Carbon coated CoS2 thermal battery electrode material with enhanced discharge performances and air stability

- A novel C@CoS2 composite is successfully prepared by hydrothermal method.
- The growth of CoS2 in the glucose solution results in a smaller grain size.
- The coating of carbon favors electron transfer and buffers polysulfides formation.
- The in situ coated carbon layer effectively prevents the oxidation of CoS2.
- The C@CoS2 composite shows competitive thermal stability and discharge property.

Cobalt disulfide (CoS2) is a promising thermal battery electrode material for its superior thermal stability and discharge performance. However, the low natural resource and poor air stability restrict its application in thermal battery fabrication. In this work, carbon coated CoS2 composite was prepared by a facile one-pot hydrothermal method with glucose as carbon source. During the growth of CoS2, the glucose molecules were in situ adsorbed and carbonized on the surface of the as-synthesized CoS2, and the resultant carbon coating provided improved electrical conductivity and discharge performances to the composite. The thermal battery cell, which was fabricated with such a composite cathode and with a Li-Si anode, can output a capacity of 235.8 mAh g−1 and an energy density of 416.9 Wh kg−1 at a cut-off voltage of 1.7 V. This carbon coated CoS2 composite also presented enhanced air stability. After being stored in dry air for 3 months, the composite can still provide a capacity of 232.4 mAh g−1 to 1.7 V, whereas the capacity of bare CoS2 stored with the same condition dropped from 202.4 mAh g−1 to 189.7 mAh g−1.

A novel carbon coated CoS2 composite is prepared and investigated as a cathode material for thermal batteries.177