High Energy Density Lithium-ion Batteries Research Articles

Controlled roll to roll pre-lithiation by lithium vacuum vapor deposition for high performance silicon based lithium-ion battery

Silicon oxides (SiOx) anode has attracted great interest for high-energy–density lithium-ion battery due to its extremely abundant reserves, low cost, and easy synthesis. Despite these merits, its low initial columbic efficiency (ICE) and poor cycle ability severely hinder it from widely using. Pre-lithiation methods are considered to be the effective strategies to overcome low ICE concerns. However, current pre-lithiation methods are always limited by their own drawbacks, such as complicated process and uncontrollable pre-lithiation degree. In this work, we reported a controlled roll-to-roll pre-lithiation method with lithium vacuum vapor deposition. Our pre-lithiation method can not only achieve controllable and uniform pre-lithiation degree of SiOx anode, but also is a process simplified design appropriate for large-scale applications. The electrochemical performance of our pre-lithiated anode achieved 10 % ICE improvement and much stable cycle, demonstrating promising potential for commercial applications.

One thousandth of quaternity slurry additive enables one thousand cycle of 5V LNMO cathode

5 V high voltage LiNi0.5Mn1.5O4 (LNMO) is one of the most promising cathode candidates for high energy density lithium-ion batteries. However, the electrochemical performance of high voltage LNMO is significantly affected by the interfacial compatibility between cathode and electrolyte. High voltage leads to decomposition of electrolyte at the cathode-electrolyte interface (CEI), consuming electrolyte and forming an uneven, unstable, and unprotected CEI, and hindering Li+ diffusion and reducing electrochemical efficiency. At the same time, along with the dissolution of transition metals and irreversible crystal structure damage over cycles, its electrochemical performance is seriously impaired. To solve these problems, it is proposed to pre-form a stable passivation layer on the LNMO surface using tiny amount of quaternity slurry additive of potassium-nonafluoro-1-butanesulfonate (KPBS). The K+ in KPBS assists construction of uniform and stable electric field at the cathode particle surface together with the Li+, which induces uniform deposition of the CEI. The lithium-ion diffusion at the interface is accelerated due to existence of rich phase boundaries between KF and LiF species within the CEI. The sulfonic acid group of KPBS is capable of inhibiting transition metal dissolution via coordination boding with Ni/Mn cations. The nona fluoro butyl structure improves the interface compatibility with the poly(vinylidene difluoride) (PVDF) binder to enhance the structure robustness of the electrode. The quadruple effects exercised by the KPBS enable the LNMO almost no capacity decay after 1000 cycles at 1C and 5 V. This work has a great potential to boost significant advance of the high energy density lithium-ion battery technology.

Defects go green: using defects in nanomaterials for renewable energy and environmental sustainability

Induction of point defects in nanomaterials can bestow upon them entirely new physics or augment their pre-existing physical properties, thereby expanding their potential use in green energy technology. Predicting structure-property relationships for defects a priori is challenging, and developing methods for precise control of defect type, density, or structural distribution during synthesis is an even more formidable task. Hence, tuning the defect structure to tailor nanomaterials for enhanced device performance remains an underutilized tool in materials design. We review here the state of nanomaterial design through the lens of computational prediction of defect properties for green energy technology, and synthesis methods to control defect formation for optimal performance. We illustrate the efficacy of defect-focused approaches for refining nanomaterial physics by describing several specific applications where these techniques hold potential. Most notably, we focus on quantum dots for reabsorption-free solar windows and net-zero emission buildings, oxide cathodes for high energy density lithium-ion batteries and electric vehicles, and transition metal dichalcogenides for electrocatalytic green hydrogen production and carbon-free fuels.

