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Lithium ion structure:
1、positive
2、negative electrode
3、Electrolyte
4、separator
5、positive lead
6、negative lead
7、Centre terminal, insulation material insulator
8、Safety vent
9、Sealing ring gasket
10, Positive temperature control terminal PTC
11、Battery shell, cover board, sole piece
Lithium battery classification:
A, according to the different cathode materials are divided into: lithium iron, lithium cobalt, lithium manganese batteries
Comparison of lithium iron, lithium manganese, lithium cobalt and lead-acid batteries
Lithium iron batteries: 1:
1. Advantages:
A, long life, long life lead-acid battery cycle life of about 300 times, while the cycle life of lithium iron phosphate batteries to more than 1000 times.
Second, the use of safety, lithium iron phosphate completely solve the problem of lithium cobalt acid and lithium manganese acid safety hazards, lithium cobalt acid and lithium manganese acid in a strong collision will produce an explosion on the safety of consumers' lives, while lithium iron phosphate to go through rigorous safety testing even in the worst traffic accidents will not produce an explosion.
Third, can be high current 2C fast charge and discharge, in the special charger, 1.5C charge within 40 minutes can make the battery full, starting current of up to 2C, and lead-acid batteries now no such performance.
Fourth, high temperature resistance, lithium iron phosphate electric heat peak up to 350 ℃ -500 ℃, while lithium manganate and lithium cobalt acid only in about 200 ℃.
Fifth, can be high current discharge (5-10C discharge).
Sixth, no memory effect. Seven, green and environmental protection.
2. Disadvantages:
First, lithium iron phosphate cathode material vibration density is small, the volume of lithium iron phosphate batteries of equal capacity is larger than lithium manganese batteries and lithium cobaltate and other lithium ion electricity.
Second, poor electrical conductivity, lithium ion diffusion rate is slow. When the high rate of charge and discharge, the actual specific capacity is low, this problem is a difficult point to limit the development of lithium iron phosphate industry.
Third, the poor low temperature performance of lithium iron phosphate batteries. Due to the inherent characteristics of lithium iron phosphate materials, determine its low-temperature performance is inferior to other anode materials such as lithium manganate. In general, for a single cell (note that it is a single rather than a battery pack, for the battery pack, the measured low-temperature performance may be slightly higher, which is related to heat dissipation conditions), its 0 ℃ capacity retention rate of about 70 to 80%, -10 ℃ for 50 to 65%, -20 ℃ for 40 to 60%. Such low-temperature performance obviously does not meet the requirements of power supply use.
Fourth: lithium iron phosphate batteries have consistency problems. Single lithium iron phosphate battery life is currently more than 2000 times, but the life of the battery pack will be greatly reduced, possibly 500 times. Because the battery pack is composed of a large number of single cells in series and into. For various reasons, the production of the battery consistency is poor, which in turn affects the performance and overall life of the battery.
3, price: lithium iron phosphate battery manufacturing costs are high. Lithium iron phosphate has the advantages of safety, environmental protection, high cycle times is undoubtedly, but the current manufacturing costs are relatively high lithium cobalt, lithium manganese acid batteries, mainly due to process and technical reasons, resulting in the capacity and yield of the material is not high.
Lithium manganese batteries: 1:
1. Price: The cathode material is cheaper, but lithium manganese batteries are the cheapest in actual use.
2. Advantages:
I. Lithium manganate is the key to the electrode material of lithium ion battery, and lithium manganate is one of the more promising lithium ion cathode materials.
II. The performance of the material has been greatly improved, with high safety and low price, so that it has a broad application prospect in the field of power battery. In recent years' research, the cycle performance of modified lithium manganate has been improved to a certain extent, and the specific capacity has been increased to a certain extent. The high temperature performance has been well solved and the pace of industrialization has been accelerated.
III. In the field of power battery, modified lithium manganate has higher safety, lower price and better density than lithium iron, which makes it the most promising power battery material. It may become the main substitute for lead-acid batteries in the next five years, becoming the main starting power supply, UPS power supply and backup power supply, and the boss of secondary batteries.
IV. In the field of lithium battery electric vehicles, compared to lithium iron phosphate and lithium cobalt batteries have a great advantage in terms of cost performance, is the most used battery for lithium electric vehicles.
