A highly crosslinked polymeric binder for silicon anode in lithium-ion batteries

The polymer binder with three-dimensional network structure is prepared by cross-linking reaction, which can well alleviate the negative effect caused by the change of Silicon. Compared with PAA single-chain structure binder, its first coulomb efficiency is increased by 8.8 %. • Polymer binder can effectively alleviate the negative effects of silicon volume expansion. • The three-dimensional network polymer binder formed by crosslinking reaction has better mechanical properties. • Three-dimensional network structure has a better electrolyte absorption rate and wetting rate. Silicon as the anode materials had great development prospect in lithium-ion batteries owing to its high capacity. However, during the cycling process, silicon anode’s huge volume expansion would cause the material's severe crushing and disintegration. In order to effectively limited its volume expansion, designed a new highly crosslinked binder, Synthesis of Oxidized Starch (OS) and Polyacrylic Acid (PAA) by crosslinked esterification reaction, and used to reduce the negative effects of Si electrode in the cycling process. Compared to the polyacrylic acid (PAA) binder, the crosslinked polymer binder could effectively increase the Silicon anode’s electrochemical performance. The initial specific discharge capacity and coulomb efficiency of the crosslinked polymer binder electrode were 3441.7 mA h g −1 and 62.39 %, while those of the polyacrylic acid (PAA) binder electrode were only 3526.9 mA h g -1 and 53.59 %. At the current density of 200 mA g -1 after 100 cycles, the discharge capacity and capacity retention of the electrode with the crosslinked polymer binder was 1386.2 mA h g −1 and 40.28 %, greater than those of the electrodes with polyacrylic acid (1068.1 mA h g −1 /30.28 %). This solution provided a design of new crosslinked polymer binder, which could be used for the pragmatic application of the anode material with large volume variation.