Li Anode Research Articles

Regulating Non‐Equilibrium Solvation Structure in Locally Concentrated Ionic Liquid Electrolytes for Wide‐Temperature and High‐Voltage Lithium Metal Batteries

AbstractThe development of high‐voltage lithium metal batteries (LMBs) encounters significant challenges due to aggressive electrode chemistry. Recently, locally concentrated ionic liquid electrolytes (LCILEs) have garnered attention for their exceptional stability with both Li anodes and high‐voltage cathodes. However, there remains a limited understanding of how diluents in LCILEs affect the thermodynamic stability of the solvation structure and transportation dynamics of Li+ ions. Herein, we propose a wide‐temperature LCILEs with 1,3‐dichloropropane (DCP13) diluent to construct a non‐equilibrium solvation structure under external electric field, wherein the DCP13 diluent enters the Li+ ion solvation sheath to enhance Li+ ion transport and suppress oxidative side reactions at high‐nickel cathode (LiNi0.9Co0.05Mn0.05O2, NCM90). Consequently, a Li/NCM90 cell utilizing this LCILE achieves a high capacity retention of 94 % after 240 cycles at 4.3 V, also operates stably at high cut‐off voltages from 4.4 V to 4.6 V and over a wide temperature range from −20 °C to 60 °C. Additionally, an Ah‐level pouch cell with this LCILE simultaneously achieves high‐energy‐density and stable cycling, manifesting the practical feasibility. This work redefines the role of diluents in LCILEs, providing inspiration for electrolyte design in developing high‐energy‐density batteries.

Regulating Non-Equilibrium Solvation Structure in Locally Concentrated Ionic Liquid Electrolytes for Wide-Temperature and High-Voltage Lithium Metal Batteries.

The development of high-voltage lithium metal batteries (LMBs) encounters significant challenges due to aggressive electrode chemistry. Recently, locally concentrated ionic liquid electrolytes (LCILEs) have garnered attention for their exceptional stability with both Li anodes and high-voltage cathodes. However, there remains a limited understanding of how diluents in LCILEs affect the thermodynamic stability of the solvation structure and transportation dynamics of Li+ ions. Herein, we propose a wide-temperature LCILEs with 1,3-dichloropropane (DCP13) diluent to construct a non-equilibrium solvation structure under external electric field, wherein the DCP13 diluent enters the Li+ ion solvation sheath to enhance Li+ ion transport and suppress oxidative side reactions at high-nickel cathode (LiNi0.9Co0.05Mn0.05O2, NCM90). Consequently, a Li/NCM90 cell utilizing this LCILE achieves a high capacity retention of 94 % after 240 cycles at 4.3 V, also operates stably at high cut-off voltages from 4.4 V to 4.6 V and over a wide temperature range from -20 °C to 60 °C. Additionally, an Ah-level pouch cell with this LCILE simultaneously achieves high-energy-density and stable cycling, manifesting the practical feasibility. This work redefines the role of diluents in LCILEs, providing inspiration for electrolyte design in developing high-energy-density batteries.

Regulating of Lithium‐Ion Dynamic Trajectory by Ferromagnetic CoF2 to Achieve Ultra‐Stable Deep Lithium Deposition Over 10000 h

AbstractCurrently, the realization of controllable Li electrodeposits to further extend the cycling life of Li metal anode remains challenging. Herein, it is reported that carbon nanosheet array‐loaded ferromagnetic CoF2 nanoparticles on carbon cloth (CC@CoF2/C) as an internal micro‐magnetic field source to manipulate the dynamic trajectory of Li+ deposition via the magnetohydrodynamic effect. This approach ensures uniform lithium‐ion distribution and improves deep plating capacity, achieving a prolonged cycle life of the dendrite‐free Li anode. Finite element simulations, in situ characterizations, and electrochemical tests confirm that magnetic CoF2 not only guides Li+ migration through Lorentz force to prevent dendritic growth but also improves uniform Li deposition due to the in situ conversion of LiF‐rich solid electrolyte interphase during electroplating. Meanwhile, a CC@CoF2/C‐based half‐cell operates stably over 10 000 h at 1 mA cm−2 with a low 7.8 mV overpotential. When matched with a commercial LiFePO4 cathode, the full cell reveals a high capacity of 122.96 mAh g−1 at a 2 C rate after 1000 cycles, retaining 91.95% capacity. The proposed strategy can be effectively expanded and adapted to investigate the deposition behavior of a wide range of metal anodes, offering a versatile and robust analytical framework for addressing diverse metal‐based electrochemical systems.

