Compared with traditional batteries, lithium-ion batteries have the following advantages
① High energy density. That is, lithium-ion batteries of the same mass or volume provide higher energy than other batteries.
The mass specific energy of lithium ion batteries is generally between 100~170w.h.kg ^﹣1, and the volume specific energy is generally between 270-460w.hL^﹣1, both of which are 2~ of nickel-cadmium batteries and nickel-hydrogen batteries. 3 times. Therefore, a lithium-ion battery with the same capacity is much lighter and much smaller in size.
②The voltage is high. Because of the use of non-aqueous organic solvents, its voltage is 2 to 3 times that of other batteries. This is also an important reason for its high energy density.
③The self-discharge rate is low. The self-discharge rate is also known as the charge retention rate, which refers to how much the battery is left without automatic discharge. The self-discharge rate of lithium-ion batteries is 3%-9%, that of nickel-cadmium batteries is 25%-30%, and that of nickel-hydrogen batteries is 30%-35%. Therefore, the lithium-ion battery retains charge for a long time under the same environment.
④ No memory effect. The memory effect refers to the decrease in the charge capacity when the battery is not fully charged and recharged. Lithium-ion batteries have no memory effect, so they can be charged at any time, so that the performance of lithium-ion batteries can be fully utilized. Ni-MH batteries, especially nickel-cadmium batteries, have a heavier memory effect, and sometimes they have to be discharged after half of the battery is used. The phenomenon of recharging. This is crucial to the working status of EV and HEV power sources.
⑤Long cycle life. In a good environment, it can be stored for more than five years. In addition, the most widely used negative electrode of lithium ion batteries is graphite. During the charge and discharge process, lithium ions are continuously extracted/intercalated in the positive and negative electrode materials to avoid damage caused by lithium dendrites inside the negative electrode. The cycle life can reach 1000~2000 times. The charge and discharge times of nickel-cadmium batteries and nickel-hydrogen batteries are generally 300 to 600 times.
⑥The lithium-ion battery adopts measures such as overcurrent protection, pressure protection, and self-melting of the diaphragm to ensure safe and reliable work.
⑦Lithium-ion battery does not contain any toxic elements such as mercury (Hg), cadmium (Cd), lead (Pb), etc. It is a truly green battery.
⑧Wide working temperature range. Lithium-ion batteries usually work normally within a range of 20-60°C, but temperature changes have a great influence on their discharge capacity.
However, lithium-ion batteries are not perfect, and have the following disadvantages.
① The internal resistance is relatively large. Because its electrolyte is an organic solvent, its diffusion coefficient is much lower than the water-soluble electrolyte of Cd-Ni and MH-Ni batteries.
②Wide charging and discharging voltage range. Therefore, a special protection circuit must be set up to prevent the occurrence of overcharge and overdischarge.
③ Poor compatibility with ordinary batteries. Because lithium batteries have a higher voltage than other batteries, they have poor compatibility with other batteries.