Battery Chemistries Research Articles

The role of cathode architecture and anion interactions on the performance of Al-substituted α-Ni(OH)2 in rechargeable Ni–Zn cells

Rechargeable alkaline Ni–Zn batteries configured with Zn sponge anodes provide an energy dense, safe alternative to Li-ion batteries for a wide range of risk-averse applications. Advanced cathodes that provide high rate and capacity performance are needed to match that of Zn sponge anodes. We show that aluminum-substituted nickel hydroxide, α-Ni0.9Al0.1(OH)2, expressed in a nanosheet morphology, can be directly deposited onto a flexible carbon nanofiber paper (CNP) using a rapid and scalable two-step microwave-assisted hydrothermal reaction. The architected electrode (α-Ni0.9Al0.1(OH)2@CNP) wires the energy-storing Ni to the carbon scaffold, resulting in high capacity and stable cycling in Ni–Zn cells, performance not obtained using conventional powder-composite cathodes. The growth reaction time and temperature influence mass loading, thickness, crystal structure, the ratio of interlayer ‘free’-to-lattice metal-coordinated ‘bound’ nitrates, and electrochemical performance. The architected α-Ni0.9Al0.1(OH)2@CNP||Zn sponge alkaline cell provides unprecedented performance, delivering high discharge capacity, storage of >1.4 electrons per Ni, good rate capability, excellent capacity retention, and high mass loading. Architected electrodes that combine 3D electronic wiring and structured active material provide a pathway to energy dense, safe, rechargeable Ni–Zn batteries and offer approaches to improve the electrochemical performance of a broad class of layered materials for multiple battery chemistries.

Thermo-electrochemical level-set topology optimization of a heat exchanger for lithium-ion batteries for electric vertical take-off and landing vehicles

Developing electric vertical take-off and landing vehicles (eVTOL) that can meet the demanding power and energy requirements entails significant challenges, one of which is due to the weight of the battery packs. To address this challenge, optimization techniques can be employed to achieve lightweight designs while satisfying thermal criteria. This study focuses on optimizing a battery heat exchanger housing a high-energy-densitycylindrical cell using the level-set topology optimization method. To accurately account for heat generation from battery electrochemistry, we investigate both a high-fidelity, the Doyle Fuller Newman (DFN) model, and a low-fidelity electrochemical model, the Single Particle Model (SPM), which are compared to experimental results for an eVTOL flight profile. The novelty of the proposed approach resides in the integration of the electrochemical models within a three-dimensional unsteady thermo-electrochemical topology optimization framework. The battery heat exchanger is optimized considering the heat generated by the batteries at the material scale due to the system power requirements. The heat generated by the battery is incorporated as a source term in an unsteady heat conduction finite element model, forming the basis of the optimization process. Our objective is to minimize the integrated thermal compliance over time while satisfying a volume constraint, employing the level-set method. The SPM proves competent in predicting the voltage profile but underestimates the temperature increase. On the other hand, the DFN model accurately predicts both the temperature increase and the voltage profile, making it suitable for the thermal analysis of cells in eVTOL vehicles. Surprisingly, steady-state optimization turns out to be sufficient to generate optimized topologies that perform similarly to transient cases for the case investigated but at a reduced cost. By integrating electrochemical modeling, level-set topology optimization, and heat transfer analysis, our study contributes to the development of lightweight and thermally efficient battery heat exchangers for eVTOL vehicles, which can be extended to battery packs. Importantly, the presented methodology is versatile and can be applied to different battery chemistries, form factors, and power profiles.

