Pressure Tuning and Sn Particle Size Optimization for Enhanced Performance in PbSnF4-Based All-Solid-State Fluoride Ion Batteries.

All-solid-state fluoride ion batteries (ASSFIBs) show remarkable potential as energy storage devices due to their low cost, superior safety, and high energy density. However, the poor ionic conductivity of F- conductor, large volume expansion, and the lack of a suitable anode inhibit their development. In this work, PbSnF4 solid electrolytes in different phases (ß- and γ-PbSnF4) are successfully synthesized and characterized. The ASSFIBs composed of ß-PbSnF4 electrolytes, a BiF3 cathode, and micrometer/nanometer size (µ-/n-) Sn anodes, exhibit substantial capacities. Compared to the µ-Sn anode, the n-Sn anode with nanostructure exhibits superior battery performance in the BiF3/ß-PbSnF4/Sn battery. The optimized battery delivers a high initial discharge capacity of 181.3 mAh g-1 at 8 mA g-1 and can be reversibly cycled at 40 mA g-1 with a high discharge capacity of over 100.0 mAh g-1 after 120 cycles at room temperature. Additionally, it displays high discharge capacities over 90.0 mAh g-1 with excellent cyclability over 100 cycles under -20 °C. Detailed characterization has confirmed that reducing Sn particle size and boosting external pressure are crucial for achieving good defluorination/fluorination behaviors in the Sn anode. These findings pave the way to designing ASSFIBs with high capacities and superior cyclability under different operating temperatures.

Two-Dimensional Electrolyte Design: Broadening the Horizons of Functional Electrolytes in Lithium Batteries.

ConspectusSince their commercialization in the 1990s, lithium-ion batteries (LIBs) have been increasingly used in applications such as portable electronics, electric vehicles, and large-scale energy storage. The increasing use of LIBs in modern society has necessitated superior-performance LIB development, including electrochemical reversibility, interfacial stability, efficient kinetics, environmental adaptability, and intrinsic safety, which is difficult to simultaneously achieve in commercialized electrolytes. Current electrolyte systems contain a solution with Li salts (e.g., LiPF6) and solvents (e.g., ethylene carbonate and dimethyl carbonate), in which the latter dissolves Li salts and strongly interacts with Li+ (lithiophilic feature). Only lithiophilic agents can be functionally modified (e.g., additives and solvents), altering the bulk and interfacial behaviors of Li+ solvates. However, such approaches alter pristine Li+ solvation and electrochemical processes, making it difficult to strike a balance between the electrochemical performance and other desired electrolyte functions. This common electrolyte design in lithiophilic solvents shows strong coupling among formulation, coordination, electrochemistry, and electrolyte function. The invention of lithiophobic cosolvents (e.g., multifluorinated ether and fluoroaromatic hydrocarbons) has expanded the electrolyte design space to lithiophilic (interacts with Li+) and lithiophobic (interacts with solvents but not with Li+) dimensions. Functional modifications switch to lithiophobic cosolvents, affording superior properties (carried by lithiophobic cosolvents) with little impact on primary Li+ solvation (dictated by lithiophilic solvents). This electrolyte engineering technique based on lithiophobic cosolvents is the 2D electrolyte (TDE) principle, which decouples formulation, coordination, electrochemistry, and function. The molecular-scale understanding of TDEs is expected to accelerate electrolyte innovations in next-generation LIBs.This Account provides insights into recent advancements in electrolytes for superior LIBs from the perspective of lithiophobic agents (i.e., lithiophobic additives and cosolvents), establishing a generalized TDE principle for functional electrolyte design. In bulk electrolytes, a microsolvating competition emerges because of cosolvent-induced dipole-dipole and ion-dipole interactions, forming a loose solvation shell and a kinetically favorable electrolyte. At the electrode/electrolyte interface, the lithiophobic cosolvent affords reliable passivation and efficient desolvation, with interfacial compatibility and electrochemical reversibility even under harsh conditions. Based on this unique coordination chemistry, functional electrolytes are formulated without significantly sacrificing their electrochemical performance. First, lithiophobic cosolvents are used to tune Li+-solvent affinity and anion mobility, promoting Li+ diffusion and electrochemical kinetics of the electrolyte to benefit high-rate and low-temperature applications. Second, the lithiophobic cosolvent undergoes less thermally induced decomposition and constructs a thermally stable interphase in TDEs, affording electrolytes with high-temperature adaptability and cycling stability. Third, the lithiophobic cosolvent modifies the local Li+-solvent-anion topography, controlling electrolyte electrochemical reversibility to afford numerous promising solvents that cannot be used in common electrolyte design. Finally, the lithiophobic cosolvent mitigates detrimental crosstalk between flame retardants and carbonate solvents, improving the intrinsic electrolyte safety without compromising electrochemical performance, which broadens the horizons of electrolyte design by optimizing versatile cosolvents and solvents, inspiring new ideas in liquid electrochemistry in other battery systems.

