Lithium battery, as an important power source in modern portable electronic equipment, electric tools, new energy vehicles and other fields, is widely used due to its high energy density, long service life and environmental protection characteristics. Understanding the basic structure of lithium battery is helpful to deeply understand its working principle and performance characteristics. This article will introduce the main components and common structural forms of lithium batteries in detail to help readers master the basic structure of lithium batteries systematically.

I. Basic composition of lithium battery

lithium battery mainly consists of positive electrode, negative electrode, electrolyte, diaphragm, Shell and other parts. All parts cooperate with each other to complete the charging and discharging process of the battery.

1. Positive electrode (Cathode)

the positive electrode is the key material for storing and releasing lithium ions in lithium batteries. It is usually made of lithium-containing metal oxide, such as lithium cobalt oxide, lithium iron phosphate, lithium nickel cobalt manganese oxide (NCM), etc. The positive electrode material determines the capacity, voltage and safety performance of the battery, which is one of the core factors that determine the performance of the battery.

2. Anode

the negative electrode is mainly made of graphite or other carbon materials and has good conductivity and lithium ion embedding ability. During the charging process, lithium ion consistsThe positive electrode is migrated to the negative electrode through electrolyte, and lithium ions migrate in reverse during discharge to complete energy release.

3. Electrolyte (Electrolyte)

electrolyte is a medium for lithium ion conduction between positive and negative electrodes. Generally, organic solvents containing lithium salt are used, such as ethylene carbonate (EC), dimethyl carbonate (DMC), etc. Electrolyte not only affects the migration speed of lithium ions, but also affects the working temperature and safety performance of the battery.

4. Diaphragm (Separator)

diaphragm is a microporous insulation material, which is placed between the positive electrode and the negative electrode to prevent short circuit caused by direct contact between the two poles and allow lithium ions to pass freely. The membrane material generally adopts polyethylene (PE) or polypropylene (PP), which has good chemical stability and mechanical strength.

5. Shell (Case)

the shell is used to wrap and protect the internal structure of the battery, ensure the mechanical strength and tightness of the battery, and prevent electrolyte leakage. Common shell materials include metal box type (such as aluminum case) and soft bag type.

II. Basic structure form of lithium battery

according to the shape and packaging mode of the battery, lithium batteries are mainly divided into three basic structural forms: cylindrical, square and soft bag. Different structural forms have their own advantages and disadvantages, which are suitable for different application scenarios.

1. Cylindrical lithium battery structure

cylindrical lithium battery is the first widely used lithium battery structure, which is similar to the common AA battery. Its main structural feature is to wrap the positive electrode, negative electrode and diaphragm into a tight "winding core", and then put it into a metal cylindrical shell.

• Structural features

  • the winding structure makes the utilization rate of electrode materials high and the energy density high.
  • Metal Shell has good mechanical strength and heat dissipation performance.
  • The structure is stable, the production process is mature, and the cost is relatively low.

• Application Field
  cylindrical batteries are widely used in notebook computers, electric tools, electric bicycles and some electric vehicles.

• Advantages and disadvantages
  the advantages are firm structure, good heat dissipation and stable performance, while the disadvantages are fixed shape., the design flexibility is poor, and the volume utilization rate is relatively low.

2. Square lithium battery structure

square lithium battery adopts flat box shell, and internal electrode also adopts winding or lamination structure. Due to its regular appearance, square batteries can make better use of space and are suitable for equipment with high requirements on volume and weight.

• Structural features

  • it adopts metal hard shell or aluminum case, which has better protection.
  • The internal electrode can adopt a winding or lamination structure.
  • High energy density and good volume utilization rate.

• Application Field
  square batteries are mainly used for mobile phones, tablet computers, electric vehicles and energy storage equipment.

• Advantages and disadvantages
  the advantages are high space utilization rate and large capacity. The disadvantages are that the heat dissipation performance is slightly worse than that of cylindrical shape, and the manufacturing process is complicated.

3. Soft Pack lithium battery structure

soft lithium battery adopts soft aluminum plastic film as the shell, and the internal electrode is usually lamination structure. Its light weight and good flexibility are suitable for applications with high requirements for light weight and diversified shapes.

• Structural features

  • flexible aluminum plastic film package, overall thin and thin.
  • The internal electrodes are of the lamination type, and the layers are closely arranged.
  • The structure is flexible and can be made into various shapes and sizes.

• Application Field
  soft Pack batteries are widely used in smart phones, tablet computers, smart wearable devices and some electric vehicles.

• Advantages and disadvantages
  the advantages are light weight, flexible shape and high volume utilization rate. The disadvantages are relatively weak mechanical strength, high protection requirements and complex safety design.

III. Internal structure of lithium battery

the internal structure of lithium battery mainly includes positive electrode sheet, negative electrode sheet, diaphragm and electrolyte. Take the winding structure as an example, the positive electrode and the negative electrode are respectively coated on metal foil substrateOn, the diaphragm is sandwiched between the two. Multilayer electrodes are tightly combined by winding or lamination to form cell. After Cell is loaded into the shell, the electrolyte is injected and sealed to complete the manufacture of the battery.

• Positive pole piece: aluminum foil coated with positive active material.
• Negative pole piece: coating copper foil of negative active material.
• Diaphragm: clamp between positive and negative poles to prevent short circuit.
• Electrolyte: infiltration electrode and diaphragm, conducting lithium ion.

IV. Influence of lithium battery structure on performance

the structure design of lithium battery directly affects its capacity, power, service life, safety and applicability. For example:

• the winding structure is beneficial to improving energy density and cycle performance.
• Lamination structure is conducive to reducing battery thickness and is suitable for light and thin equipment.
• Shell material and structure affect the heat dissipation performance and mechanical strength of the battery.
• The quality of the diaphragm determines the risk and safety of internal short circuit of the battery.

ThereforeIn the process of designing and manufacturing lithium batteries, reasonable selection of structural forms and optimization of internal structures are the keys to improve the overall performance of batteries.

Lithium battery the basic structure forms of mainly include three types of cylindrical, square and soft bag, each structure has its unique advantages and applicable scope. Positive electrode, negative electrode, electrolyte, diaphragm and Shell are the basic components of lithium battery, which together determine the electrochemical performance and safety characteristics of the battery. Understanding the basic structure of lithium batteries is helpful to better grasp the performance characteristics and application requirements of batteries and provide basic knowledge support for research and development and application in related fields.