Engineering Electrolytes with Transition Metal Ions for the Rapid Sulfur Redox and In Situ Solidification of Polysulfides in Lithium-Sulfur Batteries.

Lithium-sulfur (Li-S) batteries have been pursued due to their high theoretical energy density and superb cost-effectiveness. However, the dissolution-conversion mechanism of sulfur inevitably leads to shuttle effects and interface passivation issues, which impede Li-S battery practical application. Herein, the approach of adopting transition metal salts (CoI2) to engineering the electrolyte is proposed. Different from anchored transition metal catalysts in the cathode, soluble cobalt ions can chemically reduce and solidify polysulfides, alleviating the dependence of sulfur conversion on the conductive interface while suppressing the shuttle effect. Importantly, all elements in CoI2 are in the lowest valence state and solid complexes are formed after the redox reaction, which prevents the migration of high valent Co3+ to the anode, thus overcoming the poor compatibility between redox mediator and Li anode. Notably, I3- has the function of eliminating dead sulfur and dead lithium, which we apply to Li-S batteries. After activating I3- at a certain frequency, Li-S batteries indeed achieve a longer and more stable cycle life. By combining the regulatory behavior of anions and cations, the electrolyte is engineered for Li-S batteries with high capacity, long lifespan, and excellent rate performance.

Constructing an Artificial Interface as a Bifunctional Promoter for the Li Anode and the NCM Cathode in Lithium Metal Batteries.

The bottleneck of Li metal batteries toward practical applications lies at inferior cyclability as well as Li dendrite issues. As a promising solution, an interface engineering strategy is proposed herein for the Li anode through constructing a hybrid artificial interface. It is assembled onto the Li anode using photocontrolled free radical polymerization (photo-CRP) of polyethylene glycol diacrylate-hexafluorobutyl methacrylate and hexafluorobutyl methacrylate-trifluoroethyl carbonate (PEGDA-HFMBA@HFMBA-FEMC or PH@HF layer). Among such hybrid interfaces, the interior layer of PEGDA-HFMBA exists as a protective shield with flexibility and fracture resistance, while the exterior layer of HFMBA-FEMC plays a role as a LiF reservoir to promote Li mass transfer and its even electrodeposition. In the meantime, some excess HFMBA and FEMC monomers further dissolve into the electrolyte as molecular additives, followed by in situ generation of a thin and robust LiF-rich cathode electrolyte interface (CEI). With the resulting Li anode, Li/NCM811 full cells showcase multifold cyclability amplification in comparison to cells using Bare-Li, covering durable cyclability with a capacity retention of 81.8% after 400 cycles. When the cutoff voltage is elevated to 4.5 V or the working temperature is elevated to 45 °C, the cells still maintain a stable operation for extending 300 cycles.

Li+ Ion-Dipole Interaction-Enabled a Dynamic Supramolecular Elastomer Interface Layer for Dendrite-Free Lithium Metal Anodes.

