January 20-21, held in Beijing with the theme of "Achieving high-quality development with global trend of change" (2018) The executive chairman of the China EV 100 Executive Committee and the Chinese Academy of Sciences Ouyang Minggao Said that from the new energy vehicles growth situation, 55% of the current market are pure electric passenger car, he focused on pure electric passenger car analysis and make recommendations.Report is divided into three parts, one is the high ratio Energy lithium-ion battery technology, the second is electric vehicle energy consumption and energy-saving technologies, the third is fast charge and charging network intelligent technology.
China EV 100 Executive Vice President, Chinese Academy of Sciences Ouyang Minggao
The first part, high-energy lithium-ion battery technology.
Since the 12th FYP, great progress has been made in the power battery of electric vehicles in our country from the 15th to the 13th Five-year Plan and gradually moving towards a path of rapid development. The power of the battery system is gradually increasing and the cost is declining.
Based on domestic high-nickel cathode materials, especially NCM622 materials, the energy density of single-cell battery exceeds 200Wh / kg at the end of 2017, and the energy density of all single cells is 230 ± 20Wh / kg.
Based on a new generation of thermal runaway control technology, the energy density of the battery system approaches 160Wh / kg by the end of 2017, for example, the energy density of the ternary square-shell battery system with the monomer energy density of 195Wh / kg reaches 158Wh / kg , Single energy density of 200 watts / kg battery can do 160 watts / kg, the quality of the group can reach 77% efficiency, cycle life of more than 3000 times, of which the most important is the thermal runaway prevention technology, without the technology, Such a high specific energy is very difficult to achieve, because the single battery to completely eliminate thermal runaway, is still very difficult, so you must prevent from the system perspective of thermal runaway.
The following further research and development of special inside to make a brief introduction.
Ningde era of new energy, Lishen, Guoxuan commitment to new lithium-ion battery project, the use of high-nickel ternary positive and silicon carbon anode, flexible battery energy density reached 300 watt hours / kg, some of the performance indicators have been Close to the application requirements, here (Figure) I show some of the indicators of Ningde era of new energy B-like, basically close to the use requirements.Some units of battery safety can not fully meet the national standard, Ningde era have passed, it is safe Sex testing (Figure).
Internationally, the global target by 2020 is basically 300Wh / kg, and the domestic and international R & D activities are basically at the same level, but the research on safety needs to be strengthened. As can be seen (Figure), Japan and South Korea's goal And China is still not the same, they are more than the pursuit of volume energy, because the volume of the car than the energy may be more important, they are generally called the volume ratio of energy, but they do not have the concept of quality than energy Panasonic 280 W Hour / kg battery capacity than the energy to do 720 watts / liter.Japan and South Korea than the energy target of 270 watts / kg, 280 watt hours / kg more, this goal can be achieved by 2020 and industrialization.
On the other hand, 2017 is the hottest year for solid-state batteries, and we have to make some comments in this regard. This (Figure) is the development of solid-state batteries in various units of domestic indicators, I do not detail here, it is worth Mentioned is the Chinese Academy of Sciences, Ningbo Materials and Gan Feng Li industry in the hand in hand to plan 2020 products to enter the market, the other should say that more scientific research units.
Global solid-state batteries have been warming up in 2017 and Japan has made significant breakthroughs in inorganic sulphide solid-state electrolytes. Toyota has introduced a mass-production project for solid-state batteries and commercialized it in 2022. Of course, we have to wait a few years to see if it is able to deliver on schedule The current weight-to-weight energy is 200 Wh / kg, and the volumetric specific energy is 400 Wh / L. Unless solid-state batteries can be internally connected in series, is it possible to increase the specific energy of the system, ie, the battery becomes Bipolar, due to the current part of the liquid electrolyte to be added, so after the series will lead to the internal electrolyte outflow caused by a short circuit, so now the internal series is not much.
Over the past year, solid-state lithium-ion batteries with inorganic sulfide solid electrolyte as the core have made important progress. However, due to the stability of the solid-solid interface and the chargeability of lithium metal, the real all-solid lithium metal battery technology is far from mature . We think the development of solid battery technology line from the electrolyte point of view from the liquid, semi-solid, solid-liquid mixture, to the solid state, and finally to the solid state. Negative electrode from the graphite anode, silicon carbon anode, , But can not confirm at present.
