Prince Dong: How to solve battery safety problems? Energy density and security need balancing optimization

Prince Dong: How to solve battery safety problems? Energy density and security need balancing optimization

This year, the safety problem of electric cars is a bit more. According to the data of the State Market Supervision Administration, in 2018, there were at least 40 fire accidents involved in new energy vehicles. Since the April this year, the electric vehicle, which has occurred in the two, three-in-one electric vehicles, and the power of lithium battery safety are a sensitive topic.

Another topic that cannot be avoided. Recently, my country’s Dynamic Lithium Battery Innovation Alliance Under Secretary-General, Wang Zi, deputy secretary-general of my country Electric Automobile Charging Infrastructure Charging Alliance, Wang Zi, in the first my country International Electric Automotive Safety Technology Innovation Conference, multi-dimensional analysis of electric vehicle safety issues. He believes that the power lithium battery has no obvious technical breakthrough in the material, it is difficult to further break through the development of energy to a certain level.

. And at the same time, the negative impact in security is getting bigger and bigger..

The problem that the balance between energy density and safety and long life is not overlooked without mastering the lithium-ion battery.. my country’s Dynamic Lithium Battery Innovation Alliance Under Secretary-General, my country Electric Automotive Charging Infrastructure Charging Alliance Under Secretary-General Prince Winter Power Lithium Battery Technology Route has been the result of energy density and security game.

Prince Winter said, “We must recognize that the battery pack is a component containing high-energy substances, which is the essence of danger, and with the increase in battery comparison, the risk of accidents will increase. “In many technical routes in lithium-ion batteries, lithium iron phosphate and terpoally..

Lithium iron phosphate has high safety, long life, but the energy density is not as high as three yuan, but it can be made up of battery capacity, the low temperature performance is poor, and it is important to low temperature performance on small capacity battery, and the material consistency is also poor.. The energy density of the ternary battery is high, the consistency is good, the low temperature performance is good, but the safety is slightly poor, and the cycle life is far less than the lithium iron phosphate ion battery.

. “Currently, in my country’s phosphate ion battery has the most mature industrial chain, we have more core technologies mastering in the relevant field, and the three-yuan battery is represented by Japanese and South Korea, relatively mature..

“Prince Dong believes that this kind of technology route is more than a kind of VS Japanese and South Korea.. If the performance of the power lithium battery itself is evaluated, he enumerates 10 dimensions: 1.

The safety of the battery pack, 2. The energy density of the battery pack (rather than monomer), 3. Circulation life of the battery pack, 4 Cost, 5.

Charging magnification, 6. Battery monomer consistency, 7. Low temperature performance, 8.

The components utilization, 9. Easy to recover reuse, 10. Positive and negative material can be recycled and repaired use.

As a technology route that can lead the trend, there is no distinctive shortcoming in any of the above aspects, and the balance of all aspects is a feasible route, not a single performance indicator. For example, energy density. Therefore, from the above 10 aspects, in this pair, the three yuan and phosphonate lithium fiercely killed, painful competition, mutual winning, there is a flat hand, after these 10, the prince is a personal referee, give a Simple final conclusion: In case of safety, energy density requirements are not very high, preferred lithium iron phosphate ion batteries.

Where is the ceiling of a power lithium battery? In the face of prince, there is a clear understanding of improving the energy density of the power lithium battery: the performance of the power of electric vehicles that can industrial automobiles is improved, not only the performance of the positive and negative material, but also in many respects There is a relatively large breakthrough, it is possible to achieve the true meaning of the dynamic lithium battery.. Then, from the meaning of the industrial dynamic lithium battery, the goal proposed by the state is that it can run 400km by electric vehicle charging at 2020, and the monomer battery is reached: 300Wh / kg (350), 600WH / L (700) 0.

6 yuan / WH, battery system reached: 220WH / kg (260), 300WH / L (380), 1.0 yuan / WH, cycle life is 1500 times (80% DOD). Wang Zi Winter said that from the indicator data, if you want to achieve these indicators, it is more difficult.

. At present, domestic dynamic lithium battery company product profile is: Lithium iron phosphate, and the energy-density of energy-type lithium iron-based lithium battery in scale is substantially between 140-180Wh / kg..