High-pressure and high-temperature synthesis of black phosphorus-graphite anode material for lithium-ion batteries

Phosphorus-based materials with a high theoretical specific capacity and a fast charge-discharge rate are considered as promising anode materials for high energy density lithium-ion batteries (LIBs). Red phosphorus (RP) and black phosphorus (BP) are two main allotropes to be used as anode materials. However, huge volume expansion during charge-discharge processes hinders the application of RP and BP in LIBs. Composites of phosphorus and carbon-based materials have been extensively fabricated to withstand volume expansion of phosphorus and improve cycle performance. Here, composites of BP and graphite (BP-G) with three P-G mass ratios (8 : 2, 7 : 3, and 6 : 4) have been synthesized by a facile and scalable high-pressure and high-temperature (HPHT) method using RP and graphite composites (RP-G) prepared by ball milling as precursors. Their microstructure and bonding configurations have been analyzed by various characterization techniques. Among three RP-G composites, 7RP-3G exhibits the most excellent cycling stability, a high reversible capacity of 1331 mAh/g after 200 cycles at a current density of 0.78 A/g. However, RP-G composites show poor stability at high current densities. Among three BP-G composites, 6BP-4G shows the best cycle stability at high current densities, a reversible capacity of 634.6 mAh/g after 500 cycles at a current density of 2.6 A/g. Although, the reversible specific capacities of BP-G composites after long cycles are lower than those of RP-G, BP-G composites show more stable cycle performance than RP-G, especially at high current densities. The present work illustrates a direct and facile method to synthesize BP-G composites, and sheds light to explore new synthetic route of BP-based composites.

Li4Ti5O12-TiO2 composite coating layer enabling LiNi0.8Co0.1Mn0.1O2 electrodes with superior cycling performance

Nickel-rich LiNi0.8Co0.1Mn0.1O2 (NCM811) materials are considered to be one of the cathode candidate materials for high energy density lithium-ion batteries (LIBs), but its electrochemical instability caused by electrodes to electrolyte interface degradation needs to be overcome. Surface coatings can effectively solve this problem. However, traditional coating techniques cover particles rather than electrodes to protect a broader area. Herein, for a more precise coating, a nanoscale Li4Ti5O12-TiO2 composite coating layer (LTOTO) is directly sputtered onto the NCM811 electrodes surface. The LTOTO has superior electronic conductivity compare to Li4Ti5O12. Lithium ions and electrons can diffuse and distribute more uniformly owing to the LTOTO coating on NCM811 electrode. For NCM811 electrodes, the LTOTO coating layer serves as the cathode-electrolyte interface (CEI) within the cycling potential range. Because of its robust structure and strong chemical inertness, LTOTO may successfully shield NCM811 electrodes from electrolyte reactions. The rate performance of NCM811 electrodes is significantly enhanced after Li4Ti5O12-TiO2 coating at 5C (149.74 mAh/g). The capacity retention of NCM811/LTOTO-3 electrode at 1C is 93.2 % at the 100th cycle, which is 13.3 % higher than that of the pristine NCM811 electrodes.

Development of a Computational Fluid Dynamics Simulation Framework for Aerothermal Analyses of Electric Vehicle Battery Packs

Abstract The rise of electric vehicles has driven the extensive adoption of lithium-ion batteries (LIBs) due to their favorable attributes—compactness, low resistance, high power density, and minimal self-discharge. To enhance LIB reliability, an efficient battery thermal management system is imperative. This paper introduces a finite volume-based aerothermal analysis framework for a 32-cell high-energy density LIB pack. We also explore the effectiveness of various turbulence models in capturing local hotspots, discharge rates, and current levels across different geometries and inlet velocities. Our approach involves modeling the battery using Simcenter Battery Design Studio and importing it into Simcenter star-ccm+ for aerothermal simulations in which temperature distribution, discharge rates, current levels, and maximum temperature across are monitored for aligned, cross, and staggered configurations of the battery pack under varying inlet velocities. Our findings highlight the significant impact of boundary condition modeling on simulation stability. Also we observed that the standard k–ε model provides the most accurate predictions, with prediction accuracy within 3–10% of experimental data. Moreover, we identify substantial dependencies between heat generation and discharge current, as well as thermal gradients and inlet velocity. Finally, we conclude that the aligned cell arrangement offers the best thermal uniformity and cooling efficiency.

