Ni-rich Layered Oxide Cathode Research Articles

Influence of Cathode Calendering Density on the Cycling Stability of Li-Ion Batteries Using NMC811 Single or Poly Crystalline Particles

Abstract Calendering of battery electrodes is a commonly used manufacturing process that enhances electrode packing density and therefore improves the volumetric energy density. While calendering is standard industrial practice, it is known to crack cathode particles, thereby increasing the electrode surface area. The latter is particularly problematic for new Ni-rich layered transition metal oxide cathodes, such as NMC811, which are known to have substantial surface-driven degradation processes. To establish appropriate calendering practices for these new cathode materials, we conducted a comparative analysis of uncalendered electrodes with electrodes that have a 35% porosity and 25% for single crystal and polycrystalline NMC811. PC cathodes show clear signs of cracking and decrease in rate capability when calendered to 25% porosity, whereas SC cathodes, achieve better cycling stability and no penalty in rate performance at these high packing densities. These findings suggest that SC cathodes should be calendered more densely, we provide a comprehensive overview of both electrochemical and material characterisation methods that corroborate why PC and SC electrodes show such different degradation behaviour. Overall, this work is important because it shows how new single-crystal cathode materials can offer additional advantages in terms of rate performance and cycling stability by calendaring them more densely

Surface Coating of NCM523 Cathode Electrodes by the Difunctional Block Copolymer/Lithium Salt Composites.

Nickel-rich layered oxide cathodes, such as LiNi0.5Co0.2Mn0.3O2 (NCM523), are prevalent in high-power batteries owing to their high energy density. However, these cathodes suffer from undesirable side reactions occurring at the cathode/liquid electrolyte interface, leading to inferior interface stability and poor cycle life. To address these issues, herein, an amphiphilic diblock copolymer poly(dimethylsiloxane)-block-poly(acrylic acid) (PDMS-b-PAA) along with lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) is utilized for modifying the electrode surface. This modification causes a thin and stable cathode-electrolyte interface (CEI) on the surface of NCM523 particles, as evidenced by XPS, TEM, and EIS analysis. The introduction of this modified interface successfully suppresses the capacity fading of NCM523. After 200 cycles at a rate of 1.0 C, the capacity of the modified NCM523 cathode is 108.7 mAh g-1, with a capacity retention of 82.8%, while the control samples without the polymer modification display a capacity retention of 72.7%. These results outline the distinct advantage of electrode surface modification with diblock copolymers/LiTFSI for the stabilization of Ni-rich layered oxide cathodes.

Ni-Rich Layered Oxide Cathodes/Sulfide Electrolyte Interface in Solid-State Lithium Battery.

Because of the high specific capacity and low cost, Ni-rich layered oxide (NRLO) cathodes are one of the most promising cathode candidates for the next high-energy-density lithium-ion batteries. However, they face structure and interface instability challenges, especially the battery safety risk caused by using an intrinsic flammable organic liquid electrolyte. In this regard, a solid electrolyte with high safety is of great significance to promote the development of energy storage. Among them, sulfide electrolytes are considered to be the most potential substitutes for liquid electrolytes because of their high ionic conductivity and good processing properties. Nevertheless, the interfacial incompatibility between the sulfide electrolyte and NRLO cathode is the critical challenge for high-performance sulfide all-solid-state lithium batteries (ASSLBs). In this review, we summarize the problems of the Ni-rich cathode/sulfide solid electrolyte interface and the strategies to improve the interface stability. On the basis of these insights, we highlight the scientific problems and technological challenges that need to be resolved urgently and propose several potential directions to further improve the interface stability. The objective of this study is to provide a comprehensive understanding and insightful recommendations for the enhancement of the sulfide ASSLBs with NRLO cathode.

Ni-Rich Layered Oxide Cathodes/Sulfide Electrolyte Interface in Solid-State Lithium Battery.

Because of the high specific capacity and low cost, Ni-rich layered oxide (NRLO) cathodes are one of the most promising cathode candidates for the next high-energy-density lithium-ion batteries. However, they face structure and interface instability challenges, especially the battery safety risk caused by using an intrinsic flammable organic liquid electrolyte. In this regard, a solid electrolyte with high safety is of great significance to promote the development of energy storage. Among them, sulfide electrolytes are considered to be the most potential substitutes for liquid electrolytes because of their high ionic conductivity and good processing properties. Nevertheless, the interfacial incompatibility between the sulfide electrolyte and NRLO cathode is the critical challenge for high-performance sulfide all-solid-state lithium batteries (ASSLBs). In this review, we summarize the problems of the Ni-rich cathode/sulfide solid electrolyte interface and the strategies to improve the interface stability. On the basis of these insights, we highlight the scientific problems and technological challenges that need to be resolved urgently and propose several potential directions to further improve the interface stability. The objective of this study is to provide a comprehensive understanding and insightful recommendations for the enhancement of the sulfide ASSLBs with NRLO cathode.

