The Research On The Preparation And Discharge Performance Of NiCl₂ Nanosheets In High Power Thermal Battery

The thermal battery is a chemical power source widely used in the military field,with high current discharge,rapid activation and long storage time.At present,the low voltage?²V vs Li?characteristics of commercial thermal battery cathode materials CoS₂ and FeS₂ make their application on high-power heat batteries limited.NiCl₂ has high potential?2.64V?and high current discharge capability,and has broad application prospects in high specific power thermal battery systems.However,the low conductivity of NiCl₂ and the disadvantage of easy dissolution in the electrolyte reduce the overall electrochemical performance of the battery.NiCl₂ nanosheets were firstly prepared by chemical vapor deposition?CVD?.The discharge behavior of LiB/LiF-LiCl-LiBr/NiCl₂ thermal battery system at different current densities and temperatures was systematically studied.The nature of the dissolution and its influencing factors were revealed.The mechanism of NiCl₂ nanosheets to alleviate the leaching was clarified.NiCl₂ nanosheets were modified by hydrogen or oxygen etching to improve their conductivity and shorten the activation time.?1?NiCl₂ nanosheets with an average thickness of 4⁶nm were prepared by CVD method,and the specific surface area was 33.0m²g^-1,which was about 20 times that of the conventional NiCl₂ powder.The nanosheet structure is beneficial to increase the contact area of NiCl₂ with the electrolyte,shorten the diffusion distance of lithium ions and electrons,and improve the high current discharge capability.The assembled LiB/NiCl₂ battery was discharged at 600°C,0.75Acm^-2 and a cut-off voltage of 2.0V,and its specific power reached 27.1kWkg^-1,indicating that the NiCl₂nanosheet can be used as a high-power thermal battery cathode material.?2?It is proposed that the high-temperature dissolution of NiCl₂ positive electrode is the melting of Cl^-1;and the NiCl₂ nanosheet with large surface energy is easy to adhere to the surface of the binder MgO,effectively alleviating the melting of Cl^-1 in the electrolyte.The specific capacity of the dip is about 21%higher than that of the conventional NiCl₂ powder(600°C,0.5Acm^-2,cut-off voltage 2.0V).?3?NiCl₂ nanosheets were etched with hydrogen,and a small amount of Ni element was embedded on the edges and surfaces,and the roughness increased,which improved the conductivity of NiCl₂ nanosheets.The activation time of the battery was effectively shortened from 6.4s to 1.6s(500°C,0.2Acm^-2,cutoff voltage 2.0V).In this paper,ultra-thin NiCl₂ nanosheets were prepared by simple CVD method.The surface area was significantly improved compared with NiCl₂ powder,and it was easy to adhere to the sheet-like binder MgO,thus effectively alleviating the dissolution of Cl^-1.Hydrogen etching NiCl₂ nanosheets,embedding a small amount of Ni element on its surface and edge,increasing the roughness,improved the conductivity of the material,shortening the activation time,making NiCl₂ nanosheets a more ideal high-power thermal battery cathode material.eaturing high current discharge,rapid activation and long storage time.