A three-dimensional cross-linked water-soluble poly(vinyl alcohol)-citric acid binder enables superior-performance graphite anodes for lithium-ion batteries
摘要
Although the amount of the binder in the electrode of lithium-ion batteries (LIBs) is very low, it has a significant impact on the electrochemical performance of LIB devices. Herein, an environment-friendly and low-cost water-soluble binder was developed by the cross-linking of poly(vinyl alcohol) (PVA) and citric acid (CA). The hydrogen bond interactions between the carbonyl groups in CA and hydroxyl groups in PVA construct a three-dimensional cross-linked PVA-CA binder. The as-constructed PVA-CA exhibits satisfactory ionic conductivity of 0.9 µS cm− 1 together with swelling rate of 6.8%. The application of PVA-CA binder to graphite anode can generate outstanding performance including high peeling strength of 1.63 N, good cycling performance (308.3 mAh g− 1 at the end of 300 cycles) along with superior rate performance, which exceed polyvinylidene fluoride (PVDF) binder, due to the strong hydrogen bond interactions between binder and graphite/current collector and the abundant carboxyl and hydroxyl groups in PVA-CA binder. In addition, a full cell consisting of a graphite anode with the PVA-CA binder and a lithium iron phosphate (LiFePO4) cathode exhibits a high discharge capacity of 44.2 mAh g− 1 after 300 cycles at 2 C.