ACGNet: An interpretable attention crystal graph neural network for accurate oxidation potential prediction

LiNixCoyMn1-x-yO2 (NCM) is one of the most critical cathode materials for high energy density lithium-ion batteries in electric vehicle applications. Nevertheless, capacity degradation and long-term cycle instability due to the aging of cathode/electrolyte interfaces remain significant challenges for NCM materials. Various surface stabilization techniques, including doping and coating, can be employed for NCM modifications. Traditionally, new coating materials are identified by chemical intuition or trial-and-error synthesis, which hinders the discovery speed of high-performance coating materials. A novel neural network model named Attention Graph Convolutional Neural Network (ACGNet) has been developed to predict crystals’ electrochemical stability windows from atom and bonding features and exhibits remarkable predictive performance with a mean absolute error of 0.586 V. Then, the developed model is utilized to conduct high-throughput screening of 13,943 candidate compounds for their coating potential. Among the candidates, LiPO3 exhibits prominent potential as a coating material due to its high oxidation voltage and low preparation cost. The subsequent battery assembly experiment and electrochemical characterization reveal that the incorporation of LiPO3 significantly enhances the cycle stability of NCM batteries. In summary, our model exhibits exceptional accuracy in predicting material properties and serves as a compelling example for machine learning applications in battery materials.

Solid Electrolyte Interface Film-Forming and Surface-Stabilizing Bifunctional 1,2-Bis((trimethylsilyl)oxy) Benzene as Novel Electrolyte Additive for Silicon-Based Lithium-Ion Batteries.

The application of Si-based anodes in lithium-ion batteries (LIBs) has garnered significant attention due to their high theoretical specific capacity yet is still challenged by the substantial volume expansion of silicon particles during the lithiation process, resulting in the instability of the electrode-electrolyte interphase and deteriorative battery performance. Herein, an ortho(trimethylsilyl)oxybenzene electrolyte additive, 1,2-bis((trimethylsilyl)oxy) benzene (referred to as BTMSB), has been investigated as a bifunctional electrolyte additive for Si-based LIBs. The BTMSB can form a uniform and robust LiF-rich solid electrolyte interphase (SEI) on the surface of Si-based material particles, adapting the huge volume expansion of the Si-based electrode and facilitating lithium-ion transport. Additionally, the BTMSB demonstrates the ability to scavenge hydrofluoric acid (HF) to stabilize the electrode-electrolyte interphase. The SiOx/C∥Li batteries with 2% BTMSB exhibit improved cycle performance and current-rate capabilities, of which the capacity retention retains 69% after 400 cycles. Furthermore, Si-based anode cells with higher theoretical specific capacities (1C = 550 mAh g-1) and NCM523∥SiOx/C pouch cells are constructed and evaluated, displaying superior cycle performance. This work provides valuable insights for the development of effective electrolyte additives and the commercialization of high energy density LIBs with Si-based anodes.

Si-Based High-Entropy Anode for Lithium-Ion Batteries.

Up to now, only a small portion of Si has been utilized in the anode for commercial lithium-ion batteries (LIBs) despite its high energy density. The main challenge of using micron-sized Si anode is the particle crack and pulverization due to the volume expansion during cycling. This work proposes a type of Si-based high-entropy alloy (HEA) materials with high structural stability for the LIB anode. Micron-sized HEA-Si anode can deliver a capacity of 971 mAhg-1 and retains 93.5% of its capacity after 100 cycles. In contrast, the silicon-germanium anode only retains 15% of its capacity after 20 cycles. This study has discovered that including HEA elements in Si-based anode can decrease its anisotropic stress and consequently enhance ductility at discharged state. By utilizing in situ X-ray diffraction and transmission electron microscopy analyses, a high-entropy transition metal doped Lix (Si/Ge) phase is found at lithiated anode, which returns to the pristine HEA phase after delithiation. The reversible lithiation and delithiation process between the HEA phases leads to intrinsic stability during cycling. These findings suggest that incorporating high-entropy modification is a promising approach in designing anode materials toward high-energy density LIBs.

Molten salt splitting of CO2 with CaC2 and in-situ nitrogen doping for carbon anode of lithium/sodium-ion batteries

Carbon materials are the most attractive anodes for high-energy–density lithium-ion batteries (LIBs) and sodium-ion batteries (SIBs). Herein, a molten salt method is developed to split CO2 with CaC2 for N-doped carbon anodes of LIBs and SIBs. Molten salt accelerates the carbonization and the in-situ N doping in kinetics. The carbon materials are characterized as large specific surface, porous and low graphite degree. The graphitization and functional groups are promoted by the doping of N atoms. These structure characteristics improve the battery performance, including high specific capacity, good rate performance and excellent cycle stability. The CN60–4 h anode delivers a reversible capacity of 448 mAh·g−1 over 500 cycles at 0.5 A·g−1 and 155 mAh·g−1 over 2000 cycles at 10 A·g−1 for the anode of LIBs and SIBs, respectively. This work offers an easy and feasible method for preparing N-doped carbon anode materials for LIBs and SIBs.

