Synthesis And Modification Of High Electrochemical Performance Cathode Material NiCl₂ For Thermal Battery

NiCl₂ is considered as an ideal cathode material and potential cathode material for market application due to its big current density,high electrode potential,stable voltage platform and good thermal safety etc.However,the inherent defects of NiCl2,including poor electronic conductivity,large surface area and electrode materials porous flow,have highly limited its practical application in thermal batteries.In this research,we designed and prepared a series of Ni Cl 2 modified materials with carbon and metallic oxide,and systematacially studied the influences on electronic conductivity and electrode materials porous flow.Firstly,NiCl₂ composites,such as NiCl₂-EG,NiCl₂-GNs,NiCl₂-carbon coating?C@NiCl2?and NiCl₂-carbon-expanded graphite?C@NiCl₂-EG?were prepared by high temperature solid state method.And then,the phase structure,microstructure and discharge performance of NiCl₂ composites were systematically analyzed.The results showed that the carbon materials anchored on the surface or inserted in interlamination of NiCl₂ particles,and formed an efficient conducting network,in which,it facilitated the transmission of electrons and ions and increased the conductivity of NiCl₂ materials.The discharge performances of the thermal batteries with NiCl₂ composites as cathodes were tested at 500 ? and 100 m A/cm2.The results showed that there was no voltage delay at the initial discharge.The carbon/NiCl₂ composite displayed good electrochemical performances,in which,the C@NiCl2-EG exhibited discharge specific capacity of 292.77 m Ah/g,84.31 m Ah/g higher than pure NiCl₂,and active material using rate of 88.48 %,25.48 % higher than pure NiCl₂.Secondly,metallic-oxide/NiCl₂ composites were synthesized using metallic-oxide as the porous flow inhibitors,and we optimized Mg O and Al2O3 as the optimum porous flow inhibitors.And then,we analyzed the phase structure,microstructure and discharge performances of metallic-oxide/NiCl₂ composites.The results showed that Mg O and Al2O3 nanoparticles anchored on the NiCl₂ particles surface,and increased the high temperature stability of NiCl₂ materials,and they inhibited the electrode materials porous flow.The discharge performances of the thermal cells with NiCl₂ composites as cathodes were tested at 550 ? and 100 m A/cm2.And the results showed that the NiCl₂-MgO exhibited discharge specific capacity of 205.44 m Ah/g,and active material utilization rate of 62.09 %,while the NiCl2-Al2O3 exhibited discharge specific capacity of 209.17 m Ah/g,and active material utilization rate of 63.22 %.In order to improve the Mg O disposition uniformity,further,we synthesized NiCl₂ materials with MgO coating.The results showed that MgO nanoparticles anchored on the NiCl2 particles surface uniformly,and MgO@ NiCl₂ exhibited discharge specific capacity of 221.62 m Ah/g,72.10 m Ah/g higher than pure NiCl₂,and active material using rate of 66.98 %,21.78 % higher than pure NiCl₂.Finally,we analyzed the economic cost of the carbon/Ni Cl 2 composite and metallic-oxide/NiCl2 composite,and contrasted with CoS2 cathode material.The results indicate that the economic costs of NiCl₂ composites are lower than Co S2 materials,and the NiCl2 composites are expected to be a new cathode material for thermal batteries.