Overview of ternary lithium battery
There are many kinds of cathode materials for lithium-ion batteries. According to the different cathode materials, they can be divided into lithium cobalt oxide, lithium manganate, ternary materials, lithium iron phosphate and lithium titanate. Ternary lithium battery refers to a lithium battery that uses three transition metal oxides of nickel, cobalt, and manganese as the cathode material. Because it combines the advantages of lithium cobalt oxide, lithium nickelate and lithium manganate, its performance is better than the above Any single component cathode material. Experimental analysis shows that three elements with different valences form a superlattice structure, and there is an obvious synergistic effect between the three components, which makes the material more stable, and the discharge platform is as high as 3.6V, so it is considered to be the most promising application. One of the cathode materials. Ternary batteries have excellent electrochemical characteristics such as high energy density, good safety and stability, support for high-rate discharge, and affordable cost advantages. They are obtained in the field of small and medium-sized lithium batteries such as consumer digital electronic products, industrial equipment, and medical instruments. It has been widely used and has shown strong development potential in the field of power lithium batteries such as intelligent robots, AGV logistics vehicles, drones and new energy vehicles.
The current research on ternary materials mainly focuses on the preparation of precursors, the synthesis of materials, and the relationship between electrochemical properties and structure. Most of the transition metal elements Ni, Co, and Mn in the material exist in +2, +3, and +4 valence states, respectively. During the charging and discharging process, only Ni2+/Ni4+ and Co3+/Co4+ occur electrochemical reactions, while Mn basically does not Participating in electrochemical reactions only serves to stabilize the structure of the material. Regarding the preparation method, the synthetic methods commonly used in industry are: high temperature solid phase method, co-precipitation method, sol-gel method, hydrothermal synthesis method, combustion method, etc. Ternary material is a lithium battery cathode material with excellent comprehensive performance. Change the molar ratio of the three materials within a certain range, and add the corresponding additives (binder, conductive agent, current collector, etc.) to obtain On the one hand, it has outstanding performance characteristics, such as power ternary lithium battery, capacity ternary lithium battery, ultra-low temperature ternary lithium battery and so on.
Ternary polymer lithium battery
Ternary polymer lithium battery refers to a lithium battery that uses lithium nickel cobalt manganate (Li (NiCoMn) O2) as the positive electrode material and uses a gel polymer electrolyte. As the transmission medium of ion movement, electrolyte is generally composed of solvent and lithium salt. The electrolyte of lithium secondary battery mainly includes liquid electrolyte, ionic liquid electrolyte, solid polymer electrolyte and gel polymer electrolyte. Gel polymer electrolyte is composed of polymer, organic solvent and lithium salt, and is prepared by mixing organic electrolyte with solid polymer matrix. Because it exists in the form of gel, it has the advantages of both solid electrolyte and liquid electrolyte. Since the electrolyte is confined in the polymer chain, it also has higher ionic conductivity (up to 10%) in a wide temperature range. -3S/cm). Its biggest advantage is the high mechanical strength of the diaphragm, and the film provides a large surface area. The thinner the film, the higher the energy density, because more active materials can be embedded in the battery. In addition, its electrochemical stability is also very good, high temperature resistance, most high-temperature batteries on the market use polymer electrolytes.
Ternary power lithium battery
The so-called power battery means that the battery supports high-rate and high-current discharge, high power density, and releases more energy per unit time. The rate-discharge capability refers to the ability to maintain the battery capacity when the charge-discharge rate increases. The rate of charge and discharge is represented by xC. 1C means that the nominal capacity of the battery can be used up in 1h, while the rate of discharge at 2C can be used for 30min.
The power/rate performance of a battery is closely related to the design of the battery and is affected by many factors, such as electrolyte, separator, type of active material, size of active particles, and so on. Among these factors, the thickness of the electrode is the main factor affecting the large current discharge capability. The rate discharge capability can be greatly improved by thinning the electrode, because the thin electrode has smaller electronic and ionic resistance, but the thinning of the electrode will result in less active material in the electrode, so the battery capacity will be reduced. Therefore, the main technical challenge of the ternary power lithium battery is to increase the high current discharge capacity without reducing the capacity.
For the ternary power lithium battery, the most researched and most mature technology is undoubtedly the Japanese company Panasonic. The experimental stage has been able to achieve 30C discharge, and the power-type 18650 ternary lithium battery has successfully achieved the discharge rate of commercial mass production. It can reach 12C and the capacity is as high as 3300mAh. There are also domestic manufacturers that achieve a higher discharge rate, but the stability of the battery needs to be improved, especially after a period of use, its cycle life and rate discharge capacity will be greatly reduced. Studies have reported that through particle coating and modification methods, the rate performance of lithium batteries can be improved.
Ternary low temperature lithium battery
The temperature characteristic of the battery is an indicator of battery reliability, and the performance of the battery can also be evaluated by changing the ambient temperature. The low-temperature characteristics of lithium batteries are mainly investigated from low-temperature discharge characteristics and cycle life. The most important thing for low-temperature batteries is to maintain the fluidity of the material under low-temperature conditions, so that lithium ions can freely shuttle between the positive and negative electrodes to achieve battery charging and discharging. For example, using a low melting point electrolyte to reduce the particle size of the active material will enhance the low temperature performance of the battery. This is because the increase in the channel of lithium ions makes up for the slow movement of lithium ions at low temperatures to a certain extent.
At present, domestic and foreign ternary lithium battery manufacturers can basically achieve a discharge temperature of -20 degrees, and the discharge capacity is greater than 50%, and the cycle life is about 400 times, which can fully meet the common electrical appliances and electrical scenarios. However, in special products such as aerospace, special equipment, or in severe cold environments such as northern and high mountains, lithium batteries must be able to reach a lower discharge temperature to meet harsh operating conditions. Dongguan Juda Electronics Co., Ltd. Special Cell Research Institute has gathered a large number of electrochemical experts and senior engineers and professors in the industry. With a strong R&D team, it has successfully developed a low-temperature -40°C discharge with a discharge capacity of 67%. Ultra-low temperature lithium batteries mainly for military and special applications, and successfully realized commercial mass production.
