O2 Batteries Research Articles

Nickel-doped cobalt phosphide with phosphorus-vacancy-abundant as an efficient catalyst for non-aqueous and quasi-solid-state Li–O2 batteries

High-performance electrocatalysts are required to tackle the challenges for Li-O2 batteries. Elemental doping and vacancy engineering can modify the local electronic structure, and thus enhance the adsorption and catalytic activity. Nickel-doped cobalt phosphides, rich in phosphorus vacancies, are synthesized to boost the electrochemical efficiency in Li-O2 batteries. These nanocomposites exhibit high performance in non-aqueous Li-O2 batteries, with low overpotential and cycling stability up to 741 cycles at 500 mAh/g. Additionally, with quasi-solid-state electrolytes, the batteries can retain operation for 91 cycles. This study underscores the potential of elemental doping and vacancy engineering in transition-metal-phosphides for Li-O2 battery development.

Comparative study on the thermal runaway characteristics of Li(NixCoyMnz)O2 batteries

Lithium-ion batteries (LIBs) generate substantial gas during the thermal runaway (TR) process, presenting serious risks to electrochemical energy storage systems in case of ignition or explosions. Previous studies were mainly focused on investigating the TR characteristics of Li(NixCoyMnz)O2 batteries with different cathode materials, but they were conducted in isolation. In this study, the thermal runaway characteristics of prismatic cells that use Li(NixCoyMnz)O2 (with x ranging from 0.33 to 0.9) cathode materials in an inert environment, which are commonly used or proposed for energy storage applications, are examined. The findings of this research show that the normalized gas generation rate remains consistent, regardless of the battery capacity or experimental chamber volume, with a value of 0.1 ± 0.03 mol∙Ah⁻1. High-capacity cells have short jetting durations, and a high nickel content leads to increased mass loss rates. The flammability limits of the gases expelled during thermal runaway, represented by the lower flammability limit (LFL), remain stable at 8 ± 1.8 % with minimal variations. However, the upper flammability limit (UFL) varies significantly, ranging from 30 % to 60 %. Increasing the battery capacity or reducing the experimental chamber volume increases the explosion index. The explosive, combustibility, and jetting duration characteristics of the emitted gases from five different battery chemical compositions provide valuable insights for risk assessment in future electrochemical energy storage systems.

Integrated platinum-fullerene nanocatalyst as efficient cathode kinetic promoter for advanced lithium−oxygen batteries

Efficient and robust platinum-carbon electrocatalysts are of great significance for long-term service of high-performance Li–O2 batteries. Herein we developed an ultra-low platinum loading platinum-fullerene electrocatalyst by ultraviolet-assisted method. The catalyst features crystalline platinum nanodots integrated into C60 nano-fullerene matrices (Pt–C60), which demonstrates excellent mass-activity, 28.8 times higher than that of commercial Pt/C catalysts, exhibiting an ultra-low cell overpotential of 0.43 V while maintaining an excellent cycle stability over 150 cycles. XPS and Raman spectra disclose the integrated nature of Pt–C bonding interaction, and computational modeling reveal the improved electrocatalytic activity and cathode reaction kinetics. Comprehensive investigations demonstrate that the synergistic contribution of component and structure in integrated Pt–C60 catalyst is responsible for high-efficiency and long-life of Li–O2 batteries. Notably, Pt–C covalent integrated design provides a paradigm of catalyst engineering for developing high-activity and low-cost Pt/C catalysts, and easy synthesis method allows them to be mass-produced and potentially-used in catalyst fields.

