Rechargeable Lithium Batteries Research Articles

Operando monitoring of thermal runaway in commercial lithium-ion cells via advanced lab-on-fiber technologies

Operando monitoring of complex physical and chemical activities inside rechargeable lithium-ion batteries during thermal runaway is critical to understanding thermal runaway mechanisms and giving early warning of safety-related failure. However, most existing sensors cannot survive during such extremely hazardous thermal runaway processes (temperature up to 500 °C accompanied by fire and explosion). To address this, we develop a compact and multifunctional optical fiber sensor (12 mm in length and 125 µm in diameter) capable of insertion into commercial 18650 cells to continuously monitor internal temperature and pressure effects during cell thermal runaway. We observe a stable and reproducible correlation between the cell thermal runaway and the optical response. The sensor’s signal shows two internal pressure peaks corresponding to safety venting and initiation of thermal runaway. Further analysis reveals that a scalable solution for predicting imminent thermal runaway is the detection of the abrupt turning range of the differential curves of cell temperature and pressure, which corresponds to an internal transformation between the cell reversible and irreversible reactions. By raising an alert even before safety venting, this new operando measurement tool can provide crucial capabilities in cell safety assessment and warning of thermal runaway.

Fabricating Lithium Metal Foils with Desired Morphology

Rechargeable lithium batteries (RLB) are the hope for the next generation energy storage and power source systems due to the promise to achieve the highest specific energy. Reliable performance of RLB, particularly with long lifespan, requires high quality lithium metal anode that can withstand repetitive stripping and deposition during cycle aging. Fabricating lithium metal of desired thickness is thus critical to enable and achieve high specific energy design. Morphology of lithium metal foil with densely packed large grains is desired. To consistently reach the desired morphology in practice is however difficult. Such a difficulty challenges us from the lack of proper understanding of lithium deposition at the fundamental level. Recent understanding on lithium nucleation and growth gave us a new perspective to formulate and achieve proper morphological control, which might lead to a new pathway for desired lithium metal foil fabrication technique.

Real-Time Detection and Speciation of Mn Dissolution in a Li-Ion Battery Cathode

Rechargeable lithium-ion batteries (LIB) are widely used in portable electronic devices, electric vehicles, medical devices, etc. thanks to their improved performance in recent decades. The properties of the cathode still largely limit the overall performance, as the cathode usually has lower theoretical capacity and suffers from more serious degradation effects.1 Among these, dissolution of transition metals is an important but poorly understood side reaction. On the one hand, it dominates the cathode capacity fading by causing irreversible loss of active redox sites, phase transformation, cation mixing, grain fracture, etc. On the other hand, the dissolved transition metal ions can exacerbate the formation of the solid electrolyte interphase (SEI) on the anode through a dissolution-migration-deposition (DMD) process.2 Here, we focus on the dissolution of manganese from LiMn2O4 (LMO), a benchmark cathode material, through real-time analysis of the electrolyte by combining online inductively coupled plasma–optical emission spectroscopy (online ICP-OES) and rotating ring-disc electrode (RRDE) collection, Figure 1. Both methods offer real-time dissolution information as functions of time and potential/state of charge, while the former shows superior detection limits and the latter provides oxidation state information of the dissolving species.According to online ICP-OES, we find that Mn dissolves readily from fully lithiated LMO when brought in contact with aqueous 0.2 M Li2SO4, but that a dissolution-passivation process stops further detectable dissolution until well past fully delithiated λ-MnO2. The dissolution becomes detectable again on the returning scan to the potential of pristine LMO, and grows exponentially in the overlithiated region.3 Our RRDE results indicate that Mn2+ is the dominating dissolved Mn species only in overlithiation region, whereas it only accounts for a minor proportion in the dissolved species from delithiation region. The data from both techniques suggest that the dissolution of Mn is related to the surface state of the electrode, rather than its degree of lithiation, as widely believed in the past.4 Our results provide a better understanding of the mechanism of transition metal dissolution in cathode materials, as well as an entry point for screening next-generation cathodes and metal ion batteries with superior degradation characteristics.5

Lithium-Ion Battery Cathode-Electrolyte Interface

The global energy crisis, consumption of fossil fuels, and the associated environmental issues have stimulated extensive interest in searching for sustainable energy storage and conversion systems. Rechargeable lithium-ion batteries (LIBs) are widely used in mobile devices, hybrid, and electric vehicles. Electrode-electrolyte interface has a strong impact on battery capacity decrease and long-term cycling stability. In order to improve fundamental understanding of the involved phenomena to accelerate the rational design of cathode materials and stable interface, Li(Ni,Co,Mn)O2 (NCM) is a cathode material for rechargeable LIB and also a promising electrocatalyst for oxygen evolution reaction (OER). Their battery performance and catalytic activity are highly correlated to their structures. Multiple processes occurring at the cathode/electrolyte interface led to overall performance degradation. One failure mechanism is the dissolution of transition metals from the cathode. Our efforts employ thin film as a model cathode to monitor the Mn dissolution. Using LiMn2O4 and NCM as cathode materials, we will focus on electrochemical characterization, cation mixing, oxygen evolution, and thin film deposition with controlled crystal structures and composition. We will further introduce our work employing the scanning electrochemical microscope to study LIBs degradation and cathode-electrolyte interface in situ and in real-time.

