Electrochemically induced crystalline-to-amorphization transformation in sodium samarium silicate solid electrolyte for long-lasting sodium metal batteries
Ge Sun, Chenjie Lou, Boqian Yi, Wanqing Jia, Zhixuan Wei, Shiyu Yao, Ziheng Lu, Gang Chen, Zexiang Shen, Mingxue Tang, Fei Du
Abstract
Abstract Exploiting solid electrolyte (SE) materials with high ionic conductivity, good interfacial compatibility, and conformal contact with electrodes is essential for solid-state sodium metal batteries (SSBs). Here we report a crystalline Na 5 SmSi 4 O 12 SE which features high room-temperature ionic conductivity of 2.9 × 10 −3 S cm −1 and a low activation energy of 0.15 eV. All-solid-state symmetric cell with Na 5 SmSi 4 O 12 delivers excellent cycling life over 800 h at 0.15 mA h cm −2 and a high critical current density of 1.4 mA cm −2 . Such excellent electrochemical performance is attributed to an electrochemically induced in-situ crystalline-to-amorphous (CTA) transformation propagating from the interface to the bulk during repeated deposition and stripping of sodium, which leads to faster ionic transport and superior interfacial properties. Impressively, the Na|Na 5 SmSi 4 O 12 |Na 3 V 2 (PO 4 ) 3 sodium metal batteries achieve a remarkable cycling performance over 4000 cycles (6 months) with no capacity loss. These results not only identify Na 5 SmSi 4 O 12 as a promising SE but also emphasize the potential of the CTA transition as a promising mechanism towards long-lasting SSBs.