Ternary Lithium Battery Overview

- Aug 15, 2019-

There are many kinds of cathode materials for lithium ion batteries. According to different cathode materials, they can be divided into lithium cobaltate, lithium manganate, ternary materials, lithium iron phosphate and lithium titanate. The ternary lithium battery refers to a lithium battery using three transition metal oxides of nickel, cobalt and manganese as a positive electrode material. Since it combines the advantages of lithium cobaltate, lithium nickelate and lithium manganate, the performance is superior to the above. Any single component cathode material. The experimental analysis indicates that the three different valence elements form a superlattice structure, and there are obvious synergistic effects 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. One of the positive electrode materials. The ternary battery has high energy density, good safety and stability, excellent electrochemical characteristics such as high-rate discharge, and moderate cost advantage. It is 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.


At present, the 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 exist in the valence state of +2, +3, and +4. In the process of charge and discharge, only Ni2+/Ni4+ and Co3+/Co4+ occur, and Mn is basically not. Participation in the electrochemical reaction only serves to stabilize the structure of the material. Regarding the preparation method, synthetic methods commonly used in the industry include high temperature solid phase method, coprecipitation method, sol-gel method, hydrothermal synthesis method, combustion method and the like. The ternary material is a lithium battery cathode material with superior comprehensive performance. The molar ratio of the three materials can be changed within a certain range, and the corresponding additives (binder, conductive agent, current collector, etc.) can be added to obtain a certain On the one hand, there are outstanding performance characteristics, such as power type ternary lithium battery, capacity type ternary lithium battery, ultra-low temperature ternary lithium battery and so on.


Ternary polymer lithium battery


The lithium terpolymer lithium battery refers to a lithium battery using a lithium metal cobalt lithium manganate (Li(NiCoMn)O2) ternary positive electrode material and a gel polymer electrolyte. As the transmission medium of ion motion, the electrolyte generally consists of a solvent and a lithium salt. The electrolyte of the lithium secondary battery mainly has a liquid electrolyte, an ionic liquid electrolyte, a solid polymer electrolyte and a gel polymer electrolyte. The gel polymer electrolyte is composed of a polymer, an organic solvent and a lithium salt, and is obtained by mixing an organic electrolyte and a solid polymer matrix. Because it exists in a gel state, it has the advantages of both a solid electrolyte and a liquid electrolyte. Since the electrolyte is confined in the polymer chain, it has a high ionic conductivity over a wide temperature range (up to 10). -3S/cm). The biggest advantage is that the diaphragm is mechanically strong and the film provides a large surface area. The thinner the film, the higher the energy density, as more active material can be embedded in the cell. In addition, its electrochemical stability is also very good, high temperature resistance, most of the high-temperature batteries on the market use polymer electrolytes.


Three-way power lithium battery


The so-called power battery means that the battery supports high-rate and high-current discharge, high power density, and more energy released per unit time. The rate discharge capability refers to the ability to maintain the battery capacity in the case where the charge and discharge rate is increased. The charge and discharge rate is expressed by xC, 1C means that the nominal capacity of the battery can be used up in 1h, and the discharge at 2C can be used for 30min.


The power/magnification performance of the battery is closely related to the design of the battery and is affected by many factors such as electrolyte, diaphragm, type of active material, size of active particles, and the like. Among these factors, the thickness of the electrode is a major factor affecting the ability of large current discharge. The rate discharge capability can be greatly improved by thinning the electrode because the thin electrode has a small electronic impedance and ion impedance inside. However, thinning of the electrode results in less active mass in the electrode, and thus the battery capacity is reduced. Therefore, the main technical challenge of the ternary power lithium battery is to increase the large current discharge capability without reducing the capacity.


For the ternary power lithium battery, the most research is currently, the most mature technology is the Japanese Matsushita company, the experimental stage can already achieve 30C discharge, which has successfully realized the commercial large-scale production of the power type 18650 ternary lithium battery discharge rate Up to 12C, the capacity is also up to 3300mAh. Domestic manufacturers also have higher discharge rates, 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. It has been reported that the rate performance of lithium batteries can be improved by methods such as particle coating and modification.


Ternary low temperature lithium battery


The temperature characteristics of the battery are 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 materials under low temperature conditions, so that lithium ions can freely shuttle between the positive and negative electrodes to achieve charge and discharge of the batteries. For example, using an electrolyte with a low melting point to reduce the particle size of the active material will enhance the low temperature performance of the battery because the lithium ion channel is increased to some extent to compensate for the slow movement of lithium ions at low temperatures.


At present, ternary lithium battery manufacturers at home and abroad 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 satisfy the ordinary electric appliances and electricity use scenes. However, in special products such as aerospace, military equipment, or cold environments such as the north and the mountains, lithium batteries must be able to achieve lower discharge operating temperatures to meet demanding conditions. The special electric core research institute of Dongguan Yida Electronics Co., Ltd. has gathered a large number of electrochemical experts and high-tech professors in the industry. With a strong R&D team, it successfully developed a low-temperature -40-degree discharge with a discharge capacity of 67%. It is mainly used for ultra-low temperature lithium batteries for military and special applications, and has successfully achieved commercial mass production.