A Sustainable Tamarind Kernel Powder Based Aqueous Binder for Graphite Anode in Lithium-Ion Batteries

Natural polysaccharides have gained much attention as aqueous binders for lithium-ion batteries due to low cost, abundance and non-toxicity. Herein, we report for the first time the use of Tamarind Kernel Powder (TKP) as an aqueous binder for graphite anode. The graphite electrodes have been fabricated using 3, 4 and 5 wt.% of TKP binder and their electrochemical performances are studied. Among these, the electrode with 4 wt.% binder content shows the best electrochemical performance. It delivers an initial discharge capacity of 426 mAh g(-1) and retains the capacity of 343 mAh g(-1) after 100 cycles at 0.1 C (0.1 C=37.2 mA g(-1)). It exhibits a first cycle reversible capacity of 326 mAh g(-1) at 1 C with good cycling stability for 500 cycles, which is much better than the graphite electrode with conventional PVdF (4 wt.%) binder (first cycle: 103 mAh g(-1)). In addition, it demonstrates good rate capability up to 50 C. The fabricated TKP/Graphite electrode exhibits a discharge capacity of 55 mAh g(-1) at 50 C, whereas under the similar conditions the PVdF counterpart delivers only 20 mAh g(-1). In addition, a full cell has been fabricated with NMC532/C-TK4 electrodes, which delivers a discharge capacity of 121 mAh g(-1) at 1 C with a capacity retention >84% after 50 cycles. The superior performance of the aqueous binder based graphite electrode can be ascribed to the good solubility, high lithium ion conductivity, and better wettability of TKP binder. Hence, TKP plays a remarkable role as a binder in the electrode fabrication for the application of lithium-ion batteries.