Lithium Metal Anode Research Articles

Fluorinated co-solvent electrolytes enable lithium metal batteries to operate at low temperatures

Enhancing the energy output of batteries in low temperatures is critical to broadening the application areas of advanced electronic devices, which can be accomplished by utilizing high-voltage cathodes to match lithium metal anode, optimizing electrolyte electrochemical windows and forming stable solid electrolyte interphases to provide facile ion-transmission kinetics at low temperature. Herein, we demonstrate a fluorinated ester co-solvent electrolyte, which applies 1 M LiPF6 in an ethyl 4,4,4-trifluoro butyrate/fluoroethylene carbonate (FEC) (4/1 by volume ratio) that jointly satisfies high voltage cathode and lithium metal anode reversibility at required ambient. The performance of the battery is due to the rapid dissociation of Li+ and the formation of a fluorine-rich inorganic electrolyte interface in the fluorinated solvent. Therefore, the fluorinated ester co-solvent electrolyte system can provide 209.9 mAh g−1, 194.8 mAh g−1, and 175.5 mAh g−1 when discharged at room temperature, −20 ℃ and −40 ℃, respectively, those far exceeds the performance of carbonate electrolytes. This work advances the development of low-temperature lithium metal batteries.

Recent Progress in Liquid Electrolytes for High‐Energy Lithium–Metal Batteries: From Molecular Engineering to Applications

AbstractLithium–metal batteries (LMBs) have garnered significant interests for their promising high gravimetric energy density (Eg) ∼ 750 Wh kg−1. However, the practical application of the LMBs is plagued by the high reactivity and large volume change during charging–discharging of the lithium–metal anode (LMA), seriously deteriorating the battery safety and cycle life. Great efforts have been devoted to tailoring the electrolytes to favor the Li–metal electroplating by uniformizing the deposition morphology and by suppressing the side reactions between electrolytes and LMA. The aggressive chemistries of both the LMA and its high‐voltage counterpart give new electrolyte components more opportunities, especially designing via molecular engineering. Here, a comprehensive and in‐depth overview of the scientific challenges, fundamental mechanisms, and particularly historical strategies of designing new molecules for electrolyte components including solvents, salts, and additives. Their important roles in tuning the Li+ solvation structure, interface composition, decomposition pathways, and the resultant electrochemical performance of LMBs are also presented. Finally, novel insights and promising research directions from the practical application viewpoints are proposed for future electrolyte designs for high‐voltage LMBs.

A review of recent developments in the design of electrolytes and solid electrolyte interphase for lithium metal batteries

AbstractLithium metal batteries offer a promising solution for high density energy storage due to their high theoretical capacity and negative electrochemical potential. However, implementing of these batteries faces challenges related to electrolyte instability and the formation of a solid electrolyte interphase (SEI) on the lithium (Li) metal anode. The decomposition of liquid electrolytes leading to the creation of the SEI emphasizes the significance of the type of Li salt, solvent, and additives designed and used, as well as their interactions during the formation of the SEI. For practical applications, ensuring both the reversibility of the Li metal anode and electrolyte stability at high voltages is crucial. In this review, we explore recent advancements in addressing these challenges through new designs of electrolytes and SEI engineering practices. Specifically, we investigate the effects of electrolyte systems, including carbonate‐based and ether‐based solutions, along with modifications to these electrolyte systems aimed at achieving a more stable interface with the Li metal anode. Additionally, we discuss various artificial SEI structures based on organic and inorganic components. By critically examining recent research in these areas, this review provides valuable insights into current state‐of‐the‐art strategies for enhancing the performance and safety of Li metal batteries.image

Separator‐Supported Electrode Configuration for Ultra‐High Energy Density Lithium Secondary Battery