4-Fluorobenzyl cyanide, a sterically-hindered solvent expediting interfacial kinetics in lithium-ion batteries.

The electrochemical performance of lithium-ion batteries (LIBs) is plagued by sluggish interfacial kinetics. Fortunately, the Li+ solvation structure bridges the bulk electrolyte and interfacial chemistry, providing a pathway for promoting electrochemical kinetics in LIBs. Herein, we improve the interfacial kinetics by tuning the Li+ coordination chemistry based on solvent molecular engineering. Specifically, 4-fluorobenzyl cyanide (FBCN), featuring steric hindrance and a weak Lewis basic center, is designed to construct a bulky coordination structure with Li+, weakening ion-dipole interaction (Li+-solvents) but promoting coulombic attraction (Li+-anions) at a normal Li salt concentration. This sterically-controlled solvation chemistry reduces the interfacial barrier and thus contributes to improved rate performance, as demonstrated practically in LiFePO4//graphite pouch cells. This study provides fresh insights into solvent steric control and coordination chemistry engineering, opening a new avenue for enhancing electrochemical kinetics in LIBs.

Direct lithium extraction from spent batteries for efficient lithium recycling.

The flourishing expansion of the lithium-ion batteries (LIBs) market has led to a surge in the demand for lithium resources. Developing efficient recycling technologies for imminent large-scale retired LIBs can significantly facilitate the sustainable utilization of lithium resources. Here, we successfully extract active lithium from spent LIBs through a simple, efficient, and low-energy-consumption chemical leaching process at room temperature, using a solution comprised of polycyclic aromatic hydrocarbons and ether solvents. The mechanism of lithium extraction is elucidated by clarifying the relationship between the redox potential and extraction efficiency. More importantly, the reclaimed active lithium is directly employed to fabricate LiFePO4 cathode with performance comparable to commercial materials. When implemented in 56 Ah prismatic cells, the cells deliver stable cycling properties with a capacity retention of ∼90% after 1200 cycles. Compared with the other strategies, this technical approach shows superior economic benefits and practical promise. It is anticipated that this method may redefine the recycling paradigm for retired LIBs and drive the sustainable development of industries.

Enhancing Electrode Performance through Triple Distribution Modulation of Active Material, Conductive Agent, and Porosity.

The increasing demand for large-scale energy storage propels the development of lithium-ion batteries with high energy and high power density. Low tortuosity electrodes with aligned straight channels have proved to be effective in building such batteries. However, manufacturing such low tortuosity electrodes in large scale remains extremely challenging. In contrast, high-performance electrodes with customized gradients of materials and porosity are possible to be made by industrial roll-to-roll coating process. Yet, the desired design of gradients combining materials and porosity is unclear for high-performance gradient electrodes. Here, triple gradient LiFePO4 electrodes (TGE) are fabricated featuring distribution modulation of active material, conductive agent, and porosity by combining suction filtration with the phase inversion method. The effects and mechanism of active material, conductive agent, and porosity distribution on electrode performance are analyzed by experiments. It is found that the electrode with a gradual increase of active material content from current collector to separator coupled with the distribution of conductive agent and porosity in the opposite direction, demonstrates the best rate capability, the fastest electrochemical reaction kinetics, and the highest utilization of active material. This work provides valuable insights into the design of gradient electrodes with high performance and high potential in application.

Optimizing milling and sintering parameters for mild synthesis of highly conductive Li5.5PS4.5Cl1.5 solid electrolyte.

The Li5.5PS4.5Cl1.5 electrolyte gains significant attention due to its ultrahigh ionic conductivity and cost-effectiveness in halogen-rich lithium argyrodite solid electrolytes. The conventional synthetic method for obtaining the electrolyte involves mechanical milling followed by post-annealing. However, these synthesis methods typically involve high milling speeds, elevated temperatures, and prolonged durations, resulting in both high energy consumption and potential damage to the electrolyte. In this study, we successfully obtained Li5.5PS4.5Cl1.5 with a high conductivity of 7.92 mS cm-1 using a milling speed of 400 rpm and annealing at 400 °C for 5 hours. When incorporated into a Li4Ti5O12-based all-solid-state battery, this electrolyte demonstrates stable cycling performance across varying temperatures.

