A degradable membrane based on lignin-containing cellulose for high-energy lithium-ion batteries

Traditional polyolefin separator has the defects of non-degradation and poor wettability with the electrolyte. In this paper, we have designed the porous membrane based on the lignin-containing cellulose nanofibers (LCNFs) from the unbleached pulp by a facile method. In the designed membrane, the amorphous lignin can effectively adjust the dispersion of the cellulose to form a uniform mesoporous structure. And the abundant oxygen-containing functional groups both in cellulose and lignin can promote the affinity of the membrane with the electrolyte. Finally, the prepared the LCNF porous membrane shows a high electrolyte uptake of 276 % and high ionic conductivity of 1.86 mS cm^-1. As the separator for LIBs, the batteries with high-voltage Li₃V₂(PO₄)₃ as cathode (up to 4.8 V), the batteries displayed 183 mAh g^-1 with the energy density of 669 Wh kg^-1, indicating the good application potential in high-energy LIBs. More importantly, the LCNF membrane made from the unbleached pulp has low cost and it can degraded in soil only after 16 days, which can largely reduce environment pollution of the LIBs. This research provided an efficient and low-cost method to fabricate a membrane with good biodegradability and high electrochemical performance for LIBs.