Instability of lithium bis(fluorosulfonyl)imide (LiFSI)–potassium bis(fluorosulfonyl)imide (KFSI) system with LiCoO<sub>2</sub> at high voltage

Instability of lithium bis(fluorosulfonyl)imide (LiFSI)–potassium bis(fluorosulfonyl)imide (KFSI) system with LiCoO₂ at high voltage

Zhang Shu^a), Li Wen-Jun^a), Ling Shi-Gang^a), Li Hong†^a), Zhou Zhi-Bin^b), Chen Li-Quan^a)

XPS spectra of pristine LiCoO₂ electrode surface (black line) and LiCoO₂ electrode surface after 20 charge-discharge cycles for Li/LiFSI–KFSI ( χ _LiFSI: χ _KFSI = 0.41: 0.59)/LiCoO₂ cell at a charge/discharge rate of 0.2/0.2 C at 80 °C (red line): (a) C 1s, (b) Co 2p, (c) O 1s, (d) F 1s, (e) N 1s, (f) K 2p, (g) S 2p.