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Energy storage mainly refers to the storage of electric energy. Energy storage is also a term in oil reservoirs, representing the ability of reservoirs to store oil and gas. Energy storage itself is not an emerging technology, but it is just emerging from the perspective of industry and is in the initial stage. So far, China has not reached the level that the United States and Japan treat energy storage as an independent industry and issue special support policies. Especially in the absence of a mechanism to pay for energy storage, the commercialization model of energy storage industry has not yet taken shape. The lead-acid battery is generally used in the occasion of battery energy storage and high power, which is mainly used to store the surplus energy of emergency power supply, battery car and power plant. Repeated rechargeable dry batteries can also be used for low-power occasions, such as nickel metal hydride batteries, lithium ion batteries, etc. This article follows Xiao Bian to understand the advantages and disadvantages of nine types of battery energy storage. Advantages and disadvantages of battery energy storage 1、 Lead acid battery Main advantages: 1. The raw materials are easy to get and the price is relatively low; 2. High rate discharge performance is good; 3. The temperature performance is good, and it can work at – 40~+60 ℃; 4. Suitable for floating charge, long service life, no memory effect; 5. Waste batteries are easy to recycle, which is conducive to protecting the environment. Main disadvantages: 1. Low specific energy, generally 30~40Wh/kg; 2. Its service life is less than that of Cd/Ni battery; 3. The manufacturing process is easy to pollute the environment, and must be equipped with three waste treatment equipment. 2、 NiMH battery Main advantages: 1. Compared with lead-acid battery, the energy density has been greatly improved, with the weight energy density of 65Wh/kg and the volume energy density of 200Wh/L; 2. High power density, large current charging and discharging; 3. Good low-temperature discharge characteristics; 4. Cycle life (increased to 1000 times); 5. Environmental protection and pollution-free; 6. The technology is more mature than lithium ion battery. Main disadvantages: 1. Normal operating temperature range – 15~40 ℃, poor high-temperature performance; 2. The working voltage is low, and the working voltage range is 1.0~1.4V; 3. The price is more expensive than lead-acid batteries and nickel metal hydride batteries, but the performance is worse than lithium ion batteries. 3、 Lithium ion battery Main advantages: 1. High specific energy; 2. High voltage platform; 3. Good cycle performance; 4. No memory effect; 5. Environmental protection, no pollution; At present, it is one of the electric vehicle power batteries with the best potential. 4、 Supercapacitor Main advantages: 1. High power density; 2. The charging time is short. Main disadvantages: The energy density is low, only 1-10Wh/kg. The range of super capacitor is too short to be used as the mainstream power supply of electric vehicles. 5、 Fuel cell Main advantages: 1. High specific energy and long driving distance; 2. High power density, large current charging and discharging; 3. Environmental protection, no pollution. Main disadvantages: 1. The system is complex and the technology maturity is poor; 2. The construction of hydrogen supply system lags behind; 3. There are high requirements for sulfur dioxide in the air. Due to the serious air pollution in China, the life of fuel cell vehicles in China is relatively short. 6、 Sodium sulfur battery Advantages: 1. High specific energy (theoretical 760wh/kg; actual 390wh/kg); 2. High power (discharge current density can reach 200~300mA/cm2); 3. Fast charging speed (full charge for 30min); 4. Long life (15 years; or 2500~4500 times); 5. No pollution, recyclable (recovery rate of Na and S is nearly 100%); 6. No self discharge, high energy conversion; Insufficient: 1. The working temperature is high, and the working temperature is 300~350 ℃. The battery needs to be heated and insulated to a certain extent when it is working, and the startup is slow; 2. The price is expensive, 10000 yuan/kWh; 3. Poor safety. 7、 Liquid flow battery (vanadium battery) Advantage: 1. Safe and deep discharge; 2. Large scale, unlimited tank size; 3. There is a large charge discharge rate; 4. Long service life and high reliability; 5. No emission, low noise; 6. Fast charge discharge switching, only 0.02 seconds; 7. Site selection is not restricted by region. Disadvantages: 1. Cross contamination of positive and negative electrolyte; 2. Some need expensive ion exchange membranes; 3. The two solutions have large volume and low specific energy; 4. Energy conversion efficiency is not high. 8、 Lithium air battery Fatal defects: Lithium oxide (Li2O), the product of solid reaction, will accumulate on the positive electrode, blocking the contact between electrolyte and air, thus stopping the discharge. Scientists believe that the performance of lithium air battery is 10 times that of lithium ion battery, which can provide the same energy as gasoline. The lithium air battery absorbs oxygen from the air for charging, so the battery can be smaller and lighter. Many laboratories around the world are studying this technology, but if there is no major breakthrough, it may take another 10 years to achieve commercial use. 9、 Lithium sulfur battery (lithium sulfur battery is a kind of high capacity energy storage system with great development prospect) Advantage: 1. High energy density, theoretical energy density can reach 2600Wh/kg; 2. Low raw material cost; 3. Low energy consumption; 4. Low toxicity. Although the research of lithium sulfur battery has gone through decades, and many achievements have been made in the past 10 years, it is still far from practical application.