Regulating the Gibbs Free Energy to Design Aqueous Battery‐Compatible Robust Host

AbstractLow‐cost, high‐voltage‐platform, and high‐capacity MnO2 is the most promising cathode candidate for developing high‐energy‐density aqueous zinc‐ion batteries. However, the Buckets effect of runaway phase transition and irreversible dissolution restricts the electrochemical performance of MnO2. To address this issue, this report presents a bottom‐up targeted assembly concept driven by Gibbs free energy for the design of a robust Ni‐MnO2‐xFx host via Ni2+ pre‐intercalation coupled with fluorine doping. The Gibbs free energy of the host is regulated by the coordination of interlayer reinforcement and interfacial defect repair, which prevents the “layer‐to‐spinel” transition and inhibits dissolution during long‐term cycling. As expected, this cathode provides superior H+/Zn2+ storage performance across a wide temperature range. A capacity of 180.4 mAh g−1 is retained after 1000 cycles at 2 A g−1, a high specific capacity of 293.9 mAh g−1 is retained after 250 cycles at 50 °C and 2 A g−1, and a capacity of 144.5 mAh g−1 is retained after 3000 cycles at 0 °C and 0.5 A g−1. This work provides new insights into the design of stable aqueous battery‐compatible hosts for aqueous zinc‐ion batteries as well as other battery chemistries.

In situ designing an implanted hetero-interface of high adsorption energy in composite lithium anode towards high−rate lithium metal batteries

Lithium metal is considered as the ultimate anode material for next-generation Li based battery chemistries. The constituted lithium metal batteries (LMBs) specialize in high energy density, but the inherent dendritic lithium growth as well as the serious proliferation of native solid electrolyte interphase (SEI) have been impeding their practical application, in particular under the high-rate conditions of a more concentrated Li+ flux. Herein, we report a composite anode design, in which LiF/LiC as the products of the in situ spontaneous reductive defluorination between Li and poly(tetrafluoroethylene) (PTFE) are uniformly implanted in bulk metallic Li via facile mechanical kneading. The macroscopical composite anode creates a dispersion of lithiophilic nanodomains microscopically in bulk. The built-in LiF/LiC doping of high Li adsorption energy improves the affinity towards Li+ flux and avoids the Li+-adhesion-induced Li aggregation. The construction facilitates a dense while large granular plating as well as the generation of a thin, inorganic-rich SEI to synergistically ensure a dendrite-free Li deposition behavior. The improved plating reversibility and cycling stability are verified in forms of both symmetric cell under harsh conditions up to 30 mA cm−2@30 mAh cm−2 and high-areal-capacity Li||LiFeO4 full cell for 500 cycles at 3 C. This not only expands the state-of-the-art LMBs under high-loading and power-intensive scenarios, but also preliminarily evidences its scalable and industry-adaptable potential.

Toward Safe and Reliable Aqueous Ammonium Ion Energy Storage Systems

AbstractAqueous batteries using non‐metallic charge carriers like proton (H+) and ammonium (NH4+) ions are becoming more popular compared to traditional metal‐ion batteries, owing to their enhanced safety, high performance, and sustainability (they are ecofriendly and derived from abundant resources). Ammonium ion energy storage systems (AIBs), which use NH4+ ions with tetrahedral geometry, a small hydrated ionic radius, and relatively low ionic weight, are emerging as strong candidates in non‐metal ion battery chemistry. Various electrode materials (both inorganic and organic) are investigated as hosts for NH4+ ions, however, a comprehensive understanding of these mechanisms is still lacking. This gap limits the ability to optimize performance and identify further research opportunities in AIBs. In this review, the charge storage mechanisms in AIBs are discussed, offering insights into the interactions between NH4+ ions and different electrode materials. Additionally, existing literature on electrode materials, highlighting key structural, and electrochemical achievements are summarized. The review also outlines various electrolytes and examines how their properties influence AIB performance. Finally, the shortcomings of current research are discussed and potential solutions are suggested to advance AIB technology, with the goal of inspiring researchers to explore real‐world applications for ammonium ion batteries.

