Chapter 239 The Capitalists’ Hearts Are All Black Indeed

The key to solving the problem of lithium dendrites lies in a common additive in the electrolyte.

This answer is somewhat unexpected.

After all, the industry and the battery industry have always focused on artificial SEI films or lithium salts in the electrolyte to solve the problem of lithium dendrites.

In the eyes of most experts or researchers, these two materials are the key.

If Xu Chuan had not returned with twenty years of vision and experience, he would not have directly locked his eyes on the electrolyte.

As the saying goes, the more easily overlooked a place is, the more likely it is to breed the most deadly things.

Ethylene carbonate, a material added to almost all lithium-ion batteries, has greatly improved lithium batteries.

However, it may also be the culprit of the lithium dendrite problem.

After replacing the additives in the electrolyte, Xu Chuan conducted a variety of tests on the new battery in his hand, and also simultaneously manufactured several new batteries, using different additive materials to verify the previous judgment.

The final experimental and test results show that different types of additives do affect the working performance of the new artificial SEI film.

Among them, materials such as ethylene carbonate and alkyl phosphate are particularly serious.

Organic phosphide and organic fluoride additives are relatively light, and the best-performing fluoroalkyl phosphates can even achieve a coulomb efficiency of 99.98%.

This data is enough to increase the number of charge and discharge cycles of lithium batteries to more than four thousand times.

Compared with the current standard charge and discharge times of 500 times for lithium batteries, it has more than doubled.

But at the same time, after replacing ethylene carbonate, the performance of lithium batteries, from battery capacity to charging and discharging speed to the activation performance of the electrolyte, has been significantly reduced.

Among them, the fluoroalkyl phosphate with the best coulomb efficiency has directly reduced the charge and discharge efficiency by about 25%.

And the lower the external temperature, the greater the interference to the charge and discharge efficiency, but when the temperature is too high, the instability of the electrolyte will increase accordingly.

If the temperature is too high, the battery will bulge and expand.

Although there have been no problems such as spontaneous combustion and explosion in the current tests, Xu Chuan knows that with the increase of time and the number of tests, if fluoroalkyl phosphates are used instead of ethylene carbonate, these problems will occur.

He doesn't want the battery he developed to be comparable to a certain star company.

Batteries that can explode and self-ignite at any time are useless no matter how high their capacity is, and their safety performance cannot pass the test at all.

Finding an additive that can replace ethyl carbonate has become the current focus of the Sichuan Hai Materials Research Institute.

Yu Zhen and Ye Zan temporarily stopped the research and development of artificial SEI films and electrolytes and entered this work.

In the laboratory, including those doctoral and master's students who are capable of conducting battery experiments alone, Xu Chuan also arranged experiments in pairs.

Compared with formal researchers, these people still lack a lot of ability.

However, if they can study to the doctoral stage, they will not be too bad.

These people can be trained as the team of the Sichuan Hai Materials Research Institute, and Xu Chuan will not be stingy with his resources and money.

For these doctoral and master's students, nothing is more gratifying than this.

After all, only with experiments can we have data, achievements, graduation, and qualifications.

"Boss, these are the experimental results of each group these days."

In the laboratory, Fan Pengyue handed the information in his hand to Xu Chuan, and made some simple statements: "According to your requirements, seven groups of laboratory personnel have conducted experiments on a total of fourteen different ethylene carbonate substitutes."

"In the experimental results, the two best materials are fluoroethylene carbonate and trimethylsilyl sulfite."

"These two materials can match the current artificial SEI film to a large extent. The Coulomb efficiency calculated after replacement is 99.645% and 99.721% respectively."

"But correspondingly, these two materials also have their own shortcomings after replacement."

"For example, after the replacement of fluoroethylene carbonate, the charging and discharging efficiency decreased. Problems."

"These experimental data are relatively small, and can only be used as a preliminary reference. After all, we don't have enough time to do complete experiments and tests."

"In addition, some safety tests have not been done."

In the laboratory, Xu Chuan took over the experimental data of these days from Fan Pengyue, listening to his brief description while flipping through the information in his hand.

