High-voltage lithium metal batteries (LMBs) utilizing lithium-rich manganese oxide (LRMO) cathodes offer a promising way towards high energy densities yet remain impractical when operating at high voltages, primarily due to electrolyte instability at interfaces of LRMO and Li metal electrodes. In this study, we report stable cycling of LRMO-based LMBs under ultra-high voltage conditions of 5 V via employing an aggregation-enhanced solvation electrolyte (AESE). The AESE features a solvation structure dominated by anion-wrapped aggregates, in which Li⁺ ions are under a coordination environment surrounded by numerous anions. With such a solvation structure, the AESE concurrently stabilizes the Li metal anode and LRMO cathode. It promotes a protective cathode–electrolyte interphase on LRMO and an inorganic-rich interphase on Li metal, collectively suppressing electrolyte oxidation and transition metal dissolution. Thereby, Li||LRMO cells can deliver exceptional cycling stability at 5 V, retaining >87% capacity after 200 cycles. It also sustains stable operation for 100 cycles at −20 °C. This work demonstrates the electrolyte design for 5 V-class LMBs capable of reliable operation under low-temperature conditions.

Lithium metal anodes, with a theoretical capacity of up to 3860 mAh·g⁻¹, are regarded as the cornerstone for developing next-generation high-energy-density batteries. However, several key challenges hinder their practical applications, including dendrite formation, unstable solid electrolyte interphase (SEI), side reactions with electrolytes, and associated safety risks. This review systematically explores the mechanisms of lithium nucleation, growth, and stripping in both liquid and solid-state battery systems, analyzing critical theoretical concepts like heterogeneous nucleation thermodynamics, surface diffusion kinetics, space charge effects, and SEI-induced nucleation, which are crucial for understanding the genesis of dendrite growth. Additionally, the review discusses the electrochemical-mechanical coupling failures that lead to SEI degradation and the formation of dead lithium. For liquid systems, the review proposes strategies to mitigate dendrite formation and SEI instability, which include electrolyte optimization, artificial SEI design, and electrode framework design. In solid-state batteries, the review offers a granular analysis of the interface challenges associated with polymer, sulfide, and halide electrolytes and summarizes different solutions for different solid-state electrolytes. Meanwhile, the review emphasizes the importance of advanced characterization techniques and computational modeling in understanding and regulating the interface between lithium metal and electrolytes. Looking ahead, the review highlights future research directions that emphasize the integration of cross-disciplinary approaches to tackle these interconnected challenges. By addressing these issues, the path will be clear for the rapid commercialization and widespread application of lithium metal batteries, bringing us closer to realizing stable, high-energy-density batteries that can satisfy the escalating demands of modern energy storage applications across various industries.

Enhancing the cut-off voltage of high-nickel layered oxide cathodes is an efficient way to obtain higher energy density of lithium-metal batteries (LMBs). However, the phase transition of the cathode materials and the uncontrolled decomposition of the electrolytes at high voltage can lead to irreversible dissolution of transition metal ions, which might cause the crossover effects on the lithium metal anodes. Nonetheless, the mechanism and electrolyte dependence of the crossover effects for Li metal anodes are still unclear. Herein, we investigate the crossover effects between LiNi_0.8Mn_0.1Co_0.1O₂ and Li-metal anode in two electrolyte systems. For ether-based electrolyte, its poor oxidation stability results in massive dissolution of transition metal ions, leading to dendrite growth on anode and rapid cells failure. Conversely, ester-based electrolyte exhibits good electrochemical performances at 4.5 V with little crossover effect. This study provides an idea for electrolyte systems selection for high-voltage LMBs, and verifies that the crossover effect should not be neglected in LMBs.

Nitriles as efficient electrolyte additives are widely used in high-voltage lithium-ion batteries. However, their working mechanisms are still mysterious, especially in practical high-voltage LiCoO₂ pouch lithium-ion batteries. Herein, we adopt a tridentate ligand-containing 1,3,6-hexanetricarbonitrile (HTCN) as an effective electrolyte additive to shed light on the mechanism of stabilizing high-voltage LiCoO₂ cathode (4.5 V) through nitriles. The LiCoO₂/graphite pouch cells with the HTCN additive electrolyte possess superior cycling performance, 90% retention of the initial capacity after 800 cycles at 25 °C, and 72% retention after 500 cycles at 45 °C, which is feasible for practical application. Such an excellent cycling performance can be attributed to the stable interface: The HTCN molecules with strong electron-donating ability participate in the construction of cathode-electrolyte interphase (CEI) through coordinating with Co ions, which suppresses the decomposition of electrolyte and improves the structural stability of LiCoO₂ during cycling. In summary, the work recognizes a coordinating-based interphase-forming mechanism as an effective strategy to optimize the performance of high voltage LiCoO₂ cathode with appropriate electrolyte additives for practical pouch batteries.