Rechargeable Lithium Battery Cells Fabricated Using Poly(methyl methacrylate) Gel Electrolyte and Composite of V[sub 2]O[sub 5] and Polypyrrole

Rechargeable Li battery cells were fabricated using a composite of crystalline and polypyrrole as the positive electrode material and a gel electrolyte film based on cross-linked poly(methyl methacrylate) (PMMA). The pure polypyrrole electrode and the conventional electrode the latter of which was a mixture of acetylene black, and Teflon® binder, were also used for comparison. The PMMA gel electrolyte, showing no liquid leakage even under pressure, was prepared when the amount of the electrolyte solution in the polymer gel was reduced to 65 wt %. The electrode in the battery cell showed a capacity density that was 98.4% of its capacity density obtained in the electrolyte solution. Repeat of charge-discharge tests caused capacity fading when the and the composite containing 91wt % oxide were used. However, no change in the capacity density was observed up to 50 cycles for the composite electrodes containing 84 and 60 wt % oxide and the pure polypyrrole electrode. AC impedance measurements were conducted by using a three-electrode system to obtain the interfacial properties between the positive electrode and the gel electrolyte. It was found that the interfacial resistance was largely increased by charge-discharge cycling when the electrodes showing definite capacity fading were used, but the stable electrodes did not show such behavior.