A new iron battery technology: Charge-discharge mechanism of ferrous chloride and ferric oxide electrolyte in all solid-state iron-graphite batteries.

• The solid electrolyte of iron compound powder ingots can enhance battery capacity. • The ferrous chloride will be converted into Fe 8 O 8 (OH) 8 Cl 1.35 during the charge-discharge cycle. • After charging-discharging, an abnormal layer forms at the interface of solid electrolyte and electrode, leading to interface expansion, cracks, and reduced electrode adhesion. This study investigates a Fe/SSE/GF battery. Iron (Fe) as cathode material contains higher electrical capacity and competitive advantages. The solid-state electrolyte (SSE) material is sodium silicate powder mixed with iron compound powders. There are four types of iron compounds: 1) iron oxide, 2) chlorinated/Na-rich iron oxide, 3) Cl-rich iron oxide, 4) ferrous chloride, which are compared with sodium silicate powder. The negative electrode material is graphite film (GF). According to experiments, converting iron into iron oxide or ferric chloride can enhance battery capacity (beyond 200 mAh/g) and cycle life. The reliability of the Fe/SSE/GF battery was assessed by substituting sodium silicate powder with an iron compound electrolyte and adding binder (Polyvinyl Alcohol, PVA) into powder to enhance the performance of Fe/SSE/GF. This experimental research is not only innovative but also represents a significant milestone in the field of solid-state energy storage. [ABSTRACT FROM AUTHOR]