长寿命锂电池用三维亲锂双骨架支撑锂金属负极的设计

Designing three-dimensional lithiophilic dual-skeletons-supported lithium metal anodes for long-life lithium metal batteries

锂金属被认为是下一代高能锂电池最有前途的负极材料之一.然而,锂的不均匀沉积和巨大的体积变化严重限制了锂金属阳极的实际应用.本文采用简单的熔融法制备了无枝晶的双骨架三维复合锂负极(Li-B-Sn).Li-B-Sn复合负极独特的双骨架结构由LiB纤维相和Li22Sn5相组成,有利于锂的均匀脱除和沉积,减小了体积变化,提高了Li-B-Sn负极的性能.在对称电池中,Li-B-Sn负极在10 mA cm^(-2)的大面积容量下实现了1100h的长循环寿命.此外,高负载的LiFePO_(4)正极(~11 mg cm^(-2))和Li-B-Sn复合负极组装的全电池表现出优异的电化学性能,在2 C循环430次后,容量保持率高达92.5%.基于Li-B-Sn复合负极的Li-S软包电池循环寿命超过30圈,表现出比基于Li-B负极的Li-S软包电池更好的循环稳定性.三维骨架设计为锂金属电池的实际应用带来了新思路.

Lithium metal is one of the most promising anode materials for use in the next generation of high-energy lithium batteries.However,uneven Li deposition and large volume changes severely restrict the practical use of lithium metal anodes.Here,a dendrite-free three-dimensional(3D)composite Li anode(Li-B-Sn)with dual-skeletons was pro-duced by a simple melting method.The unique dual-skeleton structure was composed of LiB fiber phase and Li22Sn5 phase,which enabled even Li stripping and plating processes and reduced the volume variations to improve the performance of the Li-B-Sn anode.The Li-B-Sn anode exhibited a long life-span of 1100 h during cycling operating under a large areal capacity of 10 mA h cm^(-2) in a symmetrical cell.In addition,full batteries assembled with the high mass loading LiFePO_(4) cathode(~11 mg cm^(-2))and the Li-B-Sn composite anode showed superior electrochemical performance,with a high capacity retention of 92.5%at 2 C after 430 cycles.Li-S pouch cells based on the Li-B-Sn composite anode survived over 30 cycles,which constituted better cycling stability than that of the Li-B anode.This work describes new 3D skeletons for practical use in lithium metal batteries.