Lithium-ion batteries (LIBs) have become indispensable energy-storage devices for various applications, ranging from portable electronics to electric vehicles and renewable energy systems. The performance and reliability of LIBs depend on several key components, including the electrodes, separators, and electrolytes. Among these, the choice of binder materials for the electrodes plays a critical role in determining the overall performance and durability of LIBs. This review introduces polymer binders that have been traditionally used in the cathode, anode, and separator materials of LIBs. Furthermore, it explores the problems identified in traditional polymer binders and examines the research trends in next-generation polymer binder materials for lithium-ion batteries as alternatives. To date, the widespread use of N-methyl-2-pyrrolidone (NMP) as a solvent in lithium battery electrode production has been a standard practice. However, recent concerns regarding its high toxicity have prompted increased environmental scrutiny and the imposition of strict chemical regulations. As a result, there is a growing urgency to explore alternatives that are both environmentally benign and safer for use in battery manufacturing. This pressing need is further underscored by the rising demand for diverse binder research within the lithium battery industry. In light of the current emphasis on sustainability and environmental responsibility, it is imperative to investigate a range of binder options that can align with the evolving landscape of green and eco-conscious battery production. In this review paper, we introduce various binder options that can align with the evolving landscape of environmentally friendly and sustainable battery production, considering the current emphasis on battery performance enhancement and environmental responsibility.

Membranes with hierarchical architectures, where pores of different sizes are integrated in tandem, are of great interest for water/oil emulsion separation due to their potential for achieving large flux, high selectivity, and mechanical durability. However, it remains challenging to modify the pore size in the nanoscale without sacrificing the flux, thus limiting the size of the oil/water droplets that can be filtered. Here, we electrospin a thin layer of azobenzene polymer (i.e., polydisperse orange 3, PDO 3) fibers on a highly porous supporting layer (i.e., an electrospun fiber network from polycaprolactone), followed by photofluidization of PDO 3 fibers to shrink the pore size from micrometer to nanometer by controlling the light exposure dosage. We show that the fabricated hierarchical membranes can be utilized for the gravity driven separation of water-in-oil emulsion droplets with size as small as 50 nm while maintaining high flux (ca. 15 000 L m⁻² h⁻¹ bar⁻¹ for surfactant-free emulsions and ca. 1000 L m⁻² h⁻¹ bar⁻¹ for surfactant-stabilized emulsions).