Composite Solid Electrolyte Composed of 3D Ceramic Ion Transport Channel and in-Situ Formed Polymer Matrix

Rechargeable lithium-ion batteries (LIBs) with high energy density and excellent cycling performance have been widely used as portable power supplies for consumer electronics. In recent years, LIBs have expanded their applications to electric vehicles (EVs) and large energy storage systems (ESSs). Existing LIBs use liquid electrolytes, which have safety issues such as inflammability, leakage, and explosion. All-solid-state lithium-ion batteries (ASSLIBs) using various solid electrolytes, such as inorganic electrolytes and polymer electrolytes, have been extensively studied to alleviate safety issues and improve energy density. In addition, composite solid electrolytes (CSEs), which combine the advantages of ceramic and polymer electrolytes, are of particular interest. However, CSE based on a polymer matrix has low ionic conductivity at room temperature, making it difficult to use as an electrolyte for high-performance ASSLIB. In this study, we designed a highly efficient 3D LAGP framework for lithium ion transport that enhances the overall conductivity of CSE. This stiffer 3D LAGP structure also inhibits the growth of Li dendrites. The polymer component of CSE is manufactured using thermal polymerization of vinyl ethylene carbonate (VEC). In addition, excellent electrode-electrolyte interface properties were achieved using in-situ thermal polymerization technology. The optimized CSE exhibited high ionic conductivity of 0.79 mS cm-1 and excellent potential stability up to 5.09 V vs. Li/Li+ at 30 °C. The Li/CSE/NCM811 cells showed excellent rate performance and cycling potential. Therefore, a CSE composed of a 3D LAGP framework and a VEC-based polymer can be used as a potential electrolyte for ASSLIBs.

Uncovering Electrochemical Cation-Storage Mechanisms in Defective Vanadium Ferrites Using Synchrotron-Quality, in-Lab X-Ray Absorption Spectroscopy

X-ray absorption spectroscopy (XAS) is a critical tool for investigating new materials for electrochemical energy storage, providing important information on metal oxidation state and element-specific coordination. Historically, XAS measurements had required the energy specificity and brilliance of a synchrotron facility, but recent advances in detectors and optics are bringing XAS capabilities to the laboratory setting with multiple commercial instruments available. At the Naval Research Laboratory, we use laboratory-based XAS to study a class of disordered vanadium ferrite (VFe2Ox) aerogels that exhibit promising performance for electrochemical energy-storage applications such as rechargeable lithium-ion batteries.1,2 The structure and composition of these materials are readily varied via modifications to the epoxide-promoted sol–gel reaction of iron chloride and vanadium isopropoxide (e.g., substitution with other cations such as Al3+),2 as well as post-synthesis thermal treatments that render disordered, defective, or nanocrystalline forms of a given composition. The resulting series of VFe2Ox materials are evaluated by XAS in both ex situ and in situ configurations, including as powder-composite cathodes versus lithium metal in pouch cells with conventional nonaqueous lithium-ion electrolyte. X-ray Absorption Near-edge Spectroscopy (XANES) at the V K-edge and Fe K-edge is used to track V and Fe oxidation state, respectively, permitting the assignment of metal-centered redox across the broad potential range over which these materials are electrochemically active (2–3.4 V vs Li/Li+). Extended X-ray Absorption Fine Structure (EXAFS) analysis provides information on V- or Fe-specific coordination as a function of composition, structure, and state-of-charge. Parallel computation efforts using Density-Functional Theory offer a complementary feedback loop with experimental XANES and EXAFS to achieve a sophisticated description of these complex battery materials.1. C. N. Chervin, J. S. Ko, B. W. Miller, L. Dudek, A. N. Mansour, M. D. Donakowski, T.Brintlinger, P. Gogotsi, S. Chattopadhyay, T. Shibata, J. F. Parker, B. P. Hahn, D. R.Rolison, and J. W. Long, J. Mater. Chem. A 3, 12059 (2015).2. C. N. Chervin, R. H. DeBlock, J. F. Parker, B. M. Hudak, N. L. Skeele, J. S. Ko, D. R.Rolison, and J. W. Long, RSC Adv. 11, 14495 (2021).

