High-Voltage Stimulation Effect on Lithium Deposition for 4.6 V-Class Lithium Metal Batteries;

摘要

Rechargeable Li-ion batteries (LIBs) are ubiquitous in present society and playan important role in consumer electronics and electric vehicles. IncreasingLIBs’ energy density is therefore becoming a crucial research challenge withgreat implications. Li metal is a high-specific-capacity anode, which suffersfrom uneven Li deposition, “dead” Li formation, dendrite growth, and theresulting severe capacity fading. Here, a strategy to enable a tremendousimprovement for LiCoO_2-based Li metal batteries (Li‖LCO) is described andexperimentally demonstrated. By simply adjusting the charge cut-off voltagefrom 4.1 to 4.6 V, a high-voltage stimulation effect (HvSE) is demonstrated,which offers a uniform, dense, and crack-free Li deposition. As a result, theLi‖LCO cell delivers a high energy density (ED) of 891 Wh kg_(-LCO)~(?1) and ahigh capacity of 217 mAh g~(?1) can be maintained for more than 69 cycles. Incontrast, the Li‖LCO cell with the lower charge cut-off voltage of 4.1 V onlydelivers a low ED (458 Wh kg_(-LCO)~(?1)), specific capacity (117 mAh g~(?1)), and“capacity diving” occurs after only 35 cycles. This HvSE is also applied to runpouch cells, which generate greater than 20 capacity and cycling performanceimprovement with the higher charge cut-off voltage.