SUGAN: A Stable U-Net Based Generative Adversarial Network.

As one of the representative models in the field of image generation, generative adversarial networks (GANs) face a significant challenge: how to make the best trade-off between the quality of generated images and training stability. The U-Net based GAN (U-Net GAN), a recently developed approach, can generate high-quality synthetic images by using a U-Net architecture for the discriminator. However, this model may suffer from severe mode collapse. In this study, a stable U-Net GAN (SUGAN) is proposed to mainly solve this problem. First, a gradient normalization module is introduced to the discriminator of U-Net GAN. This module effectively reduces gradient magnitudes, thereby greatly alleviating the problems of gradient instability and overfitting. As a result, the training stability of the GAN model is improved. Additionally, in order to solve the problem of blurred edges of the generated images, a modified residual network is used in the generator. This modification enhances its ability to capture image details, leading to higher-definition generated images. Extensive experiments conducted on several datasets show that the proposed SUGAN significantly improves over the Inception Score (IS) and Fréchet Inception Distance (FID) metrics compared with several state-of-the-art and classic GANs. The training process of our SUGAN is stable, and the quality and diversity of the generated samples are higher. This clearly demonstrates the effectiveness of our approach for image generation tasks. The source code and trained model of our SUGAN have been publicly released.

Space-Confined Guest Synthesis to Fabricate Sn-Monodispersed N-Doped Mesoporous Host toward Anode-Free Na Batteries.

Severe issues including volume change and dendrite growth on sodium metal anodes hinder the pursuit of applicable high-energy-density sodium metal batteries. Herein, an in situ reaction approach is developed that takes metal-organic frameworks as nano-reactor and pore-former to produce a mesoporous host comprised of nitrogen-doped carbon fibers embedded with monodispersed Sn clusters (SnNCNFs). The hybrid host shows outstanding sodiophilicity that enables rapid Na infusion and ultralow Na nucleation overpotential of 2 mV. Its porous structure holds a high Na content and guides uniform Na deposition. Such host provides favorable Na plating/stripping with an average Coulombic efficiency of 99.96% over 2000 cycles (at 3 mA cm-2 and 3 mA h cm-2 ). The Na-infused SnNCNF anode delivers extreme Na utilization of 86% in symmetric cells (at 10 mA cm-2 and 10 mA h cm-2 ), outstanding rate capability and cycle life in Na-SnNCNF||Na3 V2 (PO4 )3 full cells (at 1 A g-1 for over 1000 cycles with capacity retention of 92.1%). Furthermore, high-energy/power-density anode-less and anode-free Na cells are achieved. This work presents an effective heteroatom-doping approach for fabricating multifunctional porous carbon materials and developing high-performance metal batteries.

Intelligent Power System Stability Assessment and Dominant Instability Mode Identification Using Integrated Active Deep Learning.

Simulation analysis is critical for identifying possible hazards and ensuring secure operation of power systems. In practice, large-disturbance rotor angle stability and voltage stability are two frequently intertwined stability problems. Accurately identifying the dominant instability mode (DIM) between them is important for directing power system emergency control action formulation. However, DIM identification has always relied on human expertise. This article proposes an intelligent DIM identification framework that can discriminate among stable status, rotor angle instability, and voltage instability based on active deep learning (ADL). To reduce human expert efforts required to label the DIM dataset when building DL models, a two-stage batch-mode integrated ADL query strategy (preselection and clustering) is designed for the framework. It samples only the most helpful samples to label in each iteration and considers both information contents and diversity in them to improve query efficiency, significantly reducing the required number of labeled samples. Case studies conducted on a benchmark power system (China Electric Power Research Institute (CEPRI) 36-bus system) and a practical large-area power system (Northeast China Power System) reveal that the proposed approach outperforms conventional methods in terms of accuracy, label efficiency, scalability, and adaptability to operational variability.

A "tug-of-war" effect tunes Li-ion transport and enhances the rate capability of lithium metal batteries.

