and Development Program, Specially Promoted Research for Innovative Next Generation Batteries (ALCA-SPRING [JPMJAL1301])” from JST.[1] Y. Guo et al., Angew. Chem. Int. Ed., 52 (2013) 13186.[2] X. Ji et al., Nat. Mater., 8 (2009) 500.[3] S. Okabe et al., Electrochemistry, 85 (2017) 671.[4] L. Yoshida et al., ECS 238th PRiME Meeting s (2020).

Next Generation Batteries: Status and Challenges of High Energy Rechargeable Lithium Batteries

Batteries play a critical role in modern society. The electrification of transportation and deep decarbonization of the energy infrastructure require the development and deployment of high energy, low-cost battery materials and technologies. Among the many different battery chemistries investigated, rechargeable batteries using lithium metal anode remain as one of the most feasible approaches for next generation high-performance and low-cost batteries. Here we will discuss and summarize the progresses and status of the research supported by the Battery500 Consortium. The consortium addresses both fundamental level materials and mechanistic problems and cell level integration and manufacturing challenges. The scope includes developing new electrolytes to reduce the side reactions and improve lithium metal deposition/stripping efficiency, improving cathode cycling stability and cathode utilization, understanding and controlling solid electrolyte interfacial reactions, cell design, optimization and validation. The consortium has made significant progress towards high energy cells (>350 Wh kg-1) and stable cycling life (>600 cycles). The research from the consortium also sheds new lights on the degradation and failure mechanisms of high energy lithium cells and the associated the interfacial reactions.

Catalysis in Lithium-Sulfur Cathodes for Improved Performance and Stability

Among next generation batteries, lithium-sulfur batteries are expected to be first battery to find a commercial route in the next few years. The sulfur cathodes in lithium-sulfur batteries provide both a lower cost and high capacity (1675 mAh/g) in comparison to intercalation cathode materials [1]. Despite these upsides, this conversion reaction type battery suffers from few problems that hinders their adoption. Some of these problems include the sluggish reaction kinetics, low sulfur utilization, rapid capacity loss due to various sulfur loss phenomena, and low Coulombic efficiency [2]. The use of electrocatalysts was shown to significantly boost the polysulfides redox reactions and improves the battery performance [3]. Transition metals, especially platinum group metal (PGM) based catalysts are proven to effectively boost the reaction rate of polysulfides conversion during cycling due to their high electrocatalytic activity [4], [5]. However, catalyst incorporation in conversion reaction batteries systems often would lead to side reactions and strategies on how to incorporate them into the battery system have to be developed.In this work, platinum group metal (PGM) nanocatalysts were implemented in lithium-sulfur cathodes using a process that is tailored to effectively improve catalyst dispersion and to provide controlled catalyst electrolyte contact. The nanocatalysts were loaded in carbon nanotube at variable low contents 0.1 – 5 wt% (Figure 1a) and were used in cathodes with sulfur loading up to 70 wt%. Using standard lithium-sulfur electrolyte based on 1 mol/kg LiTFSI in DOL:DME (v:v = 1:1) with lean electrolyte condition, batteries based on 2032 type coin cells and multilayer pouch cells were studied. The batteries' performance was studied for their impedance growth using electrochemical impedance spectroscopy, the redox performance using cycling voltammetry, and for their sulfur utilization/sulfur loss/Coulombic efficiency using galvanostatic charge-discharge cycling. These cathodes were shown to have improved redox performance in the batteries, improved sulfur utilization, and maintained stable capacity even at high sulfur loadings of 4-5 mg/cm2. Comparison of performance of nanocatalyst-containing batteries versus control batteries show improved first cycle capacity and stabilized capacity retention in the early cycling life of the battery (Figure 1b). Elucidating the underlying phenomena of the stabilization is studied in detail revealing reduced sulfur precipitation and shuttle effects. Higher C-rate performance of up to 1C revealed similar observations of stabilization.