Towards Safer All-Solid-State Lithium Metal Batteries by an Artificial Protection Layers

Lithium ion batteries (LIB) are representing a milestone in electrochemical energy storage and are still the state-of-the-art battery system for various mobile and stationary energy storage applications. However, the practical energy density of LIBs starts to reach an asymptotic limit. Beside LIBs, an auspicious variety of battery systems comprising a better option for specific applications in terms of e.g. energy density, so establishing a diversity of specific battery systems for specific applications is a good strategy.[1 ] After initially paving the way for the LIB, the lithium metal battery (LMB) experiences a revival due to an outstanding theoretical specific capacity (3 860 mAh g−1) and low electrochemical potential (−3.04 V vs. SHE). However, continuous electrolyte consumption, the formation of an inhomogeneous SEI and high surface area lithium (HSAL), whose growth is induced by the heterogeneous and fragile structure of the SEI film, are still dominant challenges that need to be overcome. The liquid electrolytes also deal with safety issues like risk of leakage and flammability. The combination of Li metal with solid polymer electrolytes (SPE) could supress HSAL formation and avoid those safety hazards. However, SPEs deal with poor ionic conductivity at room temperature (10−8 S cm−1 ≤ σ ≤ 10−5 S cm−1) and, additionally, it is necessary to control the Li morphology during electrodeposition/dissolution to realize high-energy all-solid-state batteries (ASSB) based on Li metal anodes.[2 ,3 ] Several artificial protective coatings have been proposed to improve the LMA/SPE interface by facilitating the Li ion flux, promoting a homogeneous Li electrodeposition/dissolution and protecting the LMA against electrolyte degradation as well as enhancing the Li wetting interface. The SPE induces a more flexible interphase that withstands the volume change. Recently, metal oxides coated by atomic layer deposition (ALD) have gained attention due to a great thickness control, the possibility of monolayer deposition as well as a consequential homogeneity of the deposited protection layer. Furthermore, ALD is suitable for roll-to-roll coatings which is feasible for industrial application.[3,4 ] Herein, the setup of Li-metal-polymer batteries (LMP® technology) commercialized by Blue Solutions and applied in their “blue cars” (30 kWh, 100 Wh kg-1) was modified in several points. Li metal was coated with a metal oxide via atomic layer deposition (ALD) to form an intermetallic phase as protective layer and to improve the Li+ flux. The artificial protective coating at Li metal was combined with a PEO- and/or polyether-based SPE and the effect of the modifications on the electrochemical performance in different ASSB setups was investigated and characterized.[1] Placke, T.; Kloepsch, R.; Dühnen, S.; Winter, M. Lithium ion, lithium metal, and alternative rechargeable battery technologies: the odyssey for high energy density. Journal of Solid State Electrochemistry 2017, 21, 1939-1964.[2] Cheng, X.-B.; Zhang, R.; Zhao, C.-Z.; Zhang, Q. Toward Safe Lithium Metal Anode in Rechargeable Batteries: A Review. Chemical Reviews 2017, 117, 10403-10473.[3] Han, Z.; Zhang, C.; Lin, Q.; Zhang, Y.; Deng, Y.; Han, J.; Wu, D.; Kang, F.; Yang, Q. H.; Lv, W. A Protective Layer for Lithium Metal Anode: Why and How. Small Methods 2021, 5, 2001035.[4] Han, Y.; Liu, B.; Xiao, Z.; Zhang, W.; Wang, X.; Pan, G.; Xia, Y.; Xia, X.; Tu, J. Interface issues of lithium metal anode for high‐energy batteries: Challenges, strategies, and perspectives. InfoMat 2021, 3, 155-174.

Dendrite Growth Suppression and in-Situ Surface Observation of Lithium Battery Under an Optical Microscope

Dendrite growth is a major obstacle to the commercialization of lithium metal batteries. A dendrite formed on a Li anode can cause thermal run-aways and permanent capacity loss. Despite previous research efforts, the behavior of lithium dendrite growth is elusive since it is related to multiple factors. An in-situ optical techniques is considered as one of the major methods to study the dendrites growth behaviors and morphologies real-time.A better knowledge of the physico-chemical processes and the side reactions during a battery operation can be gained.A home-designed in-situ optical cell with a digital optical microscope was used to investigate the behavior of Li deposition on a metallic Li electrode under different electrochemical operation conditions. The impacts of electrolytes, additives and cycling conditions on the dendrite formation were investigated. The changes of the morphology and the shape of the dendrites were investigated correspondingly. Guiding by the in-situ optical observation results, polycyclic aromatic hydrocarbons (PAHs) were introduced as additives to suppress the dendrite growth. It was observed in an in-situ optical experiment, that the freshly formed dendrites can be dissolved and dispersed throughout the surface, eventually a dynamic elastic protection layer was formed. With the liquid electrolyte trapped in the protection layer, the thickness of the layer could be self-adjusted to compensate for the volume change of the Li anode during the battery cycling. Among the eight additives added to the electrolyte, several PAH additives have significant effect on suppressing dendrite growth and greatly enhance the cyclability of the Lithium electrode in a symmetry Li/Li cell. Tarascon, J.-M., & Armand, M. (2001). Issues and challenges facing rechargeable lithium batteries. Nature, 414(6861), 359–367.Tripathi, A. M., Su, W.-N., & Hwang, B. J. (2018). In situ analytical techniques for battery interface analysis. Chemical Society Reviews, 47(3), 736–851. Figure 1

