Lithium-ion batteries (LiBs) provide power for electric vehicles (EVs), and the anode plays a crucial role in their performance. Graphite materials, with excellent conductivity, thermal stability, and high performance, are the primary anode materials for lithium-ion batteries.
Graphite has become the earliest commercialized negative electrode material for lithium-ion batteries due to its advantages such as high electronic conductivity, large lithium ion diffusion coefficient, small volume change before and after lithium insertion in its layered structure, high lithium insertion capacity (theoretical capacity can reach 372mA·h/g), and low lithium insertion potential.
Analysis of parameters, advantages and disadvantages of lithium manganese oxide batteries
Lithium iron phosphate battery refers to a lithium-ion battery that uses lithium iron phosphate as the positive electrode material. The positive electrode materials of lithium-ion batteries mainly include lithium cobalt oxide, lithium manganese oxide, lithium nickel oxide, ternary materials, lithium iron phosphate, etc. Among them, lithium cobalt oxide is the positive electrode material used by most lithium-ion batteries at present. From the principle of materials, lithium iron phosphate is also an embedding and de-embedding process, and this principle is exactly the same as that of lithium cobalt oxide and lithium manganese oxide.
Ternary lithium battery classification
Ternary lithium batteries, that is, lithium batteries that use nickel cobalt manganese oxide (NCM) or nickel cobalt aluminum oxide (NCA) as the positive electrode material, have various classification methods according to different classification standards.
Introduction to Lithium-ion Batteries (LIB)
Lithium-ion batteries are mainly composed of four parts: positive electrode materials, negative electrode materials, separators, and electrolytes. The positive electrode materials must participate in chemical reactions and also provide Li+ as a lithium ion source; the negative electrode materials are also an important component of the battery, generally carbon, lithium titanate, and silicon-based alloy materials; the main function of the separator is to prevent the positive and negative electrode materials from directly contacting each other and causing a short circuit, and it is generally a porous membrane material such as polyethylene or polypropylene; the role of the electrolyte is to provide a channel for the transmission of lithium ions and promote the reversible reaction of the electrode. It is mainly composed of electrolyte lithium salts, non-aqueous organic solvents, and necessary additives.
Figure 1. Applications of lithium-ion batteries
Lithium cobalt oxide is the first commercialized cathode material for lithium-ion batteries. Its theoretical gram capacity after complete delithiation is 274 mAh/g, its true density is as high as 5.1 g/cm 3 , and its actual compacted density can reach 4.2 g/cm 3. It has an extremely high volume energy density (the advantage is prominent under high voltage) and is still the most widely used cathode material for consumer batteries.In fact, lithium cobalt oxide has three crystal structures, namely high-temperature phase HT- LiCo O 2 , low-temperature phase LT - LiCo O 2 , and rock salt phase LiCo O 2. Among them, the synthesis temperature of low-temperature phase lithium cobalt oxide is relatively low, and the crystal structure characteristics are between the layered structure and the spinel structure. The Li layer contains about 25% Co atoms, and the Co layer contains about 25% Li atoms. The bulk density is low and the electrochemical performance is poor. It is rarely used as a commercial positive electrode material. The structure of rock salt phase lithium cobalt oxide is highly disordered, and Li and Co are randomly arranged inside the crystal without obvious rules.
The formation process is an indispensable step in the manufacturing of lithium-ion batteries, as it directly affects the battery’s performan...