A lithiated zeolite-based protective layer to boost the cycle performance of lithium−oxygen batteries via redox mediator sieving

Lithium–oxygen (Li–O2) batteries with ultra-high theoretical specific energy (3500 Wh kg−1) have attracted significant attention, but the sluggish electrochemical processes of discharge product Li2O2 lead to poor cycling stability. Redox mediators (RMs) as soluble catalysts are widely used to assist with the electrochemical formation/decomposition of Li2O2. However, the shuttle effect of RMs causes severe deterioration of both RMs and Li metal anodes. Herein, for the first time we synthesize a lithiated zeolite-based protective layer on Li anodes to mitigate the shuttle effect of 2,2,6,6-tetramethylpiperidinyloxy (TEMPO) in Li–O2 batteries. The protective layer successfully blocks the migration of TEMPO toward the Li anode owing to the angstrom-level aperture size of lithiated zeolite. Due to the excellent redox-mediator-sieving capability of the protective layer, the cycle life of the Li−O2 batteries is significantly prolonged more than ten times at a current density of 250 mA g−1 and a limited capacity of 500 mA h g−1. This work demonstrates that the lithiated zeolite-based protective layer capable of molecular sieving is a facile and scalable way to mitigate the shuttle effect of RMs in Li–O2 batteries.

A magnetic/force coupling assisted lithium-oxygen battery based on magnetostriction and piezoelectric catalysis of CoFe2O4/BiFeO3 cathode

The high energy density of Li−O2 batteries surpasses all existing batteries, and it holds the potential to emerge as the most outstanding solution for energy storage in the future. However, the insulated, insoluble discharge product (Li2O2) has impeded the practical applications. Conventional catalyst design based on electronic structure and interfacial charge transfer descriptors are incapable of overcoming these limitations of Li2O2. Herein, a magnetic/force coupling assisted Li−O2 battery based on magnetostrictive and piezoelectric catalysis with CoFe2O4/BiFeO3 core-shell structure cathode was established for the first time. An external magnetic field is introduced to produce a magnetostrictive stress on CoFe2O4, contributing to the piezoelectric electron hole transport by the generated piezoelectric potential energy with a built-in electric field based on the piezoelectric catalytic mechanism, and thus promoting the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) kinetics, and reducing the overpotential during charge/discharge. The magnetic/force coupling assisted Li−O2 battery equipped with the unique CoFe2O4/BiFeO3 cathode deliver an ultra-low charging platform of 3.49 V and an ultra-high discharge platform of 2.83 V. This unique magnetic/force assisted strategy provides an important insight into solving the high overpotential in metal-air battery systems.

A Rotating Cathode with Periodical Changes in Electrolyte Layer Thickness for High-Rate Li‒O2 Batteries.

Li-O2 batteries (LOBs) possess the highest theoretical gravimetric energy density among all types of secondary batteries, but they are still far from practical applications. The poor rate performance resulting from the slow mass transfer is one of the primary obstacles in LOBs. To solve this issue, a rotating cathode with periodic changes in the electrolyte layer thickness is designed, decoupling the maximum transfer rate of Li+ and O2. During rotation, the thinner electrolyte layer on the cathode facilitates the O2 transfer, and the thicker electrolyte layer enhances the Li+ transfer. As a result, the rotating cathode enables the LOBs to undergo 58 cycles at 2.5mA cm-2 and discharge stably even at a high current density of 7.5 mA cm-2. Besides, it also makes the batteries exhibit a large discharge capacity of 6.8 mAh cm-2, and the capacity decay is much slower with increasing current density. Notably, this rotating electrode holds great promise for utilization in other electrochemical cells involving gas-liquid-solid triple-phase interfaces, suggesting a viable approach to enhance the mass transfer in such systems.

LiF/Li3N-Rich Electrode-Electrolyte Interfaces Enabled by Multi-Functional Electrolyte Additive to Achieve High-Performance Li/LiNi0.8Co0.1Mn0.1O2 Batteries.