CuS as Unique Cathode Material for Li Solid-State Batteries: Properties, Reaction Mechanism and Tomography

Copper sulfide (CuS) is a naturally occurring mineral that reacts with lithium via a conversion reaction to form Li2S and Cu. The theoretical energy density of the reaction is 961 Wh/kg, the theoretical cell voltage is 1.96 V. Among all the conversion reactions, copper sulfide shows a unique behavior as large, µm-sized copper crystallites are formed during discharge. Some years ago, it was shown that the reaction can proceed reversibly in suitable electrolytes.[1] This presentation will discuss the behavior of copper sulfide as a cathode material in solid state batteries. In this context, the low cell voltage allows the use of Li3PS4 as a solid electrolyte, which is a major advantage. Despite the large volume expansion (+74%), the material can be cycled in solid state batteries at high contents (70 wt%), again forming large copper crystallites.[2] The size of the crystallites allows the reaction to be studied by 3D X-ray tomography.[3] In addition to phase transformations, crack formation can also be observed. The latter is strongly pressure dependent and can be minimized by increasing the pressure.[1] Birte Jache, Boris Mogwitz, Franziska Klein, Philipp Adelhelm (2014) Copper sulfides for rechargeable lithium batteries: Linking cycling stability to electrolyte composition Journal of Power Sources 247: 703-711.[2] Aggunda L Santhosha, N Nazer, Raimund Koerver, Simon Randau, Felix H Richter, Dominik A Weber, Joern Kulisch, Torben Adermann, Jürgen Janek, Philipp Adelhelm (2020) Macroscopic displacement reaction of copper sulfide in lithium solid-state batteries Advanced Energy Materials 2002394: .[3] Zhenggang Zhang, Kang Dong, Katherine A Mazzio, André Hilger, Henning Markötter, Fabian Wilde, Tobias Heinemann, Ingo Manke, Philipp Adelhelm (2022) Phase Transformation and Microstructural Evolution of CuS Electrodes in Solid-State Batteries Probed by in-situ 3D X-ray Tomography Advanced Energy Materials 2203143. Figure 1

Using Pectin for Energy Storage Devices

Wearable and flexible printed electronics are more than ever in demand. The value of the flexible electronics market reached USD 26.5 million in 2021 and its revenue forecast will reach USD 63.1 million in 2030.[1] Increasing investments in research & development in these fields have already led to several achievements in the past years. Nevertheless, serious remains concerns about the ecological footprint of such technologies must be addressed early in their conception and throughout the whole electronics life cycle.[2]In printed electronics, electrical energy is supplied by energy storage devices, such as batteries. Most of the time, these systems contain polymers that can be used either as electrolyte, e.g., solid polymer electrolyte or gel polymer electrolyte, to facilitate flexible electronics/batteries fabrication or as binders in positive or negative electrodes ensuring the mechanical cohesion within the composite electrodes.[4]. Several characteristics to meet environmental-friendly flexible electronics requirements. Biobased polymers are one of the promising alternatives in this regard. Their general affinity with water makes them suitable for aqueous rechargeable batteries, implying several technologies such as aqueous rechargeable lithium-ion batteries (ARLB) or zinc rechargeable batteries (ZRB). For instance, polymer hydrogel electrolytes have recently been investigated [3]: their strength lies in promising ionic conductivity (> 10-2 S.cm-1) while maintaining a sufficient mechanical strength and elasticity to be adaptable to flexible energy storage devices.In this study, we developed a hydrogel electrolyte made of pectin, a polysaccharide contained in the cell plants’ wall, as an alternative to synthetic polymers in batteries. Hydrophobic interactions and hydrogen bonds, together with bivalent cation interactions, allow the free-standing electrolyte gelation.[5] The gelation mechanism is first studied, using NMR spectroscopy together with thermal analysis. Then, electrochemical characterization is carried out to analyze the ionic conduction pathways of the gel electrolyte. Its electrochemical stability as well as galvanostatic cycling are investigated to figure out its ability to be used as a electrolyte in hybrid device, such as zinc-lithium-ion batteries.Moving toward printed devices requires to take a closer look to the rheological properties of this system as well as its printability: these challenges will be addressed to ultimately develop an understanding of the impact of this material’s processing on the electrolyte and electrodes properties.[6] References [1]. Flexible Electronics Market Size to Hit US$ 63.1 MN by 2030. (May 2022). Acumen Research and Consulting, https://www.acumenresearchandconsulting.com/.[2]. Baran, D.; Corzo, D.; Blazquez, G. Flexible Electronics: Status, Challenges and Opportunities. Frontiers in Electronics 2020, 1, 2673-5857. DOI: 10.3389/felec.2020.594003.[3]. Liu, J.; Yuan, H.; Tao, X.; et al. Recent progress on biomass-derived ecomaterials toward advanced rechargeable lithium batteries. EcoMat 2020, 2 (1), e12019. DOI: 10.1002/eom2.12019.[4]. Bresser, D.; Buchholz, D.; Moretti, A.; Varzi, A.; Passerini, S. Alternative binders for sustainable electrochemical energy storage – the transition to aqueous electrode processing and bio-derived polymers. Energy Environm Sci 2018, 11, 3096-3127. DOI: 10.1039/C8EE00640G.[5]. Chelfouh, N.; Coquil, G.; Rousselot, S.; Foran, G.; Briqueleur, E.; Shoghi, F.; Caradant, L.; Dollé, M. Apple Pectin-Based Hydrogel Electrolyte for Energy Storage Applications. ACS Sustainable Chemistry & Engineering 2022 , Article ASAP . DOI: 10.1021/acssuschemeng.2c04600.[6]. Clement, B.; Lyu, M.; Kulkarni, S. E.; Lin, T.; Hu, Y.; Lockett, V.; Greig, C.; Wang, L. Recent Advances in Printed Thin-Film Batteries. Engineering 2022, 13, 238-261. DOI: 10.1016/j.eng.2022.04.002.