The so-called lithium iron phosphate battery refers to the lithium ion battery using lithium iron phosphate as the cathode material. This type of battery is characterized by the absence of precious metal elements (such as cobalt). Since there is no precious metal material, the raw material cost of lithium iron phosphate battery can be compressed very low. The lithium iron phosphate battery pack has the advantages of high temperature resistance, strong safety and stability, low price, and better cycling performance. 1. Comparison of energy density and endurance mileage Compared with the lithium ion battery pack of iron phosphate, the NCM lithium ion battery pack has higher energy density and voltage, so the battery pack with the same weight has larger capacity, and the car can run farther and faster. The endurance of Tesla Model S is more than 400km. BAIC EV200 uses ternary lithium-ion batteries processed by SK from South Korea, with a theoretical cruising mileage of 200km, while its predecessor EV150 uses lithium iron phosphate batteries, with a range of only 150km. 2. Space occupation comparison As for the large electric bus, the space occupation has little impact. However, for household electric vehicles, space occupation is more critical. The lithium iron phosphate battery pack with low energy density will occupy the originally small car space, and due to its greater weight, its discharge duration in use will also be greatly affected. Relatively speaking, ternary lithium-ion batteries with high energy density can save space for family cars while handling the weight problem. 3. Low temperature discharge performance comparison With 25 ℃ as the reference room temperature, the discharge capacity of the two types of batteries at 55 ℃ is almost the same as that at 25 ℃. But at minus 20 ℃, ternary lithium ion battery has distinct advantages compared with lithium iron phosphate battery pack.
4. Charging efficiency comparison In addition to the endurance, charging is also a critical link in the actual use of electric vehicles. In terms of charging efficiency, ternary lithium-ion batteries have great advantages over lithium iron phosphate battery packs. When charging below 100 Ah, there is no clear difference in constant current ratio between NCM lithium ion battery and lithium iron phosphate battery. When charging above 100 Ah, the constant current ratio of lithium iron phosphate battery decreases rapidly, and the charging efficiency decreases rapidly.

