Cationic Metal–Organic Framework Arrays to Enable Dendrite-Free Lithium Metal Anodes

The severe safety issues caused by uncontrolled lithium (Li) dendrite growth hinder the practical application of Li metal anodes. Herein, we designed cationic metal–organic framework arrays on nickel foam (NF–CMOF) as a multifunctional current collector for dendrite-free Li metal anodes. The cationic MOF (CMOF) was synthesized by grafting bis(trifluoromethane)sulfonimidate (TFSI) functional groups on the MOF nanosheets via a facile hydrothermal method. The high surface area, good lithiophilicity, and positively charged properties of CMOF nanosheets effectively facilitate uniform Li deposition. In addition, the porous array structure acts as the host to accommodate deposited Li at a low areal capacity. Furthermore, the CMOF with grafted TFSI groups induces the formation of a LiF/Li3N-rich solid electrolyte interphase, which further guarantees uniform Li deposition at high areal capacity. The full cells with Li predeposited NF–CMOF (Li@NF–CMOF) anodes maintained a high-capacity retention over 1000 cycles and achieved an enhanced rate capability at 10 C.