I. Battery Cell
A battery cell is the basic unit of a battery, responsible for storing and releasing electrical energy. Based on the casing, lithium-ion battery cells are mainly divided into two categories: hard-shell and pouch. Hard-shell packaging primarily uses steel and aluminum casings, and is further divided into cylindrical and prismatic shapes based on the arrangement of the positive and negative electrodes. Pouch packaging mainly uses aluminum-plastic film. Selecting a battery cell requires considering its capacity decay throughout its entire lifespan and evaluating its performance in various aspects to meet the requirements of the vehicle or energy storage system.
Prismatic batteries are widely used in the electric vehicle field, such as 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, dashcams, UPS power supplies, etc., to provide a stable power supply; they are also used in some electric vehicles, such as Tesla Model 3 and Model Y, with common models including 18650, 21700, and 32650.
Pouch batteries are widely used in consumer electronics products such as smartphones, tablets, and wearable devices, providing high energy density and lightweight power supply.
II. Module
We all know that the battery pack is the "heart" of a new energy vehicle, while the module is like an "organ," composed of smaller "cells" that together form a larger heart organ.
A battery module is a single physical module assembled from multiple battery cells connected in series and parallel, providing higher voltage and capacity. Module assembly requires consideration of production yield, efficiency, and the internal resistance of connection points; currently, laser welding is the preferred choice for many battery manufacturers. The design and manufacturing process of the module have a significant impact on the performance and safety of the battery pack.
III. Battery Pack
A battery pack is composed of multiple battery modules and incorporates a battery management system (BMS), representing the final product provided by the battery manufacturer to the user. The design of a battery pack needs to consider meeting the vehicle's space requirements, pure electric range requirements, selecting appropriate cell types and capacities, and understanding the operating voltage range of other electrical components in the vehicle. The structural components of a battery pack include battery modules, an electrical system, a thermal management system, a casing, and the BMS.
The electrical system consists of connecting copper busbars, high-voltage wiring harnesses, low-voltage wiring harnesses, and electrical protection devices. The high-voltage wiring harnesses are responsible for delivering battery power to the end load, while the low-voltage wiring harnesses transmit detection and control signals in real time.
Thermal management system: There are two main types of cooling: 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.
Enclosure: Composed of enclosure, enclosure cover, metal bracket, panel and fixing screws, it serves to provide support, resist mechanical impact and vibration and protect the environment.
BMS (Battery Management System): It is responsible for measuring parameters such as battery voltage, current and temperature, and also has functions such as equalization. It can transmit data to MES.
IV. Energy Storage Technology
The global energy transition is accelerating, and the energy storage industry is entering a period of rapid development. The Chinese government has issued several policies, such as the "Guiding Opinions on Accelerating the Development of New Energy Storage" and the "Implementation Plan for the Development of New Energy Storage during the 14th Five-Year Plan Period," to promote the diversified development of new energy storage technologies. Energy storage technology is one of the core technologies driving the world's clean, electrified, and efficient energy development. It is projected that by 2025, China's demand for electrochemical energy storage will exceed 80 GWh, with a compound annual growth rate of 60%. Depending on the application scenario, energy storage systems can be divided into residential storage, industrial and commercial storage, and large-scale storage.
Household energy storage: Household energy storage systems are typically used for emergency power supply in homes, photovoltaic power generation energy storage, etc. They are relatively small in scale and generally adopt a modular design for easy installation and maintenance.
Industrial and commercial energy storage: Industrial and commercial energy storage systems are applied in commercial and industrial sectors, such as industrial parks and commercial complexes. They are of medium scale and can effectively balance the grid load and reduce electricity costs.
Large-scale energy storage: Large-scale energy storage systems are typically used for grid-side energy storage. They are large in scale and can participate in ancillary services such as grid frequency regulation and peak shaving, thereby improving grid stability and reliability.
Currently, there are three main integration methods for battery pack systems: CTM (module integration), CTP (module-less integration), and CTC/CTB (integrated integration). Among them, CTP is currently the most mainstream solution. Different integration methods have their own advantages and disadvantages, and choosing the appropriate method can improve the performance and safety of the energy storage system.
