Research On Binder Of Silicon Anode Lithium Ion Battery Based On Tara Gum

At present,Si anode materials have received extensive attention because of their many advantages,and are considered to be an ideal anode material in the future to replace commercially available graphite.However,repeated charge and discharge will cause a large change in the volume of Si particles(>300%),which generates a high internal stress and causes the morphology of the silicon to be crushed.As a result,the electrode material are powdered and peeled,which greatly affects the cycle stability of the battery,and limits the commercial application of silicon anode materials.In this paper,the problem of Si negative electrode is solved by researching and developing a binder with excellent performance,thereby improving the electrochemical performance of silicon-based lithium ion batteries.The main experimental results are as following:(1)In this paper,a natural polysaccharide tara gum(TG)was used as a binder for the first time in silicon-based anode lithium ion batteries.The experimental results show that cycle performance,rate performance,and electrochemical impedance of the TG/Si electrode are better than CMC/Si electrode;After 100 cycles at 420 mA/g,the specific capacity of the TG/Si electrode remains 1339.5 mAh/g,which is 2.76 times the specific capacity of the silicon electrode of the CMC binder;Compared with the second turn,the TG/Si electrode has a discharge specific capacity retention rate of 46.64%.The mechanical strength of the TG binder is better than the commonly used CMC binder,and the binding force of the TG to the active material Si electrode is also strong.(2)We chemically modified tara gum(TG)to increase the polar groups in the TG molecule,and then used it as a binder for silicon electrodes.Through chemical grafting,acrylic acid monomer was introduced into the branched chain molecular structure of Tara gum.Here we named the grafted product TG-g-AA.The experimental results are as follows:After 100 cycles at 420 mA/g,the capacity of the TG-g-AA/Si electrode is still 1957.9 mAh/g,compared with the second cycle,the specific capacity retention rate is 73.42%;After 150 cycles at 840 mA/g,the capacity of the TG-g-AA/Si electrode is still 1474.6 mAh/g;Compared with the second cycle,the discharge specific capacity retention rate is 86.48%.It is obviously that the cycle stability of the TG-g-AA/Si electrode is better than that of the TG/Si electrode under different current density cycles.In addition,the thermal stability of TG and TG-g-AA,the peeling strength and the morphology of the electrodes were analyzed.These experimental results show that the thermal stability of TG-g-AA is better,and the binding force with the electrode is stronger.The electrode structure is kept relatively complete,which effectively limits the volume effect of Si,so the electrochemical performance is better.