Differentiated Lithium Salt Design for Multilayered PEO Electrolyte Enables a High‐Voltage Solid‐State Lithium Metal Battery

• Main Authors: Chen Wang, Tao Wang, Longlong Wang, Zhenglin Hu, Zili Cui, Jiedong Li, Shanmu Dong, Xinhong Zhou, Guanglei Cui
• Format: Article
• Language: English
• Published: Wiley 2019-11-01
• Series: Advanced Science
• Subjects: high voltage; Li metal; lithium salt; multilayered; poly(ethylene oxide) (PEO) electrolyte
• Online Access: https://doi.org/10.1002/advs.201901036

Abstract Low ionic conductivity at room temperature and limited electrochemical window of poly(ethylene oxide) (PEO) are the bottlenecks restricting its further application in high‐energy density lithium metal battery. Herein, a differentiated salt designed multilayered PEO‐based solid polymer electrolyte (DSM‐SPE) is exploited to achieve excellent electrochemical performance toward both the high‐voltage LiCoO2 cathode and the lithium metal anode. The LiCoO2/Li metal battery with DSM‐SPE displays a capacity retention of 83.3% after 100 cycles at 60 °C with challenging voltage range of 2.5 to 4.3 V, which is the best cycling performance for high‐voltage (≥4.3 V) LiCoO2/Li metal battery with PEO‐based electrolytes up to now. Moreover, the Li/Li symmetrical cells present stable and low polarization plating/stripping behavior (less than 80 mV over 600 h) at current density of 0.25 mA cm−2 (0.25 mAh cm−2). Even under a high‐area capacity of 2 mAh cm−2, the profiles still maintain stable. The pouch cell with DSM‐SPE exhibits no volume expansion, voltage decline, ignition or explosion after being impaled and cut at a fully charged state, proving the excellent safety characteristic of the DSM‐SPE‐based lithium metal battery.