Stable composite electrolytes of PVDF modified by inorganic particles for solid‐state lithium batteries

Abstract

AbstractPolymer electrolytes have been attracting much attention because of their flexibility and easy follow‐up processing, but their Li+ conductivity in lithium‐metal batteries (LIBs) is unsatisfactory. Stable composite electrolytes of poly (vinylidene fluoride) (PVDF) polymer with high lithium‐ion conductivity have been prepared by a trigger structural modification of Li6.5La3Zr1.5Nb0.25Ta0.25O12 (LLZNTO) garnet ceramic and TiO2 oxide. The influences of various amounts of TiO2 and LLZNTO on electrochemical performance were systematically examined. These composite electrolytes exhibited maximal Li+ conductivity of 2.89 × 10−4 S cm−1, which is consistent with the value of pure ceramic electrolytes. Furthermore, it possessed the stable long‐term Li cycling and the wide electrochemical window, involving repeated Li plating/stripping at 0.2 mA cm−2 over 280 h without failure. The discharge specific capacity and Coulomb efficiency for all‐solid‐state LIBs assembled with these membranes delivered outstanding cycling stability with high discharge capacities (117.9 mA h g−1) at 0.1 C rate and Coulomb efficiency reached 99.9% after 25 cycles. The high Li+ conduction capability can be ascribed function of introducing TiO2 and LLZNTO to restrain tremendously the crystalline behavior of the polymer. Furthermore, the LLZNTO can be complex with PVDF for dehydrofluorination, and it can also offer a burst transportation route for lithium ions. This system might serve as an attractive use for polymer solid electrolytes and open up new possibilities for safe all‐solid‐state LIBs.