Surface-to-bulk synergistic modification enables stable interface of Ni-rich oxide cathode for all-solid-state lithium batteries

All-solid-state lithium batteries (ASSLBs) are supposed to a highly forward-looking battery technology by reason of their conspicuous energy density and excellent safety. Ni-rich layered oxide cathodes have been extensively studied in ASSLB systems with sulfide electrolytes owing to their high voltage and preeminent specific capacity. However, the electrochemical performance of ASSLBs is severely degraded due to the interfacial physical contact failure, space charge layer effect, and chemical/electrochemical side reactions between sulfide electrolytes and Ni-rich oxide cathodes. In this work, the surface of LiNi0.92Co0.04Mn0.04O2 (NCM92) is coated with a nano-level CeO2 buffer layer and is simultaneously doped with Ce element (NCM92–1%Ce) by one-step wet chemical method. Ce doping is beneficial for maintaining structural stability and suppressing irreversible phase transition. The CeO2 buffer layer can efficaciously avoid the oxidation and decomposition phenomenon at the interface between NCM92 and sulfide electrolyte. As expected, NCM92–1%Ce cathode shows the discharge specific capacity of 141.46 mAh g−1 after 80 cycles at 0.2C with 79.32% capacity retention rate, which is much higher than that of the unmodified NCM92 cathode. The results indicate that the surface-to-bulk synergistic modification strategy can successfully improve the structure toughness and interface stability of Ni-rich oxide cathode for ASSLBs with sulfide electrolytes.

High Safety Electrolyte Design for Enabling High Energy-Density System of LiNi0.8Co0.1Mn0.1O2//Phosphorus by Simultaneously Adjusting Dual Electrode/Electrolyte Interfaces.

The demand for state-of-the-art high-energy-density lithium-ion batteries is increasing. However, the low specific capacity of electrode materials in conventional full-cell systems cannot meet the requirements. Ni-rich layered oxide cathodes such as Li(Ni0.8Co0.1Mn0.1)O2 (NCM811) have a high theoretical specific capacity of 200 mAh g-1, but it is always accompanied by side reactions on the electrode/electrolyte interface. Phosphorus anode possesses a high theoretical specific capacity of 2596 mAh g-1, but it has a huge volume expansion (≈300%). Herein, a highly compatible and secure electrolyte is reported via introducing an additive with a narrow electrochemical window, Lithium difluoro(oxalato)borate (LiDFOB), into 1m LiPF6 EC/DMC with tris (2,2,2-trifluoroethyl) phosphate (TFEP) as a cosolvent. LiDFOB participates in the formation of organic/inorganic hybrid electrode/electrolyte interface layers at both the cathode and anode sides. The side reactions on the surface of the NCM811 cathode and the volume expansion of the phosphorus anode are effectively alleviated. The NCM811//RP full cell in this electrolyte shows high capacity retention of 82% after 150 cycles at a 0.5C rate. Meanwhile, the electrolyte shows non-flammability. This work highlights the importance of manipulating the electrode/electrolyte interface layers for the design of lithium-ion batteries with high energy density.

Boron- and calcium-interspersed cathode-electrolyte interphases on Ni-rich layered oxide cathodes for advanced performance lithium-ion batteries

Although Ni-rich layered oxides (Ni-rich NCM) have become the preferred cathode materials in the electric vehicle market, their unsustainable cycling behavior arising from the extremely high reactivity at the interface has become a formidable challenge. To alleviate this problem, we propose modifying the cathode-electrolyte interphase (CEI) of Ni-rich L-NCM cathodes by incorporating B/Ca functional groups. Dual-functionalized CEI layers are prepared by heating boric acid (H3BO3) and calcium oxide (CaO) in a one-step process. Islands of B- and Ca-functionalized CEI layer are observed at the Ni-rich L-NCM cathode, and the thickness is controlled to approximately 2.4 nm. The B-functional group not only lowers the concentration of residual lithium but also compensates for the longer Li+ migration distance by providing a desirable pathway based on ion-hopping sites. The Ca functional groups increase the mechanical rigidity of the Ni-rich L-NCM cathode, which inhibits the appearance of microcracks. In terms of its cycling behavior, the capacity retention of the cell with the B/Ca-incorporated Ni-rich L-NCM cathode improves markedly (72.4%), whereas the bare Ni-rich L-NCM material only retains 44.3% of its capacity after 100 cycles.