Simple construction of multistage stable silicon-graphite nanosheets composites for lithium-ion batteries

Silicon/carbon composites are considered as the preferred anode materials for high energy density lithium-ion batteries due to their high capacity. However, the high cost of raw materials and the complex preparation process have resulted in expensive cost and poor batch stability of silicon-carbon materials, which have impeded their widespread adoption on a large scale. In this study, a multistage stable silicon-graphite nanosheets composite (Si-NSs/G-NSs@C) with intercalated and core-shell structure was produced from low-cost precursors of silicon nanosheets (Si-NSs) and graphite nanosheets (G-NSs) by simple modification-grafting-coating and heat treatment processes. Benefiting from the effective bonding, citric acid carbon coating, intercalation and core-shell structure, the Si-NSs/G-NSs@C composite exhibits excellent performance for lithium storage. The Si-NSs/G-NSs@C electrode, using the sodium alginate binder system, displays the reversible specific capacity of 821.4 mAh g−1 at 400 mA g−1, with the capacity retention rate of 80% after 200 cycles. When employing lithium polyacrylate as the binder, the composite electrode demonstrates the reversible specific capacities of 1048.9 mAh g−1 at 400 mA g−1 and 723.6 mAh g−1 at 1000 mA g−1. After 200 cycles, the capacity retention rates were 81% and 85%, respectively. In summary, the low-cost precursors, simple and controllable preparation process and excellent electrochemical performance will further promote the market application of silicon/carbon anode materials.

Rational Design of Ion-Conductive Layer on Si Anode Enables Superior-Stable Lithium-Ion Batteries.

Silicon (Si) is considered a promising commercial material for the next-generation of high-energy density lithium-ion battery (LIB) due to its high theoretical capacity. However, the severe volume changes and the poor conductivity hinder the practical application of Si anode. Herein, a novel core-shell heterostructure, Si as the core and V3 O4 @C as the shell (Si@V3 O4 @C), is proposed by a facile solvothermal reaction. Theoretical simulations have shown that the in-situ-formed V3 O4 layer facilitates the rapid Li+ diffusion and lowers the energy barrier of Li transport from the carbon shell to the inner core. The 3D network structure constructed by amorphous carbon can effectively improve electronic conductivity and structural stability. Benefiting from the rationally designed structure, the optimized Si@V3 O4 @C electrode exhibits an excellent cycling stability of 1061.1 mAh g-1 at 0.5 A g-1 over 700 cycles (capacity retention of 70.0%) with an average Coulombic efficiency of 99.3%. In addition, the Si@V3 O4 @C||LiFePO4 full cell shows a superior capacity retention of 78.7% after 130 cycles at 0.5 C. This study opens a novel way for designing high-performance silicon anode for advanced LIBs.

Grain boundary density matters in lithiation performances of aluminum foil anode for lithium ion batteries

Alloy foils are highly promising anode materials for high energy density lithium-ion batteries (LIBs). However, limited lithiation sites and inhomogeneous lithiation processes often lead to stress concentration and severe volume changes, resulting in rapid degradation of the electrode structure. In this work, the lithiation behavior and the corresponding structural evolution of aluminum (Al) foil anode are investigated by modulating the grain boundaries (GBs) density. The results show that abundant GBs network endows Al foil with uniform and distributed lithiation sites, and improved lithiation kinetics. The derived uniform volume change can effectively delocalize stress concentration, and hinder the formation of penetrated cracking network, giving rising to good structural stability and prolonged cycle life of Al foil anode. This work can enrich feasible strategies to alleviate the pulverization and serial issues of the metal foil anode by GBs density regulation for high specific energy LIBs.

In Situ Forming Gel Polymer Electrolyte for High Energy-Density Lithium Metal Batteries.

