Polymer nanocomposites are drawing considerable interest in electrical energy storage research owing to their distinctive characteristics and promising roles in various devices, such as batteries, supercapacitors, and fuel cells. This review examines the selection criteria of polymer nanocomposites for electrical energy storage applications and the current advancements in developing and producing polymer nanocomposites specifically tailored for electrical energy storage applications. Key topics covered include the selection of polymer matrices, choice of nanofillers, fabrication techniques, characterization methods, and performance evaluation of the resulting nanocomposites. The impact of nanofiller dispersion, interface engineering, and morphology control on electrical storage properties is emphasized. Proper dispersion enhances uniformity and interfacial interactions, improving electrical, mechanical, and thermal properties. Interface engineering boosts polymer-nanofiller compatibility, while morphology control optimizes nanofiller structure and arrangement for better storage efficiency. Emerging trends, challenges, and future research directions are also discussed, providing insights for developing advanced polymer nanocomposites with improved electrical energy storage capabilities.

As a key component of lithium-ion batteries, a separator with excellent electrolyte wettability and good thermal stability has an important impact on the overall performance of lithium-ion batteries. Herein, a PVDF/sepiolite electrospun layer was coated on one side of the PP separator via electrospinning technology to prepare the composite separator (xMS-PVDF@PP) with sepiolite nanofibers modified with vinyltriethoxysilane (VTES) to ameliorate their dispersibility and compatibility with PVDF polymer matrix. The effect of modified sepiolite addition amounts on the physical and electrochemical properties of composite separator was intensively studied. It is found that the as-prepared xMS-PVDF@PP composite separator displays enhanced porosity, electrolyte uptake, thermal stability and Li⁺ ion transport kinetics than pristine PP separator. Specifically, Li|LiFePO₄ battery with 20MS-PVDF@PP as separator shows the best rate and cycling performance, with a specific discharge capacity of 115.3 mAh·g^–1 at 10C rate and a capacity retention rate of 97.06% after 200 cycles at 1C rate. The sepiolite in the electrospun layer can immobilize PF₆^– anion to facilitate the uniform distribution of Li⁺ ions and then inhibit the lithium dendrite growth, as well as absorb HF to alleviate Fe²⁺ dissolution from LiFePO₄ cathode, thereby further improving the electrochemical performance of LiFePO₄ battery.