AbstractSignificant efforts are being made to develop high‐performance battery materials, particularly active materials. However, material‐dependent strategies for increasing energy density face challenges such as raw material costs and supply limitations, reducing their versatility to some extent. In this regard, the development of efficient battery designs can be a universal approach to increasing the energy density of lithium‐ion batteries with relatively low dependence on material properties. Herein, a novel configuration of an electrode‐separator assembly is presented, where the electrode layer is directly coated on the separator, to realize lightweight lithium‐ion batteries by removing heavy current collectors. Even on the hydrophobic separator, a poly(vinyl alcohol) binder enables uniform and scalable coating of aqueous electrode slurries through molecular interactions with the separator surface. Moreover, carbon nanotubes are utilized to reinforce the electronic conduction of the electrode, providing consistent electronic pathways regardless of SEI formation. Furthermore, owing to the superior permeability of liquid electrolytes through this electrode‐separator assembly, a multilayered electrode‐separator assembly can be suggested to further increase energy density when combined with a lithium metal anode. This lithium metal battery can achieve an areal capacity of ≈30 mAh cm−2 and an enhanced energy density of over 20% compared to conventional battery configurations.

Formulating PEO-polycarbonate blends as solid polymer electrolytes by solvent-free extrusion

Liquid electrolytes are currently state-of-the-art for commercial Li-ion batteries. However, their use implicates inherent challenges, including safety concerns associated with flammability, limited thermal stability, and susceptibility to dendrite formation on the lithium metal anode, that can compromise the battery lifespan. Solid-state polymer electrolytes offer an alternative to conventional liquid electrolytes, aiming to mitigate safety, stability, and performance drawbacks. This study investigates the preparation and the comprehensive characterization of polyethylene oxide (PEO) and polycarbonate (PC) blends obtained through extrusion process. The process is solvent-free and easily scalable at the industrial level; it grants the efficient dispersion and mixing of PEO and PC. Blends at different ratios of PEO (Mw of 4 × 105 and 4 × 106 g mol˗1) and two types of PCs (namely, polyethylene and polypropylene carbonate) including lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) are prepared. Optimization and investigation of the relative effects between the application of different PCs and the variable ratios of PEO/PCs on the mechanical, morphologic and electrochemical properties of the final polymeric membranes is carried out for future applications of these systems, as efficient electrolytes in all-solid-state lithium batteries.

Integration of deformable matrix and lithiophilic sites for stable and stretchable lithium metal batteries

In response to the growing interest in wearable devices, the demand for next-generation wearable devices that can endure various mechanical deformations such as folding and stretching is also increasing. As a result, the development of stretchable batteries, capable of operating under diverse conditions, is regarded as crucial for the advancement of these future wearable technologies. Many current studies on stretchable batteries suffer from limited energy density and complicated fabrication procedures. Thus, the development of batteries that meet both high stretchability and energy density remains challenging due to these factors. Herein, we propose a stretchable and lithiophilic matrix as a host for lithium (Li) metal anodes to realize stretchable Li metal batteries (LMBs), which consists of a polymer matrix embedded with silver nanoparticles (AgNPs). The lithiophilic AgNPs are incorporated both on the surface and within the elastic fiber matrix, providing facile Li nucleation kinetics and an electron-conductive network. Surface AgNPs serve as a primary electron pathway and offer numerous nucleation seeds to facilitate uniform Li electrodeposition. Meanwhile, AgNPs embedded in the matrix provide a sturdy conductive network even under mechanical deformation. Consequently, the structure-forming factors of stretchable lithiophilic Ag-incorporated matrix (SLiM) electrode contribute to enhanced electrochemical properties as a versatile Li metal host. As a proof of concept, the designed all-stretchable LMB with the SLiM electrode demonstrates minimal degradation of electrochemical performance in deformable conditions and confirms the feasibility of an LMB in stretchable application. This work provides insight into stretchable LMBs aimed at both highly deformable and high-energy-density wearable devices.

