Introduction to Lithium-ion Battery

Lithium-ion batteries are rechargeable batteries that rely mainly on lithium ions to move between positive and negative poles. During the charging and discharging process, Li + is embedded and deembedded between the two electrodes: When recharging the battery, Li + is deembedded from the positive electrode, the negative electrode is embedded through the electrolyte, and the negative electrode is in a lithium-rich state; When discharging, it is the opposite. Lithium-containing materials are generally used as batteries for electrodes. It is a representative of modern high-performance batteries.

Electrochemical reaction of lithium-ion batteries: This reversible reaction method, commonly known as lithium-ion batteries, is a cradle-type reaction. When charged, lithium-ion Li + runs from the positive to the negative pole through the diaphragm. Discharge is the opposite. This "swing" forms the basic mechanism of rechargeable lithium ion batteries.

Lithium-ion batteries are not highly toxic and have a much smaller impact than lead-acid batteries

Lithium-ion batteries have high energy density and high average output voltage. Self-discharge small, good batteries, less than 2 % per month(recoverable). No memory effects. The operating temperature range is -20 °C to 60 °C. High cycle performance, fast charging and discharging, charging efficiency up to 100 %, and output power. Long service life. It does not contain toxic and harmful substances and is called a green battery.

"Lithium-ion batteries and lithium-ion batteries are technically different. Wang Fang, chief expert in the power cell field at the China Automotive Technology Research Center and secretary general of the Battery Test and Application Technology Alliance and senior engineer, said that lithium batteries usually refer to batteries with lithium metal or lithium alloys as negative poles and using non-hydro solutions. Lithium-ion batteries refer to rechargeable secondary batteries. The negative electrode does not use metallic lithium and depends on the movement of lithium ions between positive and negative poles. However, in daily life, people are accustomed to refer to lithium ion batteries as lithium batteries or lithium batteries.

It is understood that most of the new energy vehicles(including pure electric vehicles and plug-in hybrid vehicles) promoted in our country now use lithium-ion batteries, of which lithium iron phosphate accounts for 80 % -90 %, and triple-lithium batteries are also used in passenger vehicles. Large-scale application.

In response to the online article pointing out that lithium batteries are "highly toxic dangerous goods", Wang Fang refuted that lithium batteries such as lead acid, nickel Chromium, nickel hydrogen and other traditional batteries do not produce any lead, Mercury, cadmium and other toxic harmful heavy metal elements and substances, relatively less pollution. And its electrolyte is organic solvent and lithium salt, mostly non-toxic or low toxicity; However, the decomposition or hydrolysis of lithium batteries is hydrofluoric acid and other fluorinated compounds, which are corrosive and toxic.

On the "lithium battery toxic theory", Liuhaojie, senior engineer of the 18th Institute of China Electronic Technology Group, said that lithium ion batteries themselves do not contain highly toxic substances, negative carbon and positive metal oxides are basically non-toxic. Since lithium-ion batteries are sealed, these substances will not be exposed to normal use. "In any case, the impact is much smaller than the most widely used lead-acid batteries. "

Power lithium-ion battery life up to 2000 cycles, battery management system can limit "overcharge over discharge"

How long is lithium current electric life? Does shallow and overcharged placement have an impact on battery safety and life?

"There are many factors that determine the service life of powered lithium-ion batteries, including the characteristics of the system itself, as well as manufacturing processes and operating conditions. A high quality battery system, coupled with scientific system management, can achieve a long service life. "Wang Fang said that according to the capacity attenuation to 80 % as the cut-off condition, according to the 100 % discharge depth test, the current power cell life can basically reach 2000 cycles.

"Overcharge over discharge means that the voltage of the battery in the process of charging and discharging exceeds or is lower than the specified cut-off voltage, which will cause harm to the battery performance and life. "But the BMS battery management system in the battery will be limited and protected. At low temperatures, the battery will be limited to charging and recharging when heated to a suitable temperature," Wang said. In order to ensure the safety of lithium-ion batteries, there are a series of safety protection designs from battery cells, modules, and battery systems to prevent the battery from overcharging and letting go of temperature, and timely warning and protection in the event of an anomaly, Wang said.

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