Cylindrical batteries can be divided into 14650, 18650, 21700 and other models, which are named by the size of the battery. 18650 is the most common battery model on the market at present, and it is also the most mature technology. The 21700 is a new battery that Tesla has mainly promoted in recent years. The size of a single cylindrical battery becomes larger, and the power is more. As a result, the number of battery cells has been greatly reduced, making the vehicle more advantageous in the control of battery system. After years of development, cylindrical batteries are highly standardized and easy to achieve a unified standard in the industry. In addition, cylindrical batteries also have inherent advantages in heat dissipation. When packaging, a good heat dissipation space is formed between cylinders, so some vehicles equipped with cylindrical batteries use low-cost air cooling technology. Tesla is vigorously promoting the 21700 battery technology. It is undeniable that the high adoption rate of cylindrical batteries in the industry has been affected by Tesla. As for vehicles with cylindrical batteries, it is inevitable to face the battery control problem caused by a large number of battery cells. After all, even with 21700 batteries, thousands of cylindrical batteries will be put together to form a battery pack, which is very large. In addition, because the cylindrical battery needs to use a steel shell when it is combined into a battery pack, its weight is relatively high, and its energy density is insufficient compared with the other two shapes of batteries. The prismatic battery will be more plastic, and it can be customized according to the specific needs of the product. However, this also led to the different sizes of prismatic batteries, and the manufacturing process standard was not as clear as that of cylindrical batteries. However, because of its high flexibility, it has been used in early new energy vehicles for a long time. Vehicle enterprises can customize the battery size according to different models without being limited by the cylindrical battery standard. Prismatic battery was once considered the most suitable battery design for new energy vehicles. At present, the prismatic battery has been used in many models, such as BMW’s I-series model, Roewe ERX5, and Nion ES8. In addition, BMW’s 3-series and 8-series new energy models also use the prismatic battery technology. At that time, BMW also hoped to achieve the goal of lightweight in new energy vehicles. ◆ Pouch battery The flexible battery has smaller volume and higher energy density because of the superposition manufacturing method, which is very consistent with the demand of China’s new energy vehicle market. The flexible battery can also be customized like the prismatic battery. Especially for hybrid vehicles, when considering the vehicle layout and counterweight, the advantages of soft battery are more obvious. Because the flexible battery pursues a thinner process and uses aluminum plastic film packaging that is lighter than the aluminum shell, you can even feel the flow of the internal liquid battery with your hands. The lighter battery pack can reduce the overall vehicle weight, thus providing more layout methods for vehicle enterprises. With the progress of technology, the lighter the single battery is, the more space it has to give consideration to energy density. At present, Buick’s VELITE5/VELITE5, Cadillac CT6 plug-in, XT5 hybrid model, and Nissan’s Xuanyi Pure Electric all use soft pack batteries. Generally speaking, the soft battery is more popular with Korean and American car enterprises. Hyundai and GM’s latest new energy models all use soft battery. ◆ Which is more advanced? In the current new energy vehicle market, the cylinder, prismatic and soft bag battery models all have a certain proportion of use. There is no absolute difference between good and bad, only that each has its own advantages and disadvantages. The cylindrical battery has been developed for a long time, so the manufacturing process is more mature and the cost is lower. At the same time, there are fixed international standards to measure the quality of products. However, in terms of battery layout and energy density, cylindrical batteries still have room for further improvement. The prismatic battery and the soft battery, although it is difficult to compete with the cylinder battery in standardization, can achieve customization features to better coordinate with the vehicle and meet the special needs of different manufacturers and different models. In particular, the use of aluminum film shell can ensure safety and improve efficiency through the use of flexible battery, but due to cost constraints, there are not many car enterprises using it now. Cylindrical, prismatic and flexible batteries have their own values in the market, but cylindrical ternary lithium-ion batteries have become the mainstream at present, which is also a compromise choice for vehicle enterprises after weighing performance and cost. Statistics show that from January to October 2018, the installed capacity of three yuan soft package in the field of new energy passenger vehicles was 3.06GWh, up 93.71% year on year. Since May this year, the installed capacity of soft pack battery of Thornton battery has steadily increased. Especially in October, it nearly doubled month on month, with a market share of 12.8% in the ternary soft bag market. Lou Zhongliang, the technical director of Santon New Energy, said that Santon New Energy ranked sixth in terms of the installed capacity of soft pack batteries in November. In fact, it is no accident that Thornton New Energy, which focuses on soft battery, can enter the top ten in the industry. From the top 20 installed capacity in the first ten months of this year, the market share of soft battery has shown a rapid upward trend, even surpassing that of cylindrical battery, and its future prospects are optimistic for the entire industry.