Inkjet-Printed Silver Lithiophilic Sites on Copper Current Collectors: Tuning the Interfacial Electrochemistry for Anode-Free Lithium Batteries

Anode-free lithium batteries (AFLBs) present an opportunity to eliminate the need for conventional graphite electrodes or excess lithium–metal anodes, thus increasing the cell energy density and streamlining the manufacturing process. However, their attributed poor coulombic efficiency leads to rapid capacity decay, underscoring the importance of achieving stable plating and stripping of Li on the negative electrode for the success of this cell configuration. A promising approach is the utilization of lithiophilic coatings such as silver to mitigate the Li nucleation overpotential on the Cu current collector, thereby improving the process of Li plating/stripping. On the other hand, inkjet printing (IJP) emerges as a promising technique for electrode modification in the manufacturing process of lithium batteries, offering a fast and scalable technology capable of depositing both thin films and patterned structures. In this work, a Fujifilm Dimatix inkjet printer was used to deposit Ag sites on a Cu current collector, aiming to modulate the interfacial electrochemistry of the system. Samples were fabricated with varying areas of coverage and the electrochemical performance of the system was systematically evaluated from bare Cu (non-lithiophilic) to a designed pattern (partially lithiophilic) and the fully coated thin film case (lithiophilic). Increasing lithiophilicity resulted in lower charge transfer resistance, higher exchange current density and reduced Li nucleation overpotential (from 55.75 mV for bare Cu to 13.5 mV for the fully coated case). Enhanced half-cell cyclability and higher coulombic efficiency were also achieved (91.22% CE over 76 cycles for bare Cu, 97.01% CE over 250 cycles for the fully coated case), alongside more uniform lithium deposition and fewer macroscopic irregularities. Moreover, our observations demonstrated that surface patterning through inkjet printing could represent an innovative, easy and scalable strategy to provide preferential Li nucleation sites to guide the subsequent Li deposition.

The Impact of Supersaturated Electrode on Heterogeneous Lithium Nucleation and Growth Dynamics.

The concept of a lithiophilic electrode proves inadequate in describing carbon-based electrode materials due to their substantial mismatch in surface energy with lithium metal. However, their notable capacity for lithium chemisorption can increase active lithium concentration required for nucleation and growth, thereby enhancing the electrochemical performance of lithium metal anodes (LMAs). In this study, we elucidate the effects of the supersaturated electrode which has high active lithium capacity around equilibrium lithium potential on LMAs through an in-depth electrochemical comparison using two distinct carbon electrode platforms with differing carbon structures but similar two-dimensional morphologies. In the supersaturated electrode, both the dynamics and thermodynamic states involved in lithium nucleation and growth mechanisms are significantly improved, particularly under continuous current supply conditions. Furthermore, the chemical structures of the solid-electrolyte-interface layers (SEIs) are greatly influenced by the elevated surface lithium concentration environment, resulting in the formation of more conductive lithium-rich SEI layers. The improved dynamics and thermodynamics of surface lithium, coupled with the formation of enhanced SEI layers, contribute to higher power capabilities, enhanced Coulombic efficiencies, and improved cycling performances of LMAs. These results provide new insight into understanding the enhancements in heterogeneous lithium nucleation and growth kinetics on the supersaturated electrode.

The Impact of Supersaturated Electrode on Heterogeneous Lithium Nucleation and Growth Dynamics

AbstractThe concept of a lithiophilic electrode proves inadequate in describing carbon‐based electrode materials due to their substantial mismatch in surface energy with lithium metal. However, their notable capacity for lithium chemisorption can increase active lithium concentration required for nucleation and growth, thereby enhancing the electrochemical performance of lithium metal anodes (LMAs). In this study, we elucidate the effects of the supersaturated electrode which has high active lithium capacity around equilibrium lithium potential on LMAs through an in‐depth electrochemical comparison using two distinct carbon electrode platforms with differing carbon structures but similar two‐dimensional morphologies. In the supersaturated electrode, both the dynamics and thermodynamic states involved in lithium nucleation and growth mechanisms are significantly improved, particularly under continuous current supply conditions. Furthermore, the chemical structures of the solid‐electrolyte‐interface layers (SEIs) are greatly influenced by the elevated surface lithium concentration environment, resulting in the formation of more conductive lithium‐rich SEI layers. The improved dynamics and thermodynamics of surface lithium, coupled with the formation of enhanced SEI layers, contribute to higher power capabilities, enhanced Coulombic efficiencies, and improved cycling performances of LMAs. These results provide new insight into understanding the enhancements in heterogeneous lithium nucleation and growth kinetics on the supersaturated electrode.