LiPF6-based carbonate electrolytes have been extensively employed in commercial Li-ion batteries, but they face numerous interfacial stability challenges while applicating in high-energy-density lithium-metal batteries (LMBs). Herein, this work proposes N-succinimidyl trifluoroacetate (NST) as a multifunctional electrolyte additive to address these challenges. NST additive could optimize Li+ solvation structure and eliminate HF/H2O in the electrolyte, and preferentially be decomposed on the Ni-rich cathode (LiNi0.8Co0.1Mn0.1O2, NCM811) to generate LiF/Li3N-rich cathode-electrolyte interphase (CEI) with high conductivity. The synergistic effect reduces the electrolyte decomposition and inhibits the transition metal (TM) dissolution. Meanwhile, NST promotes the creation of solid electrolyte interphase (SEI) rich in inorganics on the Li metal anode (LMA), which restrains the growth of Li dendrites, minimizes parasitic reactions, and fosters rapid Li+ transport. As a result, compared with the reference, the Li/LiNi0.8Co0.1Mn0.1O2 cell with 1.0 wt.% NST exhibits higher capacity retention after 200 cycles at 1C (86.4% vs. 64.8%) and better rate performance, even at 9C. In the presence of NST, the Li/Li symmetrical cell shows a super-stable cyclic performance beyond 500 h at 0.5 mA cm-2/0.5 mAh cm-2. These unique features of NST are a promising solution for addressing the interfacial deterioration issue of high-capacity Ni-rich cathodes paired with LMA.

Anion‐Dominated Conventional‐Concentrations Electrolyte to Improve Low‐Temperature Performance of Lithium‐Ion Batteries

AbstractLow temperatures (< −20 °C) significantly diminish lithium‐ion battery performance due to freezing issues within commercial electrolytes and the high energy barrier for Li+ desolvation at the interface. Although high‐concentration electrolytes and localized high‐concentration electrolytes enhance Li+ desolvation kinetics featuring anion‐participated solvation structures, their high viscosity and propensity for Li salt precipitation render them unsuitable for low‐temperature environments. This study introduces an anion‐dominated conventional‐concentrations electrolyte (ACCE) created by incorporating Lithium difluorophosphate(LiPO2F2)into a 1 M Lithium bis((trifluoromethyl)sulfonyl)azanide(LiTFSI) Dimethyl carbonate(DMC)/Fluoroethylene carbonate(FEC)/Methyl acetate(MA) electrolyte solution. LiPO2F2, characterized by its poor solubility and strong binding with Li+, demonstrates a pronounced tendency to integrate into the primary solvation sheath of Li+. Moreover, the synergy between LiTFSI and LiPO2F2 establishes a dual anion configuration, unveiling a dual anion‐driven mechanism. This mechanism significantly diminishes the interaction between Li+ and solvent molecules, resulting in reduced desolvation energy under low temperatures. The ACCE exhibits high ionic conductivity of 1.3 mS cm−1 at −50 °C, enabling stable cycling of Li/NCM811 cells at −50 °C, and further allows 0.75 Ah graphite(Gr)/LiNi0.8Co0.1Mn0.1O2(NCM811) batteries dischargeable at −40 °C. This study presents a practical application potential for poorly soluble lithium salts and provides a new avenue for designing electrolytes suitable for low‐temperature applications.

Long‐cycling and High‐voltage Solid State Lithium Metal Batteries Enabled by Fluorinated and Crosslinked Polyether Electrolytes

AbstractSolid‐state lithium metal batteries (LMBs), constructed through the in situ fabrication of polymer electrolytes, are considered a critical strategy for the next‐generation battery systems with high energy density and enhanced safety. However, the constrained oxidation stability of polymers, such as the extensively utilized polyethers, limits their applications in high‐voltage batteries and further energy density improvements. Herein, an in situ fabricated fluorinated and crosslinked polyether‐based gel polymer electrolyte, FGPE, is presented, exhibiting a high oxidation potential (5.1 V). The fluorinated polyether significantly improves compatibility with both lithium metal and high‐voltage cathode, attributed to the electron‐withdrawing −CF3 group and the generated LiF‐rich electrolyte/electrode interphase. Consequently, the solid‐state Li||LiNi0.6Co0.2Mn0.2O2 batteries employing FGPE demonstrate exceptional cycling performances of 1000 cycles with 78 % retention, representing one of the best results ever reported for polymer electrolytes. Moreover, FGPE enables batteries to operate at 4.7 V, realizing the highest operating voltage of polyether‐based batteries to date. Notably, our designed in situ FGPE provides the solid‐state batteries with exceptional cycling stability even at practical conditions, including high cathode loading (21 mg cm−2) and industry‐level 18650‐type cylindrical cells (1.3 Ah, 500 cycles). This work provides critical insights into the development of oxidation‐stable polymer electrolytes and the advancement of practical high‐voltage LMBs.

