The Construction And Investigation Of Three-dimensional Conductive Hydrogel Network Binder For Silicon Anodes Of Lithium-ion Batteries

Silicon(Si)has become a promising candidate for high-capacity lithium-ion batteries due to its extremely high theoretical capacity and suitable lithiation/delithiation potential.However,it always suffers from huge volume change during cycling process,which would lead to the pulverization of electrode and rapid capacity loss.The binder,as an indispensable component of lithium-ion batteries,is playing a critical role in maintaining the structural stability of the electrode upon cycling.Developing novel binders with suitable structures and properties is an effective approach to improve the electrochemical performance of Si anodes.In this paper,three-dimensional(3D)crosslinked polyacrylic acid hydrogels(PAAhg)were prepared via solution polymerization,and furthermore,3D conductive interpenetrated gel networks(PAA/PANI IPN)were successfully constructed after the in situ polymerization of aniline in PAAhg networks.The as-prepared hrdrogels were utilized as binders for Si anodes.The morphology,structure,various physics and chemical properties were investigated in detail,and electrochemical performances were also analyzed.Results show that PAAhg could significantly improve the cycle performance of Si anode and it exhibits excellent cycling stability(1853 mAh g-1 after 300 cycles)and high coulombic efficiency(~99%).PAAhg binder could form a strong chemical bonding with Si particles in three dimensions,which helps to alleviate the volume expansion,accommodate the internal strain and stabilize the solid electrolyte interphase(SEI)film.Moreover,the 3D conductive PAA/PANI IPN binder could improve the charge transfer rate during cycling by enhancing the electrical conductivity and promoting faster electrolyte impregnation and shorter Li+ migration distance,which leads to the significantly improved electrochemical performance at fast charge/discharge processes.As a result,the Si-PAA/PANI IPN electrode exhibits excellent rate performance,and a specific capacity of 1101 mAh g-1 could be retained even at a high current of 10 C.