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An increase in the energy density of lithium‐ion batteries has long been a competitive advantage for advanced wireless devices and long‐driving electric vehicles. Li‐rich layered oxide, xLi2MnO3∙(1−x)LiMn1−y−zNiyCozO2, is a promising high‐capacity cathode material for high‐energy batteries, whose capacity increases by increasing charge voltage to above 4.6 V versus Li. Li‐rich layered oxide cathode however suffers from a rapid capacity fade during the high‐voltage cycling because of instable cathode–electrolyte interface, and the occurrence of metal dissolution, particle cracking, and structural degradation, particularly, at elevated temperatures. Herein, this study reports the development of fluorinated polyimide as a novel high‐voltage binder, which mitigates the cathode degradation problems through superior binding ability to conventional polyvinylidenefluoride binder and the formation of robust surface structure at the cathode. A full‐cell consisting of fluorinated polyimide binder‐assisted Li‐rich layered oxide cathode and conventional electrolyte without any electrolyte additive exhibits significantly improved capacity retention to 89% at the 100th cycle and discharge capacity to 223–198 mA h g−1 even under the harsh condition of 55 °C and high charge voltage of 4.7 V, in contrast to a rapid performance fade of the cathode coated with polyvinylidenefluoride binder.

We report for the first time a promising approach to achieve the maximum capacity of LiNi0.8Co0.1Mn0.1O2 cathodes in a non-flammable electrolyte for safe and high-energy density lithium-ion and lithium metal batteries.

Driven by a high demand for safe lithium-ion batteries (LIBs) with no risk of fire, we develop a nonflammable organic liquid electrolyte, which is composed of 1 M lithium hexafluorophosphate salt and propylene carbonate and fluorinated linear carbonates. Herein, we report the studies of the effects of the nonflammable electrolyte on the surface chemistry and structure of the nickel-rich LiNi0.8Co0.1Mn0.1O2 (NCM811) cathode under the expanded electrochemical voltage window to 4.5 V and their correlation to cycling performance. We provide for the first time the visual evidence for the roles and effectiveness of our nonflammable organic liquid electrolyte in stabilizing both surface and bulk structures, in promoting the formation of a stable surface protective film at the NCM811 cathode and reducing crack formation, metal-dissolution, and structural degradation despite under 4.5 V high-voltage condition and thus resulting in the increased capacity up to 230 mA h g–1 at 0.2 C and unprecedented cycling performance of the NCM811 cathode under high-voltage in not only Li∥NCM811 half-cell for lithium metal batteries but also graphite∥NCM811 full-cell with vinylene carbonate additive for LIBs. The data give an insight into the design principle of nonflammable and high energy-density lithium rechargeable batteries employing a nonflammable electrolyte and stable cathode–electrolyte interface.