Sulfide-based all-solid-state lithium metal batteries (ASSLMBs) are promising for high-energy-density and safe energy storage. But the poor compatibility of sulfide electrolytes with both high-voltage cathodes and lithium metal anodes hinders their practical application. Here, we disclose a fluorine–nitrogen synergistic interfacial engineering strategy by modifying Li_5.5PS_4.5Cl_1.5 (LPSC) with lithium bis(trifluoromethanesulfonyl)imide (LiTFSI). The modified LPSC electrolyte shows a high ionic conductivity of 2.88 mS·cm⁻¹. Moreover, LiTFSI induced dual-functional interphases, a fluorine-rich cathode–electrolyte interphase (CEI) (LiF/Li_xPO_yF_z) and a fluorine–nitrogen composite solid electrolyte interphase (SEI, Li₃N/LiF/Li_xPO_yF_z), contributing to high oxidation stability (LiNi_0.8Co_0.1Mn_0.1O₂//LiIn battery retains 107% capacity retention after 13,000 cycles at 15 C) and excellent lithium dendrite inhibition ability (Li//Li: critical current density (CCD) 3.4 mA·cm⁻², stably cycling 2600 h at 0.5 mA·cm⁻²). As a result, the LiNi_0.8Co_0.1Mn_0.1O₂//Li cell with modified electrolyte demonstrates 1000 stable cycles at a high cut-off voltage of 4.5 V and wide-temperature adaptability (−20–50 °C). This work shows a facile and effective method for constructing long-life and high-energy-density sulfide based ASSLMBs.

Lithium metal batteries (LMBs) show great promise for achieving energy densities over 400 Wh·kg⁻¹. However, highly flammable organic electrolytes are a long-lasting problem that triggers safety hazards and hinders the commercial application of LMBs. Here, a nonflammable diluted highly concentrated electrolyte (DHCE) with ethoxy(pentafluoro)cyclotriphosphazene (PFPN) as a diluent is developed to simultaneously achieve high safety and cycling stability of high-voltage LMBs. The optimal DHCE not only ensures reversible Li deposition/dissolution behavior with a superior average Coulombic efficiency (CE) over 99.1% on lithium metal anode (LMA), but also suppresses side reactions and stress crack on the LiCoO₂ (LCO) under high cut-off voltage. The newly developed DHCE exhibits high thermal stability, showing complete nonflammability and reduced heat generation between the electrolyte and delithiated LCO/cycled LMA. This work offers an opportunity for rational designing nonflammable electrolytes toward high-voltage and safe LMBs.

Lithium halide electrolytes show great potential in constructing high-energy-density solid-state batteries with high-voltage cathode materials due to their high electrochemical stability and wide voltage windows. However, the high cost and low conductivity of some compositions inhibit their applications. Moreover, the effect of electronic additives in the cathode mixture on the stability and capacity is unclear. Here, the Y³⁺ doping strategy is applied to enhance the conductivity of low-cost Li₂ZrCl₆ electrolytes. By tailoring the Y³⁺ dopant in the structure, the optimal Li_2.5Zr_0.5Y_0.5Cl₆ with high conductivity up to 1.19 × 10⁻³ S cm⁻¹ is obtained. Li_2.5Zr_0.5Y_0.5Cl₆@CNT/Li_2.5Zr_0.5Y_0.5Cl₆/Li_5.5PS_4.5Cl_1.5/In-Li solid-state batteries with different carbon nanotube (CNT) contents in the cathode are fabricated. The stability and electrochemical performances of the cathode mixture as a function of CNT content are studied. The cathode mixture containing 2% (wt.) CNT exhibits the highest stability and almost no discharge capacity, while the cathode mixture consisting of Li_2.5Zr_0.5Y_0.5Cl₆ and 10% (wt.) CNT delivers a high initial discharge capacity of 199.0 mAh g⁻¹ and reversible capacities in the following 100 cycles. Multiple characterizations are combined to unravel the working mechanism and confirm that the electrochemical reaction involves the 2-step reaction of Y³⁺/Y⁰, Zr⁴⁺/Zr⁰, and Cl⁻/Cl_x⁻ in the Li_2.5Zr_0.5Y_0.5Cl₆ electrolyte. This work provides insight into designing a lithium halide electrolyte-based cathode mixture with a high ionic/electronic conductive framework and good interfacial stability for solid-state batteries.

