Is the ternary lithium battery 523 and 811 theoretically the same as the energy?

Is the ternary 523811 theory the same as energy?

What is the relationship between the theoretical capacity of different proportions of ternary cathode materials and nickel content?

The calculation of the capacity of the theoretical ternary material is as follows for the mass fraction calculation of each ternary material.

Theoretical gram capacity calculation of ternary 523 (LiNi0.5Co0.2Mn0.3O2)

The relative mass fraction of ternary 523 is 96.5545g/mol

The amount of 1g ternary 523 substances:

1g÷96.5545g/mol=0.01035685mol

The amount of charge provided by 1g of ternary 523:

0.01035685mol×96485.3383C/mol=999.284176C

Conversion unit: 999.284176C÷3.6C=277.58mAh

Then the theoretical gram capacity is about 280mAh/g

Theoretical gram capacity calculation of ternary 811 (LiNi0.8Co0.1Mn0.1O2)

The relative mass fraction of NiCoMn is similar, so theoretically the theoretical gram capacities of 523 and 811 are similar.

Theoretical and actual gram capacity

So the question is, why do 811 have a higher gram capacity than 523 when the ternary material theory has the same gram capacity?

The original capacity is related to the total content of nickel and cobalt. More specifically, since the cobalt content is generally less than 0.2 or 0.3, the most directly related is the nickel content, because nickel is in the ternary material. The valence state exhibits two valence states of +2 and +3. When lithium ions are released, the transition metal nickel undergoes a price change to achieve a charge balance. It is precisely because of this multivalent state of Ni that it can change from +2 to +3, and then from +3 to +4, so the higher the nickel content, the more lithium ions can be extracted.

In terms of energy level distribution, when the nickel content is high, the energy level of the 3D electrons in the outer layer of the transition metal and the 2P orbital overlap of the oxygen element are large, so that more lithium ions can be extracted and the capacity is higher!

The capacity of the ternary material will increase with the increase of the cut-off voltage. For example, if your voltage range is in the range of 3.0-4.2V, the amount of lithium ion elution in the ternary material is about 0.45-0.55 mol. If you increase the discharge voltage to 4.5V, the amount of lithium ions that are eluted may reach 0.60mol, and the capacity of the material is strongly related to the amount of lithium ion leaching. Therefore, the more lithium ions are removed from the positive electrode, the larger the gram capacity of the positive electrode material is, and the more capacity is released per unit mass of material, and the capacity of the battery is increased.

Sun and other team members used a half-cell (Li as the negative electrode) at different conditions of Ni, Co, and Mn at 3~4.3V, 25°C, 20mA/g (0.1C), Specific capacity of Li[NixCoyMnz]O2 (x=1/3, 0.5, 0.6, 0.7, 0.8, and 0.85). The results show that as the Ni content increases, the specific capacity increases, and the test results are as follows.

With the increasing demand for high specific energy batteries in the domestic market, it is necessary for major battery manufacturers and material manufacturers to accelerate the industrialization of high nickel materials. For practitioners, the correct understanding and deep understanding of the mechanism and application of high-nickel ternary is the first step to making competitive products.

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