The unstable lithium (Li)/electrolyte interface, causing inferior cycling efficiency and unrestrained dendrite growth, has severely hampered the practical deployment of Li metal batteries (LMBs), particularly in carbonate electrolytes. Herein, we present a robust approach capitalizing on a dynamic supramolecular elastomer (DSE) interface layer, which is capable of being reduced with Li metal to spontaneously form strong Li+ ion-dipole interaction, thereby enhancing interfacial stability in carbonate electrolytes. The soft phase in the DSE structure enables fast Li+ transport via loosely coordinated Li+-O interaction, while the hard phase, rich in electronegative lithiophilic sites, drives the generation of fast-ion-conducting solid electrolyte interface components, including Li3N and Li2S. Furthermore, the dynamically resilient DSE network composed of soft and hard phases protects Li anodes from electrolyte corrosion and accommodates volume changes during cycling. All features of the DSE layer synergistically facilitate uniform Li+ deposition and suppress Li dendrite propagation, ensuring a stable and dendrite-free Li anode. Consequently, the symmetric Li||Li cell incorporating the DSE layer achieves cycling stability exceeding 6000 h under 1 mA cm-2 and 1 mA h cm-2 conditions. Furthermore, full cell pairing DSE/Li anode with LiFePO4 (LFP) or high-voltage LiNi0.8Mn0.1Co0.1O2 (NMC811) cathodes exhibits high-efficiency Li deposition and cycling stability, even under constrained conditions of limited Li (40 μm) and ultrahigh loading NMC811 cathode (21.5 mg cm-2). This study underscores the effectiveness of the ion-dipole interaction-enabled DSE network in developing stable, high-energy-density LMBs.

Rate Capability of Fluorinated Catholyte-Based Li Primary Batteries Governed by Interfacial and Bulk Li+ Transport

Abstract Fluorinated catholytes based on fluoro–organosulfur reactants have recently been shown to offer a compelling design space for high-energy lithium (Li) primary batteries with ability to compete with carbon monofluoride (CFx) at low rates and moderate cell temperatures. However, rate capability is hindered as the operating temperature is lowered to room temperature, warranting further investigation. Here, we examined the origin of such loss in detail via impedance spectroscopy and 3–electrode cells. As temperature decreases, the Li anode disproportionately contributes to discharge overpotentials at moderate to high rates (0.3–1 mA/cm2), indicating that the Li solid electrolyte interphase (SEI) plays a pivotal role in governing performance. Despite a modest temperature change, the chemical composition of the SEI is significantly different at 25°C than at 50°C, with a lower oxygen/fluorine ratio at room temperature that impedes SEI Li+ transport. Furthermore, continuous growth in ionic resistance/viscosity of the catholyte throughout discharge are found to be the cause of cell “sudden death” at lower temperature and higher rates. This analysis indicates that development of these energy–dense primary battery chemistries for moderate-to-high–rate applications must focus on enhancing SEI Li+ conductivity and maximizing diffusivity of reactant species under solvent–lean conditions.

Melamine-based nanoscale porous organic frameworks as multifunctional separator modifiers to mitigate the polysulfide shuttle effect in lithium–Sulfur batteries

The shuttling of polysulfides between electrodes in lithium-sulfur (Li-S) batteries significantly impairs cycle stability. This study explores the use of melamine-based nanoscale porous organic frameworks (POFs) as polysulfide reservoirs to modify glass fiber (GF) separators. Melamine was reacted with dibromoalkanes of varying carbon chain lengths (n = 4, 8, and 12) to produce a series of POF materials, POF-Cn, with different nanoscale pore sizes and solubilities. The POF composites, POF-Cn/SP/PVP, which include conductive carbon Super P (SP) and a polyvinylpyrrolidone (PVP) binder, were coated onto GF membranes to create modified separators for Li-S batteries. Batteries with these modified GF separators exhibited higher initial capacities, improved rate performance, and better long-term cycle stability compared to those with non-modified separators. Among the POF composites, POF-C8/SP/PVP exhibited the best performance, with an initial specific capacity of 1392 mAh g-1 at 0.1C and a high capacity retention of 90% after 300 cycles at 0.5C. The enhanced capacity, stability, and rate performance are attributed to the nanoporous structure of POF-C8 and its high nitrogen content, which effectively traps soluble LiPSs and reduces their diffusion toward the Li anode. The good solubility of POF-C8 facilitates uniform dispersion in the modifying layer, promoting efficient polysulfide trapping and maximizing their utilization in electrochemical reactions, aided by the conductive SP in the composite.

