Development of Non-Fluorinated Cathodes Based on Li3V1.95Ni0.05(PO4)3/C with Prolonged Cycle Life: A Comparison among Na-Alginate, Na-Carboxymethyl Cellulose and Poly(acrylic acid) Binders

Non-fluorinated Li3V1.95Ni0.05(PO4)3/C-based electrodes were prepared by using sodium carboxymethyl cellulose, sodium alginate and poly(acrylic acid) as alternative binders of the standard poly(vinylidene difluoride). The effect of the binders was investigated on several aspects, starting from the rheological properties of the dispersions, to the physical-chemical properties of the layers (adhesion test, electrode porosity, surface conductivity). The prepared Li3V1.95Ni0.05(PO4)3/C-based electrodes were characterized as cathodes at different C-rates ranging from 1 C to 200 C in two different potential windows, between 3.0–4.3 and 3.0–4.8 V vs. Li/Li+. The cycle life of the LVNP/C-based electrodes was characterized for each potential window at C-rate as high as 100 C and for 10000 cycles. Electrochemical impedance spectroscopy, scanning electrode microscopy, X-ray diffraction and energy dispersive X-ray measurements were used to study the aged electrodes. Among the electrodes, the one prepared with Na-alginate binder displays the best electrochemical performance, with a specific capacity of 100 and 85 mAh g−1 delivered at 100 C when charged up to 4.3 and 4.8 V vs. Li/Li+, respectively. Moreover, in the same potential windows, it displays an excellent cycling stability over 10000 cycles at 100 C, with a capacity retention of 80% and 65%.