Battery Electrolyte Design for Electric Vertical Takeoff and Landing (eVTOL) Platforms

AbstractThe development of robust and high‐performance battery systems is crucial for the advancement of Electric Vertical Takeoff and Landing (eVTOL) vehicles for urban air mobility. This study evaluates the performance of different lithium‐ion battery chemistries under Electric Vertical Takeoff and Landing (eVTOL) load profiles. The actual flight data coupled with physical models is used to create discharge profiles for testing on developed lithium‐ion cells for eVTOLs. The performance of a standard liquid electrolyte (1.2 M LiPF6 in EC:EMC), labeled Gen‐2, is benchmarked and compared with a fast‐charging electrolyte (1.2 M LiFSI in EC:EMC), labeled XFC. Cell analysis involves the use of various techniques, such as impedance spectroscopy, polarization curves, and capacity retention measurements. Capacity retention is stable for both systems over 500 cycles, but unique discharge capacity trends are observed for different mission segments. During the initial takeoff hover stages, Gen‐2 electrolytes experience substantial voltage fade, while XFC electrolytes maintain consistent behavior. In general, the Gen‐2 electrolyte demonstrated lower discharge overpotentials and higher decay during cycling compared to the XFC electrolyte. This work highlights the complexity of eVTOL battery behavior and provides insights into battery system design, contributing to the advancement of battery energy storage solutions for urban air mobility.

Challenges and Perspectives for Direct Recycling of Electrode Scraps and End‐of‐Life Lithium‐ion Batteries

AbstractThe growing demand and production of lithium‐ion batteries (LIBs) have led to a critical concern regarding their resources and end‐of‐life management. Consequently, LIB recycling has emerged as a prominent topic in academia and in industries, driven by new worldwide governmental regulations and the increasing gap between the supply and demand of critical and strategic raw materials. Widely considered as a more sustainable and cheaper recycling method compared to pyrometallurgy and hydrometallurgy, direct recycling currently grabs the spotlight. This perspective provides insights and outlooks on the chemical and technological challenges of the innovative direct recycling approach for LIBs, addressing both the production scraps and batteries at their end‐of‐life (EOL). Technological advancements, changes in battery chemistry, along with the LIB market dynamics and collaborations between battery makers and recyclers, are key drivers of LIB waste recycling. While production scraps lend themselves well to direct recycling, EOL batteries encounter challenges in adopting this novel recycling technology. Besides, the need to assess novel direct recycling processes using Life Cycle Assessment (LCA) is also important for identifying eco‐design strategies and optimizing the processes, leading to a more sustainable energy storage system.

Zinc‐Ion Battery Chemistries Enabled by Regulating Electrolyte Solvation Structure

AbstractDesigning next‐generation alternative energy storage devices that feature high safety, low cost, and long operation lifespan is of the utmost importance for future wide range of applications. Aqueous zinc‐ion batteries play a vital part in promoting the development of portability, sustainability, and diversification of rechargeable battery systems. Based on the theory of electrolyte solvation chemistry, deep understanding of interaction between electrolyte components and their impact on the chemical properties has achieved a series of research progress. Analyzing the solvation shell of electrolyte or structure–performance relationship, and establishing more stable and high‐energy battery chemistries are inevitable requirements to suppress the electrolyte–electrode interphase side reaction and realize the functional use of zinc‐ion batteries. In this critical review, the attempt is to overview the current comprehension regarding the electrolyte solvation structure in zinc battery technology. Advanced methodology toward the interactions between zinc cations, solvent molecules, and anions in zinc aqueous electrolytes and the general rules for electrolyte design from the atomic level are summarized. Methods for viable solvation modification are then introduced regarding overcoming the remained challenges for transferring the laboratory results to next‐generation practical applications. Possible research direction with the aim of investigating the ultimate choice for future high‐performance electrolyte solvation construction is also outlined.

