Polymer Binders for High Capacity Electrode of Lithium-Ion Battery

With the development of lithium ion batteries with high energy density, the traditional graphite anode material will be replaced gradually by other materials with high specific capacity, such as alloy and metal oxides. However, these high capacity anode materials suffer from huge volume change during the cycling process, which causes the degradation of cycle performance and thus limits their application. Apart from the improvement on the active materials, the rational choice of binder is an effective way to improve the electrochemical performance of electrode. In the present paper, the development of binders used in high capacity anode in the recent decade is reviewed. With various modifications on polyvinylidene fluoride (PVDF) binder to enhance its viscoelasticity, the electrochemical properties of electrode can be improved. Compared to PVDF, the water-based carboxymentyl cellulose (CMC) binder can enhance greatly the electrochemical performance of Si-based electrodes. Better dispersion of electrode slurry, inactive to electrolyte and forming a chemical bond (covalent or hydrogen bonding) with active materials are the reasons for CMC being better than PVDF when used in the high capacity negative electrode. The structural parameters of CMC (molecular weight, degree of substitution, cationic), CMC content, pH value of the slurry and the electrode porosity have important influence on CMC electrode performance. Besides, polyacrylic acid (PAA) and Na-alginate binder are much effective in improving the cycling performance of high capacity electrode, due to their high carboxyl groups (-COOH). Other novel binders also have potential to enhance cycling performance of high capacity electrode.