What are the structure and characteristics of lithium ion batteries? Next, the structure and characteristics of lithium ion batteries will be introduced in detail.
Lithium ion batteries have been widely used in various fields, so their types, types and structures are also diverse. According to the state of the electrolyte used, it can be divided into liquid lithium-ion batteries and all-solid-state lithium-ion batteries. Currently commercial lithium-ion batteries can be classified according to the shape and composition of the battery. The battery includes three shapes: cylindrical, button and square, as shown in Figure 1 and Figure 2. In addition to the above-mentioned shapes, the polymer lithium ion battery can also be made into any shape according to needs.
Lithium ion batteries have attracted widespread attention from researchers because they have many unique advantages. Currently, lithium ion batteries have the following advantages.
①Lithium-ion battery has high specific capacity and high working voltage. The single cell voltage of lithium-ion battery is 3.6V, so it has a higher mass specific energy. The actual mass specific energy of lithium ion batteries has reached 140w•h/kg, and the volume specific energy is about 300W•h/L, while the mass specific energy and volume specific energy of the commonly used Cd-Ni batteries are 40w•h/kg and 125W•h/L, the mass specific energy and volume specific energy of MH-Ni batteries are 60w•h/kg and 165w•h/L, respectively.
②Lithium-ion battery has very good charge retention capacity, allowing wide operating temperature range. When the ambient temperature is (20±5) ℃, after 30 days of storage in an open circuit state, the battery discharge capacity is 85% of the rated capacity. Lithium-ion batteries can operate in a relatively wide temperature range, usually within a range of 20 to 60 ℃, have excellent high and low temperature discharge performance, high temperature performance is better than other batteries.
③Lithium-ion battery has long cycle life, high safety and no memory effect. The cycle performance of lithium-ion batteries is much higher than other types of batteries, and can be stored for more than 5 years in a good environment. It is economical for long-term use. It can be used repeatedly at any time by charging and discharging. For electric vehicles and hybrid vehicles, this is very important.
④Lithium-ion batteries are small in size, light in weight, and high in specific energy. Generally, the specific energy of lithium-ion batteries can reach more than twice that of nickel-cadmium batteries. Compared with nickel-hydrogen batteries of the same capacity, the volume can be reduced by 30%, and the weight can be reduced by 50%. Therefore, it is very suitable for portable electronic equipment. The key to the commercialization of electric vehicles.
Although lithium ion batteries have many advantages, lithium ion batteries also have disadvantages.
①The internal impedance of the lithium ion battery is high. Because the electrolyte of lithium-ion batteries is an organic solvent, its conductivity is lower than that of nickel-cadmium and nickel-hydrogen batteries. Therefore, the internal impedance is about 11 times greater than that of nickel-cadmium and nickel-hydrogen batteries.
②The cost of lithium-ion batteries is relatively high. The current high cost of lithium-ion batteries has become a bottleneck restricting the commercialization of electric vehicles. The main reason is that the price of the cathode material LiCoO2 is relatively high. With the continuous development of cathode technology, the range of available cathode materials is continuously expanding, which can greatly reduce the cost of lithium-ion batteries.
③Lithium-ion batteries must have special protection circuits to prevent them from overcharging. Due to the high operating voltage, compatibility with ordinary batteries is poor.
Compared with the advantages of lithium-ion batteries, these shortcomings are not the main problem, especially for some high-tech products, so the application range is very wide. What’s more, scientific researchers are constantly working hard to find cheaper electrode materials with better performance, so as to overcome the existing shortcomings and make lithium-ion batteries be used in more fields.