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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.

High-capacity Li-rich layered composite oxide, xLi 2 MnO 3 • (1-x)LiMO 2 (M = Mn, Ni, Co), is a promising candidate cathode material for high-energy electrochemical energy storage. Enabling the high-performance of high-voltage cathode relies on an electrolyte breakthrough and the solid electrolyte interface (SEI) stabilization. In this study, the 0.6Li 2 MnO 3 • 0.4LiNi 0.45 Co 0.25 Mn 0.3 O 2 (Li 1.2 Mn 0.525 Ni 0.175 Co 0.1 O 2 , LMNC) cathode is operated at 2.5-4.8 V with 5 wt% fluorinated linear carbonate, di-(2,2,2 trifluoroethyl)carbonate (DFDEC), as a high-voltage electrolyte additive, for the first time and applied to a high-energy lithium-ion battery. The cathode with DFDEC outperforms that in electrolyte only, delivering a high capacity of 250 mAhg −1 with an excellent chargedischarge cycling stability at the rate of 0.2C. Upon the use of DFDEC, the cathode surface is effectively passivated by a stable SEI composed of DFDEC decomposition products, which inhibit a detrimental metal dissolution and structural cathode degradation. A full-cell based on the SEI-stabilized LMNC cathode and graphite anode successfully demonstrates doubled energy density (∼278 Whkg −1 ) compared to ∼136 Whkg −1 of a commercialized cell of graphite//LiCoO 2 and an excellent cycling stability.

The results of the effects of electrolyte type and concentration, nanoparticle concentration, pH, and temperature on the mobility and aqueous stability of polyethylene glycol (PEG)-coated silica nanoparticles are presented. Nanoparticle mobility was evaluated based on the ability to inhibit montmorillonite swelling in aqueous solutions through visual swelling tests, and the results were quantified in terms of the swelling index. The presence of PEG-coated silica nanoparticles was found to have a positive influence on the inhibition of clay swelling only in the presence of electrolytes. Quantification of nanoparticle stability in the presence of montmorillonite particles was achieved using ultraviolet–visible (UV–vis) spectrophotometry. At the highest concentration of montmorillonite dispersion studied, interaction between the dispersed montmorillonite particles and PEG-coated silica nanoparticles resulted in nanoparticle aggregation as indicated by increased turbidity and absorbance readings. Both nanoparticle concentration and montmorillonite dispersion concentration, in addition to the presence and concentration of NaCl, were found to strongly influence the stability of the mixture.

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