In-Situ Investigation of the Cathode Electrolyte Interphase Formation, Kinetics, and Composition

Solid electrolyte interphase studies are the next avenue for improving the performance of rechargeable lithium-ion batteries. The cathode electrolyte interphase (CEI) plays a critical role in stabilizing lithium composite cathodes which are known to suffer parasitic side reactions that lead to rapid capacity fade, cathode degradation, and thermal runaway. However, the CEI is under-reported compared to the solid electrolyte interphase on the anode because of its complex surface chemistry, nanoscale structure, and the high potential that next-generation cathodes undergo during cycling. There is ambiguity in the relationship between cathode properties and the formation, kinetics, and performance of CEI, which, if resolved, could lead to a further understanding of the conditions that produce a stable CEI and provide guidance for engineering more effective CEI. In this work, lithium manganese oxides were used as a case study to investigate the CEI’s in-situ behavior in terms of formation, kinetics, and composition.

(Invited) High-Performance Lithium Metal Batteries

The success of rechargeable lithium-ion batteries (LIBs) has brought evident convenience to human society, but state-of-the-art LIBs with a carbon anode are approaching their energy density limits. Li metal is considered the ultimate anode material due to its ultra-high theoretical specific capacity of 3860 mAh g-1, which is more than 10 times higher than lithiated graphite. Nonetheless, Li anode suffers from poor safety and low cycling efficiency due to its high reactivity. Electrolytes that work with Li anode should possess excellent stability against Li metal or form a highly passivating interface. It is also critical to control the amount of Li in the cell, preferably having no excess Li at the anode side.1 In this presentation, next-generation electrolytes that enable such types of high-performance Li metal batteries will be discussed, including advanced liquid electrolytes,2 garnet-type ceramic electrolytes3–5 and hybrid electrolytes.6,7 References C. Zhou, A. J. Samson, M. A. Garakani, and V. Thangadurai, J. Electrochem. Soc., 168, 060532 (2021).C. Zhou et al., Energy Storage Mater., 42, 295–306 (2021) https://doi.org/10.1016/j.ensm.2021.07.043.S. P. Kammampata, R. H. Basappa, T. Ito, H. Yamada, and V. Thangadurai, ACS Appl. Energy Mater., 2, 1765–1773 (2019).S. P. Kammampata, H. Yamada, T. Ito, R. Paul, and V. Thangadurai, J. Mater. Chem. A, 8, 2581–2590 (2020).C. Zhou, A. J. Samson, K. Hofstetter, and V. Thangadurai, Sustain. Energy Fuels, 2, 2165–2170 (2018).S. Bag, C. Zhou, P. J. Kim, V. G. Pol, and V. Thangadurai, Energy Storage Mater., 24, 198–207 (2019) https://doi.org/10.1016/j.ensm.2019.08.019.C. Zhou, S. Bag, T. He, B. Lv, and V. Thangadurai, Appl. Mater. Today, 19, 100585 (2020) https://doi.org/10.1016/j.apmt.2020.100585.

Tracing the Powerfade: Location and Quantification of the Fluoridic Solid Electrolyte Interphase on Graphite Anodes