"Solvent-in-salt" electrolytes (high-concentration electrolytes (HCEs)) and diluted high-concentration electrolytes (DHCEs) show great promise for reviving secondary lithium metal batteries (LMBs). However, the inherently sluggish Li+ transport of such electrolytes limits the high-rate capability of LMBs for practical conditions. Here, we discovered a "tug-of-war" effect in a multilayer solvation sheath that promoted the rate capability of LMBs; the pulling force of solvent-nonsolvent interactions competed with the compressive force of Li+-nonsolvent interactions. By elaborately manipulating the pulling and compressive effects, the interaction between Li+ and the solvent was weakened, leading to a loosened solvation sheath. Thereby, the developed electrolytes enabled a high Li+ transference number (0.65) and a Li (50 µm)‖NCM712 (4 mA h cm-2) full cell exhibited long-term cycling stability (160 cycles; 80% capacity retention) at a high rate of 0.33C (1.32 mA cm-2). Notably, Li (50 µm)‖LiFePO4 (LFP; 17.4 mg cm-2) cells with a designed electrolyte reached a capacity retention of 80% after 1450 cycles at a rate of 0.66C. An 6 Ah Li‖LFP pouch cell (over 250 W h kg-1) showed excellent cycling stability (130 cycles, 96% capacity retention) under practical conditions. This design concept for an electrolyte provides a promising path to build high-energy-density and high-rate LMBs.

Cyclopentylmethyl Ether, a Non-Fluorinated, Weakly Solvating and Wide Temperature Solvent for High-Performance Lithium Metal Battery.

While recent work demonstrates the advantages of weakly solvating solvents in enhancing the cyclability of LMBs, both new designs and design strategies for high performance weakly solvating solvent, especially physicochemical properties, are still lacking. Here, we propose a molecular design to tune the solvating power and physicochemical properties of non-fluorinated ether solvent. The resulting cyclopentylmethyl ether (CPME) have a weak solvating power and wide liquid-phase temperature range. By optimizing the salt concentration, the CE is further promoted to 99.4 %. Besides, the improved electrochemical performance of Li-S battery in CPME-based electrolytes is obtained at -20 °C. The Li||LFP (17.6 mg cm-2 ) battery with developed electrolyte maintains >90 % of the original capacity over 400 cycles. Our design concept for solvent molecule provides a promising pathway to non-fluorinated electrolytes with weakly solvating power and wide temperature window for high-energy-density LMBs.

Revealing Surfactant Effect of Trifluoromethylbenzene in Medium-Concentrated PC Electrolyte for Advanced Lithium-Ion Batteries.

Despite wide-temperature tolerance and high-voltage compatibility, employing propylene carbonate (PC) as electrolyte in lithium-ion batteries (LIBs) is hampered by solvent co-intercalation and graphite exfoliation due to incompetent solvent-derived solid electrolyte interphase (SEI). Herein, trifluoromethylbenzene (PhCF3 ), featuring both specific adsorption and anion attraction, is utilized to regulate the interfacial behaviors and construct anion-induced SEI at low Li salts' concentration (<1 m). The adsorbed PhCF3 , showing surfactant effect on graphite surface, induces preferential accumulation and facilitated decomposition of bis(fluorosulfonyl)imide anions (FSI- ) based on the adsorption-attraction-reduction mechanism. As a result, PhCF3 successfully ameliorates graphite exfoliation-induced cell failure in PC-based electrolyte and enables the practical operation of NCM613/graphite pouch cell with high reversibility at 4.35 V (96% capacity retention over 300 cycles at 0.5 C). This work constructs stable anion-derived SEI at low concentration of Li salt by regulating anions-co-solvents interaction and electrode/electrolyte interfacial chemistries.

Passivating Lithiated Graphite via Targeted Repair of SEI to Inhibit Exothermic Reactions in Early-Stage of Thermal Runaway for Safer Lithium-Ion Batteries.

The self-exothermic in early stage of thermal runaway (TR) is blasting-fuse for Li-ion battery safety issues. The exothermic reaction between lithiated graphite (LiCx ) and electrolyte accounts for onset of this behavior. However, preventing the deleterious reaction still encounters hurdles. Here, we manage to inhibit this reaction by passivating LiCx in real time via targeted repair of SEI. It is shown that 1,3,5-trimethyl-1,3,5-tris(3,3,3-trifluoropropyl)cyclotrisiloxane (D3 F) can be triggered by LiCx to undergo ring-opening polymerization at elevated temperature, so as to targeted repair of fractured SEI. Due to the high thermal stability of polymerized D3 F, exothermic reaction between LiCx and electrolyte is inhibited. As a result, the self-exothermic and TR trigger temperatures of pouch cell are increased from 159.6 and 194.2 °C to 300.5 and 329.7 °C. This work opens up a new avenue for designing functional additives to block initial exothermal reaction and inhibit TR in early stage.

