In classifying the use scenarios of batteries, a distinction is made between consumer batteries (batteries for consumer electronics used in cell phones, notebooks, digital cameras, etc.), power batteries (new energy vehicles, light electric vehicles, power tools, etc.), and energy storage batteries (power stations, communication base stations, etc.).
A power battery is actually a kind of storage battery. However, due to the limitation of the size and weight of the vehicle and the acceleration requirements for starting, the power battery has higher performance requirements than an ordinary energy storage battery. Generally, compared with storage batteries, power batteries have a higher energy density, faster charging speed, and larger discharge current. Next, let's figure out the differences between power batteries and energy storage batteries from different vantage points.
As one of the fields with the greatest potential for future development of lithium batteries, energy storage batteries, and power batteries have no difference in technical principles, but due to different application scenarios, actual applications have different requirements for performance and service life, etc.
Power batteries are mainly used in electric vehicles, electric bicycles, and other electric tools, while energy storage batteries are mainly used in peak-shaving and frequency-regulating power auxiliary services, renewable energy grid connections, micro-grids, and other fields.
As a mobile power source for automobiles, power batteries have high requirements for energy density and power density. The vast majority of energy storage devices do not need to be moved. Although many manufacturers are working hard to increase the energy density of energy storage batteries, energy storage lithium batteries themselves have no direct requirements for energy density; due to the wide range of application scenarios of energy storage batteries, there are big differences between power generation side, grid-side and demand-side, and different scenarios have different requirements for power density.
Compared to power lithium batteries, energy storage lithium batteries have higher lifetime requirements. The lifetime of new energy vehicles is usually 5-8 years, while the lifetime of energy storage projects is usually expected to be more than 10 years. The cycle number of electricity lithium battery is 1000-2000 times, while the cycle number of an energy storage lithium battery is generally required to be more than 3,500 times. If the frequency of charge and discharge is increased, the cycle number requirements of the energy storage battery will be higher.
For safety and economic considerations, LiFePO4 batteries are usually used when choosing lithium battery packs as power batteries. The mainstream energy storage battery types include LiFePO4 batteries and ternary lithium batteries. With the energy density problem of lithium iron phosphate batteries solved, the proportion of lithium iron phosphate batteries has increased year by year. At the same time, with the major breakthroughs in many new battery technologies such as sodium-ion batteries and solid-state batteries, the position of LiFePO4 batteries will be no longer unchallenged.
A complete electrochemical energy storage system is mainly composed of a battery pack, battery management system (BMS), energy management system (EMS), power conversion system(PCS), and other electrical equipment. The battery pack is the most important component of the energy storage system; the battery management system is mainly responsible for battery monitoring, evaluation, protection, and equalization; the energy management system is responsible for data collection, network monitoring, and energy scheduling; the power conversion system can control the charging and discharging process of the energy storage battery pack and perform AC-DC conversion.
In the cost composition of the energy storage system, the battery is the most important part of the energy storage system, accounting for 60% of the cost; followed by the PCS(power conversion system), accounting for 20%, and the EMS (energy management system) accounting for 10%. BMS (battery management system) costs account for 5%, and others account for 5%.
Power battery PACK refers to the battery pack of new energy vehicles, which provides energy for the operation of the whole vehicle. Vehicle power battery PACK is basically composed of the following five systems: battery module, battery management system, thermal management system, electrical system, and structural system.
The cost of the power battery system consists of comprehensive costs such as batteries, structural parts, BMS, boxes, auxiliary materials, and manufacturing costs. The battery cell accounts for about 80% of the cost, and the cost of the pack (including structural parts, BMS, box, auxiliary materials, manufacturing costs, etc.) accounts for about 20% of the entire battery pack cost.
In the battery pack, BMS (battery management system) is the core, which determines whether the various components and functions of the battery pack can be coordinated, and is directly related to whether the battery pack can provide power output for electric vehicles safely and reliably. Of course, the connection process, space design, structural strength, and system interface of structural parts also have an important impact on the performance of the battery pack.
The energy storage battery management system is similar to the power battery management system, but the power battery system is on a high-speed electric vehicle and has higher requirements for the power response speed and power characteristics of the battery, SOC estimation accuracy, and the number of state parameter calculations. Relevant adjustment functions also need to be realized through BMS.