The 18650 cylindrical lithium battery cell mainly consists of five parts: a metal casing, a positive electrode, a negative electrode, a thin film, and an electrolyte. Each part performs its specific function to ensure normal charging and discharging. The detailed structure is as follows:
Cathode: The cathode material for 18650 cylindrical lithium-ion battery cells is generally lithium iron phosphate, lithium cobalt oxide, etc. The difference in each cathode material will directly affect the characteristics and cost of 18650 lithium-ion batteries.
Negative electrode: The negative electrode materials for 18650 cylindrical lithium-ion battery cells include tin-based negative electrode materials, nano-scale negative electrode materials, and carbon negative electrode materials. In the battery, the negative electrode material plays an oxidation role. It has a relatively low potential.
Electrolyte solution: Taking lithium iron phosphate as an example, it consists of a solute and a solvent. Solute: Lithium salts are commonly used, such as lithium perchlorate, lithium hexafluorophosphate, and lithium tetrafluoroborate. Solvent: Organic solvents are commonly used in lithium-ion batteries, such as diethyl ether, ethylene carbonate, propylene carbonate, and diethyl carbonate.
Advantages of 18650 cylindrical lithium battery cells
1. Long cycle life: The cycle life of 18650 lithium batteries can reach more than 500 times, which is more than twice that of ordinary batteries.
2. Large capacity: The capacity of a typical 18650 cylindrical lithium battery cell is generally between 1200mAh and 3100mAh, while the capacity of a typical battery is only around 800mAh. This is just for a single 18650 cylindrical lithium battery cell; if they are combined into an 18650 lithium battery pack, then exceeding 5000mAh is not a problem at all.
3. High safety performance: To prevent short circuits, the positive and negative terminals of 18650 lithium batteries are separated. Therefore, the possibility of a short circuit is minimized. It boasts high safety performance, is non-explosive, and non-combustible.
4. High voltage: The voltage of 18650 lithium batteries is generally above 3.6 or 3.7V, which is much higher than the 1.2V voltage of nickel-cadmium and nickel-metal hydride batteries.
5. No memory effect: Charge and discharge as needed, convenient to use.
Disadvantages of 18650 cylindrical lithium battery cells
1. Stability: Compared to polymer lithium batteries, 18650 lithium batteries are more prone to short circuits or explosions.
2. Do not overcharge: 18650 lithium battery production requires protection circuits to prevent the battery from being overcharged and causing discharge.
3. High cost: The production conditions for 18650 lithium batteries are demanding, which undoubtedly increases production costs.
