构建亲锂铜基3D集流体实现金属锂的均匀沉积

Stable Li-metal Depositon on Lithiophilic 3D CuO Nanosheet-decorated Cu Mesh

锂金属负极以其最高的理论比容量(3860m Ah·g-1)和最低的电化学电位(-3.04V(vs SHE))被誉为电池界的"圣杯"。但是锂金属电池的缺点也尤为明显:充放电过程中锂金属电池容易在负极不均匀沉积从而产生锂枝晶,锂枝晶的产生会造成固体电解质介面(SEI)膜的持续破裂,不稳定的SEI膜又会加剧锂枝晶的形成,进而刺穿隔膜,导致电池的循环性能下降,产生安全隐患,所以采取相应的措施在负极均匀沉积金属锂尤为重要。本研究使用商业化的铜网,通过碱性溶剂的氧化和空气气氛煅烧,在铜网表面形成均一的亲锂氧化铜纳米片阵列。铜网的3D结构可以有效减小电流密度,亲锂的纳米片阵列可以降低锂的沉积过电势,均匀沉积锂,有效抑制锂枝晶的产生。在电流密度为3mA·cm–2的半电池测试中,稳定循环230圈后库伦效率稳定维持在99%以上;搭配磷酸铁锂(LFP)全电池测试,在1C(0.17mA×mg-1)条件下可稳定循环300圈,容量保持率为95%。本研究为锂金属负极3D集流体的设计提供了新思路。

Lithium metal anode, due to its highest theoretical specific capacity(3860 mAh·g–1) and lowest electrochemical potential(–3.04 V(vs SHE)), has become the first choice of the next generation of electrochemical energy storage devices. It is known as the "holy grail" of the battery industry. However, the disadvantage of lithium metal battery is particularly obvious: during the charge and discharge process, lithium metal battery is easy to deposit unevenly on the anode electrode, resulting in lithium dendrite which causes the continuous rupture and formation of solid electrolyte interface(SEI) film. The unstable SEI film, intensifying the formation of lithium dendrites and then piercing the separator, causes a decline for the battery cycle performance and the safety hazard. Therefore, it is particularly important to take corresponding measures to make lithium metal uniformly deposited on the anode. In this study, the uniform lithiophilic copper oxide nanosheet array formed on the surface of commercial copper mesh through oxidation of alkaline solvent and calcination of air. The 3D structure of copper mesh can effectively reduce the current density, and the lithiophilic nanosheet array can effectively reduce the overpotential of lithium deposition simultaneously. This lithiophilic 3D copper-based current collector makes lithium deposited uniformly and effectively, and inhibits the formation of lithium dendrites. In the half-cell test at a current density of 3 mA·cm–2 the battery circulated stably for 230 cycles with Coulombic efficiency remaining above 99%. The lithium iron phosphate(LFP) full battery with the as-prepared material as current collector worked stably for more than 300 cycles at 1C(0.17 mA×mg-1) and present a capacity retention of ~95%. This study provides a new design strategy of 3D current collector for stable lithium metal batteries.