Study On The Performance And Synthesis Of Li₄Ti₅O₁₂

In this paper, basing on studying of lithium-ion battery cathode material LiTi5O12,we researched one or two metal substituents in Li4Ti5O12. The crystal structure and surface of material was described by x-ray diffraction and scanning electron microscope,and the electrochemical properties was tested by galvanostatic charge-discharge, electrochemical impedance spectroscopy and cyclic voltammetry.We prepared Li4Ti5O12 by high energy ball milling and high temperature solid state method.The phase analysis showed:the crystal structure of the characteristic peak matched with the standard spinel Li4Ti5O12 spinel (JCPDS card number 72-0426), the samples were synthesized with Fd-3m structure, the sample size was uniform and the crystal particles distribution was also uniform;The electrochemical tests showed:the initial discharge capacity of Li4Ti5O12 by high energy ball milling significantly was higher than by high temperature solid state method, its initial specific discharge capacity of 0.5 C was 149.95 mAh·g-1, the specific discharge capacity at the 50th cycle was 121.52 mAh·g-1. We researched the high-rate discharge tests of spinel Li4Ti5O12 which prepared by high energy ball milling, the electrochemical tests showed:with increasing the discharge rates,the discharge capacity and discharge platform ladder were reduced;We researched Al3+, Mg2+ monobasic doping and Al3+, Mg2+ dibasic doping which prepared by high energy ball milling method. The results showed:Al3+ monobasic doping, the sample Li3.90Al0.10Al0.10Ti5O12 (x=0.10) had better electrochemical performance, its initial specific discharge capacity of 0.5 C was 162.21 mAh·g-1,the discharge platform was flat,the specific discharge capacity at the 50th cycle was 151.91 mAh·g-1, the capacity retention rate was 93.65%; Mg2+ monobasic doping, the sample Li3.9oMgo.Li3.90Mg0.10Ti5O12 (x=0.10) had better electrochemical performance, its initial specific discharge capacity of 0.5 C was 165.10 mAh·g-1,the discharge platform was flat, the specific discharge capacity at the 50th cycle was 143.13 mAh·g-1, the capacity retention rate was 85.70%; Al3+, Mg2+ dibasic doping, Al3+, Mg2+ did not significantly affect the discharge platform of Li4Ti5O12 as cathode material for lithium-ion battery, the material did not significantly improve cycling performance, Al3+, Mg2+ dibasic doping resulted in lower capacity may be decrease reversible Li+.We researched Sn4+, Ni4+ monobasic doping and Sn4+, Ni4+dibasic doping which prepared by high temperature solid state method. The results showed:Sn4+ monobasic doping, the sample ST2(Sn:Ti=1:9) had better electrochemical performance, its initial specific discharge capacity of 0.5 C was 138.69 mAh·g-1, the discharge platform was flat around the voltage of 2.42 V,the specific discharge capacity at the 50th cycle was 124.30 mAh·g-1, the capacity retention rate was 89.62%; Ni4+ monobasic doping,the sample NT2(Ni:Ti=1:9) had better electrochemical performance, its initial specific discharge capacity of 0.5 C was 139.49 mAh·g-1, the discharge platform was flat around the voltage of 2.32 V,the specific discharge capacity at the 50th cycle was 126.68 mAh·g-1, the capacity retention rate was 90.82%; Sn4+, Ni4+ dibasic doping, it reduced LiTi5O12 as cathode material for lithium-ion battery discharge voltage platform and improved the cycling performance with increasing Ni4+ doping.