Study on microstructure and charge–discharge mechanism of all solid‐state indium‐graphite batteries

Abstract

This study centers on indium‐ion solid‐state batteries. Indium is a soft metal that provides excellent adhesion and does not generate dendrites during the charge–discharge process. The solid‐state electrolyte material, sodium‐based silicate, is an environmentally friendly material that offers better thermal stability compared to liquid electrolytes and reduces packaging requirements. The positive electrode material, a graphite film (GF), features a layered structure, enabling the stable insertion and extraction of ions. In this experiment, graphite film doped sodium phosphate (GFN) are used as positive electrodes, sodium‐based silicate powder through cloth deposition (battery cloth deposition [BCD]) is used as the electrolyte and indium is used as the negative electrode. To improve the low capacity of indium electrodes, indium is alloyed with silver and prepared by thermal evaporation method. The results show that the In‐30Ag with Cu substrate (weight ratio of In‐30 wt.% Ag) exhibits higher cycling capacity (61 mAhg−1). To further increase the capacity, the substrate of In‐30Ag is replaced from copper foil to aluminum foil. According to result, the capacity of In‐30Ag with Al substrate (91 mAhg−1) exhibits 1.6 times higher compared to In‐30Ag with Cu substrate. However, In‐30Ag with Al substrate after vacuum heat treatment, the thin film exhibits melting and agglomeration, leading to a decrease in capacity. Thus, the unheated In‐30Ag (Al substrate)/2×BCD/GFN system is subjected to large‐area module testing using an industrial fan as the load, confirming its practical applications.