Lithium battery cell and lithium battery pack: Understanding their differences

Lithium battery cell and lithium battery pack: Understanding their differences

What is lithium battery cell?

Each lithium battery cell contains a positive electrode (cathode), a negative electrode (anode), a separator, and an electrolyte. 

The basic structure and chemical reactions of lithium battery cells enable them to store and release electrical energy. 

Common types of lithium battery cells include:

1. 18650: With a diameter of 18mm and a height of 65mm, it is widely used in electric toys and power tools.

2. 21700: With a diameter of 21mm and a height of 70mm, it has a higher energy density than 18650 batteries.

3. Li-po: Adopting flexible packaging, widely used in GPS Tracker and Bluetooth speakers.

What is lithium battery pack?

A lithium battery pack is a battery system assembled from multiple lithium battery cells. Lithium battery packs typically include 

a Battery Management System (BMS), NTC, and other auxiliary components to ensure the safe and efficient operation of the battery pack. 

Lithium battery packs can connect multiple battery cells in series or parallel according to application requirements to achieve the required 

voltage and capacity.

The design and structure of battery pack should consider the 

following aspects:

1.BMS: BMS is responsible for monitoring the voltage, temperature, and status of each battery unit, ensuring that the battery operates 

within a safe range, and managing charging and discharging.

2.Heat dissipation system: Lithium battery packs generate heat during the charging and discharging process. Heat dissipation systems 

(such as fans and liquid cooling systems) can effectively reduce the temperature and prevent overheating.

3.Mechanical structure: The battery pack's outsize case and internal bracket must have sufficient mechanical strength to withstand 

external environmental influences such as vibration and impact.

The difference between lithium cells and lithium battery packs

1.Composition and structure:

Lithium battery cell: A single battery cell with a simple structure usually consists of a positive electrode, negative electrode, separator, 

and electrolyte.

Lithium battery pack: a system composed of multiple battery cells, including complex management and protection mechanisms 

such as battery management system (BMS), heat dissipation system, and protection circuit.

2.Features and Applications:

Lithium battery cell: As a basic unit, a single battery cell is mainly used in small electronic devices, such as mobile phones, flashlights, etc.

Lithium battery pack: suitable for scenarios that require high energy and power, such as electric vehicles, energy storage systems, electric tools, etc.

3.Management and protection:

Lithium battery cells: A single battery cell usually does not have complex management and protection functions, and needs to be paid attention to during use.

Lithium battery pack: Built in BMS and protection circuit, it can monitor and manage the status of battery cells in real time, ensuring safety and performance.

Summary

Lithium battery cells and lithium battery packs play different but equally important roles in lithium battery technology. Lithium ion batteries serve as the

basic unit, providing the foundation for energy storage; Lithium battery packs integrate these cells together through complex system design and management 

to meet various high-energy requirements. Understanding their differences and applications can help us better choose and use lithium battery technology.