NASICON Li_1.3Al_0.3Ti_1.7?PO₄?₃ Soild Electrolyte And Its Research In The Positive Electrode Of Lithium Ion Battery

This thesis mainly focuses on NASICON Li1.3Al0.3Ti1.7(PO4)3(LATP)solid electrolyte.We synthesized LATP by wet chemical method and explored its research for the positive electrode of lithium ion battery.The main work is as follows:(1)The LATP solid electrolyte ceramic sheet with high density and ionic conductivity was prepared by wet chemical method.Compared with undoped LiTi2(PO4)3(LTP),Al3+doping will reduce the ionic conductivity from 10-6 S/cm increased to 10-4 S/cm.Diffusion activation energy calculation results indicate that the synthesized LATP diffusion activation energy is small(0.23 eV).(2)The surface of LiNi0.8Co0.1Mn0.1O2(NCM811)is uniformly coated with LATP solid electrolyte by rotary evaporation.The LATP coating can reduce the side reaction between NCM811 and the electrolyte,and it is beneficial for the transport of Li+in the coating.Therefore,the cycle stability of NCM811 is effectively improved,and the capacity retention rate can reach 83.7%(unmodified:77.3%)after 100 cycles of electrochemical charge and discharge at 1 C rate.(3)For the first time,the lithium storage performance of LATP solid electrolyte as a cathode material for lithium ion batteries was studied.The reversible specific capacity of this positive electrode material depends on the solid electrolyte ion conductivity.The reversible specific capacities of LTP and LATP(at 5 C rate)are:84.0 mAh/g and 116.5 mAh/g,respectively;Due to the high ionic conductivity,the positive electrode material can obtain excellent rate performance.After 1000 cycles of electrochemical charge and discharge at 5 C,10 C and 20 C rates,the capacity retention rate of the positive electrode material is 97.4%,95.1%and 94.6% respectively.