Chitosan oligosaccharide derived polar host for lithium deposition in lithium metal batteries

Abstract

Rechargeable lithium metal batteries are among the most versatile platforms for high energy electrochemical energy storage. Unfortunately, uncontrollable growth of lithium dendrite triggers serious safety hazards, low Coulombic efficiency, and short cycling life, impeding the commercial application of lithium metal anode in the advanced energy storage technology, such as lithium-air and lithium‑sulfur (LiS) batteries. Herein, Chitosan oligosaccharide (CSO), an abundant bioderived material was employed to guide uniform lithium deposition and growth. CSO offers three features simultaneously, polar functional groups (-OH and -NH2), natural porous structure, and abundant sources. CSO with a large number of polar groups has strong interactions with Li ions, which could guide the Li ions to form uniform Li deposition. Moreover, the porous structure of CSO could serve as a Li host to accommodate the huge volume change during Li plating and stripping process. Additionally, CSO is a low-cost, abundant, and nontoxic bioderived material, which is suitable for large-scale production of the CSO-Li anode. The proposed strong interactions of CSO with Li ions were confirmed by density functional theory calculations. As expected, the CSO modified electrode demonstrates an outstanding average Coulombic efficiency of over 98% for 600 cycles at a current density of 2 mA cm−2. And stable cycling performances were achieved in the CSO-Li/CSO-Li symmetrical cells. Moreover, when paired with the LiFePO4 cathode, Li4Ti5O12 anode, high-mass-loading LiNi0.5Co0.2Mn0.3O2 cathode, and S cathode, the cells using the CSO-Li anodes show the higher capacities and better cycling stabilities compared with those of the cells using the bare Li anodes.