In recent years much efforts have been focused on design of silicon based anode which has very high theoretical capacity. For the stabilization of silicon based anode which undergoes extremely large volume changes, variety of approaches have been examined both in terms of active material design and binder material design. We prepared novel alternating poly(borosiloxane) [1] via dehydrocoupling polymerization which was found to show self-healing behavior. This was successfully applied as a coating material for silicon based anode. Further, BIAN (bis-imino-acenaphthene) based n-type conjugated polymer [2,3,4,5] formed hydrogen bonding based network when combined with poly(acrylic acid).  The resulting composite binder material was found to be quite efficient for stabilization of silicon based anode to maintain more than 2000 mAh/g of specific discharging capacity during 600 cycles.  In post-mortem  studies on SEM images, it was seen that self-healing hydrogen bonding based anode composite was free from cracks even after 400 cycles.

For further improvement of BIAN based binder for silicon based anode, crosslinking reaction of BIAN based conjugated polymer with dibromohexane was carried out. Due to mechanical robustness after crosslinking and also to ionic structure which promotes ionic diffusion, further improvement in performance was observed. The resulting anodic half cell delivered around 2500 mAh/g of specific discharging capacity during 1000 cycles.

Both poly(borosiloxane) and BIAN based conjugated polymer have low LUMO level, which enables sacrificial reduction of binders prior to the reduction of ethylene carbonate to form thin SEI layer. Dynamic impedance spectroscopy also supported low SEI resistance for these systems.

References
[1] S.G, Patnaik; T.P, Jayakumar; Y, Sawamura; N, Matsumi ACS Appl. Ener. Mater, 2021, 4, 2241.
[2] S.G, Patnaik; R, Vedarajan; N, Matsumi J. Mater. Chem. A, 2017, 5, 17909.
[3] S.G, Patnaik; R, Vedarajan; N, Matsumi ACS Appl. Ener. Mater, 2018, 1, 1183.
[4] A. Gupta; R, Badam; A, Nag; T, Kaneko; N, Matsumi ACS Appl. Ener. Mater, 2021, 4, 2231.
[5] A. Gupta; R, Badam; N, Matsumi ACS Appl. Ener. Mater, 2022, 5, 7977.