Introduction of Lithium Battery
"Lithium batteries are a class of batteries made of lithium metal or lithium alloy as the negative electrode material, using non-aqueous electrolyte solution. 1912 lithium metal batteries were first proposed and studied by Gilbert N. Lewis. . Because the chemical properties of lithium metal is very lively, making the processing, preservation and use of lithium metal, the environmental requirements are very high. Therefore, lithium batteries have not been used for a long time. With the development of science and technology, lithium batteries have now become the mainstream.
Lithium batteries can be broadly divided into two categories: lithium metal batteries and lithium ion batteries. Lithium-ion batteries do not contain lithium in the metallic state and are rechargeable. The fifth generation of rechargeable batteries lithium metal batteries were born in 1996, and their safety, specific capacity, self-discharge rate and performance-to-price ratio are better than lithium-ion batteries. Because of its own high technical requirements constraints, only a few companies in a few countries are now producing such lithium metal batteries.
Lithium-ion battery structure
Lithium-ion battery is an alternative to the lithium metal battery that appeared a few years ago. The primary components of the battery are the positive and negative electrodes, electrolyte, barrier and shell.
Positive electrode - the choice of carbon electrode that can absorb lithium ions, when discharged, lithium into lithium ions, from the battery anode, to reach the cathode of lithium-ion batteries.
The negative electrode ---- material is selected as close as possible to the lithium potential can be embedded in lithium compounds, such as a variety of carbon materials including natural graphite, synthetic graphite, carbon fiber, the central phase of the small ball of carbon, and metal oxides.
Electrolyte - the choice of LiPF6 ethylene carbonate, propylene carbonate and low viscosity diethyl carbonate and other alkyl carbonate with a mixed solvent system.
Barrier --- The use of polyethylene micro porous film such as PE, PP or their composite film, especially PP/PE/PP three-layer barrier not only has a low melting point, but also has a high puncture resistance strength, which plays a thermal stability effect.
Shell - the choice of steel or aluminum materials, cover body components have the function of explosion-proof power failure.
Lithium battery soft pack and hard pack lithium battery differences introduced
Lithium-ion battery operating principle
The operating principle of lithium-ion battery refers to its charging and discharging principle.
When the battery is charged, lithium ions are generated at the positive electrode of the battery, and the generated lithium ions move through the electrolyte to the negative electrode. The carbon as the negative electrode is in the form of a layer structure, which has many micro-pores, and the lithium ions that reach the negative electrode are embedded in the micro-pores of the carbon layer, and the more lithium ions embedded, the higher the charging capacity. At this moment, the chemical reaction generated at the positive electrode is
Introduction of the difference between Li-ion battery </a> soft pack and hard pack Li-ion battery
By the same token, when the battery is discharged (i.e., the process we use the battery), the lithium ions embedded in the carbon layer of the negative electrode come out and move back to the positive electrode. The more lithium ions that return to the positive electrode, the higher the discharge capacity. We generally refer to the battery capacity is the discharge capacity. At this moment, the negative electrode produces the following chemical reaction.
Lithium battery soft pack and hard pack lithium battery difference introduction
It is easy to see that in the process of charging and discharging lithium-ion batteries, lithium ions are in motion from the positive pole → negative pole → positive pole. If we compare the lithium-ion battery to a rocking chair, the two ends of the rocking chair for the north and south poles of the battery, and lithium ions are like excellent sportsman, running back and forth in the two ends of the rocking chair. Therefore, experts have given the lithium-ion battery a beloved name rocking chair battery.
Soft pack lithium battery introduction
Soft pack lithium battery is just a liquid lithium-ion battery covered with a polymer shell. In the structure of the choice of aluminum-plastic film packaging, in the case of safety hazards soft pack batteries will at most only bulge cracked.
Soft pack lithium battery parameters
Nominal voltage: 3.7V
Operating voltage: 2.4~4.2V
Nominal capacity: 1250mAh
Standard discharge continuous current: 0.2C
Maximum discharge continuous current: 0.5C
Operating temperature: Charging: 0~45℃
Discharge: -20~60℃
Product scale: MAX9.5*35*52mm
Product internal resistance: ≤150mΩ
Over-discharge maintenance voltage 2.5±0.05V
Lead wire type: national standard wire UL1007/24#, wire length 55mm maintenance parameters: overcharge maintenance voltage / 4.325±0.025V per string
Overcurrent value: 2~4A
Introduction of the differences between soft pack and hard pack lithium batteries
The advantages of soft pack battery
1. Good safety performance
Soft pack battery, unlike the steel-case aluminum-case battery cells will produce an explosion.
2. Light weight
Soft pack batteries are 40% lighter than steel-cased lithium batteries of equal capacity, and 20% lighter than aluminum-cased batteries.
3. Large capacity
Soft pack batteries have 10-15% higher capacity than steel-cased batteries of equal standard scale, and 5-10% higher than aluminum-cased batteries.
4. Small internal resistance
The internal resistance of soft pack battery is smaller than that of lithium battery, and now the minimum internal resistance of domestic soft pack battery cells can be less than 35mΩ, which greatly reduces the self-consumption of battery power.
5. Sensitive planning
The shape of the soft pack battery can be customized according to the customer's needs and new cell types can be developed.
Disadvantages of soft pack battery
Fewer types of existing soft pack battery cells to meet market demand.
High cost to develop new types.
Difference between Li-ion battery soft pack and hard pack
Lithium battery soft pack and hard pack difference refers primarily to the material of the lithium battery shell, if there is packaging outside, it is not easy to see, it is necessary to see the battery body, the weight of the steel-shell battery will focus on the same volume than the battery, but the aluminum shell and soft pack is not easy to distinguish, but the soft pack battery will be a little softer than the aluminum shell battery, it is easy to break by hand deformation.
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