A cerium-doped NASICON chemically coupled poly(vinylidene fluoride-hexafluoropropylene)-based polymer electrolyte for high-rate and high-voltage quasi-solid-state lithium metal batteries

The isolated inorganic particles within composite polymer electrolytes (CPEs) are not correlated to the Li + transfer network, resulting in the polymer dominating the low ionic conductivity of CPEs. Therefore, we developed novel quasi-solid-state CPEs of a Ce-doped Na super ion conductors (NASICON) Na 1.3+ x Al 0.3 Ce x Ti 1.7− x (PO 4 ) 3 (NCATP) chemically coupled poly(vinylidene fluoride-hexafluoropropylene) (PVDF-HFP)/Li-bis(trifluoromethanes-ulfonyl)imide (LiTFSI) matrix. A strong interaction between Ce 3+ from NCATP and TFSI − anion from the polymer matrix contributes to the fast Li + transportation at the interface. The PVDF-HFP/NCATP CPEs exhibit an ionic conductivity of 2.16 × 0 −3 S cm −1 and a Li + transference number of 0.88. A symmetric Li/Li cell with NCATP-integrated CPEs at 0.1 mA cm −2 presents outstanding cycling stability over 2000 h at 25 °C. The quasi-solid-state Li metal batteries of Li/CPEs/LiFePO 4 at 2 C after 400 cycles and Li/CPEs/LiCoO 2 at 0.2 C after 120 cycles deliver capacities of 100 and 152 mAh g −1 at 25 °C, respectively.