Long-cycling and High-voltage Solid State Lithium Metal Batteries Enabled by Fluorinated and Crosslinked Polyether Electrolytes.

Solid-state lithium metal batteries (LMBs), constructed through the in situ fabrication of polymer electrolytes, are considered a critical strategy for the next-generation battery systems with high energy density and enhanced safety. However, the constrained oxidation stability of polymers, such as the extensively utilized polyethers, limits their applications in high-voltage batteries and further energy density improvements. Herein, an in situ fabricated fluorinated and crosslinked polyether-based gel polymer electrolyte, FGPE, is presented, exhibiting a high oxidation potential (5.1 V). The fluorinated polyether significantly improves compatibility with both lithium metal and high-voltage cathode, attributed to the electron-withdrawing -CF3 group and the generated LiF-rich electrolyte/electrode interphase. Consequently, the solid-state Li||LiNi0.6Co0.2Mn0.2O2 batteries employing FGPE demonstrate exceptional cycling performances of 1000 cycles with 78 % retention, representing one of the best results ever reported for polymer electrolytes. Moreover, FGPE enables batteries to operate at 4.7 V, realizing the highest operating voltage of polyether-based batteries to date. Notably, our designed in situ FGPE provides the solid-state batteries with exceptional cycling stability even at practical conditions, including high cathode loading (21 mg cm-2) and industry-level 18650-type cylindrical cells (1.3 Ah, 500 cycles). This work provides critical insights into the development of oxidation-stable polymer electrolytes and the advancement of practical high-voltage LMBs.

Mo‐Doped BiVO4 as a Fast Electrode Reaction Kinetics Catalyst in Na−O2 Batteries

AbstractThe highly insulated solid discharge products in sodium‐oxygen (Na−O2) batteries induce large polarization and thus heavily threaten their cycle life. Controlment of discharge products taking efficient catalyst is a best way to solve this problem. Here, Mo‐doped BiVO4 as the catalyst produces large amounts of carrier, thus boosting the battery reaction and reducing the overpotential under the light assistance. Compared with the BiVO4 without Mo doping, the doped one has a lower recombination of photogenerated carriers, thus benefiting a large polarization suppression and Na−O2 batteries running for over 270 cycles under 3.65 V as well as a fine rate performance. Besides, Mo doping reduces the size of BiVO4, beneficial for the carrier transportation and more reactions due to the large specific surface area. Experiment combined with theoretical calculation shows that Mo doping is advantageous to enhancing catalytic activity of BiVO4 due to a lower work function for easier electron extraction, thus enhancing Na2O2 decomposition capability. This work undoubtedly inspires photocatalysts′ use for solving the insulated solid discharge products decomposition in metal‐O2 batteries and provides a guide for other photocatalysts possibilities.

Thermal runaway propagation behavior and gas production characteristics of NCM622 battery modules at different state of charge

Due to the complex thermal runaway propagation behavior of lithium-ion battery modules and the generation of a substantial amount of combustible mixed gases during the process, their safety performance is compromised, hindering their large-scale application in the fields of energy storage and automotive industries. Therefore, in this paper, the thermal runaway propagation behavior and gas production characteristics of Li (Ni0.6Co0.2Mn0.2) O2 battery modules with different state of charge were investigated in closed space. The results show that no thermal runaway occurred in the battery module when the state of charge was below 25% in closed space. With the decrease of the state of charge, both the internal thermal propagation speed and the surface temperature of the lithium-ion battery were reduced. The total gas production volume from 17.48 mol to 6.17 mol when the state of charge was reduced from 100% to 50%. The main gases produced during thermal runaway were CO2, CO, H2, CH4, and C2H4. With the decrease of the state of charge, the content of CO2 increased, the content of C2H4 and CO decreased, and the content of H2 and CH4 remained unchanged with the state of charge. The results contribute to safety measures for preventing thermal runaway accidents in lithium-ion batteries, offering guidance for the secure design of lithium-ion battery packs, and thus enhancing the overall safety of lithium-ion batteries.