Regulating Electrochemical Growth of Metals at Rechargeable Battery Electrodes

Control of crystallography of thin metal electrodeposit films has recently emerged as key to achieving long operating lifetimes in next-generation electrochemical systems for energy storage. Very recent studies show that the crystallography of metal deposits impacts both morphological evolution and chemical kinetics of the interfaces between metal anodes and electrolytes in a battery. We report that the large crystallographic heterogeneity, e.g., broad orientational distribution, that appears characteristic of commercial metal foils results in rough morphology upon plating/stripping. On this basis, we develop an accumulative roll bonding (ARB) methodology—a severe plastic deformation process—that uses commercial metal foils as input. Zn metal—a promising, low-cost-competitive battery anode material— is used as a first example to interrogate the proposed concept. We demonstrate that the ARB process is highly effective in achieving uniform, mono-domain quality crystallographic control on macroscopic materials. After the ARB process, the Zn grains exhibit a strong (002) texture (i.e. [002]Zn//ND). We report further that the texture transitions from a classical bipolar pattern to a nonclassical unipolar pattern under large nominal strain, almost completely eliminating the orientational heterogeneity of the foil. Evaluated as anodes in aqueous Zn coin cells, the strongly (002)-textured Zn suppresses the rough plating/stripping landscape, promotes uniform, homoepitaxial growth of Zn and remarkably improve the continuous plating/stripping performance by nearly two orders of magnitude under practical conditions (e.g., 4 mAh at 40 mA/cm2). The performance improvements are readily scaled to achieve pouch-type Zn full batteries that deliver exceptional reversibility. The ARB process is thermo-mechanical and can in principle be applied to any metal chemistry to achieve similar crystallographic uniformity, provided the appropriate temperature and accumulated strains are employed to achieve severe levels of plastic deformation. We evaluate this concept using ARB to induce strong texturing phenomena in commercial Li and Na foils, which unlike Zn (HCP) are BCC crystals, and demonstrate its success using morphological and electrochemical analysis of these metals as electrodes. Our simple process for creating strong textures in both hexagonal and cubic metals and illustrating the critical role such built-in crystallography plays underscores potentially transformative opportunities for developing scalable, highly reversible thin metal anodes (e.g. hexagonal Zn, Mg, and cubic Li, Na, Ca, Al) with specific crystal textures for next generation batteries that have practical N:P ratios.Key

(Invited) Identification of Lithium Hydride and Nanocrystalline Lithium Fluoride in the SEI of Lithium Metal Anodes and the Stabilization of High Ni Layered Structure at Ultra-High Voltage through Cathode Electrolyte Interphase Engineering