In situ forming gel polymer electrolyte (GPE) is one of the most feasible ways to improve the safety and cycle performances of lithium metal batteries with high energy density. However, most of the in situ formed GPEs are not compatible with high-voltage cathode materials. Here, this work provides a novel strategy to in situ form GPE based on the mechanism of Ritter reaction. The Ritter reaction in liquid electrolyte has the advantage of appropriate reaction temperature and no additional additives. The polymer chains are cross-linked by amide groups with the formation of GPE with superior electrochemical properties. The GPE has high ionic conductivity (1.84 mS cm-1 ), wide electrochemical stability window (>5.25V) and high lithium ion transference number (≈0.78), compatible with high-voltage cathode materials. The Li|LiNi0.6 Co0.2 Mn0.2 O2 batteries with in situ formed GPE show excellent long-term cycle stability (93.4%, 300 cycles). The density functional theory calculation and X-ray photoelectron spectroscopyresults verify that the amide and nitrile groups are beneficial for stabilizing cathode structure and promoting uniform Li deposition on Li anode. Furthermore, the in situ formed GPE exhibits excellent electrochemical performance in Graphite|LiMn2 O4 and Graphite|LiNi0.5 Co0.2 Mn0.3 O2 pouch batteries. This approach is adaptable to current battery technologies, which will be sure to promote the development of high energy-density lithium-ion batteries.

Recent advances of SiO x -based anodes for sustainable lithium-ion batteries

The world is facing an ever-growing global energy crisis with unprecedented depth and complexity. The sustainable development of high energy density lithium-ion batteries for electric vehicles and portable electric devices has become a feasible way to deal with this problem. Silicon suboxides (SiO_<i>x</i>) have been deemed as one of the most promising anode materials because of their ultrahigh theoretical lithium storage capacity, proper working potential, natural abundance, and environmental friendliness. However, the mass utilization of SiO_<i>x</i>-based anodes is severely obstructed by their low electrical conductivity and inevitable volume expansion. While lithium silicate and lithium oxide formed in the first lithiation process act as buffer layers to some extent, it is urgent to address the accompanying low initial Coulombic efficiency and unsatisfactory cycling stability. In this review, we summarized recent advances in the synthesis methods of SiO_<i>x</i>-based materials. Besides, the benefits and shortcomings of the various methods are briefly concluded. Then, we discussed the effective combination of SiO_<i>x</i> with carbon materials and designs of porous structure, which could considerably enhance the electrochemical performance in detail. Furthermore, progresses on the modified strategies, advanced characteristics and industrial applications for SiO_<i>x</i>-based anodes are also mentioned. Finally, the remaining challenges encountered and future perspectives on SiO_<i>x</i>-based anodes are highlighted.

LT-LiMn0.5Ni0.5O2: A Unique Co-Free Cathode for High Energy Li-Ion Cells

Over the past decade, designing advanced, high energy density lithium-ion batteries has become necessary because of the increasing demand for electric vehicles and energy storage devices. Research efforts have focused largely on developing layered, Ni-rich cathode materials due to their high specific capacity. However, their structural and thermal instability and the relatively high cost of nickel raises a concern about their long-term viability.1 Developing next generation cathode materials, based on earth abundant elements such as manganese and iron, has therefore attracted much research interest.2 In the late 1990s, the Mn-based spinel cathode, LiMn2O4 (LMO), dominated the early development of Li-ion batteries for the electric vehicle market. The 3-D network of channels provided by the Mn2O4 spinel framework for Li+-ion diffusion channels enables a good rate performance. However, the operational capacity of Li1-xMn2O4 spinel cathodes in a lithium cell at ~4 V over the range 0<x£1 is limited by its low electrochemical capacity relative to layered cathodes. Although deep-discharging the cell at ~3 V allows the insertion of extra Li ions into the spinel framework (i.e., Li1+xMn2O4, 0£x£1), a rapid fade of capacity occurs as a result of a severe crystallographic (Jahn Teller) distortion, which prevents the use of the lower voltage reaction in commercial cells.In this presentation, a novel LT-LiMn0.5Ni0.5O2 (LT-LMNO) cathode material with unique electrochemical properties will be reported, where LT refers to its low synthesis temperature (400 °C). In striking contrast to a layered electrode with the same composition, HT-LiMn0.5Ni0.5O2 (where HT = high temperature synthesis, ~850 °C), LT-LMNO has a composite configuration with structurally-integrated lithiated spinel- and layered-like components.3, 4 It provides an electrochemical capacity almost twice that of LMO. This discovery provides a new strategy for developing next-generation. Mn-rich spinel-based cathodes.References Bianchini, M.; Roca-Ayats, M.; Hartmann, P.; Brezesinski, T.; Janek, J., There and Back Again - The Journey of LiNiO2 as a Cathode Active Material. Chem. Int. Ed. Engl. 2019, 58 (31), 10434-10458.Croy, J. R.; Gutierrez, A.; He, M.; Yonemoto, B. T.; Lee, E.; Thackeray, M. M., Development of Manganese-rich Cathodes as Alternatives to Nickel-rich Chemistries. Power Sources 2019, 434, 226706.Thackeray, M. M.; Lee, E.; Shi, B.; Croy, J. R., Review: From LiMn2O4 to Partially-Disordered Li2MnNiO4: The Evolution of Lithiated-Spinel Cathodes for Li-Ion Batteries. Electrochem. Soc. 2022, 169 (2), 020535.Shi, B.; Gim, J.; Li, L.; Wang, C.; Vu, A.; Croy, J. R.; Thackeray, M. M.; Lee, E., LT-LiMn5Ni0.5O2: A Unique Co-free Cathode for High Energy Li-ion Cells. Chem. Comm. 2021, 57 (84), 11009-11012.

