Fabrication of the Ni-NiCl2 Composite Cathode Material for Fast-Response Thermal Batteries

Abstract

Thermal batteries with a high power density and rapid activation time are crucial for improving the fast response ability of sophisticated weapons. In this study, an Ni-NiCl2 composite was prepared via hydrogen reduction and employed as a cathode material. Discharge tests on a battery assembled using the fabricated composite revealed that its initial internal resistance decreased and the activation time reduced. Notably, the Ni-NiCl2 cathode increased the energy output by 47% (from 6.76 to 9.94 Wh in NiCl2 and Ni-NiCl2, respectively) with a cut-off voltage of 25 V; the power density of the novel battery system reached 11.4 kW/kg. The excellent performance of the thermal battery benefited from the high electrode potential and low internal resistance of Ni-NiCl2. This study contributes to the development of high-performance electrode materials for next-generation thermal battery-related technologies.

Recent Developments of Cathode Materials for Thermal Batteries

“…It is urgent to develop new cathode materials for thermal batteries with high power and energy output capability, miniaturization, and micromation to adapt to the rapid development of weapon and space exploration system ( Tian et al, 2021 ), which is difficult for these traditional cathode materials ( Liu et al, 2017b ). The detailed synthesis, characterization, and performance tests of NiCl 2 are exhibited in Supplementary Figures S10–S12 .…”

“…However, the high solubility of NiCl 2 in molten salt electrolyte can cause short circuit. Due to the low conductivity and poor electrochemical activity of NiCl 2 , the activation time is longer, so a certain amount of conductive additives must be added to improve its conductivity ( Jai Prakash, 2000 ; Jin et al, 2017b ; Gui et al, 2020 ; Tian et al, 2021 ).…”

“…The discharge voltage and specific power of the prepared NiCl 2 via hydrogen etching technique were 2.43 V and 7.59 kW/kg. The fabricated the Ni-NiCl 2 composite cathode material via hydrogen reduction by Tian et al (2021 ) showed higher voltage and much shorter activation time, and half of the internal resistance and the power density was up to 11.4 kW/kg.…”

Instantaneous Activation of NiCl2 Cathode towards Thermal Battery by Constructing NiCl2–NiO Heterojunction

“…Thermal battery is a type of disposable power supply using inorganic molten salt as electrolyte, which is extensively served as power sources for weapon and military equipment in virtue of its high power output, dependability, and ruggedness. − Higher indexes for thermal battery have been proposed with the rapid development of weapons . Nickel chloride (NiCl 2 ) possesses a fairly high electrochemical window (2.64 V vs Li), remarkable thermal stability, and a higher theoretical specific capacity of 414 mAh g –1 , which has been identified as the ideal high-power cathode material. − Nevertheless, the application of NiCl 2 as an electrode material is generally restricted in power packages for fast-response and high-power output equipment due to its poor conductivity with the wide band gap (2.4–2.8 eV), resulting in a hysteretic reaction process, prolonged activation time, and lower output voltage. ,,, …”

“…Optimized conductivity could be ascribed to the formation of amorphous carbon on the NiCl 2 surface. Tian et al 8 prepared Ni−NiCl 2 composites by calcining NiCl 2 in a hydrogen atmosphere. Compared with a pure NiCl 2 cathode, the Ni−NiCl 2 cathode, with a lower initial resistance (0.054 Ω) and a shorter activation time (0.49 s), could achieve an improvement of the energy output by 47%, which benefited from the generation of metallic Ni on substrate NiCl 2 , leading to an elevated conductivity for cathode materials.…”