New energy is gradually replacing traditional energy and becoming the leading industry in new energy. Vigorously promoting new energy is a need for development and an important measure to protect the environment. Compared with traditional batteries, energy storage batteries used in new energy storage systems have begun to develop towards high-tech direction, with longer service life and energy storage efficiency. They have reached a critical turning point in technology, making the development and application prospects of new energy storage systems broad.
1.Overview of energy storage methods
1.1 Electromagnetic energy storage
The application of energy storage technology in new energy systems can achieve effective energy storage, and different energy sources can be stored and converted in different ways. By using science and technology to convert water, thermal energy, cold energy, and wind energy into the electrical energy required for the power system, in order to meet electricity demand and ultimately achieve the conversion and storage of electrical energy. In the process of electromagnetic energy conversion, electromagnetic energy storage technology can be used to convert electrical energy into applicable electromagnetic energy through frequency converters and supercapacitors, ultimately relying on electromagnetic energy storage technology to store electrical energy for use when needed. At the same time, when storing and converting electrical energy, it is necessary to collect the internal power supply resistance and current of the system in real time based on the actual operation of the power supply system, scientifically convert electromagnetic energy, and reduce energy loss issues. In the case of insufficient power, the reasonable application of electromagnetic energy storage technology can convert electromagnetic energy into usable energy and improve the reliability of the power engineering industry.
1.2 Physical energy storage
Physical energy storage has the advantages of large volume, low cost, and good recyclability, which can provide continuous energy supply for large-scale power generation projects. Physical energy storage mostly utilizes natural resources, which are environmentally friendly and sustainable, but it must prepare special sites and meet the requirements of geographical conditions. The commonly used methods for storing physical energy include pumped energy storage, compressed air, and flight energy accumulation. The method with high energy conversion rate is pumped storage, which has a huge storage capacity and low cost. Compressed air energy storage has a high safety factor performance and is an important means to solve large-scale energy production projects. However, compressed air storage sites have special requirements for geological conditions. During the energy storage process, energy storage is the first step. Energy storage refers to the use of excess wind energy from wind turbines by compressors for basic energy storage operations, air compression and cooling. Compressed and cooling air must be stored in waste or recently constructed oil and gas mines to release energy in the well; Then, the energy is released to act on the heating device, causing it to heat the air under high pressure and, with the help of the heating gas, enter the material inside the air combustion chamber to support combustion. The burned gas will drive the gas turbine. Flight energy storage and compressed air energy storage have similarities, mainly divided into two parts: energy accumulation and energy release. By converting the mechanical and electrical energy of rotating flight to obtain energy, it has the characteristics of clean energy, efficient conversion, and fast storage.
2.Advantages of energy storage batteries
The energy storage battery has sufficient compatible application conditions during the energy storage process, and can implement a layout plan on the distribution network side, thereby reducing the energy consumption of power enterprises during peak periods and ensuring the normal electricity demand of users and enterprises. Meanwhile, energy storage batteries can generate significant economic benefits. Firstly, it can limit the power transmission of the grid during peak hours, thereby achieving the effect of reducing costs; Secondly, it significantly improves power efficiency; Finally, energy storage batteries expand the cycle of energy distribution facilities. Through technological research and the development of energy storage batteries, production costs can be reduced, playing a positive role in promoting the promotion of battery energy storage.
3.Main types of energy storage batteries
Due to the randomness and disparity of new energy in energy production, its development is limited, and these two reasons also make energy production unstable and unable to work continuously to achieve efficient power generation. To solve this problem, energy storage batteries can be used to ensure the reliability and safety of new energy. At the same time, stored electricity can be released during periods of particularly severe energy consumption to ensure people’s electricity demand and effectively alleviate the impact of peak energy consumption on the power industry. In addition, attention should be paid to the energy conversion issue of new energy. In order to achieve the goal of efficient utilization of new energy, higher efficiency is needed to store or release energy. The energy storage system device should also consider the conversion relationship between energy storage capacity and production efficiency.