Cation Vacancy Modulated Interfacial Electronic Interactions for Enhanced Electrocatalysis in Lithium–Oxygen Batteries

AbstractLi–O2 batteries deliver ultrahigh theoretical specific energy while suffering from low energy efficiency and poor cyclability due to sluggish kinetics of oxygen electrode reactions. Herein, a strategy of engineering interfacial electron structure of MXene‐based composites is presented to boost oxygen electrode reactions for advancing Li–O2 batteries with the cation vacancy‐rich CoSe@MXene (VCo‐CoSe2@MXene) as the case study. The formation of interfacial Co─C bond between VCo‐CoSe2 and Ti3C2 MXene and its enhanced covalency after introducing Co vacancy leads to promoted electron transfer from Ti3C2 MXene to CoSe2 and optimized electronic structure of interfacial Co sites, especially the second Co sites neighboring Co vacancy, which serve as the active centers for oxygen redox reactions. On this basis, VCo‐CoSe2@MXene‐based Li─O2 batteries exhibit low overpotential (0.35 V) and excellent cycling stability (250 cycles at 500 mA g−1). This work proposes an effective strategy to develop MXene‐based electrocatalysts for Li–O2 batteries by tailoring interfacial electron structure.

Thermal Runaway Characteristics and Gas Analysis of LiNi0.9Co0.05Mn0.05O2 Batteries

Layered ternary materials with high nickel content are regarded as the most promising cathode materials for high-energy-density lithium-ion batteries, owing to their advantages of high capacity, low cost, and relatively good safety. However, as the nickel content increases in ternary layered materials, their thermal stability noticeably decreases. It is of paramount importance to explore the characteristics of thermal runaway for lithium-ion batteries. In this study, two high-nickel LiNi0.9Co0.05Mn0.05O2 batteries were laterally heated to thermal runaway in a sealed chamber filled with nitrogen to investigate the thermal characteristics and gas compositions. The temperature of the battery tabs was measured, revealing that both batteries were in a critical state of thermal runaway near 120 degrees Celsius. A quantitative analysis method was employed during the eruption process, dividing it into three stages: ultra-fast, fast, and slow; the corresponding durations for the two batteries were 3, 2, 27 s and 3, 3, 26 s. By comparing the changes in chamber pressure, it was observed that both batteries exhibited a similar continuous venting duration of 32 s. However, the pressure fluctuation ranges of the two samples were 99.5 and 68.2 kPa·m·s−1. Compared to the other sample, the 211 Ah sample exhibited larger chamber pressure fluctuations and reached higher peak pressures, indicating a higher risk of explosion. In the experimental phenomenon captured by a high-speed camera, it took only 1 s for the sample to transition from the opening of the safety valve to filling the experimental chamber with smoke. The battery with higher energy density exhibited more intense eruption during thermal runaway, resulting in more severe mass loss. The mass loss of the two samples is 73% and 64.87%. The electrolyte also reacted more completely, resulting in a reduced number of measured exhaust components. The main components of gaseous ejections are CO, CO2, H2, C2H4, and CH4. For the 211 Ah battery, the vented gases were mainly composed of CO (41.3%), CO2 (24.8%), H2 (21%), C2H4 (7.4%) and CH4 (3.9%), while those for the other 256 Ah battery were mainly CO (30.6%), CO2 (28.5%), H2 (21.7%), C2H4 (12.4%) and CH4 (5.8%). Comparatively, the higher-capacity battery produced more gases. The gas volumes, converted to standard conditions (0 °C, 101 kPa) and normalized, resulted in 1.985 L/Ah and 2.182 L/Ah, respectively. The results provide valuable guidance for the protection of large-capacity, high-energy-density battery systems. The quantitative analysis of the eruption process has provided assistance to fire alarm systems and firefighting strategies.