Solid-electrolyte interphase (SEI) plays a pivotal role in the performance of lithium metal anode, which is promising for high energy batteries. Understanding SEI composition is important but very challenging. Here we report on the use of synchrotron-based X-ray diffraction and pair distribution function analysis to identify and differentiate the two elusive components, LiH and LiF, in the SEI of lithium metal anodes. LiH is identified as a component of SEI in high abundance, and the possibility of its misidentification as LiF in the literature is discussed. LiF in the SEI is found to have different structural features from LiF in bulk phase, including larger lattice parameter and smaller grain size (<3 nm). These characteristics favor Li+ transport, and explain why an ionic insulator, like LiF, has been found to be a favored component for SEI. PDF analysis of the SEI reveals key amorphous components related to solvent or anion decomposition.Nickel-rich layered cathode materials with high energy density are very promising for next generation batteries when coupled with lithium metal anode. However, the practical capacities accessible are far less than the theoretical value due to their structural instability during cycling, especially when charged at high voltages. Such challenge has been attributed to the concomitant electrolyte instability and cathode structural and morphological degradation. Therefore, various approaches have been developed through electrolyte engineering and bulk cathode material modifications. In this presentation, we will report a simple interphase engineering approach by using an ionic electrolyte additive, lithium difluorophosphate (LiDFP). Through theoretical calculation, we found that self-decomposition product PO2F of LiDFP additive is adsorbed strongly and uniformly on the Ni-rich cathode, which is further decomposed to Li3PO4 and LiF through the catalytic effect of transition metals. The new interphasial chemistry contributed from LiDFP stabilizes the bulk structure of Ni-rich cathode materials and prevents the performance degradation by suppressing the dissolution of transition metals and undesired structural changes. Even after 200 cycles with charge limit as high as 4.8 V, no rock-salt phase can be detected in LiNi0.76Co0.10Mn0.14O2 (NMC76), and the cell consisting of NMC76 cathode and lithium metal anode retains 97% of the initial capacity (235 mAh/g). Various advanced characterizations were used, on both atomic and electrode levels, to reveal the mechanism how a new interphase stabilizes the layer structures in bulk electrode. The dissolution of nickel was identified to be most serious at high voltage, rather than the widely believed manganese dissolution. The transition metal dissolution can be effectively suppressed by LiDFP additive. Furthermore, the cathode surface protected by LiDFP-derived interphase is shown to regulate a more uniform lithium distribution within the bulk cathode particles and effectively mitigate the strain and crack formation. Machine-learning assisted nano-tomography discovered that such interphase-bulk interaction is most effective for those small-sized, spherically-shaped particles.Acknowledgement:The work done at Brookhaven National Laboratory was supported by the Assistant Secretary for Energy Efficiency and Renewable Energy, Vehicle Technology Office of the U.S. DOE through the Advanced Battery Materials Research (BMR) Program, (Battery500 Consortium), and Applied Battery Research for Transportation (ABRT) program under contract No. DE-SC0012704. This work used the resources of the Center for Functional Nanomaterials, a U.S. DOE office of Science User Facility, at Brookhaven National Laboratory, and beamlines 5-ID, 7-BM, 23-ID-2, and 28-ID-2 of the National Synchrotron Light Source II, a US DOE Office of Science user facility operated for the DOE Office of Science by Brookhaven National Laboratory under contract no. DE-SC0012704. The work done at Pacific Northwest National Laboratory was supported by the Assistant Secretary for Energy Efficiency and Renewable Energy, Office of Vehicle Technologies of the US Department of Energy through the Advanced Battery Materials Research (BMR) Program (Battery500 Consortium) under contract No. DE-AC02-05CH11231. The work at ARL was performed under JCESR, an Energy Research Hub funded by Basic Energy Science, US Department of Energy.

Improvement of Sulfur Cathode Reversibility by Specific Chemical Lithium Pre-doping Method

