Jinzhu Wang,Jipeng Hao,Chaomin Duan,Xinchao Wang,Kai Wang,Cheng Ma
Solid-state fluoride-ion batteries (FIBs) circumvent multiple formidable bottlenecks of lithium-ion batteries, but their overall performance remains inferior due to the absence of appropriate solid electrolytes. Presently the conductivity of most solid electrolytes for FIBs is too low to enable room-temperature cycling, while the few sufficiently conductive ones only allow for very low discharge voltages because of the narrow electrochemical stability window (ESW). Here, high room-temperature conductivity and a decent ESW are simultaneously achieved by designing a solid electrolyte CsPb 0.9 K 0.1 F 2.9 . Its room-temperature conductivity is 1.23 × 10 −3 S cm −1 , comparable to the most conductive system reported so far (PbSnF 4 , 5.44 × 10 −4 –1.6 × 10 −3 S cm −1 ), but the ESW is several times broader. With these appealing characteristics simultaneously achieved in the solid electrolyte, a cell with much higher voltages than other room-temperature-operable solid-state FIBs in literature is successfully constructed, and stably cycled at 25 °C for 4581 h without considerable capacity fade.
A dual-halide solid electrolyte, Li 3 YCl 3 Br 3 , was synthesized using a wet-chemistry route instead of the conventional mechanical ball-milling route. Li 3 YCl 3 B r3 exhibits an ion conductivity of 2.08 mS/cm and an electro- chemical stability window of 3.8 V. Additionally, an all-solid-state lithium-ion battery using Li 3 YCl 3 Br 3 and LiNi 0.83 Co 0.11 Mn 0.06 O 2 (NCM811) as the cathode material achieves a capacity retention of 93% after 200 cycles at 0.3 C and maintains a specific capacity of 115 mA·h/g during 2 C cycling. This exceptional performance is attributed to the high oxidative stability of Li 3 YCl 3 Br 3 and the in-situ formation of Y 2 O 3 inert protective layer on the NCM811 surface under high voltage. Consequently, the study demonstrates the feasibility of a simple, cost-effective wet-chemistry route for synthesizing multi-component halides, highlighting its potential for large-scale production of halide solid electrolytes for practical applications.