Briefly describe the characteristics and advantages of lithium batteries

Lithium batteries have attracted great interest and attention due to their high specific energy, long cycle life and wide operating temperature range. What is particularly attractive is that the average price of each cycle battery is not high, and it is on a downward trend. The advantages and characteristics of the lithium battery are described in more detail below.

Compared with other high-energy secondary batteries (such as Ni-Cd batteries, Ni-MH batteries, etc.), lithium-ion batteries have significant advantages in performance, mainly in the following aspects.

(1) High operating voltage

Replacing metallic lithium as a negative electrode with a carbon-intercalated lithium compound such as graphite or petroleum coke causes a decrease in battery voltage. However, due to their low lithium insertion potential, the voltage loss can be minimized. At the same time, choose the appropriate lithium-intercalation compound as the positive electrode of the battery, and choose the appropriate electrolyte system (which determines the electrochemical window of the lithium battery), which can make the lithium battery have a higher working voltage (-4V), which is much higher than that of the aqueous solution battery.

(2) Large specific capacity

Although replacing the metal lithium with carbon material will reduce the material quality specific capacity, in fact, in the metal lithium secondary battery, in order to ensure a certain cycle life of the battery, the negative metal lithium is usually more than three times excessive, so the quality of the lithium battery The actual reduction in specific capacity is not large, and the volumetric specific capacity is hardly reduced.

(3) High energy density

The higher operating voltage and volumetric specific capacity determine the higher energy density of the secondary lithium battery. Compared with Ni-Cd batteries and Ni-MH batteries, which are widely used at present, secondary lithium batteries have the highest energy density and still have great development potential.

(4) Good safety performance and long cycle life

The reason why the battery with metal lithium as the anode is unsafe is that the positive electrode structure of the lithium ion battery is changed by multiple charge and discharge to form porous dendrites, and when the temperature is raised, it undergoes a strong exothermic reaction with the electrolyte, and dendrites It can pierce the diaphragm and cause an internal short circuit. The lithium battery does not have this problem and is very safe. In order to avoid the presence of metallic lithium in the battery, the voltage should be controlled during charging. For safety reasons, the lithium battery is equipped with multiple safety devices. Lithium-ion battery insertion and deintercalation during charging and discharging without any structural changes on the cathode and anode (the crystal lattice will have some expansion and contraction during insertion and deintercalation), and because lithium intercalation compounds are more than metallic lithium Stable, lithium dendrites are not formed during charge and discharge, which significantly improves the safety performance of the battery, and the cycle life is also greatly improved. Lithium batteries were excluded from dangerous goods by the US Department of Transportation's Dangerous Goods Transportation Division and IAIT (International Air and Transportation Association) in 1989 and 1990, respectively.

(5) Small self-discharge rate

The lithium battery uses a non-aqueous electrolyte system, and the lithium-inlaid carbon material is thermodynamically unstable in the non-aqueous electrolyte system. During the first charge and discharge process, a solid electrolyte mesophase (SEI) film is formed on the surface of the carbon negative electrode due to the reduction of the electrolyte, allowing lithium ions to pass but not allowing electrons to pass, and the electrode electrode active materials in different charged states. It is in a relatively stable state and therefore has a low self-discharge rate.

(6) Clean and pollution free

Lithium batteries do not contain toxic substances such as lead, blessings, mercury, etc., and because the batteries must be well sealed, there is very little gas released during use, which does not pollute the environment. The solvent used to dissolve the binder during the manufacturing process can also be completely recovered. Sony and other large-scale lithium battery manufacturers have started recycling lithium batteries and recycling of materials (such as metal drills) since 1997. In addition, Sony's lithium battery was certified in 1996 to comply with IS014001 international environmental standards [71O]

(7) High current efficiency

Unlike any secondary battery of an aqueous solution system in the past, a lithium battery does not generate gas during normal charging and discharging, and the current efficiency is close to 100%. This property is particularly suitable for use as a battery pack for power storage and conversion.

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