Lithium titanium battery technology explained

Lithium titanate battery is a kind of lithium titanate, which is used as the cathode material of lithium ion battery. It can be composed of 2.4V or 1.9V lithium ion secondary battery with lithium manganate, ternary material or lithium iron phosphate and other cathode materials. In addition, it can also be used as a positive electrode, with lithium metal or lithium alloy negative electrode to form a 1.5V lithium secondary battery. Due to the high safety, high stability, long life and green characteristics of lithium titanate.

Composition of lithium titanate battery

Anode: lithium iron phosphate, lithium manganate or ternary materials, lithium nickel manganate.

Negative electrode: lithium titanate material.

Diaphragm: A lithium battery diaphragm with carbon as the negative electrode.

Electrolyte: lithium battery electrolyte with carbon as the negative electrode.

Battery case: Lithium battery case with carbon as the negative electrode.

Characteristics of lithium titanium battery

Lithium titanate (LTO) material is used as negative electrode material in batteries. Due to its own characteristics, the interaction between materials and electrolyte is easy to occur and gas precipitation is generated in the process of charging and discharging cycle reaction. Therefore, ordinary lithium titanate batteries are prone to gas expansion, leading to bulge in the battery core and a significant decline in electrical performance. The theoretical cycle life of lithium titanate battery is greatly reduced. The test data show that the ordinary lithium titanate battery will produce gas phenomenon after about 1 500-2 000 cycles, leading to the normal use, which is also an important reason to restrict the large-scale application of lithium titanate battery.

The performance improvement of lithium titanate (LTO) battery is a comprehensive reflection of the performance improvement of individual materials and the organic integration of key materials. To the need of fast charging and long service life, in addition to the anode materials, and other key raw materials for lithium ion batteries (including anode materials, diaphragm, and electrolyte), at the same time, combining with the engineering technology of special experience, finally formed a "no bilge gas" lithium titanate LpTO battery products, and realized the first batch of application on the electric bus.

The test data show that under the condition of 6C charge, 6C discharge, 100%DOD, the cycle life of lithium titanate LpTO single battery is more than 25 000 times, the residual capacity is more than 80%, and the gas swelling phenomenon produced by the cell is not obvious, does not affect its life; The practical application of Chongqing fast-charging pure electric bus also shows that after battery grouping, the electric performance is also quite excellent, which can ensure the daily commercial operation of pure electric bus.

Advantages of lithium titanate battery

Lithium titanate battery has the characteristics of small size, light weight, high energy density, good sealing performance, no leakage, no memory effect, low self-discharge rate, rapid charge and discharge, long cycle life, wide working environment temperature range, safe and stable green environmental protection, so it has a very wide application prospect in the field of communication power supply.

As an anode material, lithium titanate has a potential plateau of 1.55V, more than 1V higher than conventional graphite anode material, which means that the battery is safer despite some loss of energy density. Technical expert Lu Blu-ray has said that the battery fast charging of the negative voltage demand is relatively low, but if it is too low, lithium battery is easy to precipitate very active lithium metal, this lithium ion is not only conductive, but also can react with electrolyte, and then release heat, produce combustible gas, fire. Because of the high voltage of 1V to avoid the negative voltage of 0, lithium titanate indirectly avoids the precipitation of lithium ions, so as to ensure the safety of the battery.

Because lithium titanate battery can be safely used in high temperature and low temperature environment, it also reflects its important advantage of wide temperature resistance (especially low temperature resistance). At present, the safe operating temperature area of Yinlong lithium titanate battery is between -50 degrees and 65 degrees, while the ordinary graphite negative battery starts to decay when the temperature is below -20 degrees, and the charging capacity is only 14% of the total charging capacity when the temperature is -30 degrees, which can not work properly in cold weather. 

In addition, lithium titanate batteries are known as zero-strain materials because they have only a 1% change in volume even when overcharged, giving them an extremely long life. Wei Yincang, chairman of Yinlong, once said that the life of Yinlong lithium titanate battery can reach 30 years, which is comparable to the service life of a car, while the average life of ordinary graphite anode battery is only 3-4 years. In terms of life cycle, lithium titanate battery cost is lower.

The final advantage of lithium titanate is the fast charge and discharge ability, high charge rate. At present, the charging rate of Yinlong lithium titanate battery is 10C or even 20C, while the charging rate of ordinary graphite anode material is only 2C-4C. Based on these technical characteristics of lithium titanate battery, the industry believes that it meets the needs of new energy buses and large energy storage equipment.

Disadvantages of lithium titanate batteries

Although the excellent safety performance makes the research of lithium ion titanate battery become a hot spot, the low electronic conductivity (10-13s /cm) and lithium ion diffusion coefficient (10-10~10-13cm2/S) of Li4Ti5O12 material itself greatly limit the application of charging and lowering at large magnification. Some scholars have shown that the nanoparticle size of Li4Ti5O12 can expand the effective reaction area and reduce the diffusion distance, thus significantly improving the magnification performance of the material. However, it should be pointed out that the process of nano-sized material particles is often difficult and requires high cost, so it is difficult to achieve large-scale industrial production at present.

Lithium titanate battery in the cycle will occur continuous gas production, leading to battery pack swelling, especially serious at high temperature, affect the contact between positive and negative electrodes, increase the battery impedance, affect the performance of the battery. This is also one of the main obstacles limiting the wide application of lithium titanate as an anode material in batteries.