Cobalt and nickel are strategic materials, the next goal - the high-energy battery cathode is mainly cobalt-free nickel-free materials in the 400 watt / kg high specific energy battery, the National Battery Innovation Center launched a lithium-rich manganese-based solid solution Of engineering and technology research, which is a sample of the battery they do at 350 wattsh / kg, but the attenuation is very serious.In this regard, the Physics Department of the Chinese Academy of Sciences did some work on the decay of the lithium-rich manganese-based solid solution materials in undertaking national special projects. In addition, the new structure of lithium-rich cathode material worth noting is mainly undertaken by the project team of Peking University. For the first time, a specific capacity of 400 mAh / g of positive electrode material is studied, which is a major breakthrough for the traditional lithium ion cathode material. Ternary 811 cathode capacity of only 210 mAh / g, and now the new structure of lithium-rich cathode material has been achieved 400 mAh / g, which lithium-ion batteries to achieve the goal of 500 watt hours / kg, of course At present, this is still basic research.
Due to the high potential of lithium-rich positive electrode, the oxygen participation reaction must be over 4.4 volts, whereas the traditional liquid electrolyte can not be matched. Therefore, the possible approach is to combine the lithium-rich positive electrode material with the solid electrolyte so that the high-capacity lithium-rich positive electrode, The negative solid state battery will become one of the important targets for the long-term development of power battery.We used to think that lithium-sulfur and lithium-air battery is the future direction of development, and now an alternative.Lithium-sulfur battery than the energy can However, the lithium-sulfur battery volume ratio of energy to weight ratio of energy is basically 1: 1, for cars in terms of volume and energy is more important, so lithium-sulfur batteries for cars is challenging, it is energy storage May be more promising.
Finally, I want to emphasize that the development of high energy-efficient electric vehicle battery is always the top safety and security.There are many experts and entrepreneurs mentioned this morning, security, I emphasize here again, security is the first, than the Energy and other performance indicators Second, I now focus on power battery safety, which is my battery safety laboratory at Tsinghua University.
The second part, electric vehicle energy consumption and energy saving technology.
As we all know, the overall energy consumption of electric vehicles is high at present, and there is great potential for energy saving. The significance of energy saving is greater than that of fuel vehicles. Why? Because electric vehicles do not have energy, they can at least go far. Is a pure electric car users, has opened a few years pure electric cars, I deeply understand that high power consumption.In this regard, the world are increasing driving range, driving range increase need to rely on the battery than the energy increase, However, OEMs can not throw all the electric vehicles into the battery factory. The core technology of vehicle integration is to reduce the power consumption, which is the most important manifestation of the integration level of a pure EV. As we all know, On behalf of the car energy consumption of 100 kilometers of 13.7 degrees of electricity, to the second generation, the third generation are basically 100% of electricity in 100 kilometers. In theory, A-class car to do 10 kilometers of electricity is possible, so new energy Car key special has a research and development program, this project is undertaken by Changan, pure electric cars by 2020 (4.5 meters captain) vehicle power consumption 100 km 100% (working conditions), only to reduce power consumption is possible to reduce Under the premise of cost High driving range, this is the best way.
How to reduce power consumption? We have a variety of key technologies, I will briefly introduce here.
First of all, We have to learn BMW i3, Weight down , Our current vehicle weight is too large, not described in detail here.
Second, low resistance , We have to learn from Tesla, Tesla electric SUV drag coefficient of 0.24, our traditional fuel SUV drag coefficient can be high to 0.4, this is a big difference, directly from the traditional SUV to change the electric SUV in fact, the energy consumption Is not appropriate.One-generation electric passenger car energy saving focus is to reduce the electric SUV drag coefficient, this can use a new platform, can not be completely directly from the traditional car change.
Third, electric drive efficiency We have to see that foreign multinational auto parts groups are now competing to develop integrated electric drive axle and enter the Chinese market, connecting with our country's electric drive enterprises, some of our country enterprises have begun to cooperate with them, of course, these are all enterprise behaviors , But we still have to pay enough attention in this respect.For example, the motor controller input to the shaft efficiency, they can reach 92%, but generally we see the current level of 82% in China - 85%. Recently, the domestic leading enterprises have also done intensive research in this area. Under the condition of NEDC, the average efficiency can be close to 90%. We must make progress towards this goal.
The next is the braking energy recovery, the international benchmark braking recovery efficiency generally high, Nissan Leaf energy recovery vehicle energy consumption improvement of 20.5%. Nissan's E-Power single-accelerator operation, the basic brake pedal , Which is very significant to reduce energy consumption.I opened the car BMW, brake feedback is very heavy, basically do not have to drive in the city brakes.
China's braking energy recovery technology has made progress, but the practical application of weak, such as Tsinghua University team brake feedback technology used in the Beiqi E150, energy consumption can be improved to 23.7%, but the actual use and promotion of vehicles in poor condition, in urgent need improve.