1.IntoroductionRecently, lithium-ion batteries (LIBs) have been required in terms of a high energy density for large-scale applications such as power supplies for electric vehicles. Lithium-sulfur (Li-S) batteries are, therefore, expected as next generation batteries because of their high energy density.Sulfur is utilized as cathode material for Li-S batteries because of a high specific capacity. However, sulfur has a low electric conductivity and a risk of dissolution into an electrolyte during a charge-discharge process [1]. L. Nazar et al. applied activated carbon as substrate for sulfur to help electric conduction and prevent dissolution of sulfur [2]. The activated carbon allows Li-S batteries to show high specific capacity with high reversibility. Even if these problems are solved, however, Li-S batteries have a further problem of excessive initial irreversible capacity during the first discharge process. Li pre-doping is a useful technique to cancel the large irreversible capacity in actual LIBs. Abe et al. reported a chemical lithium pre-doping method for a graphite using lithium naphthalenide [3]. Studies have been reported on the use of such pre-doping to improve the performance of Li-S batteries, for instance, with a sulfur-Ketjenblack composite cathode [4]. In our previous study, we have applied that method to a sulfur cathode composed of microporous activated carbon and sulfur before cell assembly and developed a Li2S cathode that suppressed the initial irreversible capacity during the first discharge process. However, the Li2S cathode showed an unignorable initial irreversible capacity and poor cycle life [5].This work attempts to improve the reversible capacity of the Li2S cathode by a specialized chemical lithium pre-doping method. Our report would lead to the proposal of novel cathode and anode options in Li-S batteries. Method 2-1. Fabrication of lithium naphthalenide solutionAs Li metal and Li2S are both sensitive to moisture in air, all the following synthesis processes were carried out in an Ar-filled glove box. Lithium naphthalenide, a dark green solution was prepared by mixing an equal mol amount of Li metal with naphthalene in a cyclic ether solvent.2-2. Fabrication of Li2S-AC cathodesEach sulfur cathode was prepared by mixing the S-AC (a composite of microporous activated carbon and sulfur), acetylene black, carboxymethyl cellulose, and styrene butadiene rubber at a respective weight ratio of 93: 3: 2: 2 and coating the resulting aqueous slurry on a carbon paper.The 1M lithium naphthalenide solution was dropped on the sulfur cathode. After 20 min reaction, the cathode was rinsed several times with 2–dimethoxyethane (DME) to remove the residues of reagents. The cathode was then dried under reduced pressure for 12 h. After that, the resulting Li2S cathode was impregnated with a mixture of vinylene carbonate (VC) and fluoroethylene carbonate (FEC) (VC: FEC = 1: 1 by weight). After 20 min impregnation, the cathode was dried under reduced pressure for 12 h.2-3. Assembling of cellsCells were assembled with the Li2S electrode and Li metal foil as an anode. Lithium bis(trifluorosulfonyl)imide (LiTFSI): tetraglyme (G4): 1,1,2,2–tetrafluoroethyl–2,2,3,3–tetrafluoropropyl ether (D2) at a respective ratio of 10: 8: 40 (by mol) was used as the electrolyte.3.Major results and discussionThe Li2S cathode without the VC/FEC impregnation showed an initial charge capacity of 1791 mAh g-1 and an initial discharge capacity of 1298 mAh g-1, indicating a large irreversible capacity. In contrast, the Li2S cathode with the VC/FEC impregnation showed 1446 mAh g-1 and 1422 mAh g-1, respectively. Thus, the impregnation with VC/FEC reduced the initial irreversible capacity and improved the initial charge capacity. According to these results, Li remaining in the sulfur cathode would be partially consumed to form a film by the impregnation with VC/FEC. In addition, the capacity retention of the Li2S cathode with and without the VC/FEC impregnation was 73 % and 64 % at the 30th cycle, respectively. This suggests that the Li2S cathode with the film leads to better cycle performance than that without the film.We will also report the results of surface composition analysis of the Li2S cathode with and without the VC/FEC impregnation by Hard X-ray Photoelectron Spectroscopy (HAXPES).

Controlling the Morphology of Electrodeposited Lithium Metal Via Seeded Growth: Stepwise Spherial to Fibrous Lithium Growth

Lithium metal has been gained intense research interest because of its high specific capacity and lowest electrochemical potential for next generation battery systems with high energy density. However, the utilization of Li metal as an anode material has been limited due to the uncontrolled Li deposition and side reactions on Li metal surface that induce low coulombic efficiency, poor cycle performance and safety issues. Controlling morphology of electrodeposited Li metal is one major direction to resolve these issues. Identification of Li deposition mechanism governing the morphology evolution is prerequisite for establishing strategy for controlling morphology. Herein, we explore governing deposition mechanism from the morphology evolution at varied current (0.2- 1.8 mA cm-2) and suggest a strategy for growing low surface area Li fibers.We found that fibrous Li growth follows the initial spherical Li particle formation when the Li sphere size reaches the critical value. The diameter of the initially formed Li particles decreases with the current density. Initially formed spherical Li particles at a low current density (0.2 mA cm-2) are sufficiently large to grow with a fibrous morphology. Thus, the spherical particles evolve to fibrous Li during subsequent growth. On the other hand, at a higher current density, the Li particles are initially smaller than the critical size and thus cannot immediately grow into a fibrous morphology. Spherical growth of the existing Li particles and additional nucleation on the current collector surface continue, resulting in multilayer Li particles. After Li particles reach the critical size, Li can grow with a fibrous form. Due to the preferential deposition on the existing fibrous Li, the morphology of spherical Li particles smaller than the critical size does not change. Therefore, only fibrous Li deposits were formed at low current density (0.2 mA cm-2), but both spherical and fibrous Li deposits were formed at higher current densities.Based on the morphology evolution mechanism, seeded Li deposition strategy was proposed to minimize the surface area of Li deposits and improve cycling stability of Li metal electrode. The stepwise spherical to fibrous Li growth was achieved by changing the current from low to high (0.2 to 1.8 mA cm-2). Li deposits morphology was well controlled by this strategy resulting in all fibrous morphology with smooth surface. The Li deposits of seeded growth strategy achieved smaller surface area, suppressed side reactions and improved cycle life more than four times compared to that of constant current deposition with same average current density (1 mA cm-2). Figure 1

