Sustainable okra gum for silicon anode in lithium-ion batteries

Abstract

Silicon (Si), due to its wide availability and highest theoretical capacity (4200 mAh·g−1) amongst other anode candidates, has drawn tremendous attention as a promising alternative of the existing graphitic anode in current-generation lithium-ion batteries (LIBs). However, the greatest challenge associated with using Si anodes is the huge volume changes which occur during the lithiation-delithiation process and result in pulverization of the electrode which shortens battery life. In this work, the thick and slimy mucilage from commonly cultivated okra pods is extracted, precipitated, and used as the binder to solve the challenges of silicon anodes. The extracted okra gum (OG) consisting of abundant branched polysaccharides, a non-toxic, bio-friendly, and water-soluble polymer offers excellent penetrating binding network and interfacial chemical binding forces. As a result, the as-prepared Si-OG electrode displays a discharge capacity of 1434 mAh·g−1 at a rate of 0.1C after 50 cycles which is about 1.5 times greater than that of the Si- carboxymethylcellulose (CMC) electrode. This improvement could be attributed to the greater Si-anchoring and viscoelastic properties of the OG binder than that of the CMC binder. The success of this work suggests that this sustainable, green, and low-cost okra gum binder is promising in constructing reliable silicon anodes for next-generation large energy capacity LIBs.