With the development of lithium battery technology and the gradual decrease in the cost of industrial and commercial energy storage systems, lithium batteries have been widely used in various fields. Its advantages such as high energy density, long service life and more in line with environmental protection concepts are highlighted. In the future of the digital era, more equipment will be electrified.
As new energy is the cornerstone of the digital society, the future development trend of lithium batteries is limitless. This article mainly introduces what is in a lithium battery.
1.what is in a lithium battery in different parts?
- Voltage: unit volt V
Voltage is the potential difference across the battery, which can be compared to the water pressure across a water pipe.
- Current : Ampere A
The directional movement of charges creates an electric current. Electric current can be the movement of electrons in conductors such as wires, or the movement of ions in the electrolyte in the positive and negative electrodes.
- Capacity: ampere-hour Ah
The amount of electricity stored in a battery is measured in amps per hour, which represents the amount of electricity that is continuously charged or discharged from the battery in one hour. For example, a 20Ah battery means that it can discharge continuously for 1 hour with a current of 20A, and it can discharge for 2 hours with a current of 10A.
Approximate value of appropriate voltage marked by the manufacturer This value will last the longest discharge time. For example, the working voltage of ternary lithium battery is between 2.8V and 4.2V, and the nominal voltage is 3.7V. The working voltage of lithium iron phosphate is between 2.5V and 3.65V, and the nominal voltage is 3.2V. We are designing a battery pack When calculating the voltage, the nominal voltage is used as the base.
- Nominal capacity
The capacity of the battery cell to store electrical energy marked by the manufacturer is generally expressed in mAh or Ah (1000mAh=1Ah). Nominal capacity is an important basis for designing battery packs, calculating capacity and ensuring consistency.
- Magnification C
The ratio of current to battery nominal capacity when the battery is charging and discharging. This is a very important parameter for lithium batteries. The maximum charge and discharge time and charge and discharge current of the battery can be calculated based on the rate. For example, for a 2Ah 5C battery, 5C means that 2Ah of electricity can be discharged in 0.2 hours at the fastest, which is the maximum continuous discharge of the battery. The current can reach 10A.
The fastest discharge time formula: 1÷5C=0.2 hours
Maximum discharge current formula: 2Ah×5C=10A.
The battery can also be compared to a bucket. 1C means that there is a faucet. When the faucet is fully opened, the water in the bucket will drain out in just one hour. 5C means that the bucket has 4 more faucets of the same size as before. The faucet is fully opened.
Under normal conditions, the flow rate of 5C is five times that of 1C, and the time it takes to drain a bucket of water is only one-fifth of that of 1C. Battery cells with larger magnifications are more expensive. Batteries with appropriate magnification must be selected according to the usage scenario.
For example, drones, model aircraft, power tools, etc. have restrictions on size and weight, but the motor power is large and the continuous discharge current is large. What is in In terms of a lithium battery, it is impossible to make the voltage and capacity of the battery large enough.
In this case, it can be compensated by high-rate batteries, generally above 10C. Low-speed vehicles generally have higher voltage and capacity, and 3C or 5C batteries are basically sufficient. The higher the magnification, the smaller the internal resistance.
2. What is lithium battery short circuit?
The current forms a loop between the positive and negative electrodes directly through the internal or external wires of the battery without passing through external electrical appliances, causing all current to flow back to the battery. This situation is called a short circuit.
Internal short circuits mainly include forced internal short circuits caused by metal objects piercing the battery shell, and expansion and deformation of the battery cells after overcharging, resulting in contact short circuits between the positive and negative materials inside the battery cells.
External short circuits are mainly caused by unreasonable layout of the protective board cables, and extrusion causing the insulation rubber of the cables to fall off and cause a short circuit. Short circuits between the battery shell and the bus bar, the shell and the shell, etc. caused by insufficient insulation measures when the battery cells are arranged.
When a short circuit occurs, the current will be very large, which will lead to air crash consequences. Most accidents of lithium batteries are caused by short circuits, so the hidden danger of short circuits must be eliminated in practical operations. If you are interested, here is more information about top bes manufacturers.
3. What are overcharge, over-discharge and over-current of lithium batteries?
The working voltage and current of a single lithium battery, that is, the cell, must be within the rated range, otherwise it will not only cause permanent damage to the cell, but may also cause catastrophic consequences such as explosion and combustion.
