Lithium ion battery applications in energy storage
In the energy storage system, lithium battery, lead carbon battery and lead acid battery are all used to store electric energy. There is no essential difference. Battery capacity and charge and discharge current design of them are the same. Compared with lead-acid batteries, lithium battery energy storage is a new thing. There is no standard product at present. Unlike lead-acid batteries, there are many specifications and models. General manufacturers are based on the quantity of electricity to determine the specifications. In this article, we will talk about lithium ion battery applications in energy storage.
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Lithium ion battery applications in energy storage power station
Lithium ion battery applications scenarios can be divided into three categories: consumption, power and energy storage. The earliest applications are in mobile phones, laptops, digital cameras and other consumer products. Currently they account for about half of all types of lithium battery shipments worldwide. With the increase of global demand for new energy vehicles, the proportion of power lithium batteries is increasing year by year, and it currently accounts for more than 40%. Power battery will become the main lithium ion battery applications scenario of lithium battery in the future.
According to the standard, power batteries with a capacity of less than 80% can no longer be used in new energy vehicles, while ordinary energy storage batteries have lower requirements. After retirement, the power battery can also be used in the energy storage system. Energy storage lithium battery as a new lithium ion battery applications scenario is also gradually raising attention. Energy storage is one of the important means to solve the intermittent fluctuation of new energy wind power and photovoltaic and realize the function of “cutting peak and smoothing valley”. At present, the mainstream lithium energy storage battery has two types: one is lithium ternary lithium the other is lithium iron phosphate, and the power density of them is much higher than the lead carbon battery. Relatively speaking, ternary lithium is higher than lithium iron phosphate.
The biggest difference between lithium batteries and lead-acid batteries
The biggest difference between lithium batteries and lead-acid batteries is that lithium batteries must be equipped with a battery management system. Lithium battery has the advantages of light weight, large energy storage capacity, large power, no pollution and long life, but lithium battery is very sensitive to over current and over voltage. High-capacity batteries are made up of many small-capacity single batteries (such as 18650) through a large number of series and parallel connections. If there are many parallel batteries, it is easy to cause the current imbalance of each branch.
Therefore, the battery management system must be introduced to add control. Lead acid battery has many advantages, such as good high current characteristics, small self-discharge, stable performance, safe and clean. The current daily maintenance of lead acid battery mainly through manual completion on the battery connection status, terminal voltage and other troubleshooting. do not need BMS battery management system.
Battery Management System(BMS)
Battery Management System (BMS) is a device composed of microcomputer technology and detection technology. It dynamically monitors the running status of battery pack and battery unit, accurately measuring the remaining power of the battery, and at the same time providing charge and discharge protection for the battery to make the battery work in the best state. To extend its service life, reduce the operation cost, and further improve the reliability of the battery pack. The battery management system of electric vehicles should achieve the following functions:
Accurately estimate the state of charge of the power battery pack
State of Charge(SOC), the remaining battery quantity, can ensure that SOC is maintained within a reasonable range and prevent battery damage due to overcharge or overdischarge, so as to predict the remaining energy of energy storage battery or the state of charge of energy storage battery at any time.
Dynamic monitoring of the working state of the power battery pack
To ensure the safety of the battery, during the charging and discharging process, the terminal voltage and temperature, charge and discharge current and total voltage of each battery in the battery pack of the electric vehicle are collected in real time to prevent the over-charging or over-discharging phenomenon of the battery.
Balance between batteries
Balance between batteries means charge each battery in a battery string in a balanced and consistent state. Equalization technology is a key technology of battery energy management system which is being researched and developed in the world.
Selection and design of lithium battery
(1)lithium energy storage battery has a BMS system, which needs to communicate with inverters or bi-directional energy storage converters PCS. Equipment with lithium battery function and corresponding communication interface should be selected.
(2) Compared with lead-acid battery, charge and discharge current of lithium battery is different, so special attention should be paid to design. At present, there is no unified specification of lithium battery. The specifications of each manufacturer are different, then the BMS communication protocol may different too. It should be customized according to the specific requirements of the project.
Research on electrode materials for lithium-ion batteries has been exciting for nearly two decades. With the discovery of new materials and strategies, lithium ion battery applications will undoubtedly have an increasing impact on our lives in the coming years.