Aqueous Binders for Electrochemically Stable VOPO 4 2H 2 O Anodes for Li‐Ion Storage

The use of polyvinylidene difluoride (PVDF) binder dissolved in toxic N‐methyl pyrrolidone (NMP) organic solvent needs to be decreased during the manufacturing battery process to improve safety. Therefore, the development of aqueous‐based binders for negative and positive electrodes is necessary to make the production environmentally friendly. This study reports the performance of hydrothermal VOPO 4 2H 2 O anode material in combination with aqueous‐based binders such as sodium carboxymethylcellulose (CMC), polyacrylic acid (PAA) and their mixture CMC‐PAA (1:1 wt%). The aqueous binders are compared to standard PVDF as a reference binder. The cells with aqueous‐ and PVDF‐based electrodes are tested by galvanostatic, cyclic voltammetry, and electrochemical impedance spectroscopy measurements. When the CMC‐PAA aqueous binder is used, the electrode displays the most stable electrochemical performances due to a uniform distribution of the VOPO 4 with strong adhesion to the current collector for long‐term cycle life. A stable, solid electrolyte interphase layer is formed when the mixture of CMC‐PAA is used instead of a standard PVDF‐based binder. In addition, these samples display stable cycling life at different rate capabilities due to the facilitated lithium‐ion diffusion and electronic conductivity.