In terms of three raw materials, the large-scale production of three-dimensional-driven three-dimensional positivelithium ion power lithium battery is substantially between 180-260Wh / kg.. Introduction to the technical perspective, if the battery pack is 260Wh / kg, according to the energy consumption calculation of 10kWh / kg / 100km, the 40KWH battery unit of the electric vehicle in the situation cannot exceed 99.

5kg, and the total weight of the battery pack cannot exceed the total weight of the battery pack. 153kg, the soft packaging battery is more than 402Wh / kg, which is difficult to know. From this, it can be launched, and the energy that reaches 350WH / kg (if possible), it is necessary to make a large capacity (80ah or more) aluminum alloy hard shell power lithium battery, which saves the weight of the modularization.

The total weight of the 40KWH battery should be controlled within 114.3kg, which can only account for 74.7% by the battery pack, the rest of the aluminum alloy case (25kg), the heat management system (2kg), the connector and the fixing member (11.

7kg), etc. The total weight cannot exceed 38.7kg.

The weight of the station battery pack is 25.3%. The total weight of the battery pack can not exceed 153kg.

The battery pack is more than 262Wh / kg.. “Why do you think that a high energy density thinks of soft packaging battery? From the perspective of the vehicle engineering, the energy density of the power lithium battery system, not the energy density of the monomer battery.

From the monomer battery to the module, then to the system integration, the intermediate link is more, the connector between the battery, the connection cable, the box, the fixing frame, the support frame, the heat conductive structure, etc., which will have added a lot of new Weight “, Prince Dong proposed, optimization in system energy density, reliability and safety. Dynamic lithium battery safety my country’s dynamic lithium battery industry has been accumulated in ten years, especially for the understanding and understanding of dynamic lithium batteries, should be used in the current electric vehicle, it should be said to be competent.

Now, if there is no obvious technical breakthrough, it is difficult to further breakthrough after developing to a certain level than energy, and this is increasingly larger in safety.. “Many people have asked me that the fuel truck often fires, and more than electric vehicles, why do you have such a high electric car?” Prince Winter said that there is a concept to be clear: the fire car is able to find the law And many known factors are related to the key point that the flammable objects of the fuel car are fuel, which is sealed in an environment isolated from the outside, and the oxygen (combustion) and fire sources are separated, and this isolation is once Breaking (such as the engineering of the engine, the engine is high), there will be an accident.

. The flammable objects of the power lithium battery system are electrolyte, and it is and the combustion ooler (the positive electrode material will decompose production oxygen) and fire sources (internal short circuits, and high temperature) are sealed in the same container environment. In the case, it is especially true that it’s safe uncertainty.

. In the winter of the winter, he said that he had a cold and 2003 SARS virus who caused the harm caused by human beings? Of course, it is a cold, but human fear SARS, because about SARS virus, we did not treat drugs at the time..

Therefore, before the law of the lithium-ion battery, the balance between control energy density and safety and long life cannot be overlooked before the law.. 1.

How do I know the power lithium battery? The power lithium battery is in advance before birth: battery module and battery pack (system) can be assembled, can be installed, maintainable design, adjustability, recycling, convenient dismantling design, etc.. These properties are very important, can’t make batteries to resolve these performance problems, and lithium-ion batteries are “explosive” temper, why lithium ion batteries will transform “bombs on time”? Lithium-ion batteries are important consisting of six parts, are positive, aluminum foil, negative electrode, copper foil, diaphragm, electrolyte.

The electrolyte inside the battery contains a large amount of organic matter, such as carbonate, diethyl carbonate, dimethyl phosphate.. These guys have their own burnout attributes one by one, and the face is written “away from the fire” four words.

. In addition, once the positive and negative poles of the battery is shorted, it will heat up, even sparks, so people will naturally think that it is necessary to use something to take the positive and negative, so it introduces the diaphragm. After the battery diaphragm is thinned, once the film is broken, the problem will be very serious.

. The lithium-ion battery itself also hides the hidden danger of piercing the diaphragm. This type of phenomenon is “dendritic crystal”.

