Titanium–Polyoxometalate Crosslinked Metallo–Supramolecular Polymer as Artificial Interfacial Layer for Highly Persistent and Low–Temperature Tolerant Lithium Metal Batteries

Abstract The uncontrolled lithium (Li) dendrite growth and fragile native solid electrolyte interphase formation have severely hindered the practical development of Li metal batteries. Herein, a coordinatively cross‐linked metallo‐supramolecular polymer as anodic interfacial protective layer (MSP‐IPL) is developed by utilizing titanium(IV)–polyoxometalates (Ti‐POMs) as hexatopic linkers to bridge organic and inorganic moieties. The constructed MSP‐IPL possesses high electrochemical stability, superior ion‐transfer ability, and good air stability. Due to its high film formation uniformity and mechanical tenacity, the MSP‐IPL can effectively avoid nonuniform Li deposition caused by the tip effect, thus inhibiting Li dendrite proliferation. The uniformly distributed Ti‐POMs in polymer skeleton can efficiently bind with PF 6 − anions, thus increasing Li + transference number and promoting homogeneous Li + distribution. The reprocessability and self‐healing ability endowed by dynamic coordination bonds enable the MSP‐IPL to accommodate electrode volume changes and maintain good interface contact. Consequently, high‐loading Li||LiFePO 4 and Li||LiNi 0.8 Co 0.1 Mn 0.1 O 2 batteries based on MSP‐IPL‐coated Li anodes demonstrate impressive cyclability and extraordinary rate capability. Even at a low temperature of −20 °C, the MSP‐IPL‐coated Li||NCM811 batteries can still cycle stably for over 500 cycles (equivalent to 138 days) with a considerable capacity retention of 86.8%. This work presents a promising solution for developing practical low‐temperature Li metal batteries.