Li2CO3 As the Parasitic Reaction Root for Exacerbated Material Degradation and Performance Deterioration of Ni-Rich Cathode

Nickel-rich transition metal oxides is widely regarded as promising cathode materials for high energy density lithium-ion batteries for emerging applications in electric vehicles. However, achieving high energy density in Ni-rich cathodes is generally accompanied with substantial obstacles of lifetime and safety. The major issues of Ni-rich cathodes at high working potentials are originated from the unstable cathode-electrolyte interface, while the underlying mechanism of parasitic reactions to material degradation at the surface of cathode materials is not well understood. In this work, we report the parasitic-reaction-driven structural degradation in LiNi0.83Mn0.1Co0.07O2 cathode by altering interfacial chemistry by synthesizing cathode material in different environments. Our home-build high precision leakage current (HpLC) system verifies that Li2CO3 impurity generated in harsh synthesis environment is a nature root of electrolyte decomposition and parasitic reactions on Ni-rich cathodes. Different rates of parasitic reactions are strongly correlated to drastic discrepancy in electrochemical performance of Ni83 cathodes at different synthesis conditions. The post-mortem characterizations reveal that parasitic reactions promote severe rock-salt phase transformation with more Ni reduction and O deficiency at the surface of cathode materials. This study suggests the significance of developing impurity-free and mitigated parasitic reactions in Ni-rich transition metal oxides for enabling high energy density. Acknowledgement Research at the Argonne National Laboratory was supported by the U.S. Department of Energy (DOE), Office of Energy Efficiency and Renewable Energy, Advanced Manufacturing Office. Argonne National Laboratory is operated for the DOE Office of Science by UChicago Argonne, LLC, under Contract DE-AC02-06CH11357. Figure 1

Enabling the Production of Homogeneous High-Load Positive Electrodes by Tailoring the Electrode Formulation – a Conductive Additive and Solvent Approach

