Highly-Stable Li Ion Batteries Based on Porous Si Anode and Localized High Concentration Electrolytes

Abstract

Si is one of the most promising anode materials for the next generation of lithium (Li) ion batteries (LIBs). Stability of Si based anode mainly depends on two factors: one is a stable nano-structure of Si which can tolerate large volume expansion/shrinking during Li injection/extraction process, another is a stable SEI layer formed in Si surface which are mechanically stable during cycling process. In this work, we report a scalable approach to prepare nano-structured Si particles in combination with a highly stable SEI layer formed in Localized High Concentration Electrolytes (LHCE) tailored for Si based LIBs. Comparing with the similar Si based anode materials available commercially, the new nano-Si based anode developed in this work exhibits a more than 20% improvement in cycle life (80% capacity retention) when the baseline electrolyte (1.2 M LiPF6 in EC-EMC (3:7 by wt.) +10 wt.% FEC) is used. Comparing with the baseline electrolyte, the new electrolytes developed in this work enabled a more then 30% increase in cycle life when the same anode material was used. These electrolytes are stable with both Si based anode and high voltage cathode such as Ni rich LiNixCoyMn1-x-yO2 (x ≥ 0.6), LiCoO2 etc. Therefore, they have great potential for both electrical vehicles and consumer electronics applications.