A complete analysis of battery cells, modules, battery packs and energy storage technologies
In the new energy sector, battery cells, modules, and battery packs are the core components of energy storage systems. Energy storage systems are categorized into household storage, commercial storage, and large-scale storage based on their application scenarios. This article provides a brief introduction to these concepts.
1. Battery Cell
The battery cell is the basic unit of a battery, responsible for storing and releasing electrical energy. Lithium-ion battery cell packaging is primarily categorized into hard-shell and soft-shell packaging. Hard-shell packaging is primarily made of steel or aluminum, and is categorized into cylindrical and square shapes depending on the arrangement of the positive and negative electrodes within. Soft-shell packaging primarily utilizes aluminum-plastic film. When selecting a battery cell, consider its capacity decay throughout its lifecycle and evaluate its performance to ensure it meets the requirements of the vehicle or energy storage system.
Prismatic batteries are widely used in electric vehicles, such as the Tesla Model S and Model X. They are also widely used in large-scale energy storage systems, such as grid-side energy storage and industrial park energy storage.
Cylindrical batteries are widely used in various power tools, driving recorders, UPS power supplies, etc., providing a stable power supply. Cylindrical batteries are also used in some electric vehicles, such as Tesla Model 3 and Model Y. Common models include 18650, 21700, and 32650.
Soft-pack batteries are widely used in consumer electronics such as smartphones, tablets, wearable devices, etc., providing high energy density and lightweight power supply.
Prismatic cells, cylindrical cells and soft-pack cells
2. Module
We all know that the battery pack is the “heart” of new energy vehicles , and the module is like “tissue”, composed of smaller “cells” that constitute the larger heart organ.
A battery module is a single physical unit composed of multiple cells connected in series and parallel, providing higher voltage and capacity. Module assembly requires consideration of production yield, efficiency, and the internal resistance of the connection points. Currently, laser welding is the preferred method for many battery manufacturers. The module’s design and manufacturing process significantly impact the performance and safety of the battery pack.
1P13S square shell battery module
3. Battery Pack
A battery pack, comprised of multiple battery modules and incorporating a battery management system (BMS), is the final product delivered by the battery manufacturer to the user. Battery pack design must consider the vehicle’s space requirements, all-electric range requirements, the appropriate cell type and capacity, and the operating voltage range of other electrical components. The battery pack’s structural components include the battery modules, electrical system, thermal management system, housing, and BMS.
Electrical system: It consists of connecting copper bars, high-voltage wiring harness, low-voltage wiring harness and electrical guarantee devices. The high-voltage wiring harness is responsible for transmitting battery power to the end load, while the low-voltage wiring harness transmits detection signals and control signals in real time.
Thermal management system: TMS, There are two main methods: air cooling and liquid cooling. Liquid cooling can be divided into cold plate liquid cooling and immersion liquid cooling. Its function is to ensure that the battery operates at a reasonable ambient temperature and improve the battery cycle life.
Housing: Composed of the housing itself, housing cover, metal brackets, panels, and fixing screws, it serves to provide support, resist mechanical impacts and vibrations, and protect the internal components.
BMS (Battery Management System): Responsible for measuring battery parameters such as voltage, current and temperature. It also has functions such as balancing and can transmit data to MES.
Explosion diagram of new energy vehicle power battery pack
4. Energy Storage Technology
The global energy transition is accelerating, ushering in a period of rapid development for the energy storage industry. The Chinese government has issued a number of policies, such as the “Guiding Opinions on Accelerating the Development of New Energy Storage” and the “14th Five-Year Plan for New Energy Storage Development,” to promote the diversified development of new energy storage technologies. Energy storage is one of the core technologies driving the world’s clean, electrified, and efficient energy transition. China’s demand for electrochemical energy storage is projected to exceed 80GWh by 2025, with a compound annual growth rate of 60%. Energy storage systems can be categorized into household storage, commercial storage, and large-scale storage, depending on the application scenario.
A large containerized lithium-ion battery energy storage power station
Household storage : Household energy storage systems are usually used for home emergency power supply, photovoltaic power generation and energy storage, etc. They are relatively small in scale and generally adopt a modular design for easy installation and maintenance.
Industrial and commercial storage : Industrial and commercial energy storage systems are used in commercial and industrial fields, such as industrial parks and commercial complexes. They are medium-sized and can effectively balance the grid load and reduce electricity costs.
large-scale storage : Large energy storage systems are usually used for grid-side energy storage. They are large in scale and can participate in auxiliary services such as grid frequency regulation and peak regulation to improve grid stability and reliability.
Currently, there are three main approaches to integrating battery pack systems: CTM (module integration), CTP (module-free integration), and CTC/CTB (all-in-one integration). CTP is currently the most mainstream solution. Different integration methods have their own advantages and disadvantages. Choosing the right one can improve the performance and safety of energy storage systems.