Investigation of polyimide as an anode material for lithium-ion battery and its thermal safety behavior

As a type of a conjugate polymer with a reversible oxidizing-reducing property, polyimide is considered a representative polymer material for use as electrodes in lithium-ion batteries. Pyromellitic dianhydride is polymerized to form polyimide for use as an anode material in a lithium-ion battery, and its electrochemical and thermal properties are investigated. The first discharge capacity of the as-synthesized polyimide electrode material is 1520 mAh g−1, the charge capacity is 832 mAh g−1, and the discharge and charge capacities after 50 cycles are 587 mAh g−1 and 573 mAh g−1, respectively. In addition, the thermal behavior of the PI polymer electrode material is investigated by differential scanning calorimetry (DSC) measurements and compared with that of the graphite anode material. Under the same lithium intercalation condition, the heat release of polyimide and graphite are 242 J g−1 and 658 J g−1, respectively. Experimental results reveal that polyimide exhibits superior thermal properties than those observed at the graphite electrode at least in the initial cycle in lithium-ion batteries.