Hybrid humics/sodium carboxymethyl cellulose water-soluble binder for enhancing the electrochemical performance of a Li-ion battery cathode

A hybrid water-soluble humics-based binder (humics/sodium carboxymethyl cellulose (CMC)) was studied to enhance the electrochemical performance of a Li-ion battery cathode (LiFePO4) in this work. Molecular dynamics simulations of binder active fractions with related materials (LiFePO4 and Al) were performed to explore the binding mechanisms. Humics serve to connect the active material and provide a conducting bridge in the cathode. To improve the adhesion between the particles and current collector, CMC is added as an auxiliary fraction with a mass ratio of humics to CMC of 3:1. The scanning electron microscope results indicate that the morphology of the electrode with the hybrid humics/CMC binder is more uniform than that of electrodes with conventional polyvinylidene fluoride and CMC binders. The electrochemical performance and cycling stability of the cathode materials are obviously enhanced. The reversible specific capacity can reach 152.3 mAh g−1 at 0.5 °C after 100 cycles. The rate capability is greatly improved, with a specific capacity as high as 105 mAh g−1 at 8 °C. The humics/CMC composite can be regarded as a novel, environmentally friendly and high-efficiency binder for application in Li-ion batteries.