Preparation And Investigation On The Properties Of Li₄Ti₅O₁₂ Anode Materials For Lithium-ion Batteries

In recent years, the environment pollution and energy shortage problems resulting from the overuse of fossil fuels are becoming the main obstacle of sustainable development of human.For this reason, people developed a variety of new energy and energy storage devices. Lithium ion battery is believed to be the most promising energy storage equipment, which has high working voltage, high energy density, long cycle life, excellent safety performance and lots of other advantages.The main active materials of modern commercial lithium ion batteries are graphite carbon, which are cheap and easy to processing.However, the intercalation potential of graphite anode is close to 0 V vs. Li+/Li, so when overcharge or quick charge it will easily produce lithium dendrite and cause short circuit. The latest spinel lithium titanate anode known as "zero strain" material has a high intercalation potential of 1.55 V, which is free from lithium dendrite and has minimal volume change when charging and discharging.But its low electrical conductivity, less than 10"13 s·cm-1, limits its rate performance.Thus, improving the conductivity of Li4Ti5O12 is the main job to improve its performance.First we synthesized Li4Ti5O12 nanoparticles through the traditional solid-state reaction.Different kinds of carbon source including glucose and urea were discussed on the influence of its structure, morphology and electrochemical performance.We found it had remarkable performance improvement with urea as carbon source of Li4Ti5O12.Furthermore, we first synthesized amorphous TiO2 precursor by the hydrolysis of tetrabutyl titanate, then combining with Li source LiOH·H2O and adjusting the dosage of the precursor and processing temperature, we successfully made Li4Ti5O12 nanomaterials in the Ar/H2 mixed atmosphere.The sample that was preparedunder the most appropriate dosage of precursors and processing temperatureshowed the best electrochemical performance. It was able to deliver a reversible capacity of 143.2 mAh·g-1 in 5 C after 500 charge and discharge, and even in a rate as high as 20 C it still had a reversible capacity of 123.2 mAh·g-1.