Origins and Importance of Intragranular Cracking in Layered Lithium Transition Metal Oxide Cathodes.

Li-ion batteries have a pivotal role in the transition toward electric transportation. Ni-rich layered transition metal oxide (LTMO) cathode materials promise high specific capacity and lower cost but exhibit faster degradation compared with lower Ni alternatives. Here, we employ high-resolution electron microscopy and spectroscopy techniques to investigate the nanoscale origins and impact on performance of intragranular cracking (within primary crystals) in Ni-rich LTMOs. We find that intragranular cracking is widespread in charged specimens early in cycle life but uncommon in discharged samples even after cycling. The distribution of intragranular cracking is highly inhomogeneous. We conclude that intragranular cracking is caused by local stresses that can have several independent sources: neighboring particle anisotropic expansion/contraction, Li- and TM-inhomogeneities at the primary and secondary particle levels, and interfacing of electrochemically active and inactive phases. Our results suggest that intragranular cracks can manifest at different points of life of the cathode and can potentially lead to capacity fade and impedance rise of LTMO cathodes through plane gliding and particle detachment that lead to exposure of additional surfaces to the electrolyte and loss of electrical contact.

Surface reactivity versus microcracks in Ni-rich layered oxide cathodes: Which is critical for long cycle life？

Capacity fading of Ni-rich cathode is thought to originate from the formation of inactive rock-salt phase induced by surface reactivity and the isolation of active material caused by microcracks due to anisotropic volume contraction of grains. It is generally assumed that inhibiting the formation of microcracks within secondary particle by radially aligned microstructure is a vital aspect for suppressing capacity fading. However, the new researches about reduction of microcracks simply by certain electrolytes call a question on the origin of microcracks and the critical factor for the cycle life of cathodes. Herein, LiNi0.92Co0.04Mn0.04O2 cathodes with different surface characteristic and radially aligned microstructure were synthesized by doping with high valence elements using some hydroxide precursor. The effects of W6+ and/or Mo6+ induced surface phase and microstructure on electrochemical performance were investigated. Despite the inferior radially aligned, size-refined primary grains and higher degree of microcracks, W6+ doped cathode still possesses alleviated parasitic reactions, higher crystal structural stability and capacity retention than Mo6+ doped materials, because of the enhanced cathode-electrolyte interfacial stability. The results contend that the consequence of surface reactivity on determining cycle life of Ni-rich cathodes is more critical than that of microcracks, and efforts relating to constructing intact and uniform stable surface phase will exhibit greater potential to promote the performance of Ni-rich cathodes than microstructural refinement.

Advancements in Addressing Microcrack Formation in Ni–Rich Layered Oxide Cathodes for Lithium–Ion Batteries

AbstractNickel–rich layered oxides of LiNi1–x–yCoxMn(Al)yO2 (where 1–x–y>0.6) are considered promising cathode active materials for lithium‐ion batteries (LIBs) due to their high reversible capacity and energy density. However, the widespread application of NCM(A) is limited by microstructural degradation caused by the anisotropic shrinkage and expansion of primary particles during the H2→H3 phase transition. In this mini–review, we comprehensively discuss the formation of microcracks, subsequent material degradation, and related alleviation strategies in nickel–rich layered NCM(A). Firstly, theories on microcracks′ formation and evolution mechanisms are presented and critically analyzed. Secondly, recent advancements in mitigation strategies to prevent degradation in Ni–rich NCM/NCA are highlighted. These strategies include doping, surface coating, structural optimization, and morphology engineering. Finally, we provide an outlook and perspective to identify promising strategies that may enable the practical application of Ni–rich NCM/NCA in commercial settings.