Uniform Poly(vinyl ethylene carbonate) based metal-organic framework separator for smooth lithium-ion electrodeposition

Nanoporous feature in Metal-Organic Frameworks (MOFs) could tune Li+-solvated species and provide high potential for stabilizing lithium metal anodes. However, the inevitable voids within MOF crystallites accommodating free liquid electrolyte, which re-solvates Li+-solvated compounds and vanishes nanopores' advantage for controlling Li+-solvates. Herein, we report an in-situ carbonate photopolymerization reaction within MOF channel that constitutes a uniform nanoporous separator (PVEC-MOF) for smoothing Li+ electrodeposition. PVEC-MOF membrane exhibits accelerating lithium-ion conduction and superior electrochemical performance according to the interconnected ionic nano-channels, whose overpotential maintains at about 0.01 V after 600 cycles in Li-symmetric cell without forming lithium dendrite. Furthermore, employing PVEC-MOF separator in high-voltage cathode material (LiNi0.6Co0.2Mn0.2O2) based Li-metal batteries could effectively enhance electrochemical property and prolong cycling lifespan. This work provides a novel strategy to convert traditional MOF family into uniform nanoporous lithium-ion battery separator, which promotes Li+ smooth electrodeposition and inhibits lithium dendrites in high-energy-density lithium-metal batteries.

Bi-Functional Materials for Sulfur Cathode and Lithium Metal Anode of Lithium-Sulfur Batteries: Status and Challenges.

Over the past decade, the most fundamental challenges faced by the development of lithium-sulfur batteries (LSBs) and their effective solutions have been extensively studied. To further transfer LSBs from the research phase into the industrial phase, strategies to improve the performance of LSBs under practical conditions are comprehensively investigated. These strategies can simultaneously optimize the sulfur cathode and Li-metal anode to account for their interactions under practical conditions, without involving complex preparation or costly processes. Therefore, "two-in-one" strategies, which meet the above requirements because they can simultaneously improve the performance of both electrodes, are widely investigated. However, their development faces several challenges, such as confused design ideas for bi-functional sites and simplex evaluation methods (i. e. evaluating strategies based on their bi-functionality only). To date, as few reviews have focused on these challenges, the modification direction of these strategies is indistinct, hindering further developments in the field. In this review, the advances achieved in "two-in-one" strategies and categorizing them based on their design ideas are summarized. These strategies are then comprehensively evaluated in terms of bi-functionality, large-scale preparation, impact on energy density, and economy. Finally, the challenges still faced by these strategies and some research prospects are discussed.

Accelerating Lithium Deposition Kinetics Via Lithiophilic Ag‐Decorated Graphitic Carbon Nitride Spheres for Stable Lithium Metal Anode

This study presents a novel Li metal host material with a unique hollow nano‐spherical structure that incorporates Ag nano‐seeds into a graphitic carbon nitride (g‐C3N4) shell layer, referred to as g‐C3N4@Ag hollow spheres. The g‐C3N4@Ag spheres provide a managed internal site for Li metal encapsulation and promote stable Li plating. The g‐C3N4 spheres are uniformly coated using polydopamine, which has an adhesive nature, to enhance lithium plating/stripping stability. The strategic presence of Ag nano‐seeds eliminates the nucleation barrier, properly directing Li growth within the hollow spheres. This design facilitates highly reversible and consistent lithium deposition, offering a promising direction for the production of high‐performance lithium metal anodes. These well‐designed g‐C3N4@Ag hollow spheres ensure stable Li plating/stripping kinetics over more than 500 cycles with a high coulombic efficiency of over 97%. Furthermore, a full cell made using LiNi0.90Co0.07Mn0.03O2 and Li‐g‐C3N4@Ag host electrodes demonstrated highly competitive performance over 200 cycles, providing a guide for the implementation of this technology in advanced lithium metal batteries.

