Knowledge popularization, what is 18650 battery cell?

2024-01-30 293

The 18650 cell, with its precise 18650 mm standard size and classic cylindrical appearance, stands out among many cell types. Because of its mature production process and reliable performance, this kind of cell has been widely used in various electronic equipment.

As a key component of new energy technology, the 18650 battery cell not only improves the overall efficiency of energy storage systems, but also promotes innovation in industries such as portable electronics and electric vehicles. Next, let's explore the characteristics of the 18650 cell and its application prospects in the rapidly changing energy world.

The 18650 cell is a widely used rechargeable cylindrical lithium-ion battery. The battery is named for its dimensional characteristics, which are approximately 18 mm in diameter and 65 mm in length, with the "0" at the end indicating that it is cylindrical.

18650 cells are favored in many fields because of their high energy density, long life and stable discharge characteristics.

Development history

1991: SONY commercializes the first lithium-ion battery, marking the beginning of the era of modern rechargeable batteries.

1996: Panasonic introduces the first 18650 cell, a specification that later became the mainstay of the lithium-ion battery market.

2006: Tesla Motors releases its first electric car, the Roadster, with a high-capacity battery pack consisting of thousands of 18,650 cells.

2010: Tesla introduces the Model S, which uses a battery pack with a larger capacity of 18,650 cells to achieve a longer range.

2013: Announced a partnership between Panasonic and Tesla to establish the Gigafactory, which will specialize in producing 18650 batteries to meet the demand for Tesla electric vehicles.

2015: Manufacturers such as LG Chem and Samsung SDI begin to introduce higher-capacity 18650 cells that offer longer range and higher energy density.

2017: It is announced that Tesla will work with Panasonic to develop a larger capacity 21700 cell, which will be used for the first time in the Model 3.

2018: Tesla announces it will build its own Gigafactory in Shanghai, China, to produce 18,650 cells and 21,700 cells to meet market demand.

2020: With the rapid growth of the electric vehicle market and the popularity of renewable energy, 18650 cells continue to be widely used in electric vehicles, energy storage systems and portable electronic devices.

2021: Some battery manufacturers are starting to introduce higher capacity, higher energy density 18650 cells to meet growing demand and improve battery performance.

Material system

As the mainstream form of cylindrical lithium-ion batteries, the 18650 battery cell has a very rich material system, and the material system of lithium batteries mainly involves positive electrode materials, negative electrode materials, electrolyte and diaphragm. The following are the material systems used in these major parts:

Positive electrode material

Lithium cobalt oxide (LiCoO2) : A material widely used in early lithium-ion batteries, providing a higher energy density, but at a higher cost and with poor thermal stability.

Lithium nickel-manganese-cobalt oxide (LiNiMnCoO2, NMC) : Balances energy density, cost and safety and is widely used in electric vehicles and portable electronic devices.

Lithium nickel cobalt aluminum oxide (LiNiCoAlO2, NCA) : provides a high energy density and is commonly used in applications requiring high performance, such as some models of electric vehicles.

Lithium iron phosphorus (LiFePO4, LFP) : has good thermal stability and long life, but relatively low energy density, suitable for applications with high safety requirements.

Lithium manganese oxide (LiMn2O4, LMO) : has good power characteristics and thermal stability, but has a short cycle life.

Negative electrode material

Graphite: The most commonly used anode material, is widely used because of its good stability and low cost.

Hard carbon: has higher first efficiency and better power characteristics than graphite, and is often used in special applications.

Lithium titanium oxide (Li4Ti5O12, LTO) : provides excellent cycle stability and safety, but has a low energy density.

Electrolyte

It is composed of lithium salts (e.g., lithium hexafluorophosphate LiPF6) dissolved in one or more organic solvents (e.g., EC: ethyl carboxate, DEC: diethyl carboxate, DMC: dimethyl carboxate, etc.).

Diaphragm

Mainly made from polyolefin materials such as polypropylene (PP) and polyethylene (PE), which exist in multilayer or single-layer form and are used to isolate positive and negative electrodes while allowing lithium ions to pass through.

These different material systems affect the performance of the 18650 cell, including energy density, power density, cycle life, safety and cost. Different applications have different requirements for these parameters, so various factors need to be considered in the design of cells to meet specific needs. With the development of the technology, new materials and compounds are being studied to further improve the performance and safety of the cell.

Application field

Power tool

18650 cell is widely used in power tools, such as electric drill, electric screwdriver, electric saw and so on. Its high energy density and high discharge power enable power tools to provide lasting service time and efficient working performance.

Portable electronic equipment

18650 batteries are widely used in portable electronic devices, such as laptops, tablets, mobile phone charging banks and so on. Their relatively large capacity and rechargeable characteristics allow these devices to provide lasting use time and can be re-used by charging.

Energy storage system

With the rapid development of renewable energy, energy storage systems have become a key component. 18650 cells are widely used in energy storage systems to store energy from renewable sources such as solar and wind energy for daytime or non-wind time use.

Consumer electronics

The 18650 cell is also used in other consumer electronics products, such as handheld game consoles, electronic cigarettes, drones and so on. Their high energy density and rechargeable characteristics allow these products to provide lasting use time and stable performance.

In SUMMARY:

18650 cells are still a very high share of the lithium market, whether it is new energy vehicles, or other emerging areas such as energy storage and play an important role.

In the progress of science and technology, it can be predicted that the 18650 battery cell will be further optimized and innovative in the future, and will not be eliminated by the market in a short time as a classic cylinder typical. However, higher energy density and longer cycle life are the main development directions. This will lead to a more durable power supply for areas such as portable electronic devices, power tools and electric vehicles, and promote the development of new energy sectors.