Study On Preparation And Performance Of Silicon-Based Anode Binder For Lithium-ion Battery

In the information era,the application of lithium-ion battery has gradually extended from portable electronic equipment to a series of large-scale electronic devices represented by electric vehicles,thus becoming a research hotspot in the field of energy and industrial development.People pursue lithium-ion battery with higher specific capacity,longer cycle life and lower cost.Silicon-based materials have been widely studied due to their high theoretical specific capacity,but the volume change of silicon in the process of lithiation/delithiation hinders the commercialization process.In addition to the morphology control with cost a lot,the design of silicon-based battery binder can effectively improve the electrochemical performance of the electrode.In this paper,the modified polyacrylic acid polymer was obtained by the polymerization initiated by amylase hydrolysis,and then it was thermally esterified with sodium alginate to obtain the binder material with suitable three-dimensional network structure.The further assembled silicon based button cell has excellent electrochemical performance.The specific capacity is 2548 mAh g-1 at 1 A g-1 after 100 cycles,and the impedance rises from 70 ? to 282 ? after 200 cycles.The cycle performance is excellent at multiple rate.After 300 cycles,the reversible specific capacity tested at 0.5 A g-1 was maintained at 426 mAh g-1,and the average cycle capacity decreased by 0.08%.The results show that the binder can effectively protect the integrity of electrode structure and improve the electrochemical performance of the battery.On the basis of the three-dimensional network structure mechanism,in order to further explore the applicability of silicon based binder,we reintroduce fluorinated material 2-(perfluorobutyl)ethyl acrylate,and then polymerize it with acrylic acid and acrylamide to obtain polymer with a large number of polar functional groups,and then moderately thermally esterified with sodium alginate,and finally dual cross-linked network structure binder consists of physical crosslinking and a large number of reversible hydrogen bonds.The silicon based button cell thus assembled has excellent cycle performance.Under the current destiny of 4 A g-1,the mass specific capacity of 200 cycles is maintained at 1557 mAh g-1,and the impedance rises from 165 ? to 410?.It is proved that 2-(perfluorobutyl)ethyl acrylate and acrylamide play an important role in the improvement of the binder system.The binder can maintain 600 mAh g-1 after 200 cycles at 0.5 A g-1 in the silicon/graphite composite electrode.After adjusting the ratio,700 cycles of long cycle can be realized in the silicon oxide/graphite composite electrode at 1 A g-1 high current destiny,and the capacity is maintained at 310 mAh g-1.After increasing the mass loading to 3.72 mg cm-2,the area specific capacity is maintained at 1.1 mAh cm-2.The results show that the binder can stabilize the electrode structure and weaken the negative effect of silicon expansion.