High-performance anode material for Li-ion batteries from bismuth molybdate incorporating F-free binder

Abstract

In the pursuit of high-performance anode materials for Li-ion batteries over the past few decades, bismuth molybdate (BMO) has emerged as a promising candidate. However, its interaction with traditional polyvinylidene fluoride (PVDF) binder is not favorable, leading to rapid degradation of cyclic capacity. Furthermore, PVDF is considered an environmentally toxic binder. Therefore, finding a suitable binder that enhances the cycle life of this material and is more environmentally friendly is essential. In this study, BMO material was successfully grown at a low annealing temperature (200 °C) in an air environment. Analyses including X-ray diffraction, transmission electron microscopy, and scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy were employed to obtain a comprehensive understanding of the material morphology and structure. BMO was identified as a polycrystalline Bi₂MoO₆ material consisting of approximately 6.94 nm grains and 300–500 nm long rods with diameters ranging from 10 to 25 nm. In addition, an amorphous phase was observed in the BMO material. The effect of the binder on the electrochemical properties of BMO was evaluated using two binders: PVDF and poly(acrylic acid) (PAA). The BMO electrode using the PAA binder (BMO_PAA) demonstrated significantly better performance as an anode for lithium-ion batteries (LIBs) than that using the PVDF binder (BMO_PVDF). The BMO_PAA anode attained a 60th-cycle specific capacity of 738 mAh g⁻¹ at 0.1 A g⁻¹, whereas this value for the BMO_PVDF electrode was 202 mAh g⁻¹. Therefore, this report presents the synthesis of a superior anode material for LIB fabrication that is compatible with a PAA binder, an environmentally friendly, fluorine-free binder.