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Thermal Stability of Nanocrystalline NiS 2 as High Specific Capacity Thermal Battery Cathode Material
Author(s) -
Yang Wenju,
Zhou Lingping,
Luo Zeshunji,
Zhu Jiajun,
Yang Wulin,
Li Deyi,
Fu Licai
Publication year - 2020
Publication title -
advanced engineering materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.938
H-Index - 114
eISSN - 1527-2648
pISSN - 1438-1656
DOI - 10.1002/adem.202000299
Subject(s) - nanocrystalline material , materials science , cathode , grain size , thermal decomposition , diffractometer , thermal stability , battery (electricity) , electrochemistry , grain growth , chemical engineering , grain boundary , analytical chemistry (journal) , composite material , nanotechnology , scanning electron microscope , microstructure , electrode , thermodynamics , chemistry , power (physics) , physics , organic chemistry , chromatography , engineering
Nanocrystallization can shorten the Li + transport distance, resulting in the enhancement of electrochemical activity for cathode materials. However, nanocathode materials tend to be thermally unstable, further leading to poor electrochemical performance of a battery system. This disadvantage can be especially detrimental for thermal batteries because they are often operated at high temperatures (≥450 °C). Herein, the decomposition character of NiS 2 at 500 °C is investigated. The decomposition temperatures of NiS 2 are found to decrease from 510 to 350 °C with the grain size decreasing to 39 nm, due to the dramatically increased surface energy. The decomposition product is confirmed to be NiS, evidenced by a high‐temperature X‐ray diffractometer. The useful mass of the cathode will reduce once the discharging temperature is higher than 500 °C. Namely, although the small grain size shorthens the Li + transport distance, the discharge performance of the NiS 2 cathode may also decrease due to its inferior thermal stability. For the Li‐B/LiF–LiCl–LiBr/NiS 2 system, the NiS 2 with the grain size of 70 nm shows the highest specific capacity of 831 mAh g −1 under the discharging temperature of 500 °C, with the cut‐off voltage of 0.5 V, compared with other grain sizes from 39 to 112 nm.