A positive-temperature-coefficient electrode with thermal protection mechanism for rechargeable lithium batteries

A new positive-temperature-coefficient (PTC) material was prepared simply by blending of conductive Super P carbon black (CB) with insulating poly(methyl methacrylate) (PMMA) polymer matrix, which was empolyed as a coating layer on the aluminium foil substrate to fabricate a sandwiched Al/PTC/LiCoO2 cathode. The experimental results from cyclic voltammetry, charge-discharge measurements and impedance spectroscopy demonstrated that the PTC electrode has a normal electrochemical performance at ambient temperature, but shows an enormous increase in the resistance at the temperature range of 80–120°C. This PTC behavior greatly restrains the reaction current passing through the electrode at elevated temperatures, capable of acting as a self-actuating safety mechanism to prevent the battery from thermal runaway.