Projecting future critical material demand and recycling from China's electric passenger vehicles considering vehicle segment heterogeneity

Critical factors like electric vehicle market penetration, battery chemistry, and battery capacity determine future critical material demand and recycling potential from electric vehicles. However, current studies largely ignored the heterogeneity among vehicle segments. This study introduces a vehicle-model-based big-data driven approach to unveil electric vehicle characteristics at fleet-wide and vehicle-segment levels. Further, a bottom-up model was built to project the battery material flow dynamics in 8 scenarios, identifying middle and large vehicle segments as primary contributors. In the Business-As-Usual (BAU) scenario, demand for lithium, nickel, cobalt, and manganese by 2050 will reach 182, 447, 61, and 44 kt, respectively, with recycled materials meeting 59 %, 58 %, 60 %, and 57 % of demand. The demand and recycling of critical materials have significant inherent uncertainty, with demand potentially fluctuating from one-quarter to twice the BAU level. Policies can greatly reduce primary resources for critical materials by guiding battery usage preferences and promoting recycling.

Noncombustible gel polymer electrolyte inspired by bio-radical chemistry for high voltage and high safety Ni-rich lithium batteries

For high energy density lithium-ion batteries (LIBs) with nickel-rich ternary cathodes, the chemical degradation of electrolytes caused by free radical reactions and the hazards of thermal runaway have always been significant challenges. Inspired by the free radical scavenging of living organisms and multiphase synergistic flame retardant mechanism, we innovatively designed and prepared a multifunctional flame retardant HCCP-TMP that combines flame retardancy and free radical scavenging by combining hindered amine and cyclophosphazene. Only 1 wt% HCCP-TMP can make the polyacrylate-based gel polymer electrolyte (GPE) incombustible. Moreover, the equipped NCM811//Graphite pouch cells don't exhibit combustion behavior after thermal runaway and can resist mechanical abuse. Based on the above noncombustible GPE, the NCM811//Li battery exhibits capacity retention rate of 82.2 % after 100 cycles at a current density of 2 C and in the voltage range of 3.0–4.7 V, exhibiting excellent cyclability under high voltage. This simple molecular design simultaneously improves the fire safety and high voltage stability, demonstrating enormous application potential in the field of advanced LIBs with high safety and high energy density.

From Bulk to Interface: Solvent Exchange Dynamics and Their Role in Ion Transport and the Interfacial Model of Rechargeable Magnesium Batteries.

Multivalent battery chemistries have been explored in response to the increasing demand for high-energy rechargeable batteries utilizing sustainable resources. Solvation structures of working cations have been recognized as a key component in the design of electrolytes; however, most structure-property correlations of metal ions in organic electrolytes usually build upon favorable static solvation structures, often overlooking solvent exchange dynamics. We here report the ion solvation structures and solvent exchange rates of magnesium electrolytes in various solvents by using multimodal nuclear magnetic resonance (NMR) analysis and molecular dynamics/density functional theory (MD/DFT) calculations. These magnesium solvation structures and solvent exchange dynamics are correlated to the combined effects of several physicochemical properties of the solvents. Moreover, Mg2+ transport and interfacial charge transfer efficiency are found to be closely correlated to the solvent exchange rate in the binary electrolytes where the solvent exchange is tunable by the fraction of diluent solvents. Our primary findings are (1) most battery-related solvents undergo ultraslow solvent exchange coordinating to Mg2+ (with time scales ranging from 0.5 μs to 5 ms), (2) the cation transport mechanism is a mixture of vehicular and structural diffusion even at the ultraslow exchange limit (with faster solvent exchange leading to faster cation transport), and (3) an interfacial model wherein organic-rich regions facilitate desolvation and inorganic regions promote Mg2+ transport is consistent with our NMR, electrochemistry, and cryogenic X-ray photoelectron spectroscopy (cryo-XPS) results. This observed ultraslow solvent exchange and its importance for ion transport and interfacial properties necessitate the judicious selection of solvents and informed design of electrolyte blends for multivalent electrolytes.