- Overcharging: The lowest working voltage of ternary lithium battery is 2.8V and the highest working voltage is 4.2V. The lowest working voltage of lithium iron phosphate battery is 2.5V and the highest working voltage is 3.65V. In the battery charging system overcharging will cause the cell voltage to exceed the maximum operating voltage, which is overcharging.
Overcharging can cause expansion and deformation of the battery core, permanent damage, or thermal runaway caused by internal short circuit, which may eventually lead to major accidents such as combustion and explosions.
- Over-discharge: Excessive discharge will cause the cell voltage to be lower than the minimum operating voltage, which is over-discharge. In what is in a lithium battery, over-discharge can also cause permanent damage to the battery core and cause thermal runaway safety hazards caused by the large amount of heat generated by the battery core.
- Overcurrent: If the battery charging and discharging current is too large and exceeds the rated current of the battery, it is overcurrent. Overcurrent will also cause irreversible damage to the battery. The rated charge and discharge current of the battery is subject to the battery cell manufacturer’s specifications.
4.what is in a lithium battery--cell
In what is in a lithium battery, the most commonly used batteries are still ternary lithium and lithium iron phosphate. The main shapes are 18650, but the lithium-ion battery pack with large single cells has lower cost and lower assembly process requirements, and is increasingly favored in the field of low-speed power batteries.
When designing a set of batteries, the main factors to consider when selecting batteries are: voltage, capacity, volume, cost, etc. Take a set of 60V20Ah battery pack as an example. If it is made of 2000mAh 18650 ternary lithium battery, the total voltage of 60V will require 60V÷3.7V=16.2 strings, that is, 17 strings will be connected in series, and the total capacity of 20Ah will require 20Ah÷ 2Ah = 10 cells, that is, each string requires 10 cells in parallel. The battery pack is 10P17S, which requires a total of 10P × 17S = 170 cells. The formula can be summarized as:
        The total voltage of the battery pack V÷the nominal voltage of a single cell V=the number of series connections of the battery pack S
        The total capacity of the battery pack Ah÷the nominal capacity of a single cell Ah=the number of parallel connections in each string of the battery pack P
        The number of series connections of the battery pack S × the number of parallel connections of the battery pack P = the total number of cells in the battery pack
Good lithium battery cells can make good batteries, so they must be screened for consistency before assembly. If there is no automatic sorting machine, you must also use it. The internal resistance meter is manually screened. Some beginners omit this step because the supplier has already done the capacity matching, which will cause great hidden dangers to the battery pack. What is in a lithium battery follows the principle of consistency screening.
This is a combination of cells from the same manufacturer and the same batch. The voltage difference does not exceed 5mV and the internal resistance difference does not exceed 3mΩ.
If the number of cells purchased is small, it cannot be achieved. This error requirement must also be able to select the voltage and match it with a small internal resistance difference.
Therefore, consistency and capacity are the core indicators when purchasing batteries. At present, most of the batteries purchased in small batches are B-grade batteries or disassembled batteries, and the consistency of the batteries is particularly important.
5.what is in a lithium battery--composition
What is in a lithium battery The lithium battery material composition mainly includes positive electrode material, negative electrode material, separator and electrolyte.
- Cathode material
Among lithium battery cathode materials, the most commonly used materials are lithium cobalt oxide, lithium manganate, lithium iron phosphate and ternary materials (polymers of nickel, cobalt and manganese).
- Negative electrode material
Among the negative electrode materials, the current negative electrode materials of lithium batteries are mainly natural graphite and artificial graphite. Anode materials being explored include nitrides, PAS, tin-based oxides, tin alloys, nano-anode materials, and other intermetallic compounds.
- Diaphragm
Marketed separator materials are mainly polyolefin (Polyolefin) separators based on polyethylene (PE) and polypropylene (PP). In the structure of lithium batteries, the separator is one of the key inner components.
- Electrolyte
The electrolyte is prepared from high-purity organic solvents, electrolyte lithium salts, necessary additives and other raw materials under certain conditions and in certain proportions.
How to capture and store excess power as a backup energy source has become a major challenge. Stationary energy storage technology will play an important role in solving this problem and become an important part of the future energy infrastructure.
This article presents an in-depth analysis of the top 10 smart energy storage systems in China in 2023. With China’s increasing focus on renewable energy integration and grid stability, these systems have emerged as cutting-edge solutions.
This article introduces the top 10 PV manufactures in China, they are TONGWEI GROUP, LONGIJinKO Solar, TBEA, Trinasolar, JA solar, TCL-ZHONGHUAN, SUNGROW, CHNT, Risen.
+86 – 18925002618
