1. Definition of cylindrical lithium battery

Cylindrical lithium battery is a kind of lithium ion battery. Its shape is cylindrical, so it is called cylindrical lithium battery. Cylindrical lithium battery is divided into lithium cobalt oxide (LiCoO2), lithium manganate (LiMn2O4), Lithium nickel cobalt manganate (LiNiMnCoO2 or NMC), lithium nickel cobalt aluminate (LiNiCoAlO2 or NCA), lithium iron phosphate (LiFePO4) and lithium titanate (Li4Ti5O12). There are many types of cylindrical lithium batteries, the common ones are 14500, 14650, 18500, 18650, 21700, 26650, 32650, etc., which are widely used in various equipment.

2. Cylindrical lithium battery structure

The structure of a typical cylindrical battery includes: shell, cap, positive electrode, negative electrode, separator, electrolyte, PTC element, gasket, safety valve, etc. Generally, the battery case is the negative electrode of the battery, the cap is the positive electrode of the battery, and the battery case is made of nickel-plated steel plate.

3. The advantages of cylindrical lithium batteries

The production process is mature, the PACK cost is low, the battery product yield rate is high, and the heat dissipation performance is good. Cylindrical batteries have formed a series of internationally unified standard specifications and models with mature technology and suitable for continuous mass production. The specific surface area of the cylinder is large, and the heat dissipation effect is good. Cylindrical batteries are generally sealed batteries, and there are no maintenance problems during use. The battery shell has high pressure resistance, and there will be no phenomena such as square, flexible packaging battery swelling during use.

4.Cylindrical lithium battery cells, modules and battery packs

1. Cylindrical lithium battery： The battery cell is the smallest unit of a lithium battery pack and also an electric energy storage unit. It must have a higher energy density to store as much electric energy as possible to make the equipment work longer. In addition, the life of the lithium battery is also the most critical factor, any damage to a battery will cause damage to the entire battery pack. 

2. Lithium battery module： When multiple cells are encapsulated by the same housing frame and communicate with the outside through a unified boundary, this constitutes a module. 

3. Lithium battery pack When several modules are jointly controlled or managed by the BMS and thermal management system, this unified whole is called a lithium battery pack.

Cylindrical lithium battery safety test items

In order to ensure the safety of cylindrical lithium batteries, domestic and foreign institutions have formulated various safety testing standards for cylindrical lithium batteries. General testing standards generally divide safety testing items into the following four categories: 

Electrical test: overcharge, overdischarge, external short circuit, forced discharge, etc. 

Mechanical test: squeeze, acupuncture, shock, vibration, drop tester, etc. 

Thermal test: high and low temperature cycle, combustion, microwave heating, etc. 

Environmental simulation: high-altitude and low-pressure simulation, salt spray test, etc.

ACEY provides all kinds of battery environment testing equipment, welcome to consult.