Base-Driven Ring-Opening Reactions of Vinylene Carbonate

Vinylene carbonate (VC) is the most commonly applied performance-enhancing electrolyte additives in Li-ion batteries to date. Despite numerous studies, there is a lack of consensus regarding the various reaction pathways of VC and their implications. VC has primarily been observed to either polymerize forming poly(vinylene carbonate) (poly(VC)) or decompose releasing major amounts of CO2, two seemingly contradictory processes. Herein, we present evidence of additional reaction pathways of VC highlighting its role as a H2O scavenging agent. In contrast to the typical electrolyte solvent ethylene carbonate, VC reacts much more rapidly with water impurities, especially when in contact with hydroxides, forming products less likely to influence cell performance. Efficient removal of water and hydroxides is essential to preserve the stability of Li-ion electrolyte solvent and salt, hence guaranteeing a long lifetime of the battery. Model studies pinpointing reaction pathways of electrolytes and additives, as presented herein, are critical not only to improve modern Li-ion cells but also to establish design principles for future battery chemistries.

Comparison of lithium sources on the electrochemical performance of LiNi0.5Mn1.5O4 cathode materials for lithium-ion batteries

In order to fulfill the demand for high energy and capacity, an electrode with high-voltage capability, namely LiNi0.5Mn1.5O4 (LNMO) that has an operating potential of up to 4.7 V vs Li/Li+, is currently becoming popular in Li-ion battery chemistries. This research produced LNMO by using a solid-state method with only one-step synthesis route to compare its electrochemical performance with different lithium sources, including hydroxide (LNMO-LiOH), acetate (LNMO-LiAce), and carbonate (LNMO-LiCar) precursors. TGA/DSC was first performed for all three sample precursors to ensure the optimal calcination temperature, while XRD and SEM characterized the physical properties. The electrochemical measurements, including cyclic voltammetry and charge-discharge, were conducted in the half-cell configurations of LNMO//Li-metal using a standard 1 M LiPF6 electrolyte. LNMO-LiOH samples exhibited the highest purity and the smallest particle size, with values of 93.3% and 418 nm, respectively. In contrast, samples with higher impurities, such as LNMO-LiCar, mainly in the form of LixNi1-xO (LiNiO), displayed the largest particle size. The highest working voltage possessed by LNMO-LiOH samples was 4.735 V vs Li/Li+. The results showed that LNMO samples with LiNiO impurities would affect the reaction behavior that occurs at the cathode-electrolyte interface during the release of lithium-ions, resulting in high resistance at the battery operations and decreasing the specific capacity of the LNMO during discharging. The highest value, shown by LNMO-LiOH, was up to 92.75 mAh/g. On the other side, LNMO-LiCar only possessed a specific capacity of 44.57 mAh/g, indicating a significant impact of different lithium sources in the overall performances of LNMO cathode.

Multifunctional Dual‐Metal‐Salt Derived Ternary Eutectic Electrolyte for Highly Reversible Zinc Ion Battery

AbstractDeep eutectic electrolytes offer opportunities for tailoring solvation structure and interface chemistry in advanced batteries, but developing deep eutectic electrolytes for high‐performance zinc ion batteries (ZIBs) remains a challenge. Herein, multifunctional dual‐metal‐salt derived ternary eutectic electrolytes (DMEEs) are designed via a supporting salt strategy for dendrite‐free and long‐lifespan ZIBs. DMEEs are constructed by zinc trifluoromethanesulfonate (Zn(OTF)2), supporting salt of lithium bis(trifluoromethanesulfonyl)imide, and neutral ligand of N‐methylacetamide. Noticeably, supporting salt with weak lattice energy not only induces the reconstruction of intermolecular interactions to form ion pairs and ion aggregates but also tailors the Zn2+ solvation structure and solid electrolyte interface (SEI). The developed DMEEs possess a dual‐anion‐rich Zn2+ solvation shell and induce an inorganic‐rich hybrid SEI, which effectively suppresses side reactions and obtains a dendrite‐free Zn anode with high reversibility. Remarkably, Zn//Zn cells demonstrate cycling stability for over 3000 h, and Zn//PANI full cells deliver no significant capacity decay after 5000 cycles at a high current density of 5 A g−1. This work opens a new avenue to design advanced deep eutectic electrolytes, and the deep understanding of solvation structure and SEI offers guidelines for developing high‐performance batteries.

