Impacts of different polymer binders on electrochemical properties of LiFePO4 cathode

Impacts of different polymer binders (PVdF, PAA and PMMA) on electrochemical performance of the LiFePO4 cathode in Li-ion batteries are investigated. From CV result, the voltage between redox peaks of the LiFePO4 with PVdF, PAA and PMMA binders are 0.26, 0.20 and 0.23 V, respectively. The current of the LiFePO4 with PMMA binder shows the highest value of 1.4 mA. The apparent diffusion coefficient of the LiFePO4 with PVdF, PAA and PMMA binders is 8.30 × 10−12, 2.57 × 10−11 and 9.13 × 10−11 cm2 s−1, respectively. The discharge capacities of the LiFePO4 with PVdF, PAA and PMMA binders are 106, 143 and 154 mAh g−1 at an initial cycle, respectively. FE-SEM studies clearly demonstrate that plate-like PAA and PMMA coating on the electrodes form a protective film, which may decrease the amount of the deposits, thus decreasing crack and crystallization on the electrode surface. Achieved results indicate that PVdF, PAA and PMMA binders show better properties than the traditional one, especially PMMA one.