A promising composite room temperature solid electrolyte via incorporating LLZTO into cross-linked ETPTA/PEO/SN matrix for all solid state lithium batteries

Composite solid electrolyte (CSE), especially the composite room temperature solid electrolyte (CRTSE), is emerging as the promising electrolyte for all-solid-state lithium batteries (ASSLB) due to their ability to combine the desirable properties of ceramic and polymer-based electrolytes and the room temperature operation condition. In this paper, the CRTSE with polyethylene oxide (PEO), bis(fluorosulfonyl)imide (LiTFSI), succinonitrile (SN), LLZTO inorganic fillers, and cross-linked ethoxylated trimethylolpropane triacrylate (ETPTA) was proposed. With the help of lithium dendrite suppression via cross-linked microscopic pore structure, enhancement of the ionic conductivity via LLZTO fillers, and wide electrochemical window via SN, the obtained LCSE showed high ionic conductivity (2.12 x 10-4 S cm-1), high Li+ transfer number (tLi+ = 0.55), and stable electrochemical window (5.0 V vs Li/Li+) at room temperature. The Li symmetrical cell with LCSE can cycle over 500 h stably with current density of 0.1 mA cm-2 and 0.5 mA cm-2 at room temperature. The full solid-state LiFePO4 cell can successfully work over 200 cycles with capacity retention ratio of about 70% at room temperature.