Persistent organonickel complexes as general platforms for Csp2-Csp3 coupling reactions.

The importance of constructing Csp2-Csp3 bonds has motivated the development of electrochemical, photochemical and thermal activation methods to reductively couple abundant aryl and alkyl electrophiles. However, these methodologies are limited to couplings of very specific substrate classes and require specialized sets of catalysts and reaction set-ups. Here we show a consolidation of these myriad strategies into a single set of conditions that enable reliable alkyl-aryl couplings, including those that were previously unknown. These reactions rely on the discovery of unusually persistent organonickel complexes that serve as stoichiometric platforms for C(sp2)-C(sp3) coupling. Aryl, heteroaryl or vinyl complexes of Ni can be inexpensively prepared on a multigram scale by mild electroreduction from the corresponding C(sp2) electrophile. Organonickel complexes can be isolated and stored or telescoped directly to reliably diversify drug-like molecules. Finally, the procedure was miniaturized to micromole scales by integrating soluble battery chemistries as redox initiators, enabling a high-throughput exploration of substrate diversity.

Assessing performance in lithium-ion batteries recycling processes: A quantitative modeling perspective

In the shift toward sustainable energy solutions, the efficiency of lithium-ion battery (LIB) recycling within the supply chain is of paramount importance. This study evaluates the performance of LIB recycling processes by advancing a quantitative modeling approach. Through process simulations, a comprehensive assessment of pyrometallurgical and hydrometallurgical LIB recycling processes is presented by focusing on the key parameters that influence material recoveries and yields. Recycling efficiency indicators, accounting for the quantity and quality of recycled materials, are introduced and their dependence on the share of different battery chemistries and formats in the spent batteries feed is assessed via numerical simulations. A sensitivity analysis of process parameters identifies the unit operations mostly affecting the recycling performance, highlighting process criticalities. The model presented and its outcomes provide a valuable guide for stakeholders in the LIB industry, aiding informed decision-making to enhance sustainability and resource recovery in the ecosystem of electrochemical energy storage.

Dual-gate design enables intrinsic safety of high-energy batteries

The safety issue hampers the application of high-energy lithium-ion batteries in electric vehicles, grid energy storage, electric ships and aircrafts. The chemical cross-talk, which refers to the migration of energetic intermediates between cathode and anode, initiates battery self-heating and accelerates the intensive heat release during battery thermal failure. However, blocking the chemical cross-talk is extremely hard. Previously, we may expect a thermally stable separator can guard the gate between battery cathode and anode, however, large amount of hot gas breaks the defense mechanically not thermally. Draining the cross-talk gas is of equal importance with blocking it. Herein, a dual-gate design notion is proposed, using separator as “block gate” and vent valve as “removal gate” to regulate the spatial distribution of energetic species to reduce the major heat release during battery thermal runaway. The design is validated by more than 50 battery chemistries. Typically, the maximum temperature of NMC811||Gr pouch cell decreases from >800 °C to <300 °C, the highest temperature rising rate decreases from 761.0 °C/s to 0.013 °C/s. The morphology and crystalline change of cathode verify that the chemical cross-talk is successfully suppressed. Moreover, such design has little side effect on the electrochemical performance of batteries. The dual-gate design breaks the bottleneck for the safety design of high energy batteries, providing insight into the safe utilization of electrochemical energy storage materials.

Facile Lithium Densification Kinetics by Hyperporous/Hybrid Conductor for High-Energy-Density Lithium Metal Batteries.

