A Polymer Layer of Switchable Resistance for the Overcharge Protection of Lithium-Ion Batteries

—The polymer layer based on a nickel complex with salen-type ligand is proposed for protecting rechargeable lithium-ion batteries from overcharge. This polymer has a switchable resistance and can pass into the insulator state when the threshold potential is exceeded. This allows avoiding the development of side processes such as electrolyte decomposition on the cathode. The effect of the polymer layer was tested on model systems and on prototypes of lithium-ion batteries.