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.

Icosahedral metal nanocrystals, with their inherent strain, offer exceptional catalytic properties. However, synthesizing these nanocrystals with high morphological yield remains a significant challenge, limiting the potential of strain engineering for catalyst design. In this study, we introduce a robust oxidative etching and regrowth strategy to synthesize high-yield (~ 90%) icosahedral Au nanocrystals with tunable sizes (12–43 nm). By employing triiodide (I₃⁻) as an oxidative agent, we selectively enrich multiply twinned seeds—the required seed type for icosahedral formation—by removing impurity seeds. Additionally, sulfite ions (SO₃²⁻) selectively cap the Au {111} facet, directing crystal growth toward the desired icosahedral shape. The resulting Au nanocrystals demonstrate strain-enhanced electrocatalytic performance in CO₂ reduction, achieving a Faradaic efficiency of 97.5% for CO production, significantly higher than their non-strained counterparts. This strategy offers a promising pathway for creating well-defined metal nanocrystals, opening new possibilities for both fundamental catalysis research and practical applications.

The continuous lithium consumption during cycling severely reduces the energy density of the lithium battery, and thus, lithium compensation is essential. Herein, Li_xC₆O₆ (x = 2, 4) was proposed as an air-stable high-efficiency sacrificial additive in the cathode to compensate for the lost lithium ions in solid-state lithium batteries. Below a delithiation (oxidation) potential as low as 3.8 V, Li₂C₆O₆ can release most of its Li⁺ ions (294.8 mAh g⁻¹ in theory). Similarly, Li₄C₆O₆ is also characteristic of low oxidation potential and high delithiation capacity (547.8 mAh g⁻¹ in theory). The feasibility of using Li_xC₆O₆ as the self-sacrificial additive in the cathode was verified with the marked increase of the initial charge capacity of the Li||LiFePO₄ (half) cells and the initial discharge capacity of Cu||LiFePO₄ (full) cells, and the improved electrolyte/cathode interface stability and interface contact, in the solid-state poly(ethylene oxide)-lithium bis(trifluoromethane)sulfonimide (PEO-LiTFSI) electrolyte. In addition, the structure and delithiation of Li_xC₆O₆ and the impacts of its decomposition product on the PEO-LiTFSI solid electrolyte were also evaluated on the basis of the comprehensive physical characterizations and the density functional theory (DFT) calculations. These findings open a new avenue for elevating the energy density and/or elongate the lifespan of the solid-state secondary batteries.