Boosting Li-Ion Conductivity of Fluoride Solid Electrolyte by Low-Temperature Molten Salt Ablation and Particle Boundary Doping.

Halide solid electrolytes (SEs) are attracting great attention, owing to their high ionic conductivity and excellent high-voltage compatibility. However, severe moisture sensitivity, poor thermal stability, and instability at the lithium metal anode interface with chloride and bromide SEs retard their applications in solid-state lithium metal batteries. Fluoride SEs are expected to solve these problems, but they are now plagued by inadequate room-temperature (RT) ionic conductivity. Herein, a low-temperature molten salt (LiCl+1.33AlCl3) ablation method is proposed to enhance the ionic conductivity of monoclinic Li3GaF6 by particle boundary doping. The RT ionic conductivity of Li3GaF6 is correspondingly increased by 2 orders of magnitude, and the conductivity reaches 10-4 S cm-1 at 60 °C. The improved ionic conductivity benefits from the enhancement of interfacial ion transport, with the formation of more conductive chlorine-doped Li3GaF6-xClx and in situ binder LiAlCl4 to cement surrounding nanoparticles. The as-synthesized Li3GaF6 demonstrates outstanding humidity tolerance without conductivity degradation after exposure to a relative humidity of up to 35%. It also exhibits the widest electrochemical stability window experimentally (close to 6 V) compared with other state-of-the-art SEs. The solid-state Li/Li3GaF6/LiFePO4 cell with a stable Li+-conductive polymer interface is successfully driven for at least 200 cycles at 0.5C. Our study provides a solution to various chemical and electrochemical stability issues encountered by the halide SE family.

2D Microporous Polymers/Reduced Graphene Oxide with Built-In Lithiophilic Sites for Uniform Lithium Deposition in Lithium Metal Anode.

Lithium (Li) metal is an attractive anode material for use in high-energy lithium-sulfur and lithium-air batteries. However, its practical application is severely impeded by excessive dendrite growth, huge volume changes, and severe side reactions. Herein, a novel Li metal anode composed of lithiophilic two dimensional (2D) conjugated microporous polymer (Li-CMP) and reduced graphene oxide (rGO) sandwiches (Li-CMP@rGO) for Li metal batteries (LiMBs) is reported. In the Li-CMP@rGO anode, the conductive rGO facilitates the charge transfer while the functionalized-CMP provides Li nucleation sites within the micropores, thereby preventing dendrite growth. As a result, the Li-CMP@rGO anode can be cycled smoothly at 6mA cm-2 of current density with a platting capacity of 2 mAh cm-2 for 1000h. A Coulombic efficiency of 98.4% is achieved over 350 cycles with a low overpotential of 28mV. In a full cell with LiFePO4 cathode, the Li-CMP@rGO anode also exhibited good cycling stability compared to CMP@rGO and CMP/Super-P. As expected, the simulation results reveal that Li-CMP@rGO has a strong affinity for Li ions compared to CMP@rGO. The strategies adopted in this work can open new avenues for designing hybrid porous host materials for developing safe and stable Li metal anodes.

