Lithium titanate(LTO) battery is a kind of lithium titanate used as negative electrode material of lithium ion battery, which can be combined with positive electrode materials such as lithium manganate, ternary material or lithium iron phosphate to form a 2.4V or 1.9V lithium ion secondary battery. In addition, it can also be used as a positive electrode to form a 1.5V lithium secondary battery with metal lithium or lithium alloy negative electrode. Lithium titanate has the characteristics of high safety, high stability, long life and environmental protection.
Lithium titanate (LTO) is used as a negative electrode material in batteries. Due to its own characteristics, the interaction between LTO and electrolyte is easy to occur and gas is precipitated in the process of charge-discharge cycle reaction. Therefore, the common lithium titanate battery is easy to inflate, which leads to the battery core bulging and greatly reduces the electrical performance, which greatly reduces the theoretical cycle life of lithium titanate battery. Test data show that the common lithium titanate battery will inflate after about 1 500-2 000 cycles, which leads to the failure of normal use, which is also an important reason that restricts the large-scale application of lithium titanate battery.
The performance improvement of lithium titanate (LTO) battery is the comprehensive embodiment of the performance improvement of single material and the organic integration of key materials. According to the requirements of fast charging and long service life, besides negative electrode materials, other key raw materials (including positive electrode materials, separators and electrolytes) of lithium ion batteries were also targeted, and at the same time, combined with special engineering process experience, a "non-flatting" lithium titanate LpTO battery product was finally formed, which was first applied in batch on electric buses.
The test data show that the cycle life of lithium titanate LpTO single battery exceeds 25 000 times and the remaining capacity exceeds 80% under the conditions of charging at 6C, discharging at 6C and 100%DOD, and the inflation phenomenon of the battery core is not obvious, which does not affect its life. The actual application of Chongqing fast charging pure electric bus also shows that after the batteries are grouped, the electrical performance is quite excellent, which can ensure the daily commercial operation of pure electric bus.
Advantages
Replacing fuel vehicles with electric vehicles is the best choice to solve urban environmental pollution, among which lithium-ion power batteries have attracted wide attention of researchers. In order to meet the requirements of electric vehicles for on-board ion power batteries, developing anode materials with high safety, good rate performance and long life is a hot and difficult point. Commercial lithium ion battery cathode mainly uses carbon material, but lithium battery with carbon as cathode still has some disadvantages in application:
1. Lithium dendrites are easily precipitated during overcharge, which causes short circuit of the battery and affects the safety performance of lithium batteries;
2. It is easy to form SEI film, which leads to low first charge and discharge efficiency and large irreversible capacity;
3. The platform voltage of carbon material is low (close to lithium metal), and it is easy to cause decomposition of electrolyte, which brings potential safety hazards.
4. In the process of lithium ion intercalation and deintercalation, the volume changes greatly and the cycle stability is poor.
Compared with carbon materials, spinel Li4Ti5O12 has obvious advantages:
1. It is a zero strain material with good cycle performance;
2. The discharge voltage is stable, and the electrolyte does not decompose, which improves the safety performance of lithium batteries;
3. Compared with carbon cathode materials, lithium titanate has a high lithium ion diffusion coefficient (2 *10-8cm2/s), and can be charged and discharged at a high rate.
4. The potential of lithium titanate is higher than that of pure metal lithium, so it is difficult to produce lithium dendrites, which provides a basis for ensuring the safety of lithium batteries.
Disadvantages
1. Compared with other types of lithium-ion power batteries, the energy density will be lower.
2. The problem of flatulence has always hindered the application of lithium titanate battery.
3. Compared with other types of lithium-ion power batteries, the price is higher.
4. There are still differences in battery consistency, which will gradually increase with the increase of charge and discharge times.
