From the classification of lithium batteries, understand the mainstream technology of power batteries in three minutes

"Although lithium iron phosphate is good, it is not as good as ternary batteries."
The power batteries of new energy vehicles can be divided into secondary batteries (including lead-acid batteries, nickel-cadmium batteries, nickel-metal hydride batteries, and lithium batteries) and fuel cells.

In this issue, we continue to refine it, starting with the classification of lithium batteries, and analyzing the mainstream technical routes of power batteries on the market.

working principle
First correct a concept, lithium batteries are usually divided into two categories according to the materials used in positive and negative electrodes:

Lithium metal batteries use manganese dioxide as the positive electrode material and lithium metal or its alloy metal as the negative electrode material; lithium-ion batteries use lithium alloy metal oxides as the positive electrode material and graphite as the negative electrode material.

Lithium metal batteries are not stable enough and cannot be charged, so they are not secondary batteries. For new energy vehicles, what we usually call lithium batteries refers to lithium-ion batteries.

Let's take a look at how a lithium-ion battery works:
Lithium-ion batteries are mainly composed of four parts: positive electrode (lithium-containing compound), a negative electrode (carbon material), electrolyte, and diaphragm:

When the battery is charged, the lithium atoms on the positive electrode are ionized into lithium ions and electrons (deintercalation), and the lithium ions move to the negative electrode through the electrolyte to obtain electrons, which are reduced to lithium atoms and embedded in the micropores of the carbon layer (insertion);

When the battery is discharged, the lithium atoms embedded in the carbon layer of the negative electrode lose electrons (deintercalation) to become lithium ions, which move back to the positive electrode (intercalation) through the electrolyte;

The charging and discharging process of lithium batteries, that is, the process of continuous intercalation and deintercalation of lithium ions between the positive and negative electrodes is accompanied by the intercalation and deintercalation of equivalent electrons. The higher the number of lithium ions, the higher the charge and discharge capacity.

Classification
Due to different cathode materials, lithium-ion batteries are mainly divided into: lithium iron phosphate (LFP), lithium nickelate (LNO), lithium manganate (LMO), lithium cobaltate (LCO), and ternary lithium nickel cobalt manganate (NCM) ), ternary lithium nickel cobalt aluminate (NCA), and the negative electrode material is mainly graphite carbon material.

Technical route
Based on the above table, let's take a look at the application of different types of lithium batteries in the market.

Let's talk about lithium cobalt oxide, as the originator of lithium batteries, of course, it may also be used as a power battery to test the water first, and it was first used on the Tesla Roadster, but due to its low cycle life and safety, it has been proved that it's Not suitable for use as a power battery. In order to make up for this shortcoming, Tesla uses what is known as the world's top battery management system to ensure the stability of the battery. Lithium cobalt oxide currently has a large market share in the 3C field.

The second is the lithium manganate battery, which was first proposed by the battery company AESC. This AESC is not small, it is a joint venture between Nissan and Nippon Electric Co., Ltd. (NEC). The representative model of lithium manganate is the Nissan Leaf. Due to its low price, medium energy density, and average safety, it has a so-called better overall performance. It is precise because of this tepid nature that it is gradually replaced by new technologies.

Next is lithium iron phosphate. As BYD's flagship product, it has good stability, long life, and cost advantages. It is especially suitable for plug-in hybrid vehicles that require frequent charging and discharging, but its disadvantage is that the energy density is average.

Finally, there is the ternary lithium battery. As a rising star, the energy density can reach the highest, but the safety is relatively poor. For pure electric vehicles that have requirements for cruising range, their prospects are broader, and they are the mainstream direction of power batteries at present.