Carbon-Coated Treatment Of LaFeO₃ And Study On Performance As Negative Electrode Of Ni/Mh Battery

Perovskite-type oxide lanthanum ferrate（LaFeO₃）as a new nickel-hydrogen battery cathode material has the advantages of excellent high-temperature performance,high theoretical capacity,wide source of raw materials,low cost,environmental protection and no pollution,which can be applied in special high-temperature environments such as aerospace,thus broadening the application temperature range of nickel-hydrogen batteries.However,the material has the shortcomings of low electrical conductivity,easy agglomeration,and poor kinetic performance.To address this problem,this paper mainly adopts in situ carbon-coated to improve the high-temperature electrochemical performance of the material.The LFO@C structure of carbon layer coated with lanthanum ferrate were successfully synthesized by high temperature solid phase method to investigate the effect of different glucose addition on the electrochemical performance of the material electrode after in situ addition of glucose,and the electrochemical performance of the product is optimal when the amount of glucose is 15%（theoretical synthesized LFO mass）,and its maximum discharge specific capacity reaches 275.71 m Ahg^-1,an increase of 59.27%.LFO@C（15%glu）its HRD（%）retention at 1500 m Ag^-1 increases from the original 7.22%to 15.04%;the cyclic stability at 100 cycles of the treated electrode material is also improved.The LFO@C electrode materials were synthesized in situ by high-temperature solid-phase method using five-membered cyclic ascorbic acid,large-molecule branched-chain starch,and six-membered cyclic agar powder as carbon sources,respectively,and the maximum discharge specific capacity,multiplicative performance,and cycling stability of the sample materials are improved after the carbon material treatment.On the basis of the determination of the optimum electrochemical performance of the composite electrode synthesized using agar powder,the influence of different agar powder additions on the electrochemical performance of the material electrode was investigated.The maximum discharge of LFO@C（20%agar powder）increases from 176.7 m Ahg^-1 of the original electrode material to 328.2 m Ahg^-1.Its HRD（%）retention at a current density of 1500 m Ag^-1reaches 28.67%,which is 21.45%higher than that of the original LFO electrode material（7.22%）;The cycling stability performance at 100 cycles is also improved.The LFO@C-N electrode materials with core-shell structure were synthesized in situ by high-temperature solid-phase method using chitosan as the carbon and nitrogen sources.The effects of different chitosan additions on the electrochemical performance of the materials were investigated.The electrochemical performance of LFO@C-N（20%chitosan）is the best,and its discharge specific capacity reaches 378.5 m Ahg^-1,which is 114%higher than that of the original LFO(176.7 m Ahg^-1),its HRD（%）retention at 1500 m Ag^-1 increases from the original7.22%to 19.54%.The kinetic properties of the treated electrode material have also been improved.