Formulating Electrolytes for 4.6 V Anode-Free Lithium Metal Batteries

High-voltage initial anode-free lithium metal batteries (AFLMBs) promise the maximized energy densities of rechargeable lithium batteries. However, the reversibility of the high-voltage cathode and lithium metal anode is unsatisfactory in sustaining their long lifespan. In this research, a concentrated electrolyte comprising dual salts of LiTFSI and LiDFOB dissolved in mixing solvents of dimethyl carbonate (DMC) and fluoroethylene carbonate (FEC) with a LiNO3 additive was formulated to address this challenge. FEC and LiNO3 regulate the anion-rich solvation structure and help form a LiF, Li3N-rich solid electrolyte interphase (SEI) with a high lithium plating/stripping Coulombic efficiency of 98.3%. LiDFOB preferentially decomposes to effectively suppress the side reaction at the high-voltage operation of the Li-rich Li1.2Mn0.54Ni0.13Co0.13O2 cathode. Moreover, the large irreversible capacity during the initial charge/discharge cycle of the cathode provides supplementary lithium sources for cycle life extension. Owing to these merits, the as-fabricated AFLMBs can operate stably for 80 cycles even at an ultrahigh voltage of 4.6 V. This study sheds new insights on the formulation of advanced electrolytes for highly reversible high-voltage cathodes and lithium metal anodes and could facilitate the practical application of AFLMBs.

In‐Situ Constructing a Mixed‐Conductive Interfacial Protective Layer for Ultra‐Stable Lithium Metal Anodes

Lithium metal batteries are the most promising next‐generation energy storage technologies due to their high energy density. However, their practical application is impeded by serious interfacial side reactions and uncontrolled dendrite growth of lithium metal anode. Herein, copper 2,4,5‐trifluorophenylacetate is designed and explored to stabilize lithium metal anode by in‐situ constructing a dense and mixed‐conductive interfacial protective layer. The formed passivated layer not only significantly inhibits interfacial side reactions by avoiding direct contact between lithium metal anode and electrolyte but also effectively suppresses lithium dendrite growth due to the unique inorganic‐rich compositions and mixed‐conductive properties. As a result, the copper 2,4,5‐trifluorophenylacetate‐treated lithium metal anodes show greatly improved cycle stability under both high current density and high areal deposition capacity. Notably, the assembled liquid symmetrical cells with copper 2,4,5‐trifluorophenylacetate‐treated lithium metal anodes can stably work for more than 3000, 5000, and 4800 h at 1.0 mA cm−2–1.0 mAh cm−2, 2.0 mA cm−2–5.0 mAh cm−2, and 10 mA cm−2–5.0 mAh cm−2, respectively. Furthermore, the assembled liquid full cell with a high LiFePO4 loading (~16.9 mg cm−2) shows a significantly enhanced cycle life of 250 cycles with stable Coulombic efficiencies (>99.1%). Moreover, the assembled all‐solid‐state lithium metal battery with a high LiNi0.6Co0.2Mn0.2O2 loading (~5.0 mg cm−2) also exhibits improved cycle stability. These findings underline that the copper 2,4,5‐trifluorophenylacetate‐treated lithium metal anodes show great promise for high‐performance lithium metal batteries.

Demonstration of MAX phases as triple functional artificial solid electrolyte interphase for ultralong life lithium metal anodes

Solid electrolyte interphase (SEI) has significant role in controlling lithium (Li) dendrites. However, lack of chemical stability, mechanical strength and self-perfection for conventional SEI cannot persistently suppress Li dendrites, leading to inferior cycling life. Herein, MAX phases (Ti2SnC and Ti2SC) as triple functional artificial SEI (ASEI) with high modulus, chemical stability and self-smoothing ability are introduced on Li foils (Ti2SnC@Li and Ti2SC@Li) for ultralong life Li metal anodes (LMAs). The high mechanical strength with lithiophilicity of the MAX can induce uniform Li deposition and suppress dendrite growth, while the excellent chemical stability and self-smoothing ability of the MAX guarantee the consistency of the ASEI, achieving ultralong life of the LMAs. As a result, the Ti2SnC@Li||Li@Ti2SnC half-cells demonstrate ultralong cycling performance of 5000 h at 5 mAh cm−2 and 5 mA cm−2. The Ti2SnC@Li||LiFePO4(LFP) full-cells demonstrate ultralong stability up to 3000 cycles at 5C. At harsh conditions including 24.3 mg cm−2 of LFP, 6.0 g (Ah)−1 of electrolyte and 2.6 of negative/positive ratio, the Ti2SnC@Li||LFP full-cells maintain 2.9 mAh cm−2 after 130 cycles at 0.3C. This work demonstrates the MAX phases with high modulus, chemical stability and self-smoothing ability as triple functional ASEI for metal anode protection.

