Constructing stable lithium interfaces via coordination of fluorinated ether and liquid crystal for room-temperature solid-state lithium metal batteries

The poor compatibility of the electrodes/solid-state electrolytes (SSEs) interfaces of rechargeable room-temperature solid-state lithium metal batteries (RTSSLMBs) limit their rapid development and commercialization. Herein, fluorinated ether as a block and liquid crystal 4,4′'-Azoxyanisole as an additive are firstly used to fabricate robust SSEs for RTSSLMBs. A combination of in-situ polymerization and the construction of stable interfaces is employed to obtain excellent cycling performance in LMBs. We propose the mechanism of regulating the lithium anode interfaces by 4,4′'-Azoxyanisole with high anchoring strength in SSEs. Liquid crystal with high anchoring strength ensures the smooth electrodeposition of lithium metal, and fluorinated ether provides rich LiF for SEI, which is beneficial to inhibit the growth of lithium dendrite. The electrochemical test shows that symmetrical lithium batteries maintain steadily operation over 3500 h. Further, the novel 3D fiber-network SPEs exhibit high ionic conductivity of 0.13 mS/cm at room temperature, a wide electrochemical stability window of 4.9 V, a high lithium-ion transference number of 0.42, and better mechanical strength (Young's modulus of 6.3 GPa). As a consequence, superior cycling stability is demonstraced in Li/LiFePO4 batteries at ambient temperature. In addition, the reaction mechanism is verified by density functional theory calculations and various electrochemical characterizations. This new and universal strategy may be a new route to suppress Li dendrites, it will be helpful for the commercialization and application of RTSSLMBs.