(Invited) High Throughput Solvent-Free Manufacturing of Battery Electrodes

Research into the manufacturing of LIB electrodes is constantly evolving with new active materials, improved binders, and improved drying techniques to more efficiently produce high-quality electrodes. However, the one constant in all these endeavors is that electrode research and manufacture still generally rely on a slurry-coating process, where large amounts of potentially toxic solvents are necessary for slurry production. As such, solvent-free, also known as dry-process (DP), electrode processing has been proposed to solve the conventional lithium-ion battery electrodes fabrication disadvantages, such as high equipment costs for solvent reclamation, currently seen in industry.Currently, the solvent-free, state-of-the-art electrodes use polytetrafluoroethylene (PTFE) as a binder and the PTFE is fibrillized and dispersed in the dry powder mixture using a jet mill. One key solvent-free electrode shortcoming is that PTFE is not electrochemically stable for the anode, traditionally resulting in initial capacity losses of greater than 30% and poor mechanical strength, effectively limiting solvent-free processing to cathodes. A second shortcoming is that solvent-free electrodes generally require the addition of fibrillization promoters or processing steps that add cost and detract from performance by limiting active material content in the final electrodes.In a recent development, Navitas and its internal partners of Cabot, Arkema, the University of Tennessee, Knoxville, and Oak Ridge National Laboratory have shown the capability to produce both solvent-free anodes and cathodes utilizing an advanced dry-electrode process (ADEP) that also enables high-throughput production of next generation battery electrodes. These electrodes have improved mechanical strength, sufficient to withstand roll-to-roll manufacturing, and the anodes demonstrate an initial capacity loss of less than 15%. The group has demonstrated roll-to-roll production of solvent-free electrodes at quasi-industry standard active material compositions (90-92%) without the reliance of previously used fibrillization promoters, even at reduced PTFE concentrations in the formulation. Navitas has recently demonstrated the large format lamination of the initially formed, or “free-standing,” electrodes after they have been produced in roll-to-roll manufacturing and the integration of solvent-free electrodes in dual-layer and multi-layer pouch cells using typical industry tooling and cell production techniques.Key words: solvent-free, dry-process, fibrillization, next generation lithium-ion batteries (NGLB), advanced dry-electrode process (ADEP), initial capacity loss, free-standing, roll-to-roll, pouch cell

Evaluation of Porous Lithium Lanthanum Zirconium Oxide (LLZO) Anode Host Structures for Li-Metal Batteries

Lithium metal batteries are considered to be a leading candidate for next generation batteries due to their higher energy density and potential for safer operation when combined with solid-state electrolyte materials. However, they are still facing different challenges. A key challenge of lithium metal batteries is the volume expansion over cycling due to the non-uniform deposition of lithium on the anode leading to lithium dendrite formation compromising the battery safety, and poor lifetime. Herein, we report the use of porous Lithium Lanthanum Zirconium Oxide (LLZO) anode structures, in which lithium from the cathode is deposited into the pores during initial charging. The goal of this study is to study postmortem the lithium deposition in the porous host after different cycling conditions to measure the 7Li and 6Li isotopes depth profile by nuclear reaction analysis (NRA), namely, Proton Induced γ-Ray Emission (PIGE) and by Deuteron Induced Particle Emission (DIPE), respectively. The advantages of using NRA are that it gives an absolute measurement of Lithium without sample reliant calibration, it is a nondestructive technique, highly selective for specific light nuclides such as Lithium, and it is not affected by coordination effect.We demonstrate two different fabrication methods of porous LLZO structures, namely, electrospinning and electrospraying. Then, the fabricated LLZO structures are tested electrochemically using a half cell configuration to examine plating/stripping behavior as a function of current density and to track the overpotential evolution over cycling. Finally, the cycled anodes are investigated using NRA in particular Li concentration inside porous anode, at separator/anode interface and anode/current collector interface. Characterizing the concentration gradient of Li species within the porous and at the various interfaces can help define the current density limitations of solid-state Li metal batteries and identify Li loss failure modes so that cell lifetime can be improved.