Construction of Ordered and Fast Lithium Ion Channels in Gel Electrolytes for Li-SPAN Batteries.

As one of the most promising battery systems, the lithium sulfur battery is expected to be widely used in fields of high energy density demands. Owing to the unique solid-solid conversion mechanism, there is no shuttle effect for the Li-SPAN (sulfurized polyacrylonitrile) battery. However, the compatibility between Li anode and carbonate electrolyte has not been resolved, which prevents the SPAN from practical applications. Herein, an organic-inorganic gel carbonate electrolyte is proposed to stabilize interphases and structures of both the anode and cathode, where polyimide (PI) is used for electrolyte gelation, which can assist in the uniform distribution of inorganic components at the electrolyte interface. Furthermore, ZnS nanodots loaded on two-dimensional MoS2 flakes provide abundant Li-ion diffusion paths, improve the transfer kinetic of Li ions, and induce uniform nucleation and deposition of Li. This gel electrolyte ensures Li symmetric cells a long-term cycle life of more than 900 h under the condition of deep lithium plating/stripping at 5 mAh cm-1. Li∥Cu cells exhibit a prolonged lifespan of 800 h with a CE of 98.3%. Furthermore, the Li-SPAN battery shows stability of more than 850 cycles, with the capacity retention of 85.1%. This work provides an approach for high-energy Li-SPAN batteries with carbonate-based electrolytes.

Functional organic 7,7,8,8‐tetracyanoquinodimethane artificial layers for the dendrite suppressed lithium metal anodes

AbstractThe large‐scale industrialization of lithium metal (Li), as a potential anode for a high energy density energy storage system, has been hindered by dendrite growth. The construction of an artificial solid electrolyte interphase layer featuring high ionic and low electronic conductivity has been verified to be a high‐performance strategy to confine the dendrite growth and promote the Li anode stability. Therefore, a functional organic protective layer is homogeneously deposited on the Li anode surface via an in situ chemical reaction between tetracyanoquinodimethane (TCNQ) and Li. The as‐synthesized Lin‐TCNQ organic film could efficiently trap non‐uniform Li deposition and restrain dendrite propagation. Particularly, an asymmetric M‐TCNQ‐Li|Cu cell with the Lin‐TCNQ layer breezed through a high Coulombic efficiency of 91.15% after 100 cycles at 1.0 mA cm−2. The M‐TCNQ‐Li|NCM622 cell delivered a high capacity of 143.40 mAh g−1 at 0.2 C and maintained a good cyclic stability of 110.44 mAh g−1 after 160 cycles. The analysis results of spectroscopic tests further demonstrate that the Lin‐TCNQ with the enhanced absorption energy is conducive to lithiophilicity and decreases the overpotential of Li deposition.

A Supramolecular Deep Eutectic Electrolyte Enhancing Interfacial Stability and Solution Phase Discharge in Li−O2 Batteries

AbstractLi−O2 batteries (LOBs) have gained widespread recognition for their exceptional energy densities. However, a major challenge faced by LOBs is the lack of appropriate electrolytes that can effectively balance reactant transport, interfacial compatibility, and non‐volatility. To address this issue, a novel supramolecular deep eutectic electrolyte (DEE) has been developed, based on synergistic interaction between Li‐bonds and H‐bonds through a combination of lithium salt (LiTFSI), acetamide (Ace) and boric acid (BA). The incorporation of BA serves as an interface modification additive, acting as both Li‐bonds acceptor and H‐bonds donor/acceptor, thereby enhancing the redox stability of the electrolyte, facilitating a solution phase discharge process and improving compatibility with the Li anode. Our proposed DEE demonstrates a high oxidation voltage of 4.5 V, an ultrahigh discharge capacity of 15225 mAh g−1 and stable cycling performance of 196 cycles in LOBs. Additionally, the intrinsic non‐flammability and successful operation of a Li−O2 pouch cell indicate promising practical applications of this electrolyte. This research broadens the design possibilities for LOBs electrolytes and provides theoretical insights for future studies.