Lithium metal anode (LMA) emerges as a promising candidate for lithium (Li)-based battery chemistries with high-energy-density. However, inhomogeneous charge distribution from the unbalanced ion/electron transport causes dendritic Li deposition, leading to "dead Li" and parasitic reactions, particularly at high Li utilization ratios (low negative/positive ratios in full cells). Herein, an innovative LMA structural model deploying a hyperporous/hybrid conductive architecture is proposed on single-walled carbon nanotube film (HCA/C), fabricated through a nonsolvent induced phase separation process. This design integrates ionic polymers with conductive carbon, offering a substantial improvement over traditional metal current collectors by reducing the weight of LMA and enabling high-energy-density batteries. The HCA/C promotes uniform lithium deposition even under rapid charging (up to 5mA cm-2) owing to its efficient mixed ion/electron conduction pathways. Thus, the HCA/C demonstrates stable cycling for 200 cycles with a low negative/positive ratio of 1.0 when paired with a LiNi0.8Co0.1Mn0.1O2 cathode (areal capacity of 5.0mAhcm-2). Furthermore, a stacked pouch-type full cell using HCA/C realizes a high energy density of 344Whkg-1 cell/951WhL-1 cell based on the total mass of the cell, exceeding previously reported pouch-type full cells. This work paves the way for LMA development in high-energy-density Li metal batteries.

Averting H+-Mediated Charge Storage Chemistry Stabilizes the High Output Voltage of LiMn2O4-Based Aqueous Battery.

H+ co-intercalation chemistry of the cathode is perceived to have damaging consequences on the low-rate and long-term cycling of aqueous zinc batteries, which is a critical hindrance to their promise for stationary storage applications. Herein, the thermodynamically competitive H+ storage chemistry of an attractive high-voltage cathode LiMn2O4 is revealed by employing operando and ex-situ analytical techniques together with density functional theory-based calculations. The H+ electrochemistry leads to the previously unforeseen voltage decay with cycling, impacting the available energy density, particularly at lower currents. Based on an in-depth investigation of the effect of the Li+ to Zn2+ ratio in the electrolyte on the charge storage mechanism, a purely aqueous and low-salt concentration electrolyte with a tuned Li+/Zn2+ ratio is introduced to subdue the H+-mediated charge storage kinetically, resulting in a stable voltage output and improved cycling stability at both low and high cathode loadings. Synchrotron X-ray diffraction analysis reveals that repeated H+ intercalation triggers an irreversible phase transformation leading to voltage decay, which is averted by shutting down H+ storage. These findings unveiling the origin and impact of the deleterious H+-storage, coupled with the practical strategy for its inhibition, will inspire further work toward this under-explored realm of aqueous battery chemistry.

Fluoroethylene Carbonate: Bis(2,2,2,) Trifluoroethyl Carbonate as High Performance Electrolyte Solvent Blend for High Voltage Application in NMC811|| Silicon Oxide‐Graphite Lithium Ion Cells

LiNixMnyCozO2 cathode materials combined with Si‐based anode materials are current state‐of‐the‐art high energy density chemistries for lithium ion batteries. Increasing the upper cut‐off voltage is an intriguing approach to achieve even higher energy density in lithium ion batteries. However, poor oxidation stability of the state‐of‐the‐art electrolytes leads to transition metal dissolution (TMD), migration, and deposition (TMDMD) on the negative electrode, followed by sudden and rapid capacity fade. Furthermore, the chemical instability of the lithium hexafluorophosphate causes hydro‐fluoric acid to develop, which targets the native SiOx layers on silicon anodes and breaks the chemical bond to the carboxymethylcellulose sodium salt binder. Herein, a fluorine‐rich electrolyte formulation consisting of lithium‐bis(fluorsulfonyl)imide with fluoroethylene carbonate (FEC): bis(2,2,2,) trifluoroethyl carbonate (BFEC) was applied in NMC811||10%SiOx‐90%graphite cells to achieve high oxidation stability and prevent TMD and deposition. Up‐to‐date, this is the premier electrochemical performance reported in literature with a capacity retention of 94.5% and 92.2% with 0.5 °C and 4.5 V upper cut‐off voltage cycling at 20 and 40 °C after 100 cycles, respectively. The post mortem analysis showed that stabilization is achieved by forming inorganic‐ and salt‐rich interphases that protect the electrolyte versus decomposition at the electrode.