More Reversible Anionic Redox Chemistry for Sodium Storage Triggered By Transition Metal Regulation

As one of the next generation battery system, sodium-ion batteries (SIBs) have been attached great interest for its abundant resources, low cost and good safety. Recently, high energy density cathode materials with anionic redox chemistry in SIBs have become the mainstream. The working potential of oxygen redox in layered transition metal oxide cathodes is about 4.2 V (vs. Na+/Na), which can not only elevate the battery potential but also harvest extra capacity. Thus, reasonably utilizing the oxygen redox can drastically increase the energy density of the batteries. However, the undesired phase transition and structural distortion resulted from oxygen redox usually lead to severe voltage hysteresis and capacity decay of the cathodes. Therefore, it is of great significance to investigate the relationship between the transition metal components and cycling stability of the cathodes, which provides valuable understanding for discovering novel cathodes with more reversible and higher capacity. To improve the structure stability and promote more anionic redox, we have been focusing on tuning the structure of P2-layered cathode materials with the different transition metal ligands such as Al/Ti/Zn-Mn. We have performed in-situ XRD and ex-situ XAS characterizations to investigate the charge compensation mechanism of the cathodes. The O K-edge XAS results indicated O e g orbits variation at fully charged state and provided solid evidence of oxygen redox chemistry. Moreover, we combined EXAFS results and DFT calculations to construct the model of local structure distortion. These results provide further understanding of the oxygen redox chemistry mechanism and promote the development of high energy density SIBs. Acknowledgement The work was supported by the National Natural Science Foundation of China (No. 52071085).

Assessing Mediated Redox Flow Battery Reaction Progression

One potential next generation battery system is mediated redox flow batteries (RFBs). With mediated RFBs, soluble electroactive species (redox shuttles) deliver power via electrochemical reactions in a flow-through stack reactor much like a conventional RFB. However, the redox shuttles then undergo chemical redox in a coupled chemical reactor system with solid electroactive materials. The use of solid electroactive material for chemical energy storage results in substantial increases in volumetric energy density for the system.Mediated RFBs with different configurations for the chemical redox reactor have previously been reported. In this work, a packed bed reactor system will be described, where the impact of varying different experimental parameters on the chemical redox progression will be highlighted. Generally, the progression of the chemical redox can be tracked in the lab by taking advantage of electrochemical analytical techniques. However, additional assessment of the reaction progression using neutron imaging will also be discussed. Neutron imaging offered a unique opportunity to access the spatial progression of the chemical redox in the packed bed reactor. The combination of techniques for assessing the chemical redox progression provides insights into the limiting processes in the reactor systems.

Metal Sulfide Artificial Solid-Electrolyte Interface for Improved Lithium Anode Stability

