Interface functionalization of composite electrolyte by Lix-CeO2 layer on the surface of Li6.4La3Zr1.4Ta0.6O12

The development of all-solid-state batteries has become an inevitable trend as safety is increasingly valued. Naturally, solid-state electrolytes(SSEs) have attracted extensive attention. The composite of superionic con-ductors and polymer is considered to be a material that can achieve both high energy density and safety. Nevertheless, the compatibility between the polymer and superionic conductors is poor due to the large dif-ferences in structure and electrochemistry, resulting in a high interfacial transport energy barrier of the cation. In this work, a functional Lix-CeO2(LCO) layer is synthesized on the surface of the superionic conductor. While broadening the cation transport path at the interface, the anion of lithium salt is successfully anchored and the concentration of lithium-ion is increased. In addition, the structural compatibility and adhesion between polymer and superionic conductors are improve. Compared with the pristine electrolyte, the ionic conductivity and the lithium-ion transference number (tLi+) of LLZTO@2%LCO are as high as 2.325 x 10-3 S cm- 1(pristine sample only 7.109 x 10-5 S cm-1) and 0.44 (pristine sample is only 0.27)respectively. At 2C, the discharge specific capacity of LiFePO4(LFP)|LLZTO@2%LCO-CSE|Li can reach 134.8mAh g-1. The outstanding performance of the composite electrolyte is attributed to the interface functionalized Lix-CeO2 compound coating. Therefore, poly-mer/ceramic interface engineering to promote the interaction between the two components should be one of the directions of future research.