Long‐lifespan 522 Wh kg‐1 Lithium Metal Pouch Cell Enabled by Compound Additives Engineering

Matching high‐voltage cathodes with lithium metal anodes represents the most viable technological approach for developing secondary batteries with ultra‐high energy density exceeding 500 Wh kg‐1. Nevertheless, the instability of electrolyte/electrode interface film and commercial electrolytes with cut‐off voltage above 4.3 V is still a major concern. Herein, we present that excellent cycling stability with an ultra‐high cut‐off voltage of up to 5.0 V can be obtained by using three‐component additives containing fluoroethylene carbonate (FEC), hexadecyl trimethylammonium chloride (CTAC), and tri(pentafluorophenyl)borane (TPFPB). Excellent ionic conductivity, robust interfacial films on both electrodes, and long‐lasting uniform Li+ regulation ability can be obtained in the modifying electrolyte. Consequently, using a high plating/stripping capacity of 3 mAh cm‐2 under the current density of 1 mA cm‐2, lithium symmetric cells demonstrate stable cycling performance exceeding 800 hours. Meanwhile, the 7.3 Ah‐class Li[NixCoyMn1‐x‐y]O2 (x=0.83, NCM83)| Li pouch cells are assembled, which show a high energy density of 522 Wh kg‐1 and present excellent stability over 178 cycles with a high initial coulombic efficiency (CE) of 98.0%.

Long-lifespan 522 Wh kg-1 Lithium Metal Pouch Cell Enabled by Compound Additives Engineering.

Matching high-voltage cathodes with lithium metal anodes represents the most viable technological approach for developing secondary batteries with ultra-high energy density exceeding 500 Wh kg-1. Nevertheless, the instability of electrolyte/electrode interface film and commercial electrolytes with cut-off voltage above 4.3 V is still a major concern. Herein, we present that excellent cycling stability with an ultra-high cut-off voltage of up to 5.0 V can be obtained by using three-component additives containing fluoroethylene carbonate (FEC), hexadecyl trimethylammonium chloride (CTAC), and tri(pentafluorophenyl)borane (TPFPB). Excellent ionic conductivity, robust interfacial films on both electrodes, and long-lasting uniform Li+ regulation ability can be obtained in the modifying electrolyte. Consequently, using a high plating/stripping capacity of 3 mAh cm-2 under the current density of 1 mA cm-2, lithium symmetric cells demonstrate stable cycling performance exceeding 800 hours. Meanwhile, the 7.3 Ah-class Li[NixCoyMn1-x-y]O2 (x=0.83, NCM83)| Li pouch cells are assembled, which show a high energy density of 522 Wh kg-1 and present excellent stability over 178 cycles with a high initial coulombic efficiency (CE) of 98.0%.

Cyclosulfate additive inhibits Li dendrite disorder growth to achieve stable cycles of Li metal battery

ABSTRACT The high reactivity of lithium metal leads to the uncontrolled growth of lithium dendrites during the charging and discharging process of lithium metal batteries, which results in the poor cycle performance of batteries. In this paper, we innovatively utilized 1, 3-propanediol cyclic sulfate (PCS) as an additive to successfully construct a smooth and dense SEI layer containing sulfur element on the lithium metal anode surface. Under the action of PCS, the cells show excellent performance. After 200 cycles, cells with baseline electrolyte (BE) + 1 wt.% PCS still has a high capacity of of 148mAh g−1 and 81.38% capacity retention compared with cells with BE. In-situ optical microscopy is pioneeringly applied to showcase the generation and growth of lithium dendrites which showed that PCS participated in the formation of the SEI layer, indicating that this optimized SEI layer has better conductivity of Li+ and chemical stability, thus inhibiting malignant lithium deposition and electrolyte decomposition above the lithium metal anode.