Cobalt-Doped NiS<sub>2</sub> Micro/Nanostructures with Complete Solid Solubility as High-Performance Cathode Materials for Actual High-Specific-Energy Thermal Batteries
Hao Guo, Licheng Tang, Qianqiu Tian, Ying Chu, Bin Shi, Xucai Yin, Hua Huo, Xiaopeng Han, Chengxiang Yang, Chu Wang, Kangkang Tang, Chang Wang, Xiaohong Zhang, Jianyong Wang, Long Kong, Zhouguang Lu
Abstract
Transition-metal sulfides are key cathode materials for thermal batteries used in military applications. However, it is still a big challenge to prepare sulfides with good electronic conductivity and thermal stability. Herein, we rapidly synthesized a Co-doped NiS2 micro/nanostructure using a hydrothermal method. We found that the specific capacity of the Ni1–xCoxS2 micro/nanostructure increases with the amount of Co doping. Under a current density of 100 mA cm–2, the specific capacity of Ni0.5Co0.5S2 was about 1565.2 As g–1 (434.8 mAh g–1) with a cutoff voltage of 1.5 V. Owing to the small polarization impedance (5 mΩ), the pulse voltage reaches about 1.74 V under a pulse current of 2.5 A cm–2, 30 ms. Additionally, the discharge mechanism was proposed by analyzing the discharge product according to the anionic redox chemistry. Furthermore, a 3.9 kg full thermal battery is assembled based on the synthesized Ni0.5Co0.5S2 cathode materials. Notably, the full thermal battery discharges at a current density of 100 mA cm–2, with an operating time of about 4000 s, enabling a high specific energy density of around 142.5 Wh kg–1. In summary, this work presents an effective cathode material for thermal battery with high specific energy and long operating life.