Due to the conversion of the global energy supply from carbon emitting to renewable sources, there is the need for energy storage systems being efficient at high energy- and power densities. Many requirements are fulfilled best by Lithium-Ion Batteries (LIBs), so this technology is successfully part of battery-electric vehicles, cordless power tools and portable electronic devices. The ongoing improvement of anode- and cathode materials, together with adapted electrolytes [1] led to excellent advances in power- and energy densities. However, the increasing amount of total energy per cell underlines the importance of monitoring the cell’s health parameters (e.g. capacity fades, coulombic efficiencies, AC-and DC-impedances) in order to ensure safety and expand the lifetime [2, 3]. The Solid Electrolyte Interphase (SEI) represents a main source for cell impedances [4] and was in the case of LiPF6-based electrolytes found to be best analytically accessible by the quantitative determination of its unsolvable, fluoridic fractions (LiF) using ion-exchange chromatography [5].During this work, long term cycling tests (T = 25, 40, 60 °C, 2 C charging) of industrial 3 Ah-21700-cells with graphite anode (figure a), NMC 811 cathode and LiPF6-based electrolyte were performed (figure b). Subsequently, after defined cycling steps (10, 250, 500, 750 cycles) the cells were opened, post-mortem analysis (SEM, EDX, “broad ion beam”- (BIB) preparation) together with the drawing of anode/separators samples for the later fluoride determination took place. The samples were cleaned from LiPF6 (washing with DEC) and dried under glovebox conditions (Ar, < 0.5 ppm H2O). With the aim to quantify the SEI layer 1) in the anode bulk and 2) adhering to or inside the separator to trace reversible Li-plating, anode/separators samples were eluted separately with deionized water and the fluoride-concentration of the solutions was determined by ion-exchange chromatography (figure c - f). SEI fractions, like inorganic carbonates, alkyl carbonates, oxides, etc., were investigated using X-ray photoelectron spectroscopy (XPS) along a depth profile (figure g) using Ar-ion sputtering [6, 7].The results elaborated within this study point out a strong correlation in between the amount of fluoridic SEI and the DC-impedance rise during cycling, especially at elevated temperatures (40, 60 °C). At 25 °C different ageing mechanisms are obvious: In comparison lower fluoride concentrations together with substantial DC impedance gains suggest the temporary and superficial occurrence of reversible Li-plating, blocking important Li-ion paths via the electrolyte (e.g. anode surface pores, separator pores [8, 9]) by residual products of their SEI-films. Reference s [1] Eshetu, G. G.; Zhang, H.; Judez, X.; Adenusi, H.; Armand, M.; Passerini, S.; Figgemeier, E., Production of high-energy Li-ion batteries comprising silicon-containing anodes and insertion-type cathodes. Nat Commun 2021, 12, (1), 5459.[2] Sternad, M.; Cifrain, M.; Watzenig, D.; Brasseur, G.; Winter, M., Condition monitoring of Lithium-Ion Batteries for electric and hybrid electric vehicles. e & i Elektrotechnik und Informationstechnik 2009, 126, (5), 186-193.[3] Furtmair, M.; Wolters, A.; Kühnel, F.; Thannhuber, M.; Sötz, V.; Sternad, M., The Impact of Fast-Charging on Cell Ageing of Industrial High-Power Lithium-Ion Batteries. In IMLB 2022, Sydney, Australia, 2022.[4] Aurbach, D.; Markovsky, B.; Rodkin, A.; Cojocaru, M.; Levi, E.; Kim, H.-J., An analysis of rechargeable lithium-ion batteries after prolonged cycling. Electrochimica Acta 2002, 47, (12), 1899-1911.[5] Uitz, M.; Sternad, M.; Breuer, S.; Täubert, C.; Traußnig, T.; Hennige, V.; Hanzu, I.; Wilkening, M., Aging of Tesla's 18650 Lithium-Ion Cells: Correlating Solid-Electrolyte-Interphase Evolution with Fading in Capacity and Power. Journal of The Electrochemical Society 2017, 164, (14), A3503-A3510.[6] Shutthanandan, V.; Nandasiri, M.; Zheng, J.; Engelhard, M. H.; Xu, W.; Thevuthasan, S.; Murugesan, V., Applications of XPS in the characterization of Battery materials. Journal of Electron Spectroscopy and Related Phenomena 2019, 231, 2-10.[7] Zhu, Y.; Pande, V.; Li, L.; Wen, B.; Pan, M. S.; Wang, D.; Ma, Z. F.; Viswanathan, V.; Chiang, Y. M., Design principles for self-forming interfaces enabling stable lithium-metal anodes. Proc Natl Acad Sci U S A 2020, 117, (44), 27195-27203.[8] Lagadec, M. F.; Ebner, M.; Zahn, R.; Wood, V., Communication—Technique for Visualization and Quantification of Lithium-Ion Battery Separator Microstructure. Journal of The Electrochemical Society 2016, 163, (6), A992-A994.[9] Zier, M.; Scheiba, F.; Oswald, S.; Thomas, J.; Goers, D.; Scherer, T.; Klose, M.; Ehrenberg, H.; Eckert, J., Lithium dendrite and solid electrolyte interphase investigation using OsO4. Journal of Power Sources 2014, 266, 198-207. Acknowledgment The authors wish to thank H. Schröttner (Institute of Electron Microscopy and Nanoanalysis, Graz University of Technology) for preferential access to preparation and examination equipment. Figure 1

Control of Nanoparticle Dispersion, SEI Composition, and Electrode Morphology Enable Long Cycle Life in High Silicon Content, Nanoparticle-Based Composite Anodes for Lithium-Ion Batteries

