1 High nickel ternary material

　　Generally speaking, a high-nickel ternary cathode material means that the mole fraction of nickel in the material is greater than 0.6. Such a ternary material has the characteristics of high specific capacity and low cost, but also has low capacity retention and poor thermal stability. defect.

　　Inventory: Top 10 research developments of ternary materials for lithium batteries

　　The material properties can be effectively improved through the improvement of the preparation process. The micro-nano size and morphological structure of the particles largely determine the performance of the high nickel ternary cathode material. Therefore, the current main preparation method is to uniformly disperse different raw materials and obtain nano spherical particles with a large specific surface area through different growth mechanisms.

　　Among the many preparation methods, the combination of co-precipitation method and high-temperature solid phase method is the current mainstream method. First, the co-precipitation method is used to obtain a precursor with uniform raw materials and uniform particle size, and then after high-temperature calcination to obtain a regular surface morphology, Ternary materials with easy-to-control processes are currently the main method of industrial production.

　　The spray drying method is simpler than the co-precipitation method, and the preparation speed is faster. The morphology of the obtained material is no less than that of the co-precipitation method, which has the potential for further research. The shortcomings of high nickel ternary cathode materials, such as cation mixing and phase change during charge and discharge, can be effectively improved through doping modification and coating modification. While suppressing the occurrence of side reactions and stabilizing the structure, improving the conductivity, cycle performance, rate performance, storage performance, and high temperature and high pressure performance will still be a research hotspot.

　　2 Lithium-rich ternary materials

　　The figure below is a schematic diagram of the lithium-rich ternary cathode material xLi2MnO3˙(1-x)LiMn1/3Ni1/3Co1/3O2(0.1≤x≤0.5). Due to its special structure, more lithium can be extracted and it has a wide voltage The advantages of window and high specific volume have been favored by researchers in recent years.

　　All of this material has the characteristics of high voltage, and the first charging and discharging mechanism is different from the subsequent charging: the first charging will cause structural changes, and this change is reflected in the charging curve with two different platforms with 4.4V as the boundary. During the second charging process, the charging curve is different from the first time because Li2O is irreversibly released from the layered Li2MnO3 during the first charging process, and the plateau at about 4.5V disappears.

　　Lithium-rich ternary cathode materials with different structures can be prepared by solid phase method, sol-gel method, hydrothermal method, spray pyrolysis method, and co-precipitation method. Among them, the co-precipitation method is more commonly used, and each Each method has its own advantages and disadvantages.

　　Inventory: Top 10 research developments of ternary materials for lithium batteries

　　Li-rich ternary materials have shown good application prospects and are one of the key materials required for the next generation of high-capacity lithium-ion batteries, but for large-scale applications.

　　The future research directions of this material are mainly the following aspects:

　　(1) Insufficient understanding of the mechanism of deintercalation of lithium cannot explain the low coulombic efficiency of materials and large differences in material properties;

　　(2) The research on doping elements is not sufficient and relatively single;

　　(3) The cathode material is corroded by the electrolyte under high voltage, resulting in poor cycle stability;

　　(4) There are few commercial applications, and the safety performance is not comprehensive enough.

　　3 single crystal ternary cathode material

　　Under high voltage, with the increase of the number of cycles of lithium battery ternary materials, the secondary particles or agglomerated single crystals may be powdered at the interface of the primary particles or separated in the agglomerated single crystals, causing the internal resistance to increase and the battery capacity Fast decay and poor circulation.

　　Single crystal type high voltage ternary material can improve the efficiency of lithium ion transfer, while reducing the side reaction between the material and the electrolyte, thereby improving the cycle performance of the material under high voltage. First, the ternary material precursor was prepared by the co-precipitation method, and then under the action of the high temperature solid phase, single crystal LiNi0.5Co0.2Mn0.3O2 was obtained.

　　This material has a good layered structure. Under 3～4.4V, the 0.1 discharge specific capacity of the button battery can reach 186.7mAh/g, and the discharge specific capacity of the full battery after 1300 cycles is still 98% of the initial discharge capacity. , Is a ternary cathode composite material with excellent electrochemical performance.

　　Xinzheng Lithium uses a unique preparation process to design and assemble an advanced lithium-ion battery cathode material production line. It is the first large-scale production of micron-sized single crystal particles of modified spinel lithium manganate and nickel cobalt manganese acid in the world. Lithium ternary cathode materials have reached an annual production capacity of 500 tons.

　　Inventory: Top 10 research developments of ternary materials for lithium batteries

　　Graphene has a two-dimensional structure with a single layer of atomic thickness, stable structure, and electrical conductivity of up to 1×106S/m. Graphene has the following advantages when used in lithium-ion batteries: ①Good electrical and thermal conductivity, which helps to improve the rate performance and safety of the battery; ②Compared with graphite, graphene has more lithium storage space, which can increase the energy density of the battery; ③The particle size is on the order of micro-nano, and the diffusion path of lithium ions is short, which is beneficial to improve the power performance of the battery.

　　The 　　JAN research group used the grinding method to first mix graphene and 811 ternary materials, then stir at 50°C for 8 hours, and then dry to obtain graphene/811 composite materials. Due to the modification effect of graphene, the capacity, cycle stability and rate performance of the positive electrode material have been significantly improved.

　　Wang added graphene when preparing the ternary precursor by the precipitation method. The addition of the lamellar graphene to its cavity structure reduces the agglomeration of primary particles and relieves the external pressure to reduce the crushing of the secondary particles. The three-dimensional conductivity of graphene The network improves the material's high rate and cycle performance.

　　Inventory: Top 10 research developments of ternary materials for lithium batteries

　　5 high voltage electrolyte

　　Ternary materials have received more and more attention and research due to their high voltage windows. However, due to the low electrochemical stability window of current commercial carbonate-based electrolytes, high-voltage cathode materials have not yet been industrialized.

　　When the battery voltage reaches about 4.5 (vs.Li/Li+), the electrolyte will begin to undergo violent oxidation and decomposition, causing the battery's lithium intercalation and desorption reaction to fail to proceed normally. Improving the stability of the electrode/electrolyte interface through the development and application of new high-pressure electrolyte systems or high-pressure film-forming additives is an effective way to develop high-voltage electrolytes.

　　Inventory: Top 10 research developments of ternary materials for lithium batteries