Electrochemical energy storage in the energy storage industry

1. Introduction of various types of energy storage batteries
2. Electrochemical energy storage system components
3. The impact of temperature control on electrochemical energy storage system
4. The leading manufacturers in the electrochemical energy storage industry

Electrochemical energy storage is the mutual conversion between electrical energy and chemical energy through electrochemical energy storage reaction, so as to achieve the storage and release of electrical energy.

At present, the main applications of energy storage batteries mainly include lead-acid batteries, liquid flow batteries and lithium-ion batteries, etc. In the future, sodium battery will be gradually applied to energy storage as the industry chain matures.

Introduction of various types of energy storage batteries

Lead-acid battery is a kind of secondary battery with lead dioxide as the positive electrode, metallic lead as the negative electrode and sulfuric acid solution as the electrolyte. Because of the short cycle life, low energy density, narrow temperature range, slow charging speed, and the environmental impact of lead metal, the future application of lead-acid batteries will be greatly restricted.

Liquid flow battery technology path includes all-vanadium liquid flow battery, iron-chromium liquid flow battery, zinc-bromine liquid flow battery, etc. Among them, all-vanadium liquid flow battery has the best comprehensive performance and the highest commercialization degree.

In terms of long term energy storage, all-vanadium liquid flow batteries will have cost advantages and competitive advantages over other technology paths such as lithium batteries.

Lithium-ion batteries store energy through the embedding and de-embedding of lithium ions in the positive and negative electrode materials. Lithium-ion batteries are becoming the mainstream route for electrochemical energy storage because of their high energy density and long life.

According to the different cathode materials, lithium-ion batteries are divided into lithium cobaltate, lithium manganate, lithium iron phosphate and ternary batteries. Lithium iron phosphate batteries have significant advantages in the field of energy storage, with moderate energy density, better safety and service life than other battery types, and lower cost.

Lithium cobalt acid battery because of the scarcity of metal cobalt price is much higher than other batteries, and cycle life, safety is poor, so there are few applications in the field of energy storage. Lithium manganate battery energy density and lithium iron phosphate battery is similar, the low life cycle cost of electricity than lithium iron phosphate battery, so the application is less.

Ternary battery energy density is much higher than other battery types, service life can also reach 8-10 years, but the safety is relatively poor, the cost is much higher than lithium iron phosphate, so in the field of electrochemical energy storage does not require very high energy density, the application prospects are weaker than lithium iron phosphate.

Sodium ion batteries work similarly to lithium-ion batteries, using sodium ions in the process of embedding between the positive and negative electrodes to achieve charge and discharge.

Sodium ion battery relative to lithium iron phosphate battery safety performance, low temperature performance, fast charging performance, lower cost, and sodium resources are far more abundant than lithium resources and around the world, if sodium ion can be widely used, China will largely get rid of the current lithium resources are limited. Sodium ion battery disadvantages are mainly reflected in the lower cycle times and immature industry chain.

At present, the cycle life of sodium batteries is generally 2000-3000 times, and the immaturity of the industry chain leads to high upstream prices, so the cost advantage of sodium batteries cannot be seen. In a comprehensive manner, lithium batteries, sodium batteries and all-vanadium liquid flow batteries have more room for development.

These three are widely used with wind power, photovoltaic, all-vanadium liquid battery is mainly used for more than 4 hours of long-term electrochemical energy storage, sodium batteries will be in large energy storage power station to form a certain alternative to lithium batteries, energy density sensitivity of high commercial and industrial and household energy storage, lithium batteries will still dominate.

Electrochemical energy storage system components

The complete electrochemical energy storage system is mainly composed of battery pack, battery management system (BMS) which has function of energy storage. Here is a detailed article of energy storage BMS manufacturers for you. And there are also energy management system (EMS), energy storage converter (PCS) and other electrical equipment in energy storage system.

The battery pack is the most important component of the electrochemical energy storage system. The BMS is mainly responsible for battery monitoring, evaluation, protection and equalization. The EMS is responsible for data acquisition, network monitoring and energy dispatching. The energy storage converter can control the charging and discharging process of the electrochemical energy storage battery pack and perform AC/DC conversion.

The electrochemical energy storage battery system consists of two parts: battery pack and battery management system. The battery pack is the most costly part of the whole energy storage system, accounting for about 70%, the BMS accounts for 6%, and the energy storage battery system accounts for 76% of the cost of electrochemical energy storage.

Battery pack performance determines the safety and service life of the final product, and also ultimately determines the profitability of the electrochemical energy storage system. Unlike power batteries that pursue the ultimate energy density, energy storage batteries pay more attention to cycle life.

In order to improve the economics of electrochemical energy storage, in addition to system cost reduction, improving cycle life is also an important way.

