Which battery is best for energy storage?
4:02 pm
Energy storage power stations refer to facilities installed in power systems for storing and releasing electrical energy. Such facilities are usually located in a certain link of the power grid, such as power stations, substations or near power consumption points, such as homes or industrial parks. The main purpose of energy storage power stations is to improve the flexibility and efficiency of the power system by storing excess electricity generated when power demand is low, and then releasing this energy during peak hours or power shortages, so as to balance the power load, improve power utilization efficiency, reduce energy costs, and increase the access to renewable energy.
Batteries play a key role in side energy storage power stations. They are the core components of energy storage power stations and are used to store and release electrical energy. The type, performance and configuration of batteries have a significant impact on the efficiency, reliability and economy of the entire energy storage system. Choosing the right battery type and configuration is crucial to the design and operation of energy storage power stations.
This article mainly introduces some key contents of battery selection in detail, hoping to help you understand the relevant knowledge and choose the most suitable battery
Battery selection principles
1. Flexible configuration, easy installation and construction
The energy storage system should be flexible in configuration and have good scalability. In addition, the system construction period should be short and there should be no excessive special requirements. Energy storage batteries are easy to combine in multiple ways, which can meet higher working voltages and larger working currents; they are easy to install and maintain; they are flexible in configuration and easy to install and construct.
2. Long cycle life, high safety and reliability
The cycle life of energy storage batteries has an important impact on the reliable operation of the system. The long cycle life of energy storage batteries can reduce the replacement of batteries, which is of great significance for saving operating costs and improving the economy of the system. The battery energy storage system requires a service life of 12 years, and a cycle life of more than 6,000 times when the discharge depth is 90%. Due to the particularity of the power grid, operational safety is the primary issue to be considered in the operation of the power grid, and equipment with low safety cannot enter the power grid. The purpose of the energy storage system is to ensure the safe, efficient and stable operation of the power system. Only energy storage systems with high safety can meet the requirements. It is required that the energy storage battery should be under control even if it fails under extreme conditions, and should not explode, burn or other failures that endanger the safe operation of the power station;
3. It has good rapid response, charging and discharging capabilities and high charging and discharging conversion efficiency
The intermittent operation of the battery energy storage system requires the system to have good starting characteristics. The energy storage battery frequently switches between the charging and discharging states, requiring the battery to have a faster response speed. The system efficiency is affected by energy loss, and improving the energy conversion rate of the energy storage system during the storage process will help improve the overall efficiency of the system. In addition, the level of battery charging and discharging efficiency will also affect the cost of the system.
4. It has good environmental adaptability and a wide operating temperature range.
5. The cost is suitable.
Cost is an important reference for the selection of energy storage batteries and a determining factor for whether energy storage batteries can be promoted and applied on a large scale.
6. Second-hand batteries and inventory batteries with a production date of more than 3 months shall not be selected.
Though second-hand batteries or batteries with an inventory of more than 3 months can greatly reduce the cost of energy storage batteries, the consistency of the internal cells of the battery pack used for assembly cannot be guaranteed. Long-term operation will cause the system efficiency to decrease rapidly, and even cause safety hazards.
Gore energy storage batteries all use brand new A-grade batteries with a production cycle of less than 3 months to ensure the safety and stability of the energy storage system.
Gore energy storage batteries all use brand new A-grade batteries with a production cycle of less than 3 months to ensure the safety and stability of the energy storage system.
7. Comply with environmental protection requirements and do not cause damage or pollution to the environment during battery production, use, and recycling.
Comparison of major battery types
From the application level, the above battery types can reach the 100 MW level. From the battery performance point of view, lithium iron phosphate batteries （lifepo4 battery） and sodium sulfur batteries have higher energy ratio and charge and discharge efficiency. Sodium sulfur batteries and vanadium flow batteries have not yet formed industrialization, the supply channels are limited, and the cost is expensive.
From the perspective of operation and maintenance costs, vanadium flow batteries require pumps for fluid control, which increases the cost of operation, while lithium batteries and lead-carbon batteries have lower maintenance costs. From the perspective of cost per kilowatt-hour (present value of cost within the project cycle/present value of power generation within the life cycle), the current cost per kilowatt-hour of lead-acid (carbon) batteries and lithium iron phosphate batteries （lifepo4 battery）is equivalent, but lead-acid (carbon) batteries are not suitable for deep charging and deep discharging, and the discharge rate is low and the cycle life is low. The advantage of all-vanadium flow batteries lies in their safety, but they occupy a large area and the later maintenance is cumbersome. They are suitable for long charging and discharging time and large capacity (energy) energy storage occasions.
In summary, the advantages of lithium iron phosphate batteries (lifepo4 battery) are that they have no special requirements for the construction environment, short construction period, high energy efficiency, and flexible power and time configuration. LiFePo4 batteries are recommended.
Battery type selection
Based on the different shell packaging types, lithium iron phosphate batteries mainly include three types: square aluminum shell, soft aluminum plastic film and hard cylindrical. The internal components (positive electrode, negative electrode, diaphragm, electrolyte) of the three are very different, and the main difference lies in the shell packaging material. The advantages and disadvantages of the three are compared as shown in the following table:
In summary, the soft-pack structure and hard-pack structure of lifepo4 batteries each have their own advantages and disadvantages. The quality of the battery depends more on the quality of the material and the manufacturing process. It is recommended to use the square aluminum shell battery that is widely used in large-scale energy storage power stations.
Battery capacity selection
At present, there are many domestic manufacturers of lifepo4 batteries, with sufficient supply and relatively mature technology. For different battery capacities, the nominal voltage and operating voltage range are roughly the same, but the maximum charging rate and maximum discharge rate are different, and the larger the battery capacity, the greater its weight energy density and volume energy density.
Currently, well-known domestic battery manufacturers include CATL, Lishen, Haiji New Energy, EVE Power, BYD, AVIC Lithium Battery, Gotion High-tech and other companies. The battery is mainly 0.5C (charge and discharge for 2 hours) and 1C (charge and discharge for 1 hour) products. The capacity of mature single-cell batteries is 40Ah-320Ah, and the number of cycles of each company ranges from 4000 to 10000 times (depending on the operating conditions).
For large-capacity energy storage projects, single-cell batteries should be selected with relatively large capacity. On the one hand, it can increase power density and reduce space occupation; on the other hand, it can reduce the number of series and parallel circuits of the battery and reduce the capacity attenuation problem caused by the barrel effect. At the same time, based on the principles of “mainstream products from mainstream manufacturers” and “advanced technology”, it is recommended to use battery products with a capacity of 280Ah or above. The basic performance parameters of typical large-capacity batteries are shown in the following table.
In the future, as science and technology develop, new battery technologies will continue to emerge, and our choices will become more abundant. But no matter what, our goal is the same: to improve the performance of grid-side energy storage power stations by selecting the most suitable batteries, promote the efficient use of energy, and contribute to building a clean and sustainable energy system.