Showa Denko K.K. (SDK) has begun volume production of its “Polysol LB Series” water-based anode binder for lithium-ion batteries (LIBs). The product is a water-based emulsion containing acrylic synthetic resin particles, ensuring lower environmental impact at the time of production compared with solvent-based binders.
It provides such advantages as low electrical resistance, good temperature characteristics, and good adhesion to anode collectors, thereby contributing toward extending the life and increasing the capacity of LIBs, the company says. Having improved the product properties based on the results of sample evaluation by potential customers, SDK has decided to sell the product on a commercial scale.
In addition to the four major LIB components (cathode material, anode material, separator, and electrolyte), binders are a target of technological development as they significantly influence the performance of LIBs.
A binder causes cathode/anode active materials (for release and intake of lithium ions) to stick together. It also causes additives to stick together, and active materials to adhere to collectors. While styrene-butadiene rubber (SBR) is mainly used in binders, it has a problem of deterioration at high/low temperatures. Compared with SBR, Polysol LB Series can improve temperature characteristics by around 10%, in terms of the maintenance of capacity at the time of charge/discharge after preservation at a high temperature (60 °C) and in service capacity at a low temperature (-20 °C).
Furthermore, it exhibits high binding property with addition of a small amount due to its high dispersibility, and increases adhesion to anode collectors (made of copper) by 1.5 times, enabling reductions in inner electrical resistance.