A Natural Biopolymer Film as a Robust Protective Layer to Effectively Stabilize Lithium‐Metal Anodes

• Published in: Small (Weinheim an der Bergstrasse, Germany) Vol. 14; no. 31; pp. e1801054 - n/a
• Main Authors: Zhang, Shao‐Jian, Gao, Zhen‐Guang, Wang, Wei‐Wei, Lu, Yan‐Qiu, Deng, Ya‐Ping, You, Jin‐Hai, Li, Jun‐Tao, Zhou, Yao, Huang, Ling, Zhou, Xiao‐Dong, Sun, Shi‐Gang
• Format: Journal Article
• Language: English
• Published: Germany Wiley Subscription Services, Inc 02.08.2018
• Subjects: agarose; Anode effect; Anodic protection; Batteries; Biopolymers; Cycles; Dendritic structure; Elasticity; Foils; Ion currents; Lithium; Lithium batteries; lithium dendrites; lithium‐metal anodes; Morphology; Nanotechnology; natural biopolymers; Organic chemistry; Protective coatings; protective layers; lithium dendrites; protective layers; agarose; natural biopolymers; lithium-metal anodes
• ISSN: 1613-6810; 1613-6829
• DOI: 10.1002/smll.201801054

Li metal is considered as an ideal anode for Li‐based batteries. Unfortunately, the growth of Li dendrites during cycling leads to an unstable interface, a low coulombic efficiency, and a limited cycling life. Here, a novel approach is proposed to protect the Li‐metal anode by using a uniform agarose film. This natural biopolymer film exhibits a high ionic conductivity, high elasticity, and chemical stability. These properties enable a fast Li‐ion transfer and feasiblity to accomodate the volume change of Li metal, resulting in a dendrite‐free anode and a stable interface. Morphology characterization shows that Li ions migrate through the agarose film and then deposit underneath it. A full cell with the cathode of LiFPO4 and an anode contaning the agarose film exhibits a capacity retention of 87.1% after 500 cycles, much better than that with Li foil anode (70.9%) and Li‐deposited Cu anode (5%). This study provides a promising strategy to eliminate dendrites and enhance the cycling ability of lithium‐metal batteries through coating a robust artificial film of natural biopolymer on lithium‐metal anode. Agarose, a kind of natural biopolymer, is used to construct artificial protective film for the Li‐metal anode. Li ions can diffuse through and deposit under this film, leading to a dendrite‐free surface during repeated Li plating/stripping processes. This film can also reduce the side reaction due to its function as a physical barrier to separate the electrolyte and Li metal.