Development of advanced high-voltage electrolytes is key to achieving high-energy-density lithium metal batteries (LMBs). Weakly solvating electrolytes (WSE) can produce unique anion-driven interphasial chemistry via altering the solvating power of the solvent, but it is difficult to dissolve the majority of Li salts and fail to cycle at a cut-off voltage above 4.5 V. Herein, we present a new-type WSE that is regulated by the anion rather than the solvent, and the first realize stable cycling of dimethoxyethane (DME) at 4.6 V without the use of the “solvent-in-salt” strategy. The relationships between the degree of dissociation of salts, the solvation structure of electrolytes, and the electrochemical performance of LMBs were systematically investigated. We found that LiBF₄, which has the lowest degree of dissociation, can construct an anion-rich inner solvation shell, resulting in anion-derived anode/cathode interphases. Thanks to such unusual solvation structure and interphasial chemistry, the Li-LiCoO₂ full cell with LiBF₄-based WSE could deliver excellent rate performance (115 mAh g⁻¹ at 10 C) and outstanding cycling stability even under practical conditions, including high loading (10.7 mg cm⁻²), thin Li (50 μm), and limited electrolyte (1.2 μL mg⁻¹).

Sodium metal is a promising anode for sodium batteries due to its high theoretical capacity and low cost. However, the serious Na dendrite growth and low Coulombic efficiency, especially at high current densities/cycling capacities, severely limit the application of sodium metal anodes. Herein, trifluoromethylfullerene, C₆₀(CF₃)₆, is designed as an electrolyte additive to enable the high-rate cycling of sodium metal anodes with high Coulombic efficiency. The CF₃ groups contribute to the formation of stable NaF-rich solid electrolyte interface layer, while C₆₀ cages induce the uniform distribution of sodium ions and promote the formation of smooth and compact morphology. Thus, Na||Cu cell with C₆₀(CF₃)₆ can be cycled at 2 mA·cm⁻² and 10 mAh·cm⁻² over 180 cycles with an average Coulombic efficiency of 99.9%, and Na||Na cell can be cycled at 10 mA·cm⁻² over 600 cycles. Furthermore, Na||NaV₂(PO₄)₃@C full cell exhibits high capacity retention of 84% over 2,000 cycles at 20 C (~ 3 mA·cm⁻²).

High energy density and low cost made lithium–sulfur (Li–S) batteries appealing for the next-generation energy storage devices. However, their commercial viability is seriously challenged by serious polysulfide shuttle effect, sluggish sulfur kinetics, and uncontrollable dendritic Li growth. Herein, a dual-functional electrolyte additive, diphenyl ditelluride (DPDTe) is reported for Li–S battery. For sulfur cathodes, DPDTe works as a redox mediator to accelerate redox kinetics of sulfur, in which Te radical-mediated catalytic cycle at the solid–liquid interface contributes significantly to the whole process. For lithium anodes, DPDTe can react with lithium metal to form a smooth and stable organic–inorganic hybrid solid-electrolyte interphase (SEI), enabling homogeneous lithium deposition for suppressing dendrite growth. Consequently, the Li–S battery with DPDTe exhibits remarkable cycling stability and superb rate capability, with a high capacity up to 1227.3 mAh g⁻¹ and stable cycling over 300 cycles. Moreover, a Li–S pouch cell with DPDTe is evaluated as the proof of concept. This work demonstrates that organotelluride compounds can be used as functional electrolyte additives and offers new insights and opportunities for practical Li–S batteries.

Solid/solid interface is the major challenge for high-performance solid-state batteries. Solid electrolytes (SEs) play a crucial role in the fabrication of effective interfaces in solid-state batteries. Herein, the electrolyte distribution with varied particle sizes is tuned to construct solid-state batteries with excellent performance at different operating temperatures. Solid-state batteries with the configuration S/L (small-sized SE in composite cathode and large-sized SE in electrolyte layer) show the best performance at room temperature (168 mA h g⁻¹ at 0.2 C, retention of 99%, 100 cycles) and −20 ℃ (89 mA h g⁻¹ at 0.05 C), while the configuration S/S displays better performance at elevated temperature. The superior performance of S/L battery is associated with faster lithium-ion dynamics due to the better solid/solid interface between active materials and electrolytes. Moreover, the inferior performance at 60 ℃ is caused by the formation of voids and cracks in the electrolyte layer during cycling. In contrast, the S/S battery delivers superior performance at elevated operating temperature because of the integrated structure. This work confirms that tailoring electrolyte size has significant effect on fabricating all-climate solid-state batteries.