Lithium-ion batteries are essential for modern energy storage, yet achieving simultaneous high-temperature and high-voltage operation remains challenging due to interfacial compatibility. In this study, we introduce a polyetherimide (PEI)–polyimide (PI) functional coating on the separator that enhances wettability, thermal stability, and mechanical strength, while markedly improving cathode stability under harsh conditions. By integrating theoretical calculations with experimental validation, we demonstrate that the PEI/PI coating modulates the solvation structure of lithium-ions, thereby facilitating the interfacial desolvation process. More importantly, the PEI/PI layer regulates electrolyte decomposition at the interface, promoting the formation of a uniform and thermally stable cathode–electrolyte interphase. Consequently, LiCoO₂ cathodes exhibit improved cycling performance at 60°C. Overall, this work underscores the pivotal role of separator coatings in governing interfacial chemistry and provides a viable strategy for designing high-performance lithium-ion batteries capable of enduring both high temperatures and high

The commercialized binder carboxymethyl cellulose sodium (CMC-Na) is considered unsuitable for micro-sized SiO_x anode as it cannot endure the large volume change to retain the conductive network during repeated charge/discharge cycles. Herein, a small amount of silicon nanoparticles (SiNPs) is added during slurry preparation process as “nano-combs” to unfold the convoluted CMC-Na polymer chains so that they undergo a coil-to-stretch transition by interaction between polar groups (e.g., –OH, –COONa) of polymer and SiNPs’ large surface. Through maximizing the utilization of binders, a uniform conductive network is constructed with increased interfacial contact with micro-sized SiO_x. As a result, the SiO_x electrode with optimized (10 wt%) SiNPs addition shows significantly improved initial capacity and cycling performance. Through revisiting CMC-Na, a currently deemed unqualified binder in SiO_x anode, this work gives a brand-new perspective on the failing mechanism of Si-based anode materials and an improving strategy for electrode preparation.

Lithium (Li) metal is one of the most promising anodes for next-generation energy storage systems. However, the Li dendrite formation and unstable solid-electrolyte interface (SEI) have hindered its further application. Lithium nitrate (LiNO₃) is extensively used as an effective electrolyte additive in ether-based electrolytes to improve the stability of lithium metal. Nevertheless, it is rarely utilized in carbonate electrolytes due to its low solubility. Here, a novel gel polymer electrolyte (GPE) consisting of poly(vinylidene fluoride) (PVDF), poly(methyl methacrylate) (PMMA), poly(ethylene oxide) (PEO) with LiNO₃ additive is proposed to solve this issue. In this GPE, polyether-based PEO serves as a matrix for dissolving LiNO₃ which can be decomposed into a fast Li-ion conductor (Li₃N) in conventional carbonate electrolytes to enhance the stability and Li⁺ conductivity of the SEI film. As a result, dendrite formation is effectively suppressed, and a significantly improved average Coulombic efficiency (CE) of 97.2% in Li-Cu cell is achieved. By using this novel GPE coupled with Li anode and LiNi_0.5Mn_0.3Co_0.2O₂ (NMC532), excellent capacity retention of 94.1% and high average CE of over 99.2% are obtained after 200 cycles at 0.5 C. This work presents fresh insight into practical modification strategies on high-voltage Li metal batteries.

Graphite as a positive electrode material of dual ion batteries (DIBs) has attracted tremendous attentions for its advantages including low lost, high working voltage and high energy density. However, very few literatures regarding to the real-time observation of anion intercalation behavior and surface evolution of graphite in DIBs have been reported. Herein, we use in situ atomic force microscope (AFM) to directly observe the intercalation/de-intercalation processes of PF₆^- in graphite in real time. First, by measuring the change in the distance between graphene layers during intercalation, we found that PF₆^- intercalates in one of every three graphite layers and the intercalation speed is measured to be 2 μm·min^-1. Second, graphite will wrinkle and suffer structural damages at high voltages, along with severe electrolyte decomposition on the surface. These findings provide useful information for further optimizing the capacity and the stability of graphite anode in DIBs.