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W doping alleviates the structural stress associated with the repetitive phase transition, markedly improving cycling performance.

A self-passivating Li2ZrO3 layer with a thickness of 5–10 nm, which uniformly encapsulates the surfaces of LiNiO2 cathode particles, is spontaneously formed by introducing excess Zr (1.4 atom %). A thin layer of Li2ZrO3 on the surface is converted into a stable impedance-lowering solid–electrolyte interphase layer during subsequent cycles. The Zr-doped LiNiO2 cathode with an initial discharge capacity of 233 mA·h·g–1 exhibited significantly improved capacity retention (86% after 100 cycles) and thermal stability, compared to the undoped LiNiO2. While the spontaneously formed Zr-rich coating layer provides surface protection, the Zr ions in the LiNiO2 lattice delay the detrimental phase transition occurring in the deeply charged state of LiNiO2 and partially suppress the anisotropic strain emerging from the phase transition. Further optimization of the proposed simultaneous coating and doping strategy can mitigate the inherent structural instability of the LiNiO2 cathode, making it a promising high-energy-density cathode for electric vehicles.

Capacity degradation of highly Ni-enriched NCM cathodes is aggravated by the formation of the H3 phase in the delithiated state.

The ultrafine-grained Ni-enriched Li[Ni0.95Co0.04Mo0.01]O2 (NCMo95) cathode achieved by inhibiting particle coarsening imparts the necessary mechanical toughness and significantly extends the battery life.

Electrolytes play a critical role in controlling metalion battery performance. However, the molecular behavior of electrolyte components and their effects on electrodes are not fully understood. Herein, we present a new insight on the role of the most commonly used ethylene carbonate (EC) cosolvent both with the bulk and at the electrolyte-electrode interface. We have discovered a new phenomenon that contributes to stabilizing the electrolyte, besides the well-known roles of dissociating metal salt and forming a solid electrolyte interphase (SEI). As a paradigm, we confirm that EC can form an Li + −EC pair in a priority compared to other kinds of solvents (e.g., ethyl methyl carbonate) and then alter the Li + − solvent interactions in the electrolyte. The Li + −EC pair can dominate the desolvation structure at the electrode interface, therefore suppressing Li + −solvent decomposition due to the higher stability of Li + −EC. Our viewpoint is confirmed in different electrolytes for lithium, sodium, and potassium ion batteries, where the SEI is shown to be limited for stabilizing the electrode in the case of the less stable Li + −solvent pair. Our discovery provides a general explanation for the effect of EC and provides new guidelines for designing more reliable electrolytes for metal (ion) batteries.

High-voltage lithium-ion batteries (HV-LIBs) enabled by high voltage electrolytes can effectively boost the energy density and power density, of which critical requirements to achieve long travel-distance, fast-charging, and reliable safety performances for electric vehicles. However, operating the batteries beyond the typical conditions of LIBs (4.3 V vs.Li/Li + ) leads to a severe electrolyte decomposition, while the interfacial side reactions remain elusive. These critical issues become the bottleneck for developing electrolytes for applications

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