The automotive industry experiences a substantial change due to electrification of major parts of the transportation system by using lithium ion batteries (LIBs). To facilitate this transition, low cost and high energy density LIBs produced under the most sustainable conditions possible are required. These objectives are amongst others strongly related with the positive electrode. Thus, in order to achieve enhanced energy densities on cell level, the application of high-load positive electrodes for various cell systems ranging from lithium ion to lithium metal batteries is inevitable. However, to ensure high lithium ion mobility within thick composite electrodes and to obtain maximized capacity utilization, it is crucial to tailor the electrode microstructure. With regard to the production, detrimental effects like binder-migration can occur upon drying of thick electrodes inducing inhomogeneous distribution of binder and conductive additive within the electrode coating. Beyond that, the effect of lateral coating shrinkage resulting in electrode cracking during drying plays an increasingly significant role with increasing electrode thickness.The application of high solid contents (SC) during electrode paste processing can widely suppress the effects of binder migration and crack formation.[1,2] However, elevated SCs result in increasing paste viscosities leading to practical limitations for homogeneous electrode coating. By using nano-scale and micro-scale spherical, linear and three-dimensional conductive additives like carbon microfibers (CMF) or conductive graphite (CG) in addition to carbon black (CB), the adjustment of an appropriate paste viscosity can be facilitated. The addition of more carbonaceous additives acting as conductive additive as well as processing additive resolves the rheological requirements for an electrode paste with 80% SC and significantly influences the pore structure of the electrode. Thus, tailoring active and inactive components is crucial to enable processing of high SC electrode pastes with an appropriate viscosity in conjunction with the production of thick electrodes exhibiting an optimized pore structure benefiting the electrochemical performance. The additional introduction of carbon nanotubes (CNTs) leads to the formation of segregated networks providing more stability within the electrode and a favorable electrode microstructure. Moreover, the use of CNTs benefits the electrochemical performance by immensely boosting electronic conductivity resulting in higher rate capability and increased capacity retention. The various electrode formulations containing up to three different conductive additives were compared to the benchmark formulation without further additives in terms of electronic conductivity, adhesion, pore structure and electrochemical performance. Different electrode formulations were investigated and compared regarding the composite electrode adhesion strength, electronic conductivity, microstructure and electrochemical performance over 400 cycles in a coin cell setup with a graphitic negative electrode. However, the optimized formulation containing CNTs enables the production of thick positive electrodes exhibiting significantly higher areal capacities up to 8 mAh cm-2 with superior electrochemical properties and higher content of active material in the formulation resulting in higher energy densities on cell level. In a next step, the state-of-art processing solvent N-Methyl-2-pyrrolidon (NMP) was targeted with the goal of replacing NMP with a non-toxic solvent. The influence of a co-solvent on the electrode paste viscosity was investigated to further increase the SC, lower production costs and enable improved environmental benignity.A comprehensive study on tailoring the rheological, structural and electrochemical properties by processing additives is presented. The increase of the SC to 80% is a first step towards the reduction of the ecologic and economic footprint for LIB production while simultaneously enabling electrodes with high areal capacities exhibiting increased rate capability and capacity retention enabled by the addition of CNTs.[1] J. Seeba, S. Reuber, C. Heubner, A. Müller-Köhn, M. Wolter, A. Michaelis, Chemical Engineering Journal Volume 402, 2020, 125551. [2] L. Ibing, T. Gallasch, P. Schneider, P. Niehoff, A. Hintennach, M. Winter, F. M. Schappacher, Journal of Power Sources 423, 2019, 183–191.

Titration Techniques for the Determination of Surface Species on Cathode Active Materials

Lithium ion batteries (LIBs) are the most important energy storage technology of our time. The number of LIBs has been constantly growing during the last years as well as the range of applications where LIBs are used, increasing the need for high energy density LIBs.One of the main cathode materials for high energy density LIBs is Ni-rich LiNi0.8Co0.1Mn0.1O2 (NCM811).1 Unfortunately, due to the high Ni content this material is extremely sensitive towards water which poses a particular challenge for more sustainable aqueous processing. Contact with even traces of moisture from the air causes immediate formation of surface species such as LiOH and Li2CO3.2,3 The presence of these surface species not only leads to Li leaching from the structure and subsequent capacity loss but also facilitates side reactions with the electrolyte resulting in gas evolution and ultimately early failure of the battery.4 Developing reliable methods for the quantification of these harmful surface species can provide a link between the amount of surface species and the detrimental impact on the cell performance. Here we employed different measurement techniques to quantify the amount of LiOH and Li2CO3 on the NCM811 material surface.5 Warder titration6 and Winkler titration7 are two methods that have been long known for the determination of hydroxides and carbonates. We optimized these techniques for the determination of very small quantities of surface carbonate or hydroxide by testing the sensitivity for small lab size quantities of material and removing the possibility of additional CO2 uptake through the air. Titration as a way to quantify the amount of LiOH and Li2CO3 is a valuable measurement technique that can help to predict performance issues of the battery and can serve as a tool for quality control of cathode active materials. References (1) Armand, M.; Axmann, P.; Bresser, D.; Copley, M.; Edström, K.; Ekberg, C.; Guyomard, D.; Lestriez, B.; Novák, P.; Petranikova, M.; Porcher, W.; Trabesinger, S.; Wohlfahrt-Mehrens, M.; Zhang, H. J. Power Sources 2020, 479, 228708.(2) Hofmann, M.; Kapuschinski, M.; Guntow, U.; Giffin, G. A. J. Electrochem. Soc. 2020,(3) Jung, R.; Morasch, R.; Karayaylali, P.; Phillips, K.; Maglia, F.; Stinner, C.; Shao-Horn, Y.; Gasteiger, H. A. J. Electrochem. Soc. 2018, 165 (2), A132–A141.(4) Kim, Y. J. Mater. Sci. 2013, 48 (24), 8547–8551.(5) Schuer, A. R.; Kuenzel, M.; Yang, S.; Kosfeld, M.; Mueller, F.; Passerini, S.; Bresser, D. J. Power Sources 2022, 525 (231111).(6) Benedetti-Pichler, A. A.; Cefola, M.; Waldman, B. Ind. Eng. Chem. - Anal. Ed. 1939, 11 (6), 327–332.(7) Winkler, C. Praktische Übungen in Der Maßanalyse, 5. Auflage.; Verlag von A.Felix: Leipzig, 1920.

