Electrolyte engineering enabled hierarchical lithiophilic-lithiophobic host for high-voltage lithium-metal batteries

Abstract

High voltage lithium metal batteries (LMBs) are promising candidates for the future energy storage devices, while the notorious dead lithium and dendrites in the plating process are still hindering their practical applications. Hierarchical host structure with lithiophilic-lithiophobic characteristics can induce Li to deposit on the desired location thus effectively ameliorating these issues. Herein, Cu(NO3)2 is used as an electrolyte additive, it can not only promote the diffusion of Li+ thus decreasing the Li+ concentration gradient, but also be reduced on the anode surface to form the lithiophobic Cu particles and propel lithium to realize dense deposition. At the meantime, we also find that Cu2+ could insert into Ni rich cathodes and prohibit their phase transition or capacity loss. The optimized electrolyte FD-1.8 shows promising cycle life of more than 300 cycles in graphite||Li cells under a constant capacity of 700 mAh g−1 and practical current density, wherever that of the baseline electrolyte is less than 10 cycles. Attribute to the in-situ formed lithiophilic-lithiophobic host structure, it also retained 93.1 % of its capacity in a prototype LMB with a high energy density of ∼390 Wh kg−1 in 40 cycles.