Stabilizing the Bilateral Interfaces by a PVDF-Based Double-Layer Solid Composite Electrolyte with a Relieved Dehydrofluorination Effect for Solid-State Lithium Metal Batteries.

The dehydrofluorination effect of poly(vinylidene fluoride) (PVDF) induced by ceramic fillers with an alkaline surface compromises the comprehensive properties of the solid composite electrolyte (SCE) and leads to the deficient performance of the solid-state lithium metal batteries (SLMBs). In this work, a unique PVDF-based double-layer solid electrolyte was fabricated, which consisted of a Li6.4La3Zr1.4Ta0.6O12 (LLZTO)-filled SCE with poly(acrylic acid) (PAA) as an alkalinity-scavenging agent in contact with the Li anode, and another SCE with lithium difluoro(oxalato)borate (LiDFOB) as a film-formation additive facing the cathode. It is found that a moderate amount of PAA relieves the dehydrofluorination degree of the PVDF matrix and improves the Li plating/stripping reversibility, and the addition of LiDFOB is involved in the formation of a stable passivation film on the cathode. Consequently, the resultant double-layer SCE holds favorable overall properties, especially being well-compatible with both electrodes, endowing the SLMBs with superior cycle and rate performance at room temperature.

Stabilization Strategies of Lithium Metal Anode Toward Dendrite-Free Lithium-Sulfur Batteries.

Lithium-sulfur (Li-S) batteries are considered as a most promising rechargeable lithium metal batteries because of their high energy density and low cost. However, the Li-S batteries mainly suffer the capacity decay issue caused by the shutting effect of lithium polysulfides and the safety issues arising from the Li dendrites formation. This review outlines the current issues of Li-S batteries. Furthermore, we comprehensively summarized the challenges encountered by Li anode in Li-S batteries, such as the heterogeneous deposition of the Li anode, the unstable solid electrolyte interface (SEI) layer, and volume expansion. Moreover, research progresses in the stabilization strategies of Li anodes (physical approaches, optimization of electrolyte, surface protection layer, and design of current collector) is discussed in detail. Lastly, the remaining challenges and future research directions of Li metal anode stabilization in Li-S batteries are also present.

Li2MoO4 tailored Anion‐enhanced Solvation Sheath Layer Promotes Solution‐phase Mediated Li‐O2 Batteries

The high overpotential of Li‐O2 batteries (LOBs) is primarily triggered by sluggish charge transfer kinetics at the reaction interfaces. A typical LiBr redox mediator (RM) catalyst can effectively reduce the battery’s overpotential. However, it is prone to shuttling and corroding the Li anode, leading to RM loss and reduced energy efficiency. To address these challenges, we introduced Li2MoO4 into the LiBr‐containing electrolyte to promote the solution‐phase mediated LOBs. This addition tailors the anion‐enhanced Li+ solvation sheath layer and forms a robust anion‐derived solid electrolyte interphases (SEI) on the Li anode. The robust SEI effectively mitigates the corrosion of soluble Br3‐/Br2 and attacks by highly reactive oxygen species. Additionally, the dispersed and high‐density Li2MoO4 exhibits strong adsorption capabilities for O2/LiO2 and Br‐related species during the discharge/charge process, thereby promoting the growth and decomposition of Li2O2 in the solution phase and inhibiting the shuttle effect of Br‐related species in LOBs. Consequently, the LOBs demonstrate exceptional cycling stability (415 cycles) and high energy efficiency (86.2%), paving the way for the sustainable development and practical application of these battery systems.