Effective incorporation of cobalt near surface region for cobalt-free cathodes in lithium-ion batteries

Cobalt-free cathode materials, particularly Ni-rich layered oxide cathode materials, are ideal for electric vehicle Li-ion batteries, offering high energy density and cost-effectiveness. However, high Ni content in high-temperature synthesis leads to issues like increased Li/Ni cation mixing and reduced rate capability, mainly due to the absence of Co. Therefore, this study investigated the utilization of a small amount of Co instead of completely removing it to enhance electrochemical performance. A simple pre-calcination process was used to induce Co substitution beneath the Ni-rich layered oxide cathode materials surface. A coating process was also performed for comparison. The Li/Ni cation mixing in the Co-substituted sample during high-temperature calcination was 2.43%, demonstrating a superior value compared to the Co-coating process. Rate capability tests showed superior performance for Co-substituted sample (164.2 mAh g−1) at 2 C compared to coated sample (151.0 mAh g−1). Moreover, Co substitution improved not only the cycle stability but also the high-temperature stability at an elevated state of charge.This study focuses on the surface modification of cobalt-free cathode, providing direct insight into the effects of Co substitution and typical Co coating and suggests an optimal process that uses small amounts of Co.

Regulating interfacial chemistry and kinetic behaviors of F/Mo co-doping Ni-rich layered oxide cathode for long-cycling lithium-ion batteries over −20 °C–60 °C

Ni-rich layered oxide cathodes have shown promise for high-energy lithium-ion batteries (LIBs) but are usually limited to mild environments because of their rapid performance degradation under extreme temperature conditions (below 0 °C and above 50 °C). Here, we report the design of F/Mo co-doped LiNi0.8Co0.1Mn0.1O2 (FMNCM) cathode for high-performance LIBs from −20 to 60 °C. F– doping with high electronegativity into the cathode surface is found to enhance the stability of surface lattice structure and protect the interface from side reactions with the electrolyte by generating a LiF-rich surface layer. Concurrently, the Mo6+ doping suppresses phase transition, which blocks Li+/Ni2+ mixing, and stabilizes lithium-ion diffusion pathway. Remarkably, the FMNCM cathode demonstrates excellent cycling stability at a high cutoff voltage of 4.4 V, even at 60 °C, maintaining 90.6% capacity retention at 3 C after 150 cycles. Additionally, at temperatures as low as −20 °C, it retains 77.1% of its room temperature capacity, achieving an impressive 97.5% capacity retention after 500 cycles. Such stable operation under wide temperatures has been further validated in practical Ah-level pouch-cells. This study sheds light on both fundamental mechanisms and practical implications for the design of advanced cathode materials for wide-temperature LIBs, presenting a promising path towards high-energy and long-cycling LIBs with temperature adaptability.

In situ and Real-time Monitoring the Chemical and Thermal Evolution of Lithium-ion Batteries with Single-crystalline Ni-rich Layered Oxide Cathode.

High-capacity Ni-rich layered oxides are promising cathode materials for fabrication of lithium-ion batteries (LIBs) with high energy density. However, thermal runaway of LIBs with these cathodes leads to great safety concerns. In this study, single crystalline LiNi0.9Co0.05Mn0.05O2 (NCM-SC) has been prepared and a flexible optical fiber was buried inside the pouch-type LIBs with NCM-SC cathode to in situ study its real-time temperature evolution during charge/discharge process. NCM-SC exhibits an enhanced Li+ ions transportation efficiency and electrode reaction kinetics, which can effectively reduce the generation of polarization heat and mitigate the internal temperature rise of the pouch-type battery. Meanwhile, solid-electrolyte interface (SEI) film decomposition and gas accumulation are effectively alleviated, due to the enhanced thermal stability of SEI film formed on NCM-SC. Moreover, the single crystal architecture can effectively retard layered to spinal and rock-salt phase transition, mitigate the crack formation and structural collapse. Consequently, NCM-SC exhibits an excellent electrochemical performance and enhanced thermal stability.

Jahn-Teller Distortions and Phase Transitions in LiNiO2: Insights from Ab Initio Molecular Dynamics and Variable-Temperature X-ray Diffraction.

