Binder-free hydrothermal approach to fabricate high-performance zinc phosphate electrode for energy storage applications

Metal phosphates are an emerging class of materials with large porosity that endows them with high specific capacity and ionic conductivity. However, the binder and carbon additive are required to fabricate the electrodes which adds extra expenditure to the supercapacitor's overall fabrication cost. The binder-free electrode fabrication provides a hope to eliminate the need for binders and hence the carbon additive for supercapacitor applications. In this work, a binder-free zinc phosphate hydrate (ZPOH) based electrode is fabricated using a costeffective hydrothermal method. Two additional electrodes were also fabricated - one without carbon additive (ZPOWCB) and another with the addition of carbon additive (ZPOCB) using the conventional slurry preparation method. ZPOH electrode showed remarkable enhancement in the specific capacity compared to the other two electrodes as it achieved a specific capacity of 433 C/g at a current density of 2 A/g. Moreover, ZPOH also showed negligible charge transfer resistance (Rct), depicting good electrolyte ions interaction with the active material. Hence, the easy and simple binder-free hydrothermal approach is more suitable for preparing electrode materials for energy storage applications.