Interleukin-1 receptor-associated kinase 2 promotes inflammatory reactions by activating the nuclear factor kappa-B signaling pathway in diabetic nephropathy.

Diabetic nephropathy (DN) is a major complication of diabetes. Interleukin-1 receptor-associated kinase 2 (IRAK2) has been implicated in various diseases. This study aimed to investigate the role of IRAK2 in DN progression and its association with inflammation and the nuclear factor-kappa B (NF-κB) signaling pathway. DN model mice were generated by intraperitoneal injection of streptozotocin. IRAK2 expression was upregulated in the DN model mice. IRAK2 knockdown increased weight and reduced blood glucose levels in DN model mice. In addition, IRAK2 downregulation improved glomerular morphology in DN mice. IRAK2 knockdown reduced the levels of kidney damage biomarkers (24-h urinary protein, urine albumin-creatinine ratio, and plasma creatinine) and inflammatory cytokines (IL-6, tumor necrosis factor [TNF]-α, TNF-1R, and TNF-2R). Moreover, IRAK2 activated the NF-κB signaling pathway in DN model mice. Overexpression of NF-κB exacerbated DN progression, and IRAK2 knockdown reversed these effects. IRAK2 promoted DN progression and inflammation by activating the NF-κB signaling pathway. These findings suggest that IRAK2 is a potential therapeutic target for DN treatment.

Facile Replacement Reaction Enables Nano-Ag-Decorated Three-Dimensional Cu Foam as High-Rate Lithium Metal Anode.

In developing advanced lithium (Li) metal batteries with high-energy density, excellent cycle stability, and high-rate capability, it is imperative to resolve dendrite growth and volume expansion during repeated Li plating/stripping. 3D hosts featuring lithiophilic sites are expected to realize both spatial control and dendrite inhibition over Li nucleation. Herein, this work prepares silver (Ag) nanoparticle-decorated 3D copper (Cu) foam via a facile replacement reaction. The 3D host provides rigid skeleton to accommodate volume expansion during cycling. Ag nanoparticles show micro-structural affinity to guide efficient nucleation of Li, leading to reduced overpotential and enhanced electrochemical kinetics. As the result, under an ultrahigh current density of 10 mA cm-2, Cu@Ag foam/Li half cells demonstrate outstanding Coulombic efficiency (CE) of 97.2% more than 100 cycles. Also, Cu@Ag foam-Li symmetric cells sustain preeminent cycling over 900 h with a small voltage hysteresis of 32.8 mV at 3 mA cm-2. Moreover, the Cu@Ag foam-Li||LiFePO4 full cell demonstrates a high discharge capacity of 2.33 mAh cm-2 over 200 cycles with an excellent CE up to 99.9% at 0.6C under practical conditions (N/P = 1.3, 17.4 mg cm-2 LiFePO4). Notably, the full cell with LiFePO4 exhibits a higher areal capacity of 1 mAh cm-2 over 700 cycles under a high rate of 5C, corresponding to capacity retention up to 100% (N/P = 3, 17.4 mg cm-2 LiFePO4). This study provides a novel and simple strategy for constructing high-rate and long-life Li metal batteries.

Codoped porous carbon nanofibres as a potassium metal host for nonaqueous K-ion batteries.

Potassium metal is an appealing alternative to lithium as an alkali metal anode for future electrochemical energy storage systems. However, the use of potassium metal is hindered by the growth of unfavourable deposition (e.g., dendrites) and volume changes upon cycling. To circumvent these issues, we propose the synthesis and application of nitrogen and zinc codoped porous carbon nanofibres that act as potassium metal hosts. This carbonaceous porous material enables rapid potassium infusion (e.g., < 1 s cm-2) with a high potassium content (e.g., 97 wt. %) and low potassium nucleation overpotential (e.g., 15 mV at 0.5 mA cm-2). Experimental and theoretical measurements and analyses demonstrate that the carbon nanofibres induce uniform potassium deposition within its porous network and facilitate a dendrite-free morphology during asymmetric and symmetric cell cycling. Interestingly, when the potassium-infused carbon material is tested as an active negative electrode material in combination with a sulfur-based positive electrode and a nonaqueous electrolyte solution in the coin cell configuration, an average discharge voltage of approximately 1.6 V and a discharge capacity of approximately 470 mA h g-1 after 600 cycles at 500 mA g-1 and 25 °C are achieved.

