A supramolecular self-assembly hydrogel binder enables enhanced cycling of SnO2-based anode for high-performance lithium-ion batteries

Here, a supramolecular self-assembly hydrogel was designed for SnO2-based anode through electrostatic interaction and ionic bonding between poly(allylamine hydrochloride) (PAH) chain and gelator phytic acid. Microrheology measurement was employed to investigate the self-sorting mechanism of the hierarchical nanostructured PAH. Results confirmed that ionically cross-link PAH improves the structural integrity of SnO2 nanospheres due to the reversible ionic bonding and thus increases the lifetime of the electrodes obviously. Besides, multi-walled carbon nanotubes (MWCNTs) were applied to improve the electrochemical performance of hollow SnO2 nanospheres due to their high conductivity. Results confirmed that the conductive network constructed by MWCNTs reduces the polarization of the composites while increases the specific capacity of the electrodes. Attributed to the synergistic effect of PAH-60 and MWCNTs, the composite electrodes show excellent electrochemical performance with a reversible capacity of 574 mAh g−1 after 100 cycles at 100 mA g−1, a discharge capacity of 321 mAh g−1 at 2000 mA g−1 and a spring-back capacity of 506 mAh g−1 at 200 mA g−1. Additionally, the prepared composite electrodes were observed to have a complete network structure after rate capability test, demonstrating a superior structural stability.