Striking a balance between high theoretical capacity, Earth abundance, and compatibility with existing manufacturing infrastructure, silicon is one of the few materials that meets the requirements for a next-generation anode for rechargeable lithium-ion batteries. Due to complications with extreme volume changes during charging/discharging and reactive interfacial chemistries, however, the cycle-life of silicon-based composite anodes is unacceptable for broad use. Developing a majority silicon composite anode formulation that overcomes these challenges and is compatible with current industry manufacturing practices requires materials and chemical engineering solutions that account for both electrode morphology and interfacial chemistry. Here, we synthesize surface-functionalized silicon nanocrystals that enable a highly dispersed and homogeneous slurry that can easily be integrated into standard electrode fabrication process. We use this formulation to print a 76 wt. % silicon composite electrode. We show that the contents and the morphology of the silicon electrolyte interphase – a determining factor in the cycle life of silicon-based anodes – can be controlled with a post-synthetic thermal curing procedure. When paired against a capacity-matched lithium nickel manganese cobalt oxide LiNi0.8Mn0.1Co0.1O2 cathode, the cell retains 72% of its capacity through 1000 charge/discharge cycles while delivering an initial anode specific capacity of nearly 1000 mAh/g and an areal capacity of 2.55 mAh/cm2. Figure 1

Regenerated Ni-Rich Cathode Materials from Spent Li-Ion Batteries by a Closed Loop Process

The demand for rechargeable lithium-ion batteries (LIBs) has increased exponentially since they were first commercialized by Sony in 1991.[1] Due to the high energy density and excellent cycle stability, LIBs have been widespread utilized in electric vehicles and other applications. However, the lifespan of LIBs is limited. Thus, tons of spent LIBs are generated during the recent decades. More importantly, the price of raw materials, including lithium and cobalt salts, for producing LIBs grows significantly.[2, 3] Therefore, recycling these End-of-Life LIBs becomes a non-negligible part in the whole manufacturing process and hydrometallurgical process is the most common recycling method. Here, our group has demonstrated a closed loop recycling process, combining inorganic acid etching and coprecipitation reaction, to produce regenerated Ni-rich cathode materials. The regenerated LiNi0.83Mn0.06Co0.11O2 shows excellent performance: the first cycle discharge capacity is 214.1mAh/g at 0.05C in the voltage range of 2.8 - 4.3V and the initial columbic efficiency is 90.9%. The performance of our regenerated cathode materials is comparable to commercial cathode materials. In order to further optimize the properties of the regenerated LiNi0.83Mn0.06Co0.11O2, different elements, like Al, with various doping or coating methods will be utilized. Manthiram A. A reflection on lithium-ion battery cathode chemistry. Nature Communications 2020; 11(1):1550.Li W, Lee S, Manthiram A. High‐Nickel NMA: A Cobalt‐Free Alternative to NMC and NCA Cathodes for Lithium‐Ion Batteries. Advanced materials (Weinheim) 2020; 32(33):2002718-n/a.Hou J, Ma X, Fu J, Vanaphuti P, Yao Z, Liu Y, et al. A green closed-loop process for selective recycling of lithium from spent lithium-ion batteries. Green Chemistry 2022; 24(18):7049-7060.

A Low-Temperature Boron-Based Composite Coating for Ni-Rich Li-Ion Battery Cathode with Enhanced Cycle Life and Safety

Due to the continuously aggravating global warming crisis, the aim of reducing CO2 emissions by replacing fossil fuels with clean energy sources has raised the demand for electric vehicles (EVs) and driven research in pursuing high-energy rechargeable lithium-ion batteries (LIBs). For the cathode component, Ni-rich cathode materials such as LiNixCoyMn1-x-yO2 (NCM) have been widely adopted in commercial EVs due to their high specific capacity (~200 mAh/g) and high operating voltage (~ 4V vs. Li/Li+). However, Ni-rich cathode materials are still confronting challenges such as poor cycle stability and safety issues. To tackle these problems, a boron-based surface modification of Ni-rich cathode material (NCM) is achieved via a low-temperature process in this work. The coated NCM shows comparable rate capability but with substantially improved cycle stability. In terms of safety issues (thermal runaway process), the onset temperature of the thermal runaway process in presence of electrolyte is delayed by 40°C while the total heat release and the maximum heat flow are both decreased by over 40%. Post mortem and in situ X-ray characterizations using synchrotron radiation further illustrate the reasons of the enhanced cycle stability and safety. Results show that the boron-based composite coating is able to decrease the extent of reaction between NCM and the electrolyte during both cycling and the thermal runaway process. Our results demonstrate the use of a low-temperature boron-based composite coating as an effective surface modification method of Ni-rich cathode materials to achieve long-life and high-safety lithium-ion batteries.

