Synthesis And Modification Of Anode Material Li₄Ti₅O₁₂ For Lithium-ion Batteries

Lithium-ion batteries with high power and high energy density are one of thepromising power sources for electric device, especially for electric vehicles(EV) and otherportable electric devices. One of the challenges is to improve the safety andelectrochemical performance of lithium ion battery anode materials. Li4Ti5O12has beenaccepted as a novel anode material of power lithium ion battery instead of carbon becauseit can release lithium ions repeatedly for recharging and quickly for high current, and it hasno structural change in the charge-discharge process, and it offers a stable operatingvoltage of approximately1.55V versus Li+. So it attracts many people’s interests.Anode material Li4Ti5O12were prepared by sol-gel method in this paper, and modifiedits performance by metal ions doped. The materials were systematic studied by X-rayDiffraction(XRD)、Scan electron microscope(SEM) and constant current charge-dischargetest. Experiment results indicated that the raw materials Li/Ti, calcination temperature andreaction time played an important role in the structure and the electrochemicalperformances. Li4Ti5O12prepared by sol-gel method has been optimized. The effects ofdopant on the structure and electrochemical properties of spinel-type Li4Ti5-xCoxO12（x=0.06, x=0.12, x=0.18, x=0.24）and Li4Ti5-xMnxO12（x=0.07, x=0.14, x=0.21, x=0.28）were systematically investigated. The main results are listed as follows:(1) Anode material Li4Ti5O12for lithium-ion battery was prepared by sol-gel methodusing tetrabutyl titanate and lithium acetate as starting materials. It shows that theoptimized condition for sol-gel method was: The content of lithium was4wt%werecalcinated at800℃for12h. The prepared sample at this developed condition have a purephase, no impurity peaks with narrow size distribution, about100nm, well crystallizationand the grain well-distributed. The first discharge/charge curves of samples was152.1mA·h·g-1, and after50cycles the capacity retention was98.4%at1C. The firstdischarge/charge curves of samples was73.9mA·h·g-1, and after50cycles the capacityretention was90.3%at10C.(2) Synthesis of Li4Ti5-xCoxO12and Li4Ti5-xMnxO12.Research have shown that for Li4Ti5-xCoxO12: Co-doped samples with0.06≤x≤0.24dose almost not affect the lattice parameter of Li4Ti5O12. Doping treatment hassignificantly suppressed crystal growth, but appeared a phenomenon of agglomeration. Theconstant current charge-discharge test shows that the first discharge/charge curves of theCo-doped samples was lower than no-doped, but not influenced the cycle performance of the sample. Co-doped could make the electrochemistry result change regularly, whichwas enhance the content of the Co, the first discharge/charge curves of samples was alsoimproved.Research have shown that for Li4Ti5-xMnxO12: Co-doped samples show pure spinelphase with0.07≤x≤0.28. Doping treatment has significantly suppressed crystal growth. Butappeared a phenomenon of agglomeration. The constant current charge-discharge testshows that the first discharge/charge curves of the Mn-doped samples was lower thanno-doped. Mn-doped could not make the electrochemistry result changing regularly.