Since the discovery of ethylene carbonate as the main cause of lithium dendrites and lithium precipitation in early November, the Chuanhai Materials Research Institute has been continuously conducting experiments on it.

Although the time is very short, only about 20 days, it is enough for them to experiment with many new materials with a goal, sufficient manpower and equipment.

Of course, the experiments and tests these days are not perfect and not very formal.

Issues such as the compatibility between materials and battery safety performance testing have not been considered.

However, compared with these problems, it is more important to find an additive that can replace ethylene carbonate. As for other things, they can be gradually improved later.

Xu Chuan wants to solve this problem before going to Sweden to receive the award on December 10.

After finishing, I will go to receive a Nobel Prize. When I come back from Europe, the test of the two protective materials in the nuclear energy β radiation energy concentration conversion power project will be almost completed.

In this way, he can devote his main energy to the nuclear energy project after the Nobel Prize.

However, judging from the current progress, this wish is probably difficult to achieve.

Among the dozen additives tested, none of them is very suitable at present, and basically all have problems of one kind or another.

If we put aside the problems of lithium dendrites and lithium precipitation, ethylene carbonate is really the best among all additives.

"Maybe we can dilute the concentration of ethylene carbonate and try it? Or find a material to neutralize it?"

Looking through the test report in his hand, another way to solve the problem emerged in Xu Chuan's mind.

Ethylene carbonate will still be active in future lithium batteries in the future, and it must have its role.

"If we can find a way to solve the problem of lithium precipitation caused by ethylene carbonate, perhaps ethylene carbonate has another role."

Suddenly, another term emerged in Xu Chuan's mind.

"Planned obsolescence!"

The so-called planned obsolescence refers to an industrial strategy.

That is, the product supplier intentionally designs a limited service life for the product, so that the product is scrapped after a certain period of time.

It first appeared on light bulbs.

During Christmas in 1924, companies such as Osram, Philips, and General Electric gathered in Geneva to form a monopoly group called "phoebus", with the goal of controlling the life of light bulbs to about 1,000 hours (while the life of light bulbs could reach 2,500 hours at the time).

The government took the "phoebus" group to court, accusing the other party of its behavior. In the end, although the agreement was nominally terminated, these companies did not make any compensation.

More importantly, the alliance proposed the life control of ordinary light bulbs, which has continued. To this day, the life of most light bulbs is only 1,000 hours.

This was planned obsolescence at the time.

Then, as time went on, this agreement gradually spread to other products.

For example, batteries and chips in mobile phones and computers; ink cartridges in printers; key buttons of various electrical equipment, etc.

These things now have the ability to be planned for obsolescence, that is, after a period of use, they will be damaged for various reasons.

For manufacturers of these things, if a product can be used for a long time in the hands of users, then the number of people who buy new products will decrease after the launch of new products.

Therefore, in order to introduce new products and expand their own interests, manufacturers will inevitably choose to eliminate old products in the market, because new products face competition from old products to a certain extent.

In lithium-ion batteries, the presence of ethylene carbonate can improve the performance of lithium batteries on the one hand, and on the other hand, as the number of charge and discharge cycles increases, the lithium precipitation of the negative electrode will become more and more serious, which will naturally cause battery damage.

The impact of ethylene carbonate on lithium-ion batteries that only needs to be controlled can be said to be a natural plan to scrap.

This may be the reason why ethylene carbonate will cause lithium precipitation problems, but it still exists in lithium batteries in the future?

Xu Chuan roughly figured out where to start with the solution to the lithium precipitation problem.

If his guess just now is correct, then the solution to this problem is nothing more than controlling the content of ethylene carbonate, or using another additive.

After confirming his guess, Xu Chuan immediately started to experiment again.

Simply verifying the method in his mind, the method used is very simple, just reduce the content of ethylene carbonate in the electrolyte directly.

In the first experiment, he reduced the content of ethylene carbonate in the electrolyte by 20%, made a new lithium-ion battery, and retested it.

One-fifth of the amount is enough to ensure that if the content of ethylene carbonate really affects the lithium deposition at the negative electrode, it will definitely be reflected in the data, and with a larger arc.