High-Capacity Metal Oxide Electrodes for Lithium-Ion Batteries

It is of paramount importance to develop rechargeable lithium-ion batteries (LIBs) with higher energy to meet the demands of emerging energy storage applications. Currently, LIBs use LiCoO2 as the cathode and graphite as the anode, which shows moderate capacity of ~140 mAh g-1 and ~350 mAh g-1, respectively. As a result, the energy density is limited to 120-160 Wh kg-1. In this context, we have investigated a layered-spinel material (Li2MnO3, LiMn2O4, LiNi2/3Mn1/6Co1/6O2, NMC 811,LiFePO4) as a high-capacity cathode. This cathode exhibits a theoretical capacity of ~ 250 mAh g-1, and in our preliminary work, we demonstrated a high capacity of ~ 250 mAh g-1. We also find that this cathode shows high voltage of 4.5 V and stable cycling over 50 cycles. On the anode side, we investigated BiFeO3(BFO) as a potential high-capacity anode, which delivers a high capacity of ~750 mAh g-1, double the capacity of graphite. In the following research, we will explore the possibility of assembling Li-ion full cells using these two materials in order to demonstrate high energy density.The Li-ion storage mechanism in these two materials will also be thoroughly investigated by electrochemical and physical characterizations, such as electrochemical impedance spectroscopy (EIS), ex-situ XRD, and X-ray photoelectron spectroscopy.

Preparation and application of polyacrylonitrile electrospun nanofiber-based all-solid-state composite electrolyte for lithium metal battery

The demand for lithium-ion batteries that are both safe and high-energy is growing. Liquid electrolytes are used in traditional lithium rechargeable batteries, which pose security hazards such as volatilization, flammability, and explosion. Most of the safety problems associated with liquid electrolytes could be addressed by solid-state electrolytes. This research firstly incorporated Li6.4La3Zr1.4Ta0.6O12 (LLZTO) ceramic nanoparticle filler into electrospun polyacrylonitrile (PAN) to obtain a composite nanofiber membrane, and then added it to polyethylene oxide (PEO) polymer as a nano-polymer filler to create an all-solid-state electrolyte. By incorporating the PAN/LLZTO composite nanofiber membrane, the resulting electrolyte gains a sturdy framework that enhances its overall mechanical strength (7.8 MPa) to prevent the growth of lithium dendrites during cycling. In addition, the addition of LLZTO particles can help promote chain segment motion in a PEO matrix by increasing the ratios of amorphous to crystalline phase, which is beneficial for the rapid migration of lithium ions in the electrolyte membrane. At the same time, the interaction between LLZTO and DMF solvent can also generate an alkaline atmosphere and then promotes the cyclization of PAN, thus enhancing the ionic conductivity of the electrolyte (6.5 × 10−5cm−1 at 30 °C). The Li/Li symmetric battery assembled with the PEO-PAN/LLZTO composite electrolyte can stable cycling for 800 h at different current densities, and the Li/LiFePO4 battery can still maintain a high Coulomb efficiency of 99.7% after even 400 cycles under 1C. The research will lead to a promising electrolyte candidate for all-solid-state lithium metal batteries.

Li3PO4-Coated Graphite Anode for Thermo-Electrochemically Stable Lithium-Ion Batteries

Extensive research on electrode materials has been sparked by the rising demand for high-energy-density rechargeable lithium-ion batteries (LIBs). Graphite is a crucial component of LIB anodes, as more than 90% of the commercialized cathodes are coupled with the graphite anode. For the advanced graphite anode, the fast charge–discharge electrochemical performance and the thermal stability need to be further improved in order to meet the growing demand. Herein, a graphite anode material’s thermo-electrochemical stability was improved by the surface coating of lithium phosphate (Li3PO4; LPO). The graphite anode with a well-dispersed LPO-coating layer (graphite@LPO) demonstrated significant improvement in the cycle and rate performances. The graphite@LPO sample showed a capacity retention of 67.8% after 300 cycles at 60 °C, whereas the pristine graphite anode failed after 225 cycles, confirming the ameliorated thermo-electrochemical stability and cyclability by LPO coating. The improved thermo-electrochemical stability of the graphite@LPO anode was validated by the full-cell tests as well. The performance enhancement by LPO-coating is due to the suppression of the growth of the surface film and charge-transfer resistances during the repeated cycling, as evidenced by the electrochemical impedance spectroscopy analysis.

IoT-Based Smart Battery Management and Monitoring System for Electric Vehicles

The growing popularity of electric vehicles on a worldwide scale leads to further research to monitor their performance. The use of Internet of Things (IoT) technology will make it easier to integrate the automated real-time monitoring system with the current electric vehicle technology. The great majority of electric vehicles use rechargeable lithium-ion batteries. Use of lithium-ion batteries creates an overcharging situation in the battery, which significantly decreases battery life. It also increases the possibility of disastrous safety risks due to fire. This paper develops an IoT-based battery management system to minimize hazardous situations. The battery monitoring system (BMS) notifies the user about the condition of the battery in real time.