Lithium battery overview
A "lithium battery" is a type of battery using a lithium metal or a lithium alloy as a negative electrode material and using a nonaqueous electrolyte solution. Lithium metal batteries were first proposed and studied by Gilbert N. Lewis in 1912. In the 1970s, M.S.WhitTIngham proposed and began researching lithium-ion batteries. Due to the very active chemical properties of lithium metal, the processing, storage and use of lithium metal are very demanding on the environment. Therefore, lithium batteries have not been used for a long time. With the development of science and technology, lithium batteries have become the mainstream.
Lithium batteries can be roughly divided into two categories: lithium metal batteries and lithium ion batteries. Lithium-ion batteries do not contain metallic lithium and are rechargeable. The fifth-generation lithium-metal battery of rechargeable batteries was born in 1996, and its safety, specific capacity, self-discharge rate and performance price ratio are better than lithium-ion batteries. Due to its own high technical requirements, only a few companies in the country are producing such lithium metal batteries.
Lithium battery working principle
Lithium metal battery:
A lithium metal battery is generally a battery using manganese dioxide as a positive electrode material, metallic lithium or an alloy metal thereof as a negative electrode material, and a nonaqueous electrolyte solution.
Discharge reaction: Li+MnO2=LiMnO2
Lithium Ion Battery:
A lithium ion battery is generally a battery using a lithium alloy metal oxide as a positive electrode material, graphite as a negative electrode material, and a nonaqueous electrolyte.
How does the lithium iron phosphate battery work?
The full name of lithium iron phosphate battery is lithium iron phosphate lithium ion battery, the name is too long, referred to as lithium iron phosphate battery. Because its performance is particularly suitable for power applications, the word "power" is added to the name, namely lithium iron phosphate power battery. Some people call it "LiFe iron (LiFe) power battery."
In the metal trading market, cobalt (Co) is the most expensive, and storage is not much, nickel (Ni), manganese (Mn) is cheaper, and iron (Fe) is the cheapest. The price of the cathode material is also consistent with the price of these metals. Therefore, a lithium ion battery made of a LiFePO4 positive electrode material should be the cheapest. Another feature of it is that it is environmentally friendly.
The requirements for rechargeable batteries are: high capacity, high output voltage, good charge and discharge cycle performance, stable output voltage, high current charge and discharge, electrochemical stability, and safety during use (no overcharge, over discharge, and short circuit) Such as improper operation caused by burning or explosion), wide operating temperature range, non-toxic or less toxic, no pollution to the environment. Lithium iron phosphate battery using LiFePO4 as positive electrode has good performance requirements, especially in large discharge rate discharge (5~10C discharge), stable discharge voltage, safety (no combustion, no explosion), and life (cycle number) ), it is the best for the environment, it is the best high current output power battery.
Structure and working principle:
The internal structure of the LiFePO4 battery is shown in Figure 1. On the left is the olivine-structured LiFePO4 as the positive electrode of the battery. The aluminum foil is connected to the positive electrode of the battery. The middle is the polymer separator. It separates the positive electrode from the negative electrode, but the lithium ion Li+ can pass and the electron e- cannot pass. The right side is composed of A battery negative electrode composed of carbon (graphite) is connected to the negative electrode of the battery by a copper foil. Between the upper and lower ends of the battery is the electrolyte of the battery, and the battery is hermetically sealed by a metal casing.
When the LiFePO4 battery is charged, the lithium ion Li+ in the positive electrode migrates toward the negative electrode through the polymer separator; during the discharge, the lithium ion Li+ in the negative electrode migrates toward the positive electrode through the separator. Lithium-ion batteries are named after the lithium ions migrate back and forth during charging and discharging.
The nominal voltage of the LiFePO4 battery is 3.2V, the termination charging voltage is 3.6V, and the termination discharge voltage is 2.0V. Due to the quality and process of the positive and negative materials and electrolyte materials used by various manufacturers, there will be some differences in their performance. For example, the same model (standard battery of the same package) has a large difference in battery capacity (10% to 20%).
