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Lithium (Li) metal batteries (LMBs) with nickel (Ni)‐rich layered oxide cathodes exhibit twice the energy density of conventional Li‐ion batteries. However, their lifespan is limited by severe side reactions caused by high electrode reactivity. Fluorinated solvent‐based electrolytes can address this challenge, but they pose environmental and biological hazards. This work reports on the molecular engineering of fluorine (F)‐free ethers to mitigate electrode surface reactivity in high‐voltage Ni‐rich LMBs. By merely extending the alkyl chains of traditional ethers, we effectively reduce the catalytic reactivity of the cathode towards the electrolyte at high voltages, which suppresses the oxidation decomposition of the electrolyte, microstructural defects and rock‐salt phase formation in the cathode, and gas release issues. The high‐voltage Ni‐rich NCM811‐Li battery delivers capacity retention of 80 % after 250 cycles with a high Coulombic efficiency of 99.85 %, even superior to that in carbonate electrolytes. Additionally, this strategy facilitates passivation of the Li anode by forming a robust solid‐electrolyte interphase, boosting the Li reversibility to 99.11 % with a cycling life of 350 cycles, which outperforms conventional F‐free ether electrolytes. Consequently, the lifespan of practical LMBs has been prolonged by over 100 % and 500 % compared to those in conventional carbonate‐ and ether‐based electrolytes, respectively. [ABSTRACT FROM AUTHOR]

Single-crystalline nickel-rich cathodes are a rising candidate with great potential for high-energy lithium-ion batteries due to their superior structural and chemical robustness in comparison with polycrystalline counterparts. Within the single-crystalline cathode materials, the lattice strain and defects have significant impacts on the intercalation chemistry and, therefore, play a key role in determining the macroscopic electrochemical performance. Guided by our predictive theoretical model, we have systematically evaluated the effectiveness of regaining lost capacity by modulating the lattice deformation via an energy-efficient thermal treatment at different chemical states. We demonstrate that the lattice structure recoverability is highly dependent on both the cathode composition and the state of charge, providing clues to relieving the fatigued cathode crystal for sustainable lithium-ion batteries. The lattice strain and defects in layered oxides is critical to the intercalation chemistry and battery performance. Here, the authors demonstrate a thermal-healing of lattice defects in single-crystalline cathodes caused by the thermal-induced release of lattice strain and the structure ordering. [ABSTRACT FROM AUTHOR]

LiNi x Mn y Co 1 -x-y O 2 (NMC) is a prominent cathode material for advanced Li-ion batteries. The mechanical integrity of NMC is crucial, as it significantly influences the electrochemical stability of NMC cathodes during cycling. Despite the importance, a comprehensive understanding of the mechanical properties of NMC remains elusive, primarily due to its pronounced structural anisotropy that poses significant challenges for both experimental quantification and theoretical modeling. Herein, we employ first-principles calculations to investigate the evolution of anisotropic elastic properties of NMC (NMC532, NMC622, and NMC811) throughout the delithiation process. Our findings reveal a complex interplay of mechanical properties and structural features of NMC. As delithiation proceedings, the elastic moduli present a reduction at disparate rates along the c -axis versus those directions paralleling the ab -plane, owing to the differential bonding dynamics occurring within and between the transition metal slabs. Therefore, the anisotropy ratio of NMC exhibits exponential increase during delithiation, where the basal plane shows the near-highest Young's modulus and near-lowest shear modulus. Intriguingly, we observe that a higher Ni content in the NMC composition accelerates elastic modulus reduction, a behavior predominantly influenced by the Jahn−Teller distortion. Collectively, our insights bridge the evolution of lattice structure with the corresponding shifts in the elastic properties of NMC, laying the foundational groundwork for future material optimizations. [Display omitted] [ABSTRACT FROM AUTHOR]