In the last decade, lithium metal has burgeoned into a potential anode material from Li-ion battery to next generation battery systems because of the low redox potential (-3.040 V vs SHE.) and high gravimetric energy density [1-3]. Unlike conventional batteries, the major challenges to be addressed in lithium metal anodes are the dendritic growth, continuous lithium depletion, rapid capacity loss and low Columbic efficiency [4]. These challenges can be averted using electrolyte additives or creating artificial solid electrolyte (SEI) interphases [5]. In the present work, nanostructured transition metal sulfide (MS) and lithium transition metal sulfide (LMS) are used as artificial SEI on lithium metal anode by modifying the lithium metal/electrolyte interfaces and homogenous lithium deposition.The nanostructured transition metal sulfide and lithium transition metal sulfide were synthesized by a simple wet chemical route at relatively low temperatures (150-200 °C). The synthesized LMS were typically of high purity and were filtered, washed, ball-milled, and calcined prior to use in the battery. The microstructure, structure and chemical analysis of the synthesized metal sulfide was characterized by scanning electron microscope (SEM), X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDS) and X-ray photoelectron spectroscopy (XPS). Figure 1(a) shows the morphology of the ball-milled LMS as a layered structure with varying sizes of 10 µm to 100 nm. The EDS analysis of the ball-milled powder majorly showed an M/S ratio of 1:1 and 1:2.The LSM was deposited on Li metal substrate by sputtering technique from a LSM target in Ar atmosphere. This film deposition was carried out at different sputtering time (10 sec -100 sec) and processing pressures. Homogeneous deposition of this LSM of few tens of nanometers thickness was successfully achieved. The electrochemical performance of the LSM artificial SEI was investigated in symmetric cells of two coated Li electrodes and compared to bare Li (Figure 1(b)). At different current densities of 0.5 and 1 mA/cm2, repeated Li plating and stripping revealed an enhanced cycling performance of metal sulfide coated Li compared to bare Li electrode. To better understand the interfacial stability, electrochemical impedance spectroscopy (EIS) studies were performed at different stages of cycling. The cycling performance of coated and bare Li anode was performed in a full cell containing NMC811 as cathode. After cycling, the microstructural changes in lithium metal anode were explored using SEM. Figure 1: (a) SEM image of the ball-milled layered lithium metal sulfide and (b) Time-voltage profiles of the symmetric cells with Li anode and coated Li anode at the current density of 0.5 mA/cm2 References [1] D. Lin, Y. Liu, Y.Cui, “Reviving the Lithium Metal Anode for High-Energy Batteries”, Nature Nanotechnology, 12 (2017), 194-206.[2] D. Aurbach, B.D. McCloskey, L.F. Nazar, P.G. Bruce, “Advances in Understanding the Mechanisms Underpinning Lithium-air Batteries”, Nature Energy, 1 (2016) 16128.[3] W. Xu, J. Wang, F. Ding, X.Chen, E. Nasybulin, Y. Zhang, J.G. Zhang, “Lithium metal Anodes for Rechargeable Batteries”, Energy and Environmental Science, 7 (2014) 513-537.[4]J. Liu, Z. Bao, Y. Cui, E.J. Dufek, J.B. Goodenough, P. Khalifah, Q. Li, B.Y. Liaw, P. Liu, A. Manthiram, Y.S. Meng, V.R. Subramanian, M.F. Toney, V.V. Viswanathan, M.S. Whittingham, J. Xia, W. Xu, J. Yang, X.Q. Yang, J.G. Zhang, "Pathways for Practical High-Energy Long Cycling Lithium Metal Batteries", Nature Energy, 4 (2019) 180-186.[5] K Kim, M. Balaish, M. Wadaguchi, L. Kong, J. Rupp, “Solid State Batteries: Solid-State Li-metal Batteries: Challenges and Horizons of Oxide and Sulfide Solid Electrolytes and their Interfaces”, Advanced Energy Materials, 11 (2021) 2170002 Figure 1

Solid-State Electrolyte Fracture in Lithium Metal Batteries

Next generation batteries utilizing solid-state electrolytes to enable use of lithium metal electrodes are of significant interest due to increased energy density and the potential safety enhancements. Despite their high yield strength, high room temperature ionic conductivity, and lack of reactivity with metallic lithium, these ceramic solid electrolytes are still prone to dendrite formation and subsequent cell failure above critical current densities. One experimentally observed dendrite formation and propagation mechanism requires mechanical failure of the electrolyte via fracture. Ceramic solid electrolyte’s do not undergo ductile deformation, leaving fracture as the primary means of stress relaxation. The electrolyte’s propensity to fracture is dependent on its material properties (i.e. fracture toughness), electrode mechanical properties, and the cell operating conditions (e.g. applied current density, stack pressure, temperature). This talk will focus on electrochemical-mechanical coupling (including thermodynamic and kinetic couplings of mechanical forces with electrochemical behavior) and the relationship between the current distribution, developed stresses, and solid-electrolyte fracture initiation at Li protrusions. The effect of current focusing on stress-driven fracture, plastic deformation of lithium, and the influence of mechanical boundary conditions will be described.