The main properties of lithium iron phosphate power batteries are listed in Table 1. Other types of rechargeable battery performance are also listed in the table for comparison with other rechargeable batteries. It should be noted here that lithium iron phosphate power batteries produced by different factories may have some differences in various performance parameters; in addition, some battery performances are not included, such as battery internal resistance, self-discharge rate, charge and discharge temperature, and the like.
Overdischarge to zero voltage test:
The STL18650 (1100mAh) lithium iron phosphate power battery was used for over-discharge to zero voltage test. Test conditions: A 1100 mAh STL 18650 battery was charged at a charging rate of 0.5 C, and then discharged at a discharge rate of 1.0 C until the battery voltage was 0 C. The batteries placed in 0V are divided into two groups: one group is stored for 7 days, and the other group is stored for 30 days; after the storage expires, it is filled with a charging rate of 0.5 C, and then discharged with 1.0 C. Finally, compare the differences between the two zero voltage storage periods.
The result of the test is that the battery has no leakage after 7 days of zero voltage storage, and the performance is good, the capacity is 100%; after 30 days of storage, there is no leakage, the performance is good, the capacity is 98%; after 30 days of storage, the battery is further charged and discharged for 3 times. The capacity is restored to 100%.
This test shows that even if the battery is over-discharged (even to 0V) and stored for a certain period of time, the battery will not leak or be damaged. This is a characteristic that other types of lithium-ion batteries do not have.
What is the capacity of the 32650 lithium battery?
The 32650 lithium battery is a kind of cylindrical battery with an outer diameter of 32mm and a height of 65mm. The common lithium iron phosphate battery is common. The capacity of the 32650 lithium battery is very large, and its capacity range is from 4500 to -6500m, but generally there are more than 5000MAH.
32650 lithium iron phosphate battery parameters in detail
1, 7.2VMVB vehicle recorder 32650 iron phosphate battery
Battery model: 18650/3.6V/3000mAh
Battery specifications: 18650-2S5P/7.2V/15Ah
Nominal voltage: 7.2
Nominal capacity: 15Ah
Charging voltage: 8.4V
Charging current: ≤4A
Discharge current: 3A
Instantaneous discharge current: 5A
Discharge cut-off voltage: 5.4V
Finished product internal resistance: ≤150mΩ
Battery weight: 500g
Product size: 46*94*124mm (Max)
Charging temperature: 0 ~ 45 °C
Discharge temperature: -20 ~ 60 °C
Storage temperature: -20 ~ 35 °C
Temperature protection: 70 °C ± 5 °C
Battery case: engineering plastic, ABS+PC
Lithium battery protection: short circuit protection, over charge protection, over discharge protection, over current protection, temperature protection, I2C communication, etc.
Application areas: vehicle recorders, driving recorders, etc.
ABS+PC housing increases battery reliability and robustness
Hardware connector output: Gold-plated shrapnel connector output mode to increase conductive reliability;
Data communication management: using Seiko IC + TI software management chip, accurate data transmission, precise temperature control, * limit to eliminate security risks.
The battery pack has good safety and discharge performance and long cycle life;
The battery pack has a high cycle life and meets the concept of low carbon, energy saving and environmental protection;
2, 4V32650mAh mapping instrument lithium iron phosphate battery
Battery model: 18650/3.7V/2500mAh
Battery specifications: 18650-2S2P/7.4V/5000mAh
Nominal voltage: 7.4V
Nominal capacity: 5000mAh
Charging voltage: 8.4V
Charging current: ≤2.5A
Discharge current: 1.0A
Instantaneous discharge current: 2.5A
Discharge cut-off voltage: 5.6V
Finished product internal resistance: ≤300mΩ
Battery weight: 200g
Product size: 39.2*38.1*70mm (Max)
Charging temperature: 0 ~ 45 °
Discharge temperature: -20 ~ 60 °C
Storage temperature: -20 ~ 35 °C
Battery case: engineering plastic PC material
Lithium battery protection: short circuit protection, over charge protection, over discharge protection, over current protection, etc.
Application areas: surveying and mapping, measurement field.