The last is the thermal management, the temperature of the actual operation of the greatest impact on electricity consumption, low temperature conditions than normal operating conditions, the highest 50% higher power consumption, which is a very large change in the winter driving range has a more substantial decline.
What to do? A new generation of heat pump air conditioning technology has made important breakthroughs, ongoing industrial testing, we should pay attention to this technology. Now battery heating, these are mature technologies, but there is a technology that is the winter heating, if we use PTC Heating, 1 kilowatt can produce 1 kilowatt of heat, heat pump air conditioning COP (heating energy efficiency ratio) can reach 3, even if the minus 25 degrees can reach 1.7, that is, 1 kilowatt can provide 1.7 kilowatts of heat, the effect is very obvious , So it deserves our attention.
The third part, fast charging and charging network intelligent technology.
I would like to say two questions. One is that the private car charging pile has been building up with an increased rate. Our goal is to "get one car in a car." This is very important and should be led by the OEM. The other one we should see is that the national public Slow charge charging charge utilization less than 10%, that is to say, public slow charge exchange pile basic no one use, so the electric car charging trend will be private exchange charging pile daily slow charge + public fast charge supplement .We are now slow charge There is no problem in all aspects of cost, technology is also no problem, from the current contactless charge slowly to the future wireless charging, this technology route is also clear. The key is what kind of fast charge, this is the current we are facing The biggest problem.
As we all know, Europe and the United States plan to basically have a vehicle battery capacity of 100 kWh after 2020 and a driving range of 500 km, set a charging time of 15 minutes and propose a charging power of 350 kW.Now North America and Europe are all implementing, Japan a little later, but also after 2022. China's current passenger car DC fast charge is generally about 50 kilowatts, to achieve 350 kilowatts of high-power charging, electric car voltage to be raised to 1000 volts, charging current 400-500 A , Exceeding the performance boundaries of existing product components can have a serious impact on our existing pure EV system as a whole and pose a significant risk to the safety of all parties in 2017. As a hot issue in 2017, Repeatedly discussed at the same time, China Recharge Alliance is also conducting technical preparations for high-power charging, because as the electric car driving range increases, the battery capacity increases, the charging equipment with built-in power gradually increased demand, which is Inevitably, because the original driving range of 150 km is now raised to 300 km, the original battery 20 kWh now basically four or five If we look at the next 10 years, China's distributed renewable energy will become the main source of power generation, because the price of photovoltaic Continuing to decline, it is estimated that in 5-10 years will be lower than coal.
Therefore, charging intelligent will lead to the energy revolution. In our opinion, the future is the new energy intelligent electric car. I added two words here. There are intelligent cars in front of the electric car and new energy sources. Equal to what? Electric car + intelligent driving + charging intelligent, we now talk about driving more intelligent, relatively hot, I think it has almost become the Red Sea, but the charge is intelligent or the blue ocean, I think than driving intelligent may We need to open up another big space for energy intelligentization. Moreover, China's electric vehicles have a first mover advantage, the Internet has technological advantages, and the photovoltaic technology has an industrial advantage. If the three advantages To integrate, I believe we will be able to achieve overtaking.
Through analysis, we believe that the future development of charging development is based on battery energy storage V2G microgrid, that is, vehicle-electric interaction, with distributed renewable energy and electric vehicle microgrid to stabilize the fast charge load. As we all know, fast charge margin increased After that, the peak of fast charging power of electric vehicles is very large, meanwhile, renewable energy is intermittent peak. So how can the two peaks coordinate and interact with each other to reach a stable and stable power grid? This is what we must study and implement as soon as possible. AC slow charge, between 3 kilowatts to 20 kilowatts, accounting for more than 80% of the total charge to slow charge as the main body, coupled with fast charging power, the gradual transition from 120 kilowatts to 350 kilowatts, accounting for 15% of the charge. In the next 2-3 years, we may still need to charge 40% of the SOC in 30 minutes, 60% in half to half in 3-5 years and 75% in 15-10 minutes in 5-10 years. This is our basic development vision .
Finally, we hope that the personal charging pile strives for 1: 1 matching and becomes the charging subject. Under the scenario of electric passenger car public fast charging power station, there are roughly three stages:
First, from the current fast charge of less than 60 kilowatts to fast charge of less than 150 kilowatts by 2020, we promote self-supporting piles and study various types of charging technologies represented by high-power fast charge. By 2025, Demonstration of a new generation of charging technology, large-scale demonstration of V2G applications; 2025, the promotion of a new generation of charging technology, large-scale transformation of infrastructure to achieve new energy intelligence, in addition to intelligent driving but also to achieve intelligent new energy , To meet the passenger car's rapid power demand, while bringing the entire energy transport system revolution.
