A Novel Study on Suppressing Sodium Dendrites Using Coatings for Separator Based on the Piezoelectric Principle

Currently, sodium-ion batteries (SIBs) have a wider temperature adaptability than lithium-ion batteries, but they still perform poorly in cold weather, especially below -20°C. In such conditions, the mobility of sodium ions decreases, leading to higher internal resistance, which negatively impacts charge-discharge efficiency and battery capacity. This work introduces a novel SIBs separator consisting of a separator and a coating made from polyvinylidene fluoride (PVDF). This coating is applied to conventional battery separators and uses its piezoelectric properties to create mechanical stress, preventing the formation and growth of sodium dendrites during charge-discharge cycles. Further experimental results indicate that without the nanofiber piezoelectric coating, sodium-ion batteries short-circuit after fewer than 50 cycles at a current density of 0.2 mA due to dendrite formation. However, with the coating, the batteries can exceed 240 cycles, significantly extending their lifespan. This technology has effectively addressed the problem of battery short circuits resulting from the growth of sodium dendrites and is expected to promote the wider application of SIBs technology.