Synergistic Reduction and Oxidation Resistant Interface Modifier for High‐Voltage and High‐Loading Solid‐State Lithium Batteries

AbstractSolid‐state batteries (SSBs) with high‐voltage cathodes and Li‐anodes offer promising energy density and safety for next‐generation batteries. However, poor contact and electrochemical instability of solid electrolyte interfaces hinder their long‐term performance. Traditional rigid solidification interlayers possess restricted capability to address these issues. Herein, a composite buffer interlayer (CBI) with localized high‐concentration electrolytes (LHCEs) in a flexible polymer scaffold, tackling contact and stability problems and ensuring a perfect interface is developed. The extended electrochemical window provides it with synergistic antioxidation and antireduction capabilities, making it compatible with high‐voltage cathodes and Li anodes, while an in situ formed LiF‐Li3N rich inorganic interface ensures uniform lithium deposition and prevents dendrite formation. This CBI enables lithium symmetric cells to achieve a super high critical current density of 7.2 mA cm−2. Most impressively, coupled with a high‐voltage LiNi0.83Co0.12Mn0.05O2 cathode (NCM83), the full cell achieves 94.1% capacity retention after 125 cycles (coulombic efficiency >99.8%) at a mass loading of 14.6 mg cm−2 and a high voltage of 4.45 V. Additionally, a pouch cell with 17.2 mg cm−2 NCM83 achieves an initial discharge capacity of 3.82 mAh cm−2 an superior cycling stability (75 cycles, 89% capacity retention), showcasing the practical potential of LHCE‐CBI enabled SSBs.

Li2MoO4 tailored Anion-enhancedSolvation Sheath Layer Promotes Solution-phase Mediated Li-O2 Batteries.

The high overpotential of Li-O2 batteries (LOBs) is primarily triggered by sluggish charge transfer kinetics at the reaction interfaces. A typical LiBr redox mediator (RM) catalyst can effectively reduce the battery's overpotential. However, it is prone to shuttling and corroding the Li anode, leading to RM loss and reduced energy efficiency. To address these challenges, we introduced Li2MoO4 into the LiBr-containing electrolyte to promote the solution-phase mediated LOBs. This addition tailors the anion-enhanced Li+ solvation sheath layer and forms a robust anion-derived solid electrolyte interphases (SEI) on the Li anode. The robust SEI effectively mitigates the corrosion of soluble Br3-/Br2 and attacks by highly reactive oxygen species. Additionally, the dispersed and high-density Li2MoO4 exhibits strong adsorption capabilities for O2/LiO2 and Br-related species during the discharge/charge process, thereby promoting the growth and decomposition of Li2O2 in the solution phase and inhibiting the shuttle effect of Br-related species in LOBs. Consequently, the LOBs demonstrate exceptional cycling stability (415 cycles) and high energy efficiency (86.2%), paving the way for the sustainable development and practical application of these battery systems.

Dendrite Growth and Dead Lithium Formation in Lithium Metal Batteries and Mitigation Using a Protective Layer: A Phase-Field Study.

Lithium metal batteries (LMBs) are considered one of the most promising next-generation rechargeable batteries due to their high specific capacity. However, severe dendrite growth and subsequent formation of dead lithium (Li) during the battery cycling process impede its practical application. Although extensive experimental studies have been conducted to investigate the cycling process, and several theoretical models were developed to simulate the Li dendrite growth, there are limited theoretical studies on the dead Li formation, as well as the entire cycling process. Herein, we developed a phase-field model to simulate both electroplating and stripping process in a bare Li anode and Li anode covered with a protective layer. A step function is introduced in the stripping model to capture the dynamics of dead Li. Our simulation clearly shows the growth of dendrites from a bare Li anode during charging. These dendrites detach from the bulk anode during discharging, forming dead Li. Dendrite growth becomes more severe in subsequent cycles due to enhanced surface roughness of the Li anode, resulting in an increasing amount of dead Li. In addition, it is revealed that dendrites with smaller base diameters detach faster at the base and produce more dead lithium. Meanwhile, the Li anode covered with a protective layer cycles smoothly without forming Li dendrite and dead Li. However, if the protective layer is fractured, Li metal preferentially grows into the crack due to enhanced Li-ion (Li+) flux and forms a dendrite structure after penetration through the protective layer, which accelerates the dead Li formation in the subsequent stripping process. Our work thus provides a fundamental understanding of the mechanism of dead Li formation during the charging/discharging process and sheds light on the importance of the protective layer in the prevention of dead Li in LMBs.

