Energy storage batteries and power batteries are today's important technology in the field of energy storage and electric transportation, in essence, the two types of batteries are energy storage batteries, in the technology route is not very different, then in the end, the two types of batteries where the difference?
What is an energy storage battery?
Energy storage batteries, as the name suggests, are battery systems used to store electrical energy. They are capable of converting electrical energy into chemical energy, storing the charge in the battery and then releasing it when needed. Energy storage batteries are typically designed for long-duration energy storage and charging/discharging and play an important role in, for example, grid scheduling, peak load reduction and power management. The key characteristics of energy storage batteries are high capacity, long cycle life and stable performance.
What is a power battery?
Power batteries, on the other hand, are specialized in providing the power needed for electric vehicles. They need to have high energy density and high power output to meet the acceleration and range requirements of electric vehicles. The design of power batteries focuses on improving the charging rate, discharging rate and cycle life of the batteries. At the same time, safety is also an important aspect of concern for power batteries to ensure reliable operation under a variety of conditions.
01 Application Scenario Difference
Energy storage batteries are widely used in grid energy storage, home energy storage, industrial and commercial energy storage, communication base stations and other fields, the design requirements of energy storage batteries are mainly optimized for energy density and long-term storage to meet the demand for large-capacity and long-lasting energy storage. As the vast majority of energy storage batteries do not need to move the energy storage device,
so the lithium battery for energy storage does not have direct requirements for energy density; different energy storage scenarios have different requirements for power density; battery materials, pay attention to the expansion rate, energy density, electrode material performance uniformity, etc., in order to pursue the entire energy storage equipment, long life and low cost.
Power batteries are used in new energy passenger cars, commercial vehicles, special vehicles, engineering machinery and equipment, ships and so on. Power batteries pay more attention to power density and short-term high power output to meet the needs of electric vehicles for fast acceleration and long mileage. Compared with energy storage batteries, power batteries require higher energy density and power density. Moreover, due to the limitation of vehicle size and weight as well as the acceleration during startup, power batteries have higher performance requirements than ordinary energy storage batteries.
02 System Composition Differences
Power battery PACK basically consists of the following five systems: battery module, battery management system, thermal management system, electrical system and structural system. The cost of power battery system consists of the comprehensive cost of electric cell, structural components, BMS, case, auxiliary materials, manufacturing costs, etc. The electric cell occupies about 80% of the cost, and the cost of Pack (including structural components, BMS, case, auxiliary materials, manufacturing costs, etc.) occupies about 20% of the cost of the whole battery pack.
Energy storage battery system is mainly composed of battery pack, battery management system (BMS), energy management system (EMS), energy storage converter (PCS) and other electrical equipment. In the cost composition of the energy storage system, the battery is the most important component of the energy storage system, accounting for 60% of the cost; followed by the energy storage inverter, accounting for 20%, the EMS (energy management system) cost accounts for 10%, the BMS (battery management system) cost accounts for 5%, and the other is 5%.
03 Battery Management Differences
BMS (Battery Management System), as the core component of the battery system, determines whether the various components and functions of the battery pack can be coordinated, and is directly related to whether the battery pack can safely and reliably provide power output for electric vehicles.
Energy storage battery management system is similar to the power battery management system, but the power battery system is in the high-speed movement of the electric vehicle, the power response speed and power characteristics of the battery, SOC estimation accuracy, the number of state parameter calculations, there are higher requirements, and the related regulatory functions need to be realized through the BMS.
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Energy Storage Battery BMS |
Power Battery BMS |
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Position in the respective systems |
There is an information interaction mainly with the converter and the energy storage battery scheduling system. On the one hand, the battery management system sends important status information to the converter to determine the high-voltage power interactions; on the other hand, the battery management system sends the most comprehensive monitoring information to the PCS, the scheduling system of the energy storage plant. |
In terms of high voltage, there is an energy exchange relationship with both the motor and the charger; in terms of communication, there is an information interaction with the charger in the charging process, and in the whole application process, there is the most detailed information interaction with the vehicle controller. |
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Hardware Logic Architecture |
Hardware is generally in a two- or three-tier model, with larger scales favoring three-tier management systems. |
There is only one layer of centralized or two distributed types, basically there will not be three layers. Small cars mainly apply one layer of centralized battery management system. |
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Comparison of communication protocols |
The CAN protocol is basically used for internal communication, but the TCP/IP protocol is often used for external communication, which mainly refers to the energy storage plant scheduling system PCS. |
The CAN protocol is used in all electric vehicle environments, but only according to the internal CAN between the internal components of the battery pack, and the vehicle CAN between the battery pack and the vehicle. |
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Threshold setting |
Part of the energy storage power station is located in remote transportation inconvenience, large-scale replacement of the battery is more difficult, pay more attention to the long life and reduce the failure rate, so the upper limit of the operating current will be set relatively low, do not let the battery cell work at full load. For the energy characteristics and power characteristics of the battery cells do not require particularly high requirements, focus on cost-effective. |
Due to the limited space of the vehicle, the system parameters are set with reference to the limit parameters of the battery. |
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Comparison of SOC estimation accuracy |
Most of the storage battery application environments have relatively abundant space and stable environments, and small deviations are not easily perceived in large systems, so there is no uniform requirement for SOC. |
Requirements for SOC computing power are much higher than those of energy storage BMS, and accordingly, the management cost of a single string of batteries is also higher. |
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Applying passive equilibrium conditions |
The scale of the storage battery module is relatively large, multiple strings of batteries in series, the larger single-voltage difference will cause the capacity of the entire box to fall, the more batteries in series, the more capacity it loses, from the point of view of economic efficiency considerations, the energy storage plant is very much in need of adequate equalization, the low cost of passive equalization is very valuable |
Smaller capacity battery packs are more suitable for passive equalization when single cell consistency is strong |
04 Difference in cycle times
Power batteries and storage batteries have different requirements for service life, energy storage batteries usually need to have a longer cycle life, able to withstand thousands of charge/discharge cycles without significant performance degradation.
Take electric vehicles as an example, ternary lithium iron phosphate battery pack theoretical life of 1,200 times, according to three days to fully charge and discharge a frequency of use, ternary lithium battery life of ten years.
Energy storage battery compared to the power battery charge and discharge more frequently, in the same 10-year life under the premise of the cycle life has higher requirements, if the energy storage station and home energy storage once a day charge and discharge, lithium energy storage battery cycle life requirements can be greater than 3,500 times, if you improve the frequency of charging and discharging, the cycle life requirements are usually required to be able to reach more than 5,000 times.
05 Cost difference
Cost is also one of the differences between the two, the cost of energy storage batteries is relatively low, because it uses more mature battery technology, and the application of the working conditions is relatively simple, in large-scale applications can be realized in the economic benefits.
In contrast, the cost of power batteries is higher, mainly due to the requirements for high energy density and high power output, compatible with the long life of the battery and the need for high safety.
Can energy storage batteries and power batteries be mixed?
Energy storage batteries can not be used in electric vehicles, there are different multipliers, different internal resistance, different capacity, different voltage between the two. Energy storage batteries generally have higher energy density, but lower power density, for example: 280 over 0.5C discharge will be too high temperature, so energy storage batteries can not be used as lithium power battery.
And power lithium batteries can be used as a storage battery, you need to understand the design and configuration of the lithium battery discharge size of the control system, but the power battery and power control system have a high cost factor, which will lead to less than ideal economic benefits.
It is understood that lithium storage batteries also have power type, such as support for about 5C stable current discharge capacity in the FM is widely used. Some companies will retire down the power battery as energy storage battery secondary utilization, applied to household storage and mobile energy storage, etc..
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