An ultra stable rice husk-based hard carbon using solid-electrolyte-binder containing sodium ion

Biomass-based hard carbon is a promising anode material for sodium-ion batteries (SIBs) because of its renewability, low cost and abundant porous structure. However, irreversible electrolyte consumption caused by hard carbon due to its large specific surface area and abundant structural defects is accompanied by a thick and uneven solid-electrolyte interphase (SEI), resulting in a low initial Coulombic efficiency (ICE) and rate performance of hard carbon anode. Therefore, an advanced sodium ion contained solid-electrolyte-binder (SSEB) with abundant hydrophilic functional groups is designed. The SSEB can uniformly cover the electrode surface by connecting oxygen-containing functional groups on the hard carbon surface, and the added polyethylene oxide (PEO) can construct ion diffusion paths to promote Na + transport. As a result, a SEI with a thickness of 9 nm has been obtained, and rice husk-based hard carbon with the SSEB provided high ICE (90.7 %) and capacity retention rate of 89.7 % after 2000 cycles at 3000 mA g −1 . The new design of Na  +  contained solid-electrolyte-binder open a door for the understand and application of hard carbon for sodium-ion batteries.