3. Disadvantages: relatively low specific capacity, low high temperature cycle. Safety relative to lithium iron phosphate is poor.
Lithium cobalt batteries:
1. Price: The price of cathode material is cheaper, but lithium cobalt batteries are more expensive than lithium manganese batteries in actual use.
2. Advantages: It is the first generation of commercialized lithium-ion battery cathode material, and there are many irreplaceable advantages: good processing performance of the material, high density, relatively high specific capacity, stable structure of the material, good cycling performance, high and stable voltage platform of the material, it is the most mature and the only commercialized cathode material, in a short period of time, especially in the field of communication batteries, there are irreplaceable Advantages
3. Disadvantages: expensive, scarce resources, poor safety and other defects make it inevitably suffer the fate of being replaced in the next 5 to 10 years. Now there are two directions to replace lithium cobaltate materials, one is in the field of power batteries, lithium manganate and lithium phosphoric acid are the most promising materials, and the second is in the field of communication batteries, lithium nickel cobalt and lithium nickel cobalt manganese ternary materials are the most promising cathode materials to replace lithium cobaltate.
Lead-acid batteries:
1. Price: low price: the price of lead-acid batteries is 1/4~1/6 of the price of other types of lithium batteries.
2. Advantages: high current discharge, good reversibility of charging and discharging, wide temperature range, abundant and cheap raw materials, etc.
3. Disadvantages: a. There is a large amount of lead in lead-acid batteries, which will cause secondary pollution to the environment if they are disposed of improperly.
b. Low energy density (large volume and heavy).
The theoretical comparison of the performance of several materials produced by the battery is as follows
Battery composition LiFePO4 LiCo LiCo battery LiMn battery LiCoNi battery
C-LiFePO4 LiCoO2 LiMn2O4 Li(NiCo)O2
Safety and environmental requirements Best safety and most environmentally friendly Very poor stability, very unsafe Fairly acceptable Very poor stability, very unsafe
Cycle times Optimal Fair Unacceptable Fair Acceptable
Energy density Acceptable Good Acceptable Optimal
Long-term cost of use Most economical High Acceptable High
Temperature tolerance Very good (-40°C to 70°C) Decline above 55°C or below -20°C Rapid decline above 50°C Decline above 55°C or below -20°C
Although there are theoretically many different types of cathode materials that can be used for Li-ion batteries, the most widely used cathode material in commercially produced Li-ion batteries is still LiCoO2. material is still quite far away. However, the partial replacement of Ni with Co to obtain LiNi1-xCoxO2 with higher safety may be an important development direction in the future. LiMn2O4 with spinel structure and LiMnO2 with layered structure are considered to be one of the most competitive cathode candidates due to the abundant raw material resources, obvious price advantage and high safety performance. However, the problem of structural instability during charging and discharging will be an important research topic in the future. The actual discharge capacity of LiFePO4 with olivine structure has reached about 95% of the theoretical capacity, and has the advantages of cheap, high safety, stable structure, no environmental pollution, etc. It is considered to be the ideal cathode material for large lithium-ion batteries.
Second, according to the electrolyte material is divided into: liquid lithium batteries LIB, solid-state lithium-ion batteries PLIB belongs to a solid-state lithium-ion batteries.
Comparison of lithium-ion batteries:
Electrolyte Case/packaging Diaphragm Collector
Liquid lithium ion battery LIB Liquid Stainless steel, aluminium 25μPE Copper and aluminium foil
Polymer lithium ion battery PLIB Colloidal polymer Aluminium/PP composite film No diaphragm or individual μPE copper and aluminium foil
Because the polymer lithium-ion battery uses a colloidal electrolyte that does not leak like a liquid electrolyte, assembly is easy, making the overall battery light and thin. It is also possible to use aluminium-plastic composite film to manufacture the battery shell, thus increasing the specific capacity of the whole battery; polymer lithium-ion batteries can also use polymers as the positive electrode material, and their mass-to-energy ratio will increase by more than 50% compared to the current liquid lithium-ion batteries. In addition, polymer lithium-ion batteries have improved operating voltage and charge/discharge cycle life compared to liquid lithium-ion batteries. Based on the above advantages, lithium-ion polymer batteries are known as the next generation of lithium-ion batteries.
Third, from the shape of the general classification of cylindrical and square, while lithium-ion polymer can also be made into any shape.