The commercialization of polymer solid-state electrolytes (PSEs) is hindered by the persistent trade-off between ionic conductivity and mechanical stability, both of which are essential for high-performance energy storage systems. This review examines this challenge by analyzing the underlying mechanisms governing ion transport and mechanical degradation, while discussing targeted strategies to mitigate these limitations. Recent advances are summarized, spanning molecular-level modifications, such as dynamic crosslinking and heteroatom doping, as well as multiscale design approaches, including inorganic-organic composite architectures and engineered ion-conduction pathways. Collectively, these innovations have demonstrated the potential to achieve room-temperature ionic conductivities exceeding 1 mS·cm^-1 while maintaining sufficient mechanical robustness to suppress lithium dendrite growth. Key strategies for enhancing ionic conductivity include molecular structure regulation to promote polymer segmental motion, optimization of ion transport pathways, and the design of composite electrolytes incorporating ionophilic fillers to establish continuous conduction networks. In parallel, engineering stable electrode-electrolyte interfaces is highlighted as a critical approach to improving overall electrochemical performance and long-term stability. Furthermore, emerging opportunities such as machine-learning-assisted material discovery and scalable manufacturing technologies are discussed as promising routes toward the practical implementation of PSEs. By integrating these advances, PSEs are expected to play a pivotal role in next-generation safe, flexible, and high-energy-density batteries. This review provides a comprehensive roadmap for addressing the conductivity-stability trade-off and accelerating the commercialization of advanced PSEs.

Electrolytes play a pivotal role in determining the electrochemical performance of anode-free sodium metal batteries. Ether-based electrolytes exhibit superior compatibility with sodium metal anode, while their poor oxidation stability has historically restricted their application in high-voltage systems. Although high concentration and localized high concentration strategies have been employed to improve the oxidation resistance, their high costs and complexity remain significant barriers. Herein, a low-cost, standard-concentration (1 M) ether-based electrolyte that achieved exceptional high-voltage stability was developed. The extended ether chains endow tetraethylene glycol dimethyl ether with intrinsically enhanced oxidation resistance by lowering its highest occupied molecular orbital energy level, while maintaining excellent reduction stability. Furthermore, the BF₄⁻ anions preferentially decompose to form a robust boride- and fluoride-rich interphase at the cathode surface. This synergistic effect between the solvent and anion enables an anode-free Al@C||Na₂Fe₂(SO₄)₃ battery to deliver 500 stable cycles at a high charging cut-off voltage of 4.5 V, with an average discharging voltage of 3.8 V. This work not only demonstrates the feasibility of high-voltage ether-based electrolytes at standard concentrations, but also provides critical insights and references for the development of advanced electrolytes for next-generation batteries.

Zn-based batteries have attracted extensive attention due to their high theoretical energy density, safety, abundant resources, environmental friendliness, and low cost. They are a new energy storage and conversion technology with significant development potential and have been widely used in renewable energy and portable electronic devices. Considerable attempts have been devoted to improving the performance of Zn-based batteries. Specifically, battery cycle life and energy efficiency can be improved by electrolyte modification and the construction of highly efficient rechargeable Zn anodes. This review compiles the progress of the research related to Zn anodes and electrolytes, especially in the last five years. This review will introduce fundamental concepts, summarize recent development, and inspire further systematic research for high-performance Zn-based batteries in the future.