Low-mutual solubility NiCl2-based cathodes with high stability for thermal battery

Due to its high voltage, high capacity, and high thermal stability, NiCl 2 is considered one of the best choices for cathode materials in high-power, high-capacity thermal batteries. However, its characteristic of being easily miscible with electrolytes at high temperatures poses a huge challenge to its application. This work proposed a simple, scalable strategy through using a commercial porous MgO (PMO) as absorber and buffer layer as well as an industrial-grade multilayer graphene (MLG) as conductive agent to manage the mutual solubility process and improve the electronic conductivity. Research finds that owing to strong coupling between components, the introduction of PMO and MLG can greatly improve the electrochemical stability of NiCl 2 , resulting in excellent thermal battery performance. When the content of PMO introduced is 8 wt%, the specific capacity of Li-B|EG|N-2 battery is 285.3 mA h/g (cut-off voltage at 2.0 V) at a current density of 200 mA cm −2 , almost 3.8 times than that of the pure NiCl 2 (only 73.4 mA h/g). When the current density is 500 mA cm −2 , its specific capacity can still reach 278.3 mA h/g. Meanwhile, its peak voltage reaches 2.461 V, while that of the pure NiCl 2 battery is only 2.38 V. Especially, it exhibits high initial voltage and continuous stable voltage output. Therefore, this work provides a feasible approach for the industrial preparation of highly stable NiCl 2 -based cathodes with excellent thermal battery performance.