This problem is a disease written in a lithium-ion battery gene, and the lithium-ion battery is in the process of use, the electrode surface forms some Small burrs, these small burrs are called “dendrites”, and the longer the dethyra, the greater, and will eventually penetrate the membrane, resulting in short circuits. The thinner diaphragm, the flammable electrolyte, the dark stream is surging will grow the demethral crystal of its own growth, and the material decomposition will automatically separate oxygen. The entire lithium-ion battery is like a gunpowder barrel, a combustion, and a fire agency in a small.

In the room, then use a layer of plastic wrap, let who want to be bold, now, the most critical is to control “lighter”. 2, how to ensure the safety of the power lithium battery system? The safety of the battery system must be solved by the battery. The battery should be guaranteed, and more stable materials must be used.

. Wang Zi’s winter said that it is now deliberately putting down the safety requirements of the battery. Grasping, on the safety of the core level, select a thicker diaphragm, and should not be achieved by thinning the thickness of the energy density in the battery cell.

. Safety management at the time of charging of the battery pack is the key! Due to the power lithium-ion battery in group usage is also the core problem: one is safe, second is life, especially when charging, the difference in battery in the battery pack is increased. How to solve the service life of the battery pack, facing a huge challenge.

Factors that affect battery safety use and cycle life, in addition to battery self-process and product quality, a crucial problem is: Safety control and thermal management technology when battery formation charging. There is no perfect battery in group safety control and thermal management technology. The safety of the battery cannot be guaranteed.

Therefore, the management system of the power lithium battery charges and the safety of the battery itself.. 3.

Fast charging technology requires high power lithium battery requirements for charging speed problems, everyone hopes to achieve rapid charging, current high-energy power lithium battery charging speed can supplement 80% energy within about 40-60 minutes, about Urban commuter vehicles do not constitute an electric vehicle’s true use of obstacles, but there are some problems about the traffic problems between the use of electric cars to solve the city.. From the fast charge to the ultra-fast charge (200-400KW), the energy supplemented by 90% in 10 minutes will effectively shorten the gap between electric vehicles and internal combustion engines.

. Prince Winter said that the current design method is to reduce the thickness of the electrode, change the battery structure, and more suitable for fast charge material selection, which will add the production cost of the power lithium battery while reducing its energy density, and reducing power Life life of the lithium battery system is optimized from overall consideration. On the other hand, how to reduce the difference between the unit cells between the battery pack in the fast charge process, it is necessary to design the service life of the power lithium battery.

. 4. How to solve the safety problem of power lithium battery? Prince Dong believes that the importance of new energy vehicle safety accidents is caused by the dynamic lithium battery thermal out-of control.

The thermal out of control is not only results, the reason is not complex, the source of the accident is difficult to clear, and the safety issue should be highly valued.. The industry continues to reflect on security issues, blindly pursue high energy density into focus, professionals point out that theoretical battery energy density and safety are inverseby, the company pursue high energy density, security issues, although it is not possible to clarify the angled incident And the pursuit of energy density, but with the high nickel ternary battery enters the market, new energy vehicles face higher safety technical requirements.

How to make a balance between high energy density and improved security, become a major problem in the current industry, each company is designed from the structure of the monomer battery, module design, and battery packs to improve overall safety.. Improve the safety of the power lithium battery is important from three levels, including the structural design of the monomer battery, module design, and battery packs to improve overall safety, and the monomer battery can be added in the electrolyte.

Additive reduces its flammability, improves diaphragm temperature resistance, or improves positive material material stability, etc. However, it can be placed by the position of the battery to better dissipate heat, improve the charging method, and reduce safety hazards due to improper charging..

Since the battery pack is a component containing high-energy substances, there is a risk of dangerous, and as the battery is increased to energy and the ratio of power, the risk of accidents will increase. Therefore, it is necessary to study the balance of energy density and security, including the balance of material performance, the balance of battery module structure, balance of battery pack system level, cost acceptability, considering multi-level utilization process , Balance during the recovery of the power lithium battery material. Research on solutions include: material performance matching optimization, optimization of battery module structure, battery pack system and body integrated design, controlling manufacturing cost control, promotion multi-level utilization diluted application cost, encourage power lithium battery material repair and reuse.

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