The atomistic structure of lithium nickelate (LiNiO2), the parent compound of Ni-rich layered oxide cathodes for Li-ion batteries, continues to elude a comprehensive understanding. The common consensus is that the material exhibits local Jahn-Teller distortions that dynamically reorient, resulting in a time-averaged undistorted R3̅m structure. Through a combination of ab initio molecular dynamics (AIMD) simulations and variable-temperature X-ray diffraction (VT-XRD), we explore Jahn-Teller distortions in LiNiO2 as a function of temperature. Static Jahn-Teller distortions are observed at low temperatures (T < 250 K) via AIMD simulations, followed by a broad phase transition that occurs between 250 and 350 K, leading to a highly dynamic, displacive phase at high temperatures (T > 350 K), which does not show the four short and two long bonds characteristic of local Jahn-Teller distortions. These transitions are followed in the AIMD simulations via abrupt changes in the calculated pair distribution function and the bond-length distortion index and in X-ray diffraction via the monoclinic lattice parameter ratio, amon/bmon, and δ angle, the fit quality of an R3̅m-based structural refinement, and a peak sharpening of the diffraction peaks on heating, consistent with the loss of distorted domains. Between 250 and 350 K, a mixed-phase regime is found via the AIMD simulations where distorted and undistorted domains coexist. The repeated change between the distorted and undistorted states in this mixed-phase regime allows the Jahn-Teller long axes to change direction. These pseudorotations of the Ni-O long axes are a side effect of the onset of the displacive phase transition. Antisite defects, involving Li ions in the Ni layer and Ni ions in the Li layer, are found to pin the undistorted domains at low temperatures, impeding cooperative ordering at a longer length scale.

Constructing Matching Cathode-Anode Interphases with Improved Chemo-mechanical Stability for High-Energy Batteries.

Coupling Ni-rich layered oxide cathodes with Si-based anodes is one of the most promising strategies to realize high-energy-density Li-ion batteries. However, unstable interfaces on both cathode and anode sides cause continuous parasitic reactions, resulting in structural degradation and capacity fading of full cells. Herein, lithium tetrafluoro(oxalato) phosphate is synthesized and applied as a multifunctional electrolyte additive to mitigate irreversible volume swing of the SiOx anode and suppress undesirable interfacial evolution of the LiNi0.83Co0.12Mn0.05O2 (NCM) cathode simultaneously, resulting in improved cycle life. Benefiting from its desirable redox thermodynamics and kinetics, the molecularly tailored additive facilitates matching interphases consisting of LiF, Li3PO4, and P-containing macromolecular polymer on both the NCM cathode and SiOx anode, respectively, modulating interfacial chemo-mechanical stability as well as charge transfer kinetics. More encouragingly, the proposed strategy enables 4.4 V 21700 cylindrical batteries (5 Ah) with excellent cycling stability (92.9% capacity retention after 300 cycles) under practical conditions. The key finding points out a fresh perspective on interfacial optimization for high-energy-density battery systems.

Unravelling the peculiar role of Co and Al in highly Ni-rich layered oxide cathode materials

Currently, the limited availability of cobalt resources has had a negative impact on the progress of commercial batteries, prompting the development of cobalt-free Ni-rich cathodes. However, the complete replacement of cobalt has faced challenges due to the lack of understanding the influence of dopants on cathode material performance. In this study, we aimed to address this knowledge gap by designing and preparing LiNi0.95Co0.05-xAlxO2 (x = 0.00, 0.01, 0.02, 0.03, 0.04, and 0.05) cathode materials. The impact of cobalt and aluminum doping on the morphology, crystallographic structure and electrothermal performance of Ni-rich cathode materials has been systematically investigated. Our findings confirmed the significant role of cobalt in increasing energy density and mitigating cationic disordering. However, it is found that cobalt doping contributes to the release of lattice oxygen during cycling, leading to rapid capacity fading. Conversely, aluminum doping could stabilize the crystal structure of the cathode material, resulting in slower capacity degradation. Furthermore, the substitution of aluminum effectively mitigates the crystal growth during the synthesis of highly Ni-rich cathode materials, leading to a reduced Li+ diffusion length and thereby excellent rate performance. Specifically, LiNi0.95Al0.05O2 could deliver a high discharge capacity of around 163 mAh g−1 at 10C. This study provides valuable insights for the design of cobalt-free Ni-rich cathodes and sheds light on the possibility of cobalt elimination.

Interpretable Machine Learning To Accelerate the Analysis of Doping Effect on Li/Ni Exchange in Ni-Rich Layered Oxide Cathodes.