Decoding the Ceramics Influence in the Composite Electrolytes

As Lithium-Ion Batteries (LIBs) becomes an essential part of the everyday life, fireproof electrolytes have become an important component of the next generation battery design without compromising the performance of the battery. Composite electrolytes (CEs), consist of polymer electrolytes with highly conducting ceramic particles are promising candidates to substitute currently commercialized LIBs with liquid electrolytes. So far, experiments with CEs have discovered positive and negative effect on the overall conductivity of the CEs in the presence of ceramic particles.1–4 Therefore, exists the conflict weather the CEs are the solution to overcome the disadvantages of all-liquid and all-solid electrolytes.In this work, a 2-Dimensional CE with a uniform ceramic particle size distribution is studied via continuum modeling. we analyze the effect of interface between polymer and ceramic particle on the overall conductivity and transference number of the CEs to guide experimentalist to fabricate these interfaces carefully. It is concluded that the interplay between ohmic resistance and polymer conductivity at the polymer and ceramic particle interfaces can explain the conflicts observed in the literature. The Ohmic resistance at the interface is a critical parameter that determines whether ceramic particles enhance the overall conductivity or not. Finally, CEs does meet the criteria of the conductivity and transference number requirement in order to use in the EVs.5

Smart Battery Technology for Lifetime Improvement

Applications of lithium-ion batteries are widespread, ranging from electric vehicles to energy storage systems. In spite of nearly meeting the target in terms of energy density and cost, enhanced safety, lifetime, and second-life applications, there remain challenges. As a result of the difference between the electric characteristics of the cells, the degradation process is accelerated for battery packs containing many cells. The development of new generation battery solutions for transportation and grid storage with improved performance is the goal of this paper, which introduces the novel concept of Smart Battery that brings together batteries with advanced power electronics and artificial intelligence (AI). The key feature is a bypass device attached to each cell that can insert relaxation time to individual cell operation with minimal effect on the load. An advanced AI-based performance optimizer is trained to recognize early signs of accelerated degradation modes and to decide upon the optimal insertion of relaxation time. The resulting pulsed current operation has been proven to extend lifetime by up to 80% in laboratory aging conditions. The Smart Battery unique architecture uses a digital twin to accelerate the training of performance optimizers and predict failures. The Smart Battery technology is a new technology currently at the proof-of-concept stage.

Microstructure and discharge performance of Mg-La alloys as the anodes for primary magnesium-air batteries

Magnesium alloys are promising anode candidates for energy storage and conversion devices, which give rise to Mg-air batteries as the main development direction of next generation batteries. However, its commercial application still faces giant challenge. In this study, four types of Mg-xLa (La addition of 1, 3, 5, and 10 wt%) alloys with relatively high La content are prepared as anode materials for Mg-air batteries. The influence of La content on the microstructure and electrochemical performance are systematically investigated. All results indicate that adding 5 wt% La to Mg significantly improves the corrosion resistance and discharge activity, whilst excessive addition would accelerate self-corrosion rate due to the formation of large-area LaMg12 phase. The Mg-5La anode exhibits relatively high discharge platform and stable discharge process, and the specific discharge capacity is 1259.45 mAh g−1 with the anodic efficiency of 57.67% at 20 mA cm−2. This boost can be explained by the ameliorative microstructure in Mg-5La anode, which reduces the extended self-corrosion of α-Mg phase and accelerates the spalling of corrosion products. This work might provide some basic meaningful data for designing the advanced anode materials for Mg-air batteries.

Influence of Growth Parameters on the Electrochemical Performance of Electrodeposited Carbons

Generating useful chemicals from CO2 is driving research into carbon capture and utilization. In this work, hard carbons are electrodeposited on various substrates from molten carbonate melts in CO2 atmospheres. These electrodeposited carbons are subsequently used as anodes in sodium-ion batteries, with preliminary investigations into their performance in potassium-ion batteries. The hard carbons were characterized using X-ray diffraction (XRD) and Raman spectroscopy. Hard carbons grown on graphite substrates produced initial reversible capacities of 405 ± 29 mAh/g and capacity retention of 85.2 ± 1.1% after 50 cycles when cycled at 10 mA/g which are amongst the highest capacities reported for hard carbons to date. This work clearly illustrates that the carbons generated via CO2 mediated electrodeposition are suitable for application in next generation batteries.