Oxidation Modification And Crosslinking In New Binder For Silicon Anode

Silicon has a very high theoretical specific capacity(4200m Ah/g)and a more suitable electrode potential as a lithium-ion battery anode,and its industrial application is very promising.However,silicon undergoes a dramatic volume change(~300%)during the cycle,inevitably leading to electrode chalking and irreversible capacity loss.Binder is very important in lithium ion batteries and plays an important role in maintaining structural stability.The development of new high performance adhesives can effectively improve the performance of silicon negative electrodes.In this paper,new binders(NMC and NMR)were obtained by oxidation of CMC and CMS-Na with H2O2,and a new binder(P-NMC and P-NMR)was obtained by cross-linking polymerization of polyacrylic acid.The physicochemical properties of the binders were tested,and their electrochemical properties were tested and analyzed.Results show that at 1000 m Ah/g electrode CMC and CMS-Na binder capacity retained 26.75% and 32.23% after 100 cycles at 1000 m Ah/g,retained 17.11% and 22.67% after 200 cycles,and retained 29.89% and 39.75% at 4000 m Ah/g.NMC and NMR showed characteristic peaks of-C=O at 1740 cm-1,-OH was converted to-COOH or-CHO,and had strong hydrogen bonding interaction with Siparticles,which was helpful for alleviating the volume expansion of Siduring charge and discharge.At 1000 m Ah/g electrode NMC and NMR binder capacity retained 42.08% and 49.62% after 100 cycles at 1000 m Ah/g,retained 25.87% and 31.42% after 200 cycles,and retained 59.28 and 54.39% at 4000 m Ah/g,respectively.At 1000 m Ah/g electrode P-NMC and P-NMR binder capacity retained 55.10%和 54.25% after 100 cycles at 1000 m Ah/g,retained 31.17% and 32.39% after 200 cycles,and retained 65.92% and 57.73% at 4000 m Ah/g,respectively.In addition,the polyacrylic acid crosslinked network can increase the conductivity of the electrode to accelerate electrolyte penetration and charge transfer.