The test results are as he guessed. After reducing the content of ethylene carbonate in the electrolyte by 20%, the problem of lithium deposition at the negative electrode of the lithium battery has been greatly improved, and the coulomb efficiency of the battery has increased from about 99.91% to 99.95%.

The coulomb efficiency of 99.95% is enough to ensure that a battery still maintains more than 80% of its capacity after completing 500 charge and discharge cycles.

This has reached the standard of lithium-ion batteries used in the market today.

"The hearts of capitalists are really black."

Looking at the results of the preliminary test, Xu Chuan shook his head.

Although it was just a simple test, it was enough to make him sure that the problem was here.

No wonder ethylene carbonate is one of the causes of lithium dendrites and lithium deposition in lithium-ion batteries, and this additive is still used in large quantities in lithium batteries.

It's not that there is no more suitable material, but because it is the most suitable.

Ethylene carbonate at a certain content can increase the performance of lithium batteries while automatically executing planned scrapping to make way for the next generation of products and earn a lot of money.

Take mobile phones as an example. The life of a mobile phone battery is about one to three years.

The average selling price of a battery is about 150 to 300 yuan. After deducting various costs, it can bring at least 50 to 150 yuan in net profit.

If there are 1 billion people using mobile phones, that would be 50 to 150 billion in net profit.

In fact, the consumption of batteries in countries around the world is far greater than the corresponding number of people. After all, one person can own a mobile phone, a computer, an electric car, and other electrical appliances that need to use batteries.

No wonder that after the problem of lithium dendrites is solved in the future, ethylene carbonate is still widely used in mobile phone batteries.

This huge profit is tempting for everyone.

Of course, the performance of ethylene carbonate itself is also excellent enough. Compared with other additives, it is more suitable for this new artificial SEI film and can bring greater performance improvement.

The better the battery, the more people will buy it, even if it is more expensive.

And no battery manufacturer will not love such an "almost perfect" additive.

However, for consumers, this is a very pitfall.

After all, the increase in consumer spending is real, but these can be avoided.

After determining that reducing the content of ethylene carbonate can improve the coulomb efficiency of the battery, Xu Chuan began to arrange other researchers in the laboratory to conduct more detailed tests on the batteries in hand according to the standard test of lithium batteries.

Battery testing is a rather tedious and relatively long process.

It takes a lot of time to conduct electrical tests such as overcharge, overdischarge, external short circuit, forced discharge, and mechanical tests such as extrusion, puncture, impact, vibration, and drop.

Not to mention other things, the charge and discharge test alone must be done at least 500 times.

IEC stipulates that the standard cycle life test of lithium batteries is: after the battery is discharged to 3.0V/piece at 0.2C, it is charged to 4.2V at 1C constant current and constant voltage, with a cut-off current of 20MA. After being left for 1 hour, it is discharged to 3.0V (one cycle) at 0.2C again. After repeated cycles of 500 times, the capacity should be more than 60% of the initial capacity.

In other words, even if the charge and discharge test is carried out day and night for 20 hours, it will take at least 20 days to one month.

However, compared with the huge benefits that lithium batteries can bring, these are nothing.

As for himself, he has other arrangements.

He needs to find a material that can reduce the lithium precipitation effect of ethylene carbonate.

From the previous experimental results, the content of ethylene carbonate is directly related to the lithium precipitation of the negative electrode. Experiments show that the more ethylene carbonate is added to the electrolyte, the faster the lithium will be generated at the negative electrode.

Reducing the content of ethylene carbonate can indeed weaken the rate of lithium generation, but it will also cause a decrease in the overall performance of the battery to a certain extent.

This is what Xu Chuan does not want to see.

So it is also very important to find another additive and control it.

Xu Chuan did not give this job to the Chuanhai Materials Research Institute.

Perhaps the Chuanhai Materials Research Institute can experiment with the required additives little by little, but it may take several months or one or two years, which is too slow for Xu Chuan.

He plans to use his mathematical ability to complete the calculation of this additive!

I haven't studied mathematics for a while, and I don't know if my mathematical ability has regressed.