High efficient recycling of glass fiber separator for sodium-ion batteries

High cost and low mechanical strength are the main obstacles for the large-scale application of glass fiber separator in Na-ion batteries. Recycling of glass fiber separator is an important mean to reduce cost, but secondary film formation of glass fiber in the recycling process is the key problem. In this work, glass fibers are extracted from waste glass fiber separators and then compounded with cellulose. The recycled separator is successfully prepared through a simple slurry sieving technology. Attributed to effective combination of cellulose and glass fiber, the mechanical strength of recycled separator (81.5 Mpa) has been significantly improved relative to original fiberglass separator (0.3 Mpa), while the cost is greatly reduced. As paired with NaxNi[Fe(CN)6]/Na metal, the battery delivers fine cycle stability (93.3% of capacity retention after 500 cycles at 1 C) and high rate performance (73.2% of specific capacity retention at 10 C). The above results open a new path for the recycling of glass fiber-based separators with excellent performance and low cost.