The charging main body is slow charging -Lithium - Ion Battery Equipment
In the future, the main part of passenger car charging will be slow charging. Only about 20% of the cases require fast charging, which is only for emergency use.
Aiming at the problem of fast charging or slow charging of electric vehicles, Ouyang Minggao, an academician of the CAS Member, a professor of Tsinghua University, and director of the National Key Laboratory of Automotive Safety and Energy Conservation, pointed out the development direction of future electric vehicle charging mode at the Xumishan Conference held in Changzhou, Jiangsu Province on March 30. He said, "In the future, the main part of passenger car charging is slow charging. Only about 20% of the cases require fast charging, which is only for emergency use."(Lithium - Ion Battery Equipment)
Ouyang Minggao pointed out that slow charging has many advantages. Especially when it is combined with smart grid in the future, slow charging is not only for charging, but also to balance the fluctuations of the grid, play the role of energy storage, and also can provide power back to the grid. He believes that fast charging is only a means of emergency assistance. The investment cost should be considered for the development of fast charging. If the cost is very high, power replacement can be considered.
He thinks fast charging is only a means of emergency assistance, such as on the highway. In fact, there are obvious defects in maintaining high current fast charging. Just like pouring beer too fast will produce foam, but not enough, the electrochemical reaction inside the battery takes a certain time, and charging with too much current will cause insufficient charging.
Ouyang Minggao said that in order to make the charging speed of electric vehicles faster, from the perspective of the charger, it is possible to achieve a fast charging with a maximum output power of 350kW. However, for the power battery and the whole vehicle, the basic impact is greater. If you want to charge fast, it is not how much power the charger has, but how much the battery can accept. The core problem is the battery charging rate, which determines whether fast charging can be achieved. Charge discharge ratio refers to the speed of energy storage and release. The higher the current, the higher the charging rate, and the faster the charging. As a power battery, in addition to fast charging, it also needs to meet the basic requirements of people on the vehicle range, which is determined by the energy density (Wh/kg) of the battery. Without considering the energy density, making the electrode of the battery very thin can achieve a large charging rate; On the other hand, with the continuous improvement of battery energy density, the electrode plate of the battery needs to be made thicker to reduce the energy loss caused by polarization. Therefore, at present, the battery with a charging rate of 30C can do it, but it is difficult for the battery with high energy density to achieve a maximum charging rate of 3C, which is far from the requirement of fast charging.
"On the whole, we need more technological innovation for emergency fast charging." Ouyang Minggao said that at present, an electric vehicle needs about 60 kilowatt hours of electricity, and it only takes half an hour to fully charge with such a charging pile. In the emergency fast charging scenario, it is equivalent to charging for 1 minute to support the electric vehicle to run 10 kilometers, and charging for 15 minutes to run 150 kilometers, which can fully meet the immediate needs. When the remaining power reaches more than 70%, the charging power drops sharply. Therefore, Ouyang Minggao believes that fast charging is definitely not to fully charge the battery.
Aiming at the problem of fast charging or slow charging of electric vehicles, Ouyang Minggao, an academician of the CAS Member, a professor of Tsinghua University, and director of the National Key Laboratory of Automotive Safety and Energy Conservation, pointed out the development direction of future electric vehicle charging mode at the Xumishan Conference held in Changzhou, Jiangsu Province on March 30. He said, "In the future, the main part of passenger car charging is slow charging. Only about 20% of the cases require fast charging, which is only for emergency use."(Lithium - Ion Battery Equipment)
Ouyang Minggao pointed out that slow charging has many advantages. Especially when it is combined with smart grid in the future, slow charging is not only for charging, but also to balance the fluctuations of the grid, play the role of energy storage, and also can provide power back to the grid. He believes that fast charging is only a means of emergency assistance. The investment cost should be considered for the development of fast charging. If the cost is very high, power replacement can be considered.
He thinks fast charging is only a means of emergency assistance, such as on the highway. In fact, there are obvious defects in maintaining high current fast charging. Just like pouring beer too fast will produce foam, but not enough, the electrochemical reaction inside the battery takes a certain time, and charging with too much current will cause insufficient charging.
Ouyang Minggao said that in order to make the charging speed of electric vehicles faster, from the perspective of the charger, it is possible to achieve a fast charging with a maximum output power of 350kW. However, for the power battery and the whole vehicle, the basic impact is greater. If you want to charge fast, it is not how much power the charger has, but how much the battery can accept. The core problem is the battery charging rate, which determines whether fast charging can be achieved. Charge discharge ratio refers to the speed of energy storage and release. The higher the current, the higher the charging rate, and the faster the charging. As a power battery, in addition to fast charging, it also needs to meet the basic requirements of people on the vehicle range, which is determined by the energy density (Wh/kg) of the battery. Without considering the energy density, making the electrode of the battery very thin can achieve a large charging rate; On the other hand, with the continuous improvement of battery energy density, the electrode plate of the battery needs to be made thicker to reduce the energy loss caused by polarization. Therefore, at present, the battery with a charging rate of 30C can do it, but it is difficult for the battery with high energy density to achieve a maximum charging rate of 3C, which is far from the requirement of fast charging.
"On the whole, we need more technological innovation for emergency fast charging." Ouyang Minggao said that at present, an electric vehicle needs about 60 kilowatt hours of electricity, and it only takes half an hour to fully charge with such a charging pile. In the emergency fast charging scenario, it is equivalent to charging for 1 minute to support the electric vehicle to run 10 kilometers, and charging for 15 minutes to run 150 kilometers, which can fully meet the immediate needs. When the remaining power reaches more than 70%, the charging power drops sharply. Therefore, Ouyang Minggao believes that fast charging is definitely not to fully charge the battery.