An In Situ Gelled Polymer Electrolyte to Stabilize Lithium–Air Batteries

AbstractGel polymer‐based lithium batteries exhibit a unique combination of advantageous properties, including the favorable interfacial contact characteristic of liquid‐state batteries and the inherent stability of solid‐state batteries. For Li–air batteries operated in the semi‐open atmosphere, implementing in situ synthesized gel polymer electrolytes (GPEs) is effective in mitigating the environment‐induced challenges. In this study, a dimethyl sulfoxide (DMSO)‐based GPE in situ initiated by the toluene‐2,4‐diisocyanate (TDI) and 1,4‐benzenediboronic acid (BDBA) is designed to enable the stable operation of lithium–air batteries. The integration of in situ polymerization and polyvinyl alcohol's functional group engineering not only brings benefits to the interfacial contact and electrochemical stability of the battery but also mitigates the moisture sensitivity and volatility of the DMSO electrolyte in the ambient environment. In addition, the GPE can promote the formation of a robust protection film on the lithium surface. As a result, the designed GPE makes the batteries fully leverage their outstanding cycling stability in the ambient environment (241 cycles at 500 mA g−1 and 1000 mAh g−1). Moreover, an optimized Li–air pouch cell structure incorporating the GPE achieves a boasted energy density of 757.5 Wh kg−1, providing a significant technical pathway to bring Li–O2 batteries to practical Li–air batteries.

Double-phase electrolyte enabling the long-lasting redox mediation in Li–O2 batteries

The achievement of practical Li–O2 batteries is impeded by their low discharge capacity, large charge overpotential, and short lifespan. In general, the use of electrolyte with a high-donor-number solvent such as dimethyl sulfoxide (DMSO) is able to drive the solution-mediated pathway, alleviating the premature passivation of cathode from the surface-mediated Li2O2 film growth, gaining large Li2O2 toroidal particles, and extending the discharge lifetime. However, direct electrochemical decomposition of Li2O2 toroidal products typically occurs at a high charge potential owing to the poor solid-solid contact between cathode catalysts and Li2O2 toroids. Besides, DMSO-based electrolytes are unstable to Li anode, leading to undesired parasitic reactions. To overcome above issues, herein, a double-phase electrolyte composed of 10-methylphenothiazine (MPT)-dissolved DMSO-based catholyte and octyltrimethoxysilane (TOOS)-based anolyte is designed taking advantages of the immiscibility of DMSO and TOOS solvents and the insolubility of MPT in TOOS. Benefiting from the rapid liquid-solid reaction between MPT+ and Li2O2 products, the blocked MPT shuttling in TOOS, and the good compatibility of TOOS-based electrolyte to Li anode, the assembled Li–O2 battery delivers a reduced charge overpotential and a robust cyclability over 250 cycles. This study provides a promising strategy for electrolyte design towards next-generation high-performance Li–O2 batteries.

Interface engineering strategy via electron-defect trimethyl borate additive toward 4.7 V ultrahigh-nickel LiNi0.9Co0.05Mn0.05O2 battery

The Li metal battery with ultrahigh-nickel cathode (LiNixM1−xO2, M = Mn, Co, and x ≥ 0.9) under high-voltage is regarded as one of the most promising approaches to fulfill the ambitious target of 400 Wh/kg. However, the practical application is impeded by the instability of electrode/electrolyte interface and Ni-rich cathode itself. Herein we proposed an electron-defect electrolyte additive trimethyl borate (TMB) which is paired with the commercial carbonate electrolyte to construct highly conductive fluorine- and boron-rich cathode electrolyte interface (CEI) on LiNi0.9Co0.05Mn0.05O2 (NCM90) surface and solid electrolyte interphase (SEI) on lithium metal surface. The modified CEI effectively mitigates the structural transformation from layered to disordered rock-salt phase, and consequently alleviate the dissolution of transition metal ions (TMs) and its “cross-talk” effect, while the enhanced SEI enables stable lithium plating/striping and thus demonstrated good compatibility between electrolyte and lithium metal anode. As a result, the common electrolyte with 1 wt% TMB enables 4.7 V NCM90/Li cell cycle stably over 100 cycles with 70% capacity retention. This work highlights the significance of the electron-defect boron compounds for designing desirable interfacial chemistries to achieve high performance NCM90/Li battery under high voltage operation.

