What are the basic materials required for lithium-ion batteries.

Lithium ion batteries require several basic materials: positively charged active materials, negatively charged active materials, isolation membranes, and electrolytes. Now, let me give you a quick overview of what these materials are used for?

Understanding the positive and negative electrodes is not difficult. In order to achieve the movement of charges, you need the potential difference between the positive and negative electrode materials. So, what is an active material? We know that batteries actually convert electrical energy and chemical energy into each other to store and release energy. To achieve this, you need a material that is "easy" to react with, a material that is easily oxidized and reduced, and a material that can convert energy. Therefore, we need an "active material" to make the positive and negative electrodes of the battery.

As mentioned above, lithium is our preferred material for producing batteries, so why not use metallic lithium as the active material for electrodes? Isn't this the maximum energy density?

What is the purpose of electrolytes? Simply put, it is the "water" in the swimming pool that allows lithium ions to swim freely, so the higher the ion conductivity, the lower the resistance to swimming, the lower the electronic conductivity insulation, the better the chemical stability, the better the thermal stability and safety, giving people a broad potential window. Based on these principles, after a long period of engineering exploration, high-purity organic solvents, lithium electrolyte salts, and necessary additives have been discovered. Under certain conditions, electrolytes can be prepared in certain proportions. Organic solvents include PC propylene carbonate, EC ethylene carbonate, DMC dimethyl carbonate, DEC diethyl carbonate, EMC ethyl ester, and other materials. Lithium electrolyte contains substances such as LiPF6 and LiBF4.

The metallic form of lithium element is too "lively", and most mischievous children are disobedient and enjoy causing damage. Early research on lithium-ion batteries mainly focused on metallic lithium or its alloys as negative electrodes, but for safety reasons, they had to seek better alternatives. In recent years, with the pursuit of energy density, there has been a trend of "whole blood resurrection" in this research direction, which we will discuss later.

In order to achieve chemical stability in energy storage and release processes, that is, the safety and longevity of battery charging and discharging cycles, we need an electrode material that is reactive when needed and stable when needed. After long-term research and exploration, several lithium metal oxides have been discovered, such as lithium cobalt oxide, lithium titanate, lithium iron phosphate, lithium manganese oxide, nickel cobalt manganese ternary materials, etc., as positive or negative electrodes for battery active materials, solving the above problems. As shown in the figure, the olivine structure of lithium iron phosphate is also a very stable positive electrode material structure. During the charging and discharging process, lithium ions are stripped off without causing lattice collapse. In addition, there are also metal lithium batteries, but they are insignificant compared to lithium-ion batteries, and the development of technology ultimately needs to serve the market.

Of course, while solving stability issues, it also brings serious "side effects", namely a significant decrease in the proportion of lithium as an energy carrier and a decrease in energy density by a majority of orders of magnitude.
The negative electrode usually chooses graphite or other carbon materials as the active material, which also conforms to the above principles. The requirement is a good energy carrier, relatively stable, with relatively abundant reserves, and easy for large-scale production. Carbon element is a relatively optimal solution. Of course, this is not the only solution, and negative materials have been extensively studied in the next commentary.