Silicon-Containing Anodes for High-Energy Density Lithium-Ion Batteries

Next- Generation Lithium(Li)-based rechargeable battery technologies utilising silicon (Si) and Si-containing (Si/Gr, SiOx/Gr, SiNx etc.) anodes coupled with high-capacity/high-voltage insertion-type cathodes (IC) have gained significant attention from both academic and industrial sectors.1 This originates from their practically achievable high energy density, offering a new possibility towards the large-scale espousal of electric vehicles and effective integration of renewable energy sources. In pursuit of designing such high-energy-density electrical energy storage devices, the anode compartment plays huge role and has accordingly reaped increasing interest. In this regards, Si and Si-containing materials are considered to be the most promising choices to replace state-of-the-art graphite in the construction of Lithium-ion batteries (LIBs). This is attributed to their unparalleled high theoretical capacity, suitable operating voltage, natural abundance, environmental benignity, nontoxicity, high safety, and so forth.However, Si and Si-containing materials are endowed with their own advantages and inherent shortcomings. Colossal volume change, much lower diffusivity (σe-+ and DLi+), unstable and fragile solid electrolyte interphase (SEI) formation, electrode swelling, and electrolyte drying are among the most impending intrinsic challenges that hider the large-scale commercialization of such innovative materials. Moreover, the detailed storage mechanism, electrochemistry, failure mechanism and impact of each component in case of blended/composite anode materials (e.g., Si/Gr and SiOX/Gr) etc. remain to be key loopholes to fully understand and thus enable the systems.In this paper, accounts on the various Si-containing active materials (Si, SiOx, Si/Gr blend/composite, SiOx/Gr blend/composite, SiNx etc) including their pros and cons, recent progresses, detailed storage chemistries and mechanisms, characteristics, possible tailored remedies to evade their challenges and thus improving performances - in hope of facilitating their large-scale deployment in the market, and future prospects and research directions will be presented. Impact of atomic level peculiar properties on the material and battery cells level key performance matrices are thoroughly examined. Moreover, the specific energy (Eg) and energy (Ev) density of various insertion-type cathode materials as a function of a) the weight fraction of Si at a fixed areal capacity, b) areal capacity at various Si contents, c) various kinds of electrolytes (liquid, polymer, glass and ceramic) at a fixed areal capacity, and d) electrolyte thickness are evaluated and analyzed.The approach presented in this paper will spur new concepts and perspectives into the best use of Silicon (Si) and Si-containing anode materials for the development Next-Generation high-energy density LIBs. 1Eshetu, G. G.; Zhang, H.; Judez, X.; Adenusi, H.; Armand, M.; Passerini, S.; Figgemeier, E, “Gebrekidan Gebresilassie Eshetu, Heng Zhang, Xabier Judez, Henry Adenusi, Michel Armand, Stefano Passerini, & Egbert Figgemeier, “Production of high-energy Li-ion batteries comprising silicon-containing anodes and insertion-type cathodes.” Nat. Commun. 2021, 12 (1), 1–14.