All-solid-state fluoride-ion batteries(ASSFIBs)exhibit ultrahigh theoretical energy densities up to5000 W h L,and thus receive increasing attention.However,due to the difficulty of identifying appropriate solid electrolytes,it was commonly believed that ASSFIBs cannot exhibit satisfactory long-term cycling performance at 25℃.Recently,this situation is changed by the discovery of CsPb_(0.9)K_(0.1)F_(2.9),which shows a rare combination of high ionic conductivity and excellent electrochemical stability.Here,we discover that the performance of this material can be further improved by simply altering the reported mechanochemical synthesis approach with the solid-state reaction.The resulting material shows a room-temperature conductivity of 2.2 mS cm^(-1),outperforming the most conductive F-ion solid electrolyte reported so far(PbSnF,1.6 mS cm^(-1)).More importantly,it enables 100 cycles of stable ASSFIB operation at 25℃for the first time,with a final capacity(152.5 mA h g^(-1) after 100 cycles)also surpassing all the other room-temperature bulk-type ASSFIBs in literature(below 80 mA h g^(-1) after no more than20 cycles).