In Ni-rich layered oxide cathodes, one effective way to adjust the performance is by introducing dopants to change the degree of Li/Ni exchange. We calculated the formation energy of Li/Ni exchange defects in LiNi0.8Mn0.1X0.1O2 with different doping elements X, using first-principles calculations. We then proposed an interpretable machine learning method combining the Random Forest (RF) model and the Shapley Additive Explanation (SHAP) analysis to accelerate identification of the key factors influencing the formation energy among the complex variables introduced by doping. The valence state of the doping element effectively regulates Li/Ni exchange defects through changing the valence state of Ni and the strength of the superexchange interaction, and COOPSU-SD and MagO were proposed as two indicators to assess superexchange interaction. The volume change also affects the Li/Ni exchange defects, with a larger volume reduction corresponding to fewer Li/Ni exchange defects.

Enhancing the long-term cycling stability of Ni-rich cathodes via regulating the length/width ratio of primary particle

Ni-rich layered oxide cathode materials are promising candidates for high-specific-energy battery systems owing to their high reversible capacity. However, their widespread application is still severely impeded by severe capacity loss upon long-term cycling. It has been proven that the cyclic stability of Ni-rich cathode materials is closely related to their microstructure and morphology. Despite this, the influence of the microstructure of primary particles on the fatigue mechanism of Ni-rich cathode materials during prolonged cycling has not been fully understood. Here, two Ni-rich layered spherical agglomerate oxides consisting of the primary particle with different length/width ratios are successfully synthesized. It is found that the long-term structural stability of both materials strongly depends on the microstructure of primary crystallites, although there is no significant difference between the electrochemical and crystalline characteristics during the initial cycle. A higher primary particle length/width ratio could effectively inhibit the accumulation of microcracks and chemical degradation during long-term cycling, thereby promoting the electrochemical performance of the cathode materials (80% capacity retention after 200 cycles at 1 C compared to the 55% of the counterpart with a lower primary particle length/width ratio). This study highlights the structure-activity relationship between the primary particle microstructure and fatigue mechanisms during long-term cycling, thereby advancing the development of Ni-rich cathode materials.

Challenges and opportunities using Ni-rich layered oxide cathodes in Li-ion rechargeable batteries: the case of nickel cobalt manganese oxides

Doping, coating, surface modification, formation of composites and control of crystalline orientation can control the capacity retention of Ni-rich cathodes. Furthermore, the design of Co-free Ni-rich cathodes may provide a cost-effective solution.

Solvent-Driven Degradation of Ni-Rich Cathodes Probed by Operando Gas Analysis

High-capacity Ni-rich layered metal oxide cathodes are highly desirable to increase the energy density of lithium-ion batteries. However, these materials suffer from poor cycling stability, which is exacerbated by increased cell voltage due to higher interfacial reactivity than their lower Ni-content analogues. Here, we study the pivotal role of electrolyte solvents in determining the interfacial reactivity at charged LiNi0.33Mn0.33Co0.33O2 (NMC111) and LiNi0.8Mn0.1Co0.1O2 (NMC811) cathodes by using both single-solvent model electrolytes and the mixed solvents used in commercial cells (1, 2). Operando gas analysis reveals that the solvent-dependent reactivity for Ni-rich cathodes is related to the extent of lattice oxygen release and accompanying electrolyte oxidation. We demonstrate here the detrimental effect of ethylene carbonate (EC), a core component in conventional electrolytes, when NMC811 is charged above 4.3 V vs Li/Li+ - the observed onset potential for lattice oxygen release. Oxygen loss is enhanced by EC-containing electrolytes and correlates with more electrolyte oxidation/breakdown and cathode surface degradation, which increase concurrently above 4.4 V. The gas analysis also reveals the crosstalk effect caused by the products of the nascent oxygen from the NMC811 lattice and the electrolyte solvent, showing anodic reactivity. In contrast, NMC111, which does not release oxygen up to 4.6 V, shows a similar extent of degradation irrespective of the electrolyte. Higher lattice oxygen release with EC-containing electrolytes is coupled with higher interfacial impedance, a thicker oxygen-deficient rock-salt surface reconstruction layer, more electrolyte solvent and salt breakdown. Oxygen loss is suppressed in the EC-free electrolyte, highlighting the incompatibility between Ni-rich cathodes and conventional electrolyte solvents. W. M. Dose et al., Onset Potential for Electrolyte Oxidation and Ni-Rich Cathode Degradation in Lithium-Ion Batteries. ACS Energy Letters 7, 3524-3530 (2022).W. M. Dose et al., Electrolyte Reactivity at the Charged Ni-Rich Cathode Interface and Degradation in Li-Ion Batteries. ACS Applied Materials & Interfaces 14, 13206-13222 (2022). Figure 1