Energy storage converter (PCS) is a device connected between the battery system and the power grid to achieve bi-directional conversion of electrical energy. It can convert DC power from the battery to AC power for transmission to the grid, and also convert AC power from the grid to DC power for battery charging.

In grid-connected mode, during the low load period, the electrochemical energy storage converter rectifies the AC power from the grid into DC power to charge the battery pack, and during the peak load period, the energy storage converter converts the DC power from the battery pack into AC power and sends it back to the grid.

In off-grid mode, the energy storage converter is disconnected from the main grid to provide the local part of the load with power that meets the power quality requirements of the grid.

There is a high degree of overlap between electrochemical energy storage converters and PV inverters in terms of usage scenarios, technical principles, upstream suppliers and downstream customers, so most energy storage converter companies come from PV inverter manufacturers, and the industry competition pattern is similar. According to the data, there are currently 30 PCS listed companies.

However, the gross margin of energy storage PCS is higher than that of PV grid-connected inverter, because the demand for inverter in electrochemical energy storage scenario is more complicated than that of PV grid-connected scenario, in addition to DC to AC conversion, it also needs to have the functions of converting from AC to DC, and off-grid fast switching, etc.

Meanwhile, energy storage PCS is also a two-way converter, with energy control in both charging and discharging directions. Therefore, the technical barriers of energy storage converters are higher than those of grid-connected inverters, and the selling price and gross margin are significantly higher than those of grid-connected inverters.

The impact of temperature control on electrochemical energy storage system

Temperature control refers to the effective control and regulation of the temperature of something through heating or cooling technology.

Temperature control system cooperates with BMS to control the constant temperature and humidity of lithium battery, maintain the battery within the safe operating parameters, improve the stability of the battery during operation, and avoid the battery from entering the thermal runaway state. Energy storage temperature control technology mainly includes air cooling, liquid cooling, heat pipe cooling, and phase change cooling.

Among them, the air-cooled system has a simple structure, high reliability, long life, low cost and easy to implement, which is the mainstream technology path in China at present.

Liquid-cooled system has high heat dissipation efficiency and fast heat dissipation, and its advantages are prominent in high multiplier and high capacity scenarios, so the world electrochemical energy storage system is showing the trend of liquid cooling accelerating penetration and replacing air cooling.

Heat pipe cooling, phase change cooling need to be used with air cooling, liquid cooling, because of the higher price, currently less in the field of electrochemical energy storage applications.

The world’s electrochemical energy storage system utilization rate has increased, higher requirements for safety, the importance of temperature control system highlights, liquid cooling system with the advantages of cooling efficiency and speed, is expected to accelerate penetration.

In addition, many countries in Europe and the United States have better economics of electrochemical energy storage, and as the price of raw materials for lithium batteries decreases, the price sensitivity of temperature control systems will be reduced, which will also form a positive effect on the application of liquid cooling systems.

The same as the inverter, battery pack, due to the same source of technology, most of the electrochemical energy storage temperature control companies cut from other tracks, with technology and layout of first-mover advantage, participants include companies from precision temperature control, industrial temperature control, automotive temperature control.

Such as the main do data center, 5G base station temperature control precision temperature control products manufacturers such as Invacare, Shen Ling environment. The main industrial temperature control products with the fly shares, high Lan shares, etc. Mainly doing new energy vehicle temperature control of Songzhi shares, Aotejia, etc., these industry leaders in electrochemical energy storage temperature control products have layout.

The leading manufacturers in the electrochemical energy storage industry

At present, the utilization rate of electrochemical energy storage system is gradually improved, the system technology is becoming mature, 280Ah large electric core, liquid cooling temperature control, high voltage cascade, 1500V architecture has become the mainstream trend.

Among them, the converter of high-voltage cascade electrochemical energy storage system can be directly connected to the grid of 3kV and above without transformer, which can reduce the system cost and save energy consumption with higher cycle efficiency.

In addition, the high-voltage cascade solution is better than traditional solutions in terms of maximum conversion efficiency, power quality, stand-alone capacity, response time, reliability, and battery utilization.

At present, Jinpan Technology, Zhiguang Electric, Nanrui relay, new scenery has launched high-voltage cascade program, leading the industry’s new trend. 1500V energy storage system will be used in the system of DC voltage cables, BMS hardware modules, converters and other components of the voltage resistance from no more than 1000V to no more than 1500V.

1500V system energy density, power density can be increased by more than 35%. The system cost can be reduced by more than 5 % and the system efficiency can be increased by more than 0.3%. The penetration rate of 1500V systems in recent large electrochemical energy storage projects in China has exceeded two-thirds.

At present, Chinese system integrators include three types of participants: Li-ion battery manufacturers represented by BYD and Narada Power, PCS manufacturers represented by YangGuang Power and KELU Electronics, and independent system integrators represented by Haibositron.

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