Sulfur Vacancies and 1T Phase-Rich MoS2 Nanosheets as an Artificial Solid Electrolyte Interphase for 400Wh kg-1 Lithium Metal Batteries.

Constructing large-area artificial solid electrolyte interphase (SEI) to suppress Li dendrites growth and electrolyte consumption is essential for high-energy-density Li metal batteries (LMBs). Herein, chemically exfoliated ultrathin MoS2 nanosheets (EMoS2) as an artificial SEI are scalable transfer-printed on Li-anode (EMoS2@Li). The EMoS2 with a large amount of sulfur vacancies and 1T phase-rich acts as a lithiophilic interfacial ion-transport skin to reduce the Li nucleation overpotential and regulate Li+ flux. With favorable Young's modulus and homogeneous continuous layered structure, the proposed EMoS2@Li effectively suppresses the growth of Li dendrites and repeat breaking/reforming of the SEI. As a result, the assembled EMoS2@Li||LiFePO4 and EMoS2@Li||LiNi0.8Co0.1Mn0.1O2 batteries demonstrate high-capacity retention of 93.5% and 92% after 1000 cycles and 300 cycles, respectively, at ultrahigh cathode loading of 20mg cm-2. Ultrasonic transmission technology confirms the admirable ability of EMoS2@Li to inhibit Li dendrites in practical pouch batteries. Remarkably, the Ah-class EMoS2@Li||LiNi0.8Co0.1Mn0.1O2 pouch battery exhibits an energy density of 403 Wh kg-1 over 100 cycles with the low negative/positive capacity ratio of 1.8 and electrolyte/capacity ratio of 2.1 g Ah-1. The strategy of constructing an artificial SEI by sulfur vacancies-rich and 1T phase-rich ultrathin MoS2 nanosheets provides new guidance to realize high-energy-density LMBs with long cycling stability.

In Situ Construction of a Polymer Coating Layer on the LiNi0.8Co0.1Mn0.1O2 Cathode for High-Performance Lithium-Ion Batteries.

Lithium-ion batteries (LIBs) are known for their high energy density but exhibit poor cyclic stability and safety risks due to side reactions between the electrode and electrolyte. To address these issues, a novel approach involving construction of a polymer coating layer (PCL) via in situ self-polymerization using 2,2,3,4,4,4-hexafluorobutyl methacrylate (HFBM) as an electrolyte additive on the cathode is proposed. The PCL endows the electrolyte with a high onset oxidation potential (4.78 V) and lithium-ion transference number (0.52). The uniform and robust in situ constructed PCL can effectively inhibit the severe irreversible side reactions and suppress harmful reactions, thus providing a protective barrier against degradation. The resulting Li||LiNi0.8Co0.1Mn0.1O2 batteries exhibit an improved discharge capacity retention of 80% at 1C over 100 cycles. These results demonstrate that the in situ self-polymerization strategy holds promising potential for enhancing LIB performance and long-term stability, especially when high-voltage cathode materials are used.

Diluent modified weakly solvating electrolyte for fast-charging high-voltage lithium metal batteries

Weakly solvating electrolyte (WSE) demonstrates superior compatibility with lithium (Li) metal batteries (LMBs). However, its application in fast-charging high-voltage LMBs is challenging. Here, we propose a diluent modified WSE for fast-charging high-voltage LMBs, which is formed by adding diluent of 1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether (TTE) into the tetrahydropyran (THP) based WSE. A relatively loose solvation structure is formed due to the formation of weak hydrogen bond between TTE and THP, which accelerates the de-solvation kinetics of Li+. Besides, more anions are involved in solvation structure in the presence of TTE, yielding inorganic-rich interphases with improved stability. Li (30 µm)||LiNi0.5 Co0.2Mn0.3O2 (4.1 mAh/cm2) batteries with the TTE modified WSE retain over 64 % capacity retention after 175 cycles under high rate of 3 C and high-voltage of 4.5 V, much better than that with pure THP based WSE. This work points out that the combination of diluent with weakly solvating solvent is a promising approach to develop high performance electrolytes for fast-charging high-voltage LMBs.