In situ Triggered Rich‐LiF/Mg Multifunctional Passivation Layer for Modifying the Anode Interface of All‐Solid‐State Lithium Metal Batteries

AbstractLithium (Li) is a promising anode material for all‐solid‐state Li metal batteries (ASSLMBs) due to its high energy density. However, the interface incompatibility of Li/solid electrolyte and uneven Li deposition induces the penetration of Li dendrites. Herein, a multifunctional rich‐LiF/Mg artificial solid electrolyte interphase (SEI) layer is constructed from a MgF2‐PVDF‐HFP film to passivate the Li anode and achieve effective inhibition of Li dendrites. Notably, the triggered LixMg alloys rivet the Li6PS5Cl (LPSCl) electrolyte and Li anode together well, producing satisfactory interface contact and reducing overpotential. The mechanism of LiF and LixMg alloys to enhance the stability of the Li/LPSCl interface is further elucidated by density functional theory (DFT). Moreover, the synergistic interaction of LiF with high interfacial energy and LixMg alloys with low diffusion barrier promotes uniform deposition of Li during plating/stripping and structural stability. Therefore, the modified Li‐symmetric cell exhibits ultra‐high critical current density (2.0 mA cm−2) and considerable cyclic stability (more than 1000 h at 0.5 mA cm−2). Remarkably, NCM//LPSCl//3% MgF2‐PVDF‐HFP@Li ASSLMBs exhibit considerable long‐term cycle stability (86.9% capacity retention after 100 cycles at 0.2 C). This work highlights the critical role of the intermediate passivating layer in mitigating side reactions and preventing Li penetration.

Interface Stability and Reaction Mechanisms of Li3YCl5Br with High-Voltage Cathodes and Li Metal Anode: Insights from Ab Initio Simulations.

Recent advancements in battery technology emphasize the critical role of solid electrolytes in enhancing the performance and safety of next-generation batteries. In this study, we investigate the interface stability and reaction mechanisms of Li3YCl5Br, a promising halide-based solid electrolyte, in contact with high-voltage Ni-Mn-Co (NMC) cathodes and a Li metal anode using ab initio molecular dynamics simulations. Our findings reveal that Li3YCl5Br reacts with charged NMC cathodes. This reaction involves changes in the oxidation states of Br- anions in Li3YCl5Br and d-element cations in NMC, as well as the diffusion of Li ions from the solid electrolyte to the cathode to maintain charge balance. The reaction is confined to the interface, suggesting bulk stability. Conversely, the Li/Li3YCl5Br interface exhibits significant instability, with a chemical reaction that results in substantial structural changes and the formation of LiCl and LiBr at the solid electrolyte surface and metallic Y at the Li anode surface. These insights provide valuable information for optimizing interfacial design, aiming at improving the performance and reliability of all-solid-state batteries using halide solid electrolytes.

Trace Dual-Salt Electrolyte Additive Enabling a LiF-Rich Solid Electrolyte Interphase for High-Performance Lithium Metal Batteries.

The composition and physiochemical properties of the solid electrolyte interphase (SEI) significantly impact the electrochemical cyclability of the Li metal. Here, we introduce a trace dual-salt electrolyte additive (TDEA) that accelerates LiF production from FEC decomposition and improves the LiF distribution, resulting in earlier LiF precipitation and the formation of a LiF-rich SEI on the Li anode. TDEA at a millimolar-level concentration was found to alter the morphology of deposited Li, suppress Li dendrite formation, and increase the cycling time and operating current density for Li anodes. Li∥NCM811 full cells using TDEA-based electrolytes exhibited approximately two times longer lifespan than those without additives. Additionally, the TDEA-based electrolytes enabled a high energy density of 347 Wh kg-1 for 500-mAh pouch cells, maintaining stable cycling over 180 cycles under stringent conditions (N/P = 1.26 and E/C = 2.2 g A h-1). Our findings suggest that the proposed TDEA strategy offers a promising path to achieving high-performance Li metal batteries.