Non-flammable fluorobenzene-diluted highly concentrated electrolytes enable high-performance Li-metal and Li-ion batteries.

Lithium-ion batteries with Ni-rich cathode and flammable carbonate electrolytes are breeding severe safety concerns which hinds their application in electric vehicles. Herein, by introducing the fluorobenzene (FB) with low-density and low-cost as a cosolvent and bridge solvents in triethyl phosphate (TEP)-based diluted high-concentration electrolytes (DHCEs) system, we design a non-flammable electrolyte with a special solvation structure containing internal-external flame retardants. This non-flammable electrolyte not only solves successfully the incompatibility problem of TEP-based electrolyte to the Li-metal anode (LMA) and the graphite (Gr) anode, but also ensures the stable cycling of Li||LiNi0.7Co0.1Mn0.2O2 (86% capacity retention after 120 cycles) and Gr|| LiNi0.7Co0.1Mn0.2O2 (75% capacity retention after 200 cycles) full cells. Such design opens up a new window for developing new electrolyte systems and building safer high-energy-density batteries.

Enhancing the Reversibility of Lithium Cobalt Oxide Phase Transition in Thick Electrode via Low Tortuosity Design.

Lithium cobalt oxide (LCO) is a widely used cathode material for lithium-ion batteries. However, it suffers from irreversible phase transition during cycling because of high cutoff voltage or huge concentration polarization in thick electrode, resulting in deteriorated cyclability. Here, we design a low tortuous LiCoO2 (LCO-LT) electrode by ice-templating method and investigate the reversibility of LCO phase transition. LCO-LT thick electrode shows accelerated lithium-ion transport and reduced concentration polarization, achieving excellent rate capability and homogeneous actual operating voltage. Moreover, LCO-LT thick electrode exhibits a durable phase transition between O2 and H1-3, mitigated volume expansion, and suppressed microcrack formation. LCO-LT electrode (25 mg cm-2) delivers improved capacity retentions of 94.4% after 200 cycles and 93.3% after 150 cycles at cutoff voltages of 4.3 and 4.5 V, respectively. This strategy provides a new concept to improve the reversibility of LCO phase transition in thick electrode by low tortuosity design.

Enhancing Moisture and Electrochemical Stability of the Li5.5PS4.5Cl1.5 Electrolyte by Oxygen Doping.

Chlorine-rich argyrodite-type solid electrolyte Li5.5PS4.5Cl1.5 has been a promising choice for solid-state batteries (SSBs) because of its ultrafast Li-ion conduction. However, the poor air/moisture stability and low electrochemical stability with pristine high-voltage cathodes hinder their applications. Herein, O-substituted Li5.5PS4.5-xOxCl1.5 (x = 0, 0.075, 0.175, and 0.25) solid electrolytes are successfully synthesized. Among them, Li5.5PS4.425O0.075Cl1.5 delivers high ionic conductivity, improved moisture resistance, and enhanced electrochemical stability in higher voltage windows. SSBs using Li5.5PS4.425O0.075Cl1.5 show higher capacities and superior cyclability than those using Li5.5PS4.5Cl1.5 combined with a pristine LiNi0.8Mn0.1Co0.1O2 cathode when operated at a high end-of-charge voltage of 4.5 V (vs Li+/Li0). Moreover, the batteries exhibit outstanding performance in a wide temperature range. This work provides a strategy to modify the inherent drawbacks of sulfide electrolytes, promoting their practical applications.

Low concentration electrolyte with non-solvating cosolvent enabling high-voltage lithium metal batteries.

Developing low cost, yet high-voltage electrolyte is significant to improve the energy density and practicability of lithium metal batteries (LMBs). Low concentration electrolyte has significant merits in terms of cost and viscosity; however, their poor compatibility with high-voltage LMBs hinders its applications. Here, we develop a diluted low concentration electrolyte by replacing solvating cosolvent with a non-solvating cosolvent to facilitate the interaction between BF4 - and Li+, resulting in optimized interfacial chemistry and suppressed side reaction. Thus, the high-loading Li-LiCoO2 full cells (20.4 mg cm-2) deliver outstanding cycling stability and rate performance at a cutoff voltage of 4.6 V. More impressively, a Li-LiCoO2 pouch cell achieves an energy density of more than 400 Wh kg-1 under practical conditions with thin Li (50 µm) and lean electrolyte (2.7 g Ah-1). This work provides a rational approach to design a low concentration electrolyte, which can be extended to other high voltage battery systems.