At present, lithium-ion power batteries have replaced traditional batteries in mobile phones, portable computers, video cameras, and cameras. Large-capacity lithium-ion batteries have been tried out in electric vehicles and will become one of the main power sources for electric vehicles in the 21st century. They have been used in artificial satellites, aerospace and energy storage.
The working principle of lithium ion battery
The working principle of the lithium ion battery is that when the battery is charged, the lithium in the positive electrode material is released, passes through the diaphragm and enters the negative electrode graphite; when the battery is discharged, the lithium ions are separated from the negative electrode graphite and pass through the diaphragm back to the positive electrode material. . With the progress of charge and discharge, lithium ions are continuously inserted and extracted from the positive electrode and the negative electrode.
Features of Lithium Ion Power Battery
high voltage
The voltage of lithium-ion power batteries is three times that of nickel-cadmium batteries and nickel-hydrogen batteries, and nearly twice that of lead-acid batteries. This is also an important reason why lithium-ion power batteries have higher energy. Therefore, when forming a power battery pack with the same voltage, the number of lithium-ion power batteries used in series will be much less than that of lead-acid batteries and nickel-hydrogen batteries.
light weight
The specific energy is as high as 150Wh/Kg, which is 2 times that of Ni-MH batteries and 4 times that of lead-acid batteries, so the weight is one-third to one-fourth of lead-acid batteries with the same energy. From this perspective, lithium battery consumption There are fewer resources, and because the reserves of elements used in lithium manganate batteries are relatively large, the price of lead-acid and nickel-metal hydride batteries may be further increased, and the cost of lithium batteries will be further reduced.
long life
The number of cycles can reach 1000~3000 times. Based on the capacity retention of 70%, the number of 100% charge and discharge cycles of the battery pack can reach more than 200 times, the service life can reach 5-8 years, and the life span is about two to three times that of lead-acid batteries. With technological innovation and equipment improvement, the battery life will be longer and the cost performance will be higher and higher.
Low self-discharge rate: less than 5% per month.
wide range
Low temperature performance is good. Li-ion power batteries can work between -40°C and +55°C, while aqueous batteries (such as lead-acid batteries and nickel-hydrogen batteries) at low temperatures will greatly reduce the performance due to the deterioration of electrolyte fluidity .
no memory
There is no need to discharge like nickel-cadmium batteries and nickel-metal hydride batteries before each charge, and it can be charged anytime and anywhere. The depth of battery charge and discharge has little effect on the life of the battery. It can be fully charged and fully discharged. Our cycle test is fully charged and fully discharged.
is especially suitable for power batteries
In addition to the high voltage of lithium-ion batteries, because the protection board of the lithium-ion power battery pack can monitor each single battery with high precision, low power consumption and intelligent management, it has perfect overcharge, overdischarge, temperature, overcurrent, Short-circuit protection, lock-in self-recovery function and reliable equalization charging function greatly extend the service life of the battery. However, other types of batteries (such as lead-acid batteries) are prone to battery overcharging and over-discharging problems due to battery consistency and charger problems during use (due to various reasons such as cost, the lead-acid battery pack cannot be Each single cell is monitored and protected).
no pollution
There are no toxic substances in lithium-ion power batteries, so they are called "green batteries" and are supported by the state. As lead-acid batteries and cadmium-nickel batteries contain harmful substances such as lead and cadmium, the state will inevitably strengthen supervision and governance (elimination of export tax rebates for lead-acid batteries, increase in lead resource taxes, and restrictions on the export of lead-acid electric bicycles). The cost will also increase. Although lithium batteries are not polluting, they are considered from the perspective of resource conservation. The recycling of lithium-ion power batteries, the safety in recycling, and the cost of recycling also need to be considered.
Security risks
Due to the high energy and poor material stability of lithium-ion power batteries, lithium batteries are prone to safety problems. In 2013, the world’s well-known mobile phone and laptop battery manufacturers (the positive electrode material is lithium cobalt oxide and ternary materials), Japan's Sanyo, Sony and other companies It is required that the burst rate of the battery be controlled below 40 ppb (parts per billion). It is good for domestic companies to reach the ppm (parts per million) level, and the capacity of the power battery is higher than that of the mobile phone battery. More than a hundred times, so the safety requirements for lithium batteries are extremely high. Although lithium cobalt oxide batteries and ternary material batteries have the advantages of lighter weight and smaller size, they are not suitable for power batteries to be used in electric vehicles. The lithium ion battery of mixed crystal lithium manganate and lithium iron phosphate is the most promising lithium ion power battery.
high price
The price of a lithium-ion power battery with the same voltage and the same capacity is 3-4 times that of lead-acid. With the expansion of the lithium-ion power battery market, the reduction of costs, the improvement of performance, and the increase in the price of lead-acid batteries, the cost-effectiveness of lithium-ion power batteries is likely to exceed that of lead-acid batteries.