What is the ternary lithium battery?

In nature, lithium element is lighter, atomic weight of the smallest metal material, its atomic number is 6.94g/mol, ρ=0.53g/cm3. Lithium compounds are cheerful and easy to lose electrons to be oxidized to Li by air. Therefore, the standard electrode potential is the most negative, which is -3.045V, and the electrochemical equivalent is the least, which is 0.26g/Ah. This characteristic of lithium depends on the fact that it is a raw material with very high energy density. Ternary lithium battery refers to the choice of nickel, cobalt and manganese three kinds of connecting hydroxide as the battery cathode material of lithium secondary battery. It fully combines the advantages of good cycle characteristics of lithium cobalt oxide battery, high specific capacity of lithium nickel oxide battery, high safety factor and low cost of lithium manganese oxide battery, and uses molecular level mixing, inclusion, covering and exterior decoration to produce multiple cooperative types of nickel, cobalt and manganese composite lithium oxide. It is a kind of lithium-ion battery which is widely used in scientific research and application.

Ternary lithium battery life

Said lithium ion battery life refers to the rechargeable battery after a period of time, capacity loss for the standard capacity (normal temperature 25℃, standard atmospheric pressure, and 0.2C discharge of the rechargeable battery capacity) 70%, you can feel life stop. In the industry, the cycle life of lithium-ion batteries is usually calculated by the cycle frequency of a full pendulum. In the process of use, irreversible electrochemical corrosion will occur inside the lithium battery, resulting in reduced capacity. For example, the decomposition of the lithium manganese acid battery, the loss of activity of the active material, and the collapse of positive and negative structures will reduce the total number of placement and detachment of the lithium ion battery. Tests show that the discharge of more polymer core will also lead to faster loss of capacity, if the discharge current is lower, the charging voltage will reach the equilibrium operating voltage, can release more kinetic energy.

The theoretical life of ternary lithium battery is about 800 cycles, which is the medium level among commercial rechargeable lithium batteries. Lithium iron phosphate is about 2,000 cycles, while lithium titanate is said to be 1,000 cycles. At the present stage, popular battery manufacturers agree on more than 500 times (charge and discharge under standard conditions) in the manufacturing of terpolymer cell instructions. However, after the lithium cell is made into a battery pack, because of the consistency problem, the working voltage and internal resistance are usually unlikely to be exactly the same, and its cycle life is about 400 times. The manufacturer strongly recommends that the SOC use dialog box is 10%~90%, and it is not recommended to carry out in-depth charging and discharging, otherwise it will lead to irreversible damage to the positive and negative structure of the battery. If calculated by shallow charging and shallow discharging, the cycle life will be at least 1000 times. In addition, if lithium-ion batteries are often discharged under polymer cells and high temperatures, the rechargeable battery life will be significantly reduced to less than 200 times.

Ternary lithium battery advantages and disadvantages

Ternary lithium battery is more balanced in capacity and safety factor, it is a comprehensive and excellent rechargeable battery. The important values and advantages and disadvantages of the three chemical elements are as follows:

Co3: Reduce the positive ion mixed mass, stabilize the layered structure of raw materials, reduce the impedance value, improve the conductivity, improve the cycle and rate performance.

Ni2: It can improve the capacity of raw materials (increase the volume energy density of raw materials), and because Li and Ni are similar to each other, too much Ni may also result in the separation of lithium and nickel due to the texture condition. The higher the concentration of nickel ions in the lithium layer, the more difficult it will be to unintercalate lithium in the layered structure, resulting in the deterioration of electrochemical performance.

Mn4: It can not only reduce the cost of raw materials, but also improve the reliability and reliability of raw materials. However, too high Mn component will easily appear apical phase and destroy the layered structure, so that the capacity is reduced, cycle loss.

High energy density is the biggest advantage of this ternary lithium batteries, the platform is an important factor to the battery energy density and voltage, basically determines the battery efficiency and costs, the greater the voltage platform, the more specific capacity, so the same volume, net weight, even as Ann when rechargeable batteries, relatively high voltage platform of ternary material lithium battery life longer. The discharge voltage platform of a single terpolymer lithium battery reaches 3.7V, while that of lithium iron phosphate is 3.2V, while that of lithium titanate is only 2.3V. Therefore, from the perspective of specific energy, terpolymer lithium battery has a great advantage over lithium iron phosphate, lithium manganese acid battery or lithium titanate.

Poor safety and short cycle life are the main weaknesses of ternary lithium battery. In particular, safety performance has been a major factor limiting its large-scale assembly and large-scale integrated application. A large number of measurements show that it is difficult for ternary batteries with large capacity to pass safety tests such as acupuncture and overcharge, which is also the reason why manganese is generally introduced into large-capacity batteries, or even mixed with lithium manganate. The cycle life of 500 times is lower than the medium of lithium battery, so the main application field of ternary lithium battery is 3C digital and other consumer electronic products.

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