As far as the development status of new energy vehicles in China is concerned, there are various kinds of batteries, including lithium iron phosphate battery, lithium ternary material battery, lithium cobalt acid, manganese acid lithium and lithium titanate battery. In these five major battery forms, the most concerned indicators in the market focus on four aspects: safety, cycle life, wide temperature tolerance, rapid charging and discharging, which actually corresponds to the core interests of users: safety red line, operation cost, operation environment adaptability and operation efficiency.
It is found by the authoritative third-party test that with the continuous innovation of lithium ion battery technology, the battery with lithium cobalt oxide, lithium manganese acid, lithium ternary and lithium iron phosphate as the system gradually fails to adapt to the real market demand, and its life, charging and discharging time, operating temperature range, safety and other aspects are far less than that of lithium titanate battery. Through the study of Li4Ti5O12, a composite oxide of lithium and titanium, it is found that it has spinel structure and is a zero-strain material, and the insertion and removal of lithium ions on the negative electrode of lithium titanate do not affect its stable structure at all, which is a characteristic that traditional lithium ion batteries do not have. The use of nanometer Li4Ti5O12 as the negative electrode material for lithium ion batteries will have unparalleled advantages compared with other lithium ion batteries.
First, higher security. The unique physical properties of lithium titanate make it safer than conventional lithium-ion batteries. The reaction activity between lithium titanate and electrolyte is low, hardly generating SEI insulation film, which improves the stability and safety of the battery. At very high temperatures, lithium titanate is able to absorb oxygen produced by the positive electrode decomposition, reducing the risk of heat loss and improving battery safety. At the same time, lithium titanate fundamentally eliminated the production of lithium dendrites, reducing the risk of internal short circuit.
Second, life expectancy is extremely long. Due to the stable structure of lithium titanate, the electrode structure can be kept stable during charging and discharging, which greatly increases the cycle life of the battery to over 25,000 times.
Again, a wide range of operating temperatures and quick charging and discharging. The lithium titanate battery has high low temperature performance and quick charging and discharging function which traditional lithium ion battery does not have. Due to the lithium titanate structure stability, the surface passivation film does not form a solid liquid interface, the dynamic performance in the low temperature still can maintain normal temperature state, have + 60 ℃ to 50 ℃ – wide range of high and low temperature the ability to charge and discharge completely. Now with graphite as the cathode of lithium ion battery can discharge around to 40 ℃ (discharge), but not in – 10 ℃ and realization of conventional current charging lower temperatures. At the same time, due to the large specific surface area of nanometer lithium titanate, the electrochemical reaction speed is fast, and it has the ability of rapid charging and discharging (it can be fully charged within 6 minutes). In addition, since there is no solid-liquid interface passivating film at the cathode, the heating effect of the battery is less when working with large current, and there is no need to add extra heat insulation and heating system.
In particular, the lithium titanate battery compared with the lithium iron phosphate battery which has the highest proportion of application on the pure electric bus, the advantage is still outstanding. In addition to a slightly lower energy density than lithium iron phosphate batteries, lithium titanate batteries outperform in safety, service life, charging time, and operating temperature range. Lithium iron phosphate batteries, for example, when heated to 160 ℃, explosion, because of the SEI insulation film, not only affect the first charge and discharge efficiency, circulation capacity loss more than 10% for the first time, and higher than 45 ℃ easy decomposition, when high temperature cycle life decay very quickly. In addition, rapid charging has a great impact on cycle life, with a life span of 5-8 years. However, lithium titanate battery has no SEI insulation film, and the initial cycle has no capacity loss, and the quick charge has little impact on the cycle life. It only takes 6 minutes, with strong thermal stability, and the cycle life can be up to 10 years.
Although the single cost of lithium titanate battery than the lithium iron phosphate battery costs higher, but in the long run, the life of the lithium titanate battery is lithium iron phosphate battery life 8-15 times, usually of lithium iron phosphate batteries used in the car, every 2-3 years will need to replace a battery, even at the same time to replace the battery recycling, using lithium titanate battery car due to its long cycle life, 10-15 years to replace a battery, operation maintenance cost is lower. And because lithium titanate battery can charge and discharge fast, on the bus application can be realized in charge, the rest of the day can take advantage of the bus arrived at the terminal drivers (10-20 minutes) to rapid repairing the electric battery, can save other material system of pure electric bus night concentrated charging, need of site construction and personnel allocation, save cost and resources, is more suitable for popularization and application on buses. And the public transportation system is the main battlefield for the promotion and application of new energy buses in China.
Therefore, lithium titanate battery is the most promising player to lead the world in China’s pure electric bus, and is the pioneer to realize the “curve overtaking” and automobile power dream of China’s new energy vehicles. And the top scientific and technological forces can push the new energy industry of China and even the whole world forward greatly.