Sheet-like garnet structure design for upgrading PEO-based electrolyte

Abstract Polyoxyethylene (PEO)-based electrolyte is one of the most promising solid-state electrolyte (SSE) candidates for all-solid-state batteries due to its high flexible and salt solubility. Recently, morphological control on active fillers is confirmed as a critical issue affecting the performance of SSE. However, the lack of comprehensive research is hindering the understanding over the growth mechanism of the structured active fillers. Especially, compared with other dimensions, the studies on the growth mechanism of two-dimensional (2D) active fillers are quite limited due to the difficulties in physical methods such as exfoliation. Herein, sheet-like LLZAO (Li6.25La3Zr2Al0.25O12) (SL) is synthesized by bottom-up method to upgrade PEO matrix (SL@PEO). In addition, the growth mechanism of SL is proposed, which provides a new sight for morphology control over inorganic solid electrolytes. The SL structure provides continuous interfaces between the fillers and the polymer matrix, which ensures rapid diffusion of lithium ions. In addition, the SL can provide more nature barriers for electrolyte to suppress the lithium dendrites growth. The lithium symmetric cells adopting SL@PEO present prolonged cycling stability and higher critical current density compared with the control samples. The assembled all-solid-state LiFePO4/SL@PEO/Li batteries exhibit superior cycling stability and rate capability.