LiF-Rich Electrode–Electrolyte Interfaces Enabled by Bifunctional Electrolyte Additive to Achieve High-Performance Li/LiNi_0.8Co_0.1Mn_0.1O₂ Batteries

Abstract

Commercial Li-ion batteries use LiPF 6 -based carbonate electrolytes extensively, but there are many challenges associated with them, like dendritic Li growth and electrolyte decomposition, while supporting the aggressive chemical and electrochemical reactivity of lithium metal batteries (LMBs). This work proposes 1,1,1,3,3,3-hexafluoroisopropyl methacrylate (HFM) as a multifunctional electrolyte additive, constructing protective solid-/cathode-electrolyte interphases (SEI/CEI) on the surfaces for both lithium metal anode (LMA) and Ni-rich cathode to solve these challenges simultaneously. The highly fluorinated group (−CF 3 ) of the HFM molecule contributes to the construction of SEI/CEI films rich in LiF that offer excellent electronic insulation, high mechanical strength, and surface energy. Accordingly, the HFM-derived LiF-rich interphases can minimize the electrolyte−electrode parasitic reactions and promote uniform Li deposition. Also, the problems of LiNi 0.8 Co 0.1 Mn 0.1 O 2 particles' inner microcrack evolution and the growth of dendritic Li are adequately addressed. Consequently, the HFM additive enables a Li/LiNi 0.8 Co 0.1 Mn 0.1 O 2 cell with higher capacity retention after 200 cycles at 1 C than the cell with no additive (74.7 vs 52.8%), as well as a better rate performance, especially at 9 C. Furthermore, at 0.5/0.5 mAh cm −2 , the Li/Li symmetrical battery displays supersteadfast cyclic performance beyond 500 h when HFM is present. For high-performance LMBs, the HFM additive offers a straightforward, cost-effective route.