Are lithium-ion batteries safe?

With the $100 billion lithium industry, where does the gold compass point? BBS --2018 China (international) lithium electricity and electric technology development peak BBS was held in Shanghai from April 20 to 21. This conference was co-hosted by the first lithium power grid, heli exhibition and mind manufacturing network, and China international electric vehicle and charging and exchanging technology peak BBS was held at the same time. The BBS invited more than 40 guests to share their speeches. More than 500 enterprises related to the lithium battery industry from all over the country were present. He xiangming, chairman of the brics lithium battery summit, gave a keynote speech titled "safety and reliability of lithium ion battery".

Today I'm glad to attend the brics lithium electricity summit and meet you here, just the host has been introduced, the development of the power battery is now very quickly, there are also many problems,, and share with you today in the security and reliability of the power battery, the next share the consistency and quick charging of scientific problems, because time is short, lithium electricity mainly to share with you today why not security, what rate what concept reason, how to deal with? Security is very important we know a enterprise in Beijing's sanlitun area, for the loss of the brand is also very big, the car's ignition to the enterprise is very important, we see several examples in the past, the most typical Samsung NOTE7 is on fire, as you know, Samsung Tianjin industrial fire, Samsung in this industry, plenty of examples of fire, 2006 aircraft fire, lithium battery check words will pry open the box, get rid of the lithium battery, the plane can't check in lithium-ion batteries, the fire in the process of transportation, these examples of auto fire very, very much, if the electric bicycle also calculate, There are a lot of examples of fires, a lot of examples of horrible things, and there are going to be a lot of examples of cars. Just to give you a quick overview, the most important one is the famous Tesla, which can be found all over the world. There are three or four examples in China, a lot of them.

Why do these batteries catch fire? We see the world there are a lot of a lot of organizations, to establish standards for safety, all batteries by testing the safety of fire will still be on fire, this is the most hated security situation, the safety of these examples, a characteristic, to us, we found that the characteristics of lithium batteries are safe through security certification, is the development of several thousand times a chance, I say a line, not including small plant, the cause of the fire is the internal short circuit, short circuit inside the can't eliminate, lithium batteries all over the world happened a fire. These lithium batteries on fire are all qualified products, why there are these reasons? It's because we don't have a scientific connection between testing standards and their safety. Let's see why there isn't a scientific connection? Mainly is the abuse of security, with mechanical and electrical hot battery tests, look at the battery Ann is unsafe, is actually caused by short circuit inside, these are manufacturing defects, application, under NOTE7 and Tesla is a good battery, the concept of the two things are different, two characteristics are different, one is the abuse of security, one is the security, are two different concepts, these are the two characteristics, for the misuse of security is to do the test standard, one is the security, there is a completely different testing, since the cause is not predictable, is the concept of small, small event, to abuse of security is predictable, Every battery is used, the use of the abuse of safety standards to determine the safety of the battery is not safe because there is no link between, so the safety of the battery is not safe, through the safety of the test of the main reason, this is the most typical.

Another APU plane, about four or five smoke, smoke after the nasal was analyzed, and disconnect the battery, all open, found that there is a short circuit inside, then confirm the short-circuit, so the battery current causes the safety of the main reason is used chemical physics mechanical manufacturing, a preliminary analysis is more is the cause of temperature rise, thermal runaway, petrol filling fast, and micro short circuit, and the deformation of short circuit, etc., these factors caused the battery short circuit fever in the cause of energy security, such as lithium electrochemical internal short circuit, there is an example, if the battery put some metal materials, We will find that the metal powder there will be some point, you can do the experiment, we in the anode put a stainless steel powder in it to fill in electricity, will find that the point of the diaphragm stainless steel components, will happen is that we in the anode material powder by filling in electricity will switch to the cathode, it would have been do this batch of material of metal impurity requirements of reason, it is difficult to completely to get rid of. There are also brass, iron, stainless steel inside, which can cause the battery to heat out of control.

In addition, when charging, we have a limit on the size of the current. If the current is too large, it will cause boundary conditions, and there will be a risk if it is larger than the boundary conditions. And the diaphragm, many people come to ask me, domestic diaphragm with all the indicators are the same, and the manufacturer is not willing to, to make the battery yield is lower. We've looked at a number of reasons, and we've drawn a picture here that you can look at. There are a lot of micro pores inside, if the hole in the diaphragm is relatively large, the resistance is relatively large, migration from around, around the lithium output will cause battery stimulation. Do an experiment to verify, in China can use a very hard thing, squeeze the diaphragm, squeezing out of the diaphragm aperture, will find the right foot, will see the obvious precipitation of lithium around, so the manufacture of diaphragm is very difficult, there is a little inconsistent, can cause a lot of battery problem, the diaphragm is very high technology. Because we all know that power supply, power supply for a long time, will squeeze the pole and cause battery combustion, which is the main cause of many accidents in Tesla. If this causes can have many, many, all possibilities in this, it needs to be in the factory strict management, from design, purchase, and so on to manage the battery from this point, there is a factory they have some battery factory will burn every year, I to the factory to see, a lot of advice to improve, you can now have no, this is in the factory are the details of the need to experience, many battery manufacturers do not have this experience can cause a lot of problems.

So this is what we call deformation, and you can do it, and there are lots of places where you can cycle later deformation, and that deformation can cause the battery to get out of control. We think now the factory batteries can not simply evaluate, many corporate research, we found that the main reason of low temperature analysis of lithium, the cathode metal deposition, rechargeable lithium analysis has made the analysis, we can probably put the number of the reliability of a battery to do some analysis, we have done this, we analyzed the result of the example we doing samples of a domestic manufacturer, we view, whichever batch analysis results of Japan's battery, is the best performance, it is relative, almost domestic and South Korea, domestic first-line brand batteries with South Korea has about the same, It's basically the same thing with the consistency assessment. Japan is still the best, Japan has done a good job in details, South Korea and China have done about the same, domestic second and third line of the brand gap is very big, next I will simply report to you if a battery is made relatively safe, probably what will be the current thinking, one of the ideas of the process of heat runaway conducted in-depth analysis.

Cause thermal runaway will have a series of chemical reactions, the second high temperature to produce become disadvantage reaction, heat temperature on the rise, continuously circulation, the battery temperature rise unceasingly, will form the heat out of control, we put the process decomposition, we know what is this reaction, control of the reaction, the mechanism of control, can reduce internal heat, through chemical reaction to reduce the rate of heat, slowly heating, improve the thermal and should not be too fast, so that the battery is safe, change the path of development, for example the positive, and so on we have very good organization for a battery thermal runaway, so this is what we are doing a validation, 200 wh / 4 kg, so that the battery is safe to do 150 degrees more than 6 hours, this is a big test, including the puncture test of audition is also very big, if done, security is greatly improve here made a summary, through test to evaluate the random security of the lithium battery, different manufacturers is clear, a line of brand and second-line brand result is obvious differences. Japan's battery is the best, China and South Korea's level is similar, through the improvement of chemical materials, lithium ion battery safety can be passed.

The page contains the contents of the machine translation.