Mortise-Tenon Joints Reinforced Janus Composite Solid-State Electrolyte With Fast Kinetics for High-Voltage Lithium Metal Battery

Bilayer composite solid-state electrolytes (CSSEs) are regarded as promising candidates to meet the requirements of high-voltage lithium metal batteries due to their exceptional compatibility with both opposite electrodes. However, such a configuration usually leads to additional interfacial impedance between CSSEs and discontinuous Li + migration process, resulting in deteriorated electrochemical performances. Herein, a Janus electrolyte with mortise and tenon joints (JCSSE) is proposed for enhancing interfacial compatibility. It is composed of poly (vinylidene fluoride-co-hexafluoropropylene) (P(VDF-HFP))/ Li 6.4 La 3 Zr 1.4 Ta 0.6 O 12 layer toward cathode and poly(diallyldimethylammonium) bis(trifluoromethanesulfonyl)imide (PDADMATFSI) /UiO-66-SO 3 Li layer to Li-metal anode. Such a configuration enables not only intimate contact between the two electrolyte layers, but regulated Li + coordination environment which would improve Li + transference number. Both simulation and experimental characterization suggest that the defluorinated-P(VDF-HFP) with low highest occupied molecular orbital (HOMO) and PDADMATFSI with strong adsorption energy toward lithium metal can favor the formation of stable electrode/electrolyte interface. Optimized JCSSE exhibits a high Li + conductivity of 0.21 mS cm -1 at 25 °C and a wide electrochemical window of 5.0 V. As a result, Li//JCSSE//LiNi 0.8 Mn 0.1 Co 0.1 O 2 battery could deliver remarkable  cycling performances at 4.3 V for 100 cycles. In addition, JCSSE enables superior cyclability from 25 to 100 °C. High-voltage pouch cells employing JCSSE exhibit unexpected endurance under harsh conditions. This novel Janus electrolyte with tenon and mortise structure will accelerate the commercialization of alkali metal batteries.