3.1 Lithium ion batteries
In recent years, due to the continuous development of new batteries, as well as the improvement of electrolytes, electrodes, and batteries, lithium-ion batteries have been widely used and mainly used in ordinary household appliances. The advantages of lithium-ion batteries are mainly reflected in the following aspects: firstly, they have a long service life and can be reused multiple times. Lithium ion batteries can be continuously cycled for approximately 3000 times when they reach 80% of the total stored energy during each charge. Secondly, it has a very high energy storage density and high energy storage conversion efficiency, which can almost achieve complete conversion. However, the safety hazards of lithium-ion batteries are also evident, with relatively poor safety factors. Prolonged charging can easily cause short circuits, high temperatures, and even battery explosions. Lithium ion batteries have very high conversion efficiency and short conversion time in the energy conversion process of the power system, which can effectively save energy conversion costs. While solving the internal energy storage problem of the power system, they can ensure the smooth operation of the power system, which is a completely different characteristic of lithium-ion batteries from ordinary batteries.
The energy storage principle of lithium-ion batteries is as follows: lithium-ion batteries use two reversible intercalation and de intercalation lithium-ion compounds as positive and negative electrodes to form secondary batteries. During the charging process of the battery, lithium ions will detach from the positive electrode and be embedded into the negative electrode through the electrolyte and separator; On the contrary, during the discharge process of the battery, lithium ions will detach from the negative electrode and re embed into the positive electrode through the electrolyte and separator. Due to the relatively fixed space and position of lithium ions between the positive and negative electrodes, batteries exhibit good reversible reactions during actual charging and discharging. In addition, due to the wide variety of lithium-ion batteries, there are also certain differences in chemical reactions depending on the reactants.
Titanium lithium battery is an improved and excellent lithium-ion electronic battery. The positive electrode uses titanium lithium nanocrystals instead of traditional carbon, which allows the surface area of the positive electrode to reach 1003 m2/g, but the positive electrode composed of carbon has a surface area of only 3 m2/g. This also means that the speed of electrons leaving the anode after entering will be faster, which can further promote the battery’s performance of fast charging and providing high current. However, the disadvantage of this type of battery is that its capacity and voltage are smaller than ordinary lithium-ion electronic batteries. The energy storage battery system in the wind solar storage 500 MW comprehensive power generation demonstration system project built in Zhuhai in the early years used a lithium titanate energy storage battery with a basic unit of 2000 Ah developed domestically.
3.2 Lead acid batteries
In recent years, the frequency of use of lead-acid batteries has shown an increasing trend, and there are many factors that affect their working hours, mainly including the factory technical level and product quality of battery manufacturers, loading and discharging conditions and temperature during use. Lead acid batteries are often prone to damage during use, mainly manifested in the following aspects: Firstly, there is severe surface corrosion in lead-acid batteries, especially in the positive electrode, as most of the electrolyte contains corrosive substances; Secondly, heat is difficult to effectively control in lead-acid batteries, and the battery may dissipate heat more slowly during use, resulting in a faster heat generation rate than the heat dissipation rate, resulting in an abnormal increase in battery temperature and severe electrolyte water loss, thereby affecting its charging and discharging process; Thirdly, if the sulfuric acid content on the upper edge of the positive and negative plates is different, it is highly likely to cause sulfuric acid to react with the substrate, thereby seriously shortening the battery life.
3.3 Sodium sulfur battery
The molten liquid electrode and solid electrolyte together form a sodium sulfur battery. The positive and negative poles of the battery are molten salt of sodium polysulfide, molten metal sodium, and molten metal sulfur, respectively, allowing the sodium sulfur battery to operate at high temperatures (around 300 ℃). The biggest advantage of sodium sulfur batteries is their extremely high energy conversion rate, which allows them to discharge and charge at high power, giving them significant advantages in terms of extremely short charging and discharging times. However, when its requirements for working temperature are high (300-500 ℃) and a certain state must be maintained during charging to ensure more accurate average values for far-line measurements, safety accidents may also occur due to ceramic damage.
4. Summary
From the above analysis, it can be concluded that sodium sulfur batteries have the highest operating temperature (3000 ℃) and are equally strict with external environmental requirements; Lithium ion batteries have the highest working voltage and conversion efficiency, reaching almost 100% complete conversion; Sodium sulfur batteries have fast discharge rate changes and stable discharge process; Lead acid batteries have the lowest cost, but there are certain toxic substances present. Electricity consuming units need to choose more suitable energy storage batteries as the power generation tools in the new energy generation system based on the performance and actual needs of energy storage batteries, in order to ensure the stability and safety of system operation and generate income for enterprises.