Start as a top student and move towards the stars and the sea

Well, Ning Chen, if you have any ideas, just tell me directly.

Mr. Xu, I feel that the number of charge and discharge cycles we did before was a little too low. 50 charge and discharge cycles cannot accurately judge the various capabilities of the battery.

Hearing Ning Chen's words, Xu Zhou smiled and said:

Ning Chen, you are right. Compared with the actual use of lithium batteries, the 50 charge and discharge cycles in the experiment are definitely relatively few.

However, the first thing we are studying now is to screen out the metal substances that are most suitable for combining with porous silicon, and the proportion of substances added between them.

As long as each negative electrode material undergoes the same number of cycles, such a comparison is relatively scientific.

Mr. Xu, I understand what you mean. There is no problem with this kind of experimental idea. It's just that I hope to set up another set of experiments to specifically test the limit of a porous silicon-metal composite material and test its performance after multiple charges and discharges. The experimental phenomena manifested after the cycle.”

Xu Zhou thought for a while and felt that Ning Chen's proposal was acceptable.

Well, it is definitely better to conduct this experiment when there are enough manpower. Ning Chen, do you plan to do this experiment yourself, or leave it to the students?

Let senior brother Sui Feng do it. With senior brother Sui Feng's ability, there will definitely be no problem in completing this experiment.

Because this experiment does not require too many details, it is enough to continuously charge and discharge the lithium battery and record the reversible capacity changes of the lithium battery after each cycle.

Ning Chen didn't want to put his experiment on such a relatively basic experiment. After all, Ning Chen also had to spend a lot of energy on the research on Qiu Chengtong's conjecture.

Okay, let's leave it to Sui Feng. Then this experiment should still use the porous silicon-copper composite material I made before?

Well, let's just use that one, because we have already done 50 cycles, and then we will start counting directly from 51 times.

After making arrangements for this experiment, Ning Chen did not continue to participate in the experiment in the materials laboratory, but went back to continue studying Qiu Chengtong's conjecture.

Before the key experimental phenomena appeared, Ning Chen could not give any opinions on the next step.

Although it is possible to predict experimental phenomena in advance using brain simulation skills, the number of simulations is very limited after all. It is not yet the time when Ning Chen feels that he must use the number of simulations.

…

As the research work continued, Ning Chen continued to make a number of important progress in solving the second phase of Qiu Chengtong's conjecture.

There are dozens of pages of various theorems and their proofs involved, and on each page, Ning Chen uses the most concise language to describe and prove the theorems.

Ning Chen feels that if everything goes well, he hopes to complete the remaining work within a few weeks.

On the other hand, in the materials laboratory, the experimental progress has made some new progress.

Xuzhou adjusted the previous porous silicon-copper anode material and added aluminum oxide for wrapping, which further improved the rate performance of the anode material.

After adjustment, the reversible capacity of the lithium battery increased by several percentage points after experiencing the same number of charge and discharge cycles.

Sui Feng began to conduct battery reversible capacity tests after multiple charge and discharge cycles. After many days of continuous experiments, Sui Feng has achieved the 200th cycle.

Hey, why are there more and more experiments recently?

While doing the experiment, Sui Feng sighed.

When Ning Chen first came to the laboratory, Sui Feng's workload was suddenly reduced a lot because of Ning Chen's very high enthusiasm for experiments.

This was also the most relaxing time for Sui Feng during his graduate studies.

However, the good times did not last long. After Ning Chen ended his internship in the laboratory, Sui Feng returned to his hard life in the laboratory.

To be more precise, after that, Sui Feng only felt that his experimental tasks were even more than before.

Just when Sui Feng was thinking about this, he suddenly discovered that there were some problems with the set of experimental data he had just measured.

Strange... why did the reversible capacity of the lithium battery drop so much all of a sudden when the lithium battery was cycled for the 208th time?

Originally, the relationship between the reversible capacity of lithium batteries and the number of cycles was close to a linear function, but this time the experimental data destroyed the law of this linear function.

Sui Feng felt that this might be a very special situation. After all, when doing experiments, it is very common for individual points to appear that are obviously not on the image.

With this thought in mind, Sui Feng continued the next experiment.

But the subsequent experimental results made Sui Feng realize that this was not an accidental phenomenon.

No... starting from the 208th cycle, the reversible capacity of the lithium battery has dropped very quickly. No, I have to tell Teacher Xu about this quickly.

After all, Sui Feng was also a qualified master of materials science. Knowing that such an experimental phenomenon was contrary to their initial theory, he quickly found Xu Zhou and explained the phenomenon he had just encountered in the experiment.

What? The reversible capacity of the lithium battery suddenly dropped significantly? What's going on?

Thinking of the experimental direction proposed by Ning Chen before, Xu Zhou was very surprised by Ning Chen's scientific foresight ability.

Looking at Sui Feng's experimental data, Xu Zhou guessed the essential cause of this phenomenon.

Well, Sui Feng, you can use this negative electrode material for scanning electron microscopy now, and I'll help you say hello to the testing center.

Okay, Teacher Xu, I'll be there right away.

Normally, scanning electron microscopy requires an appointment in advance, but some teachers occasionally use their breaks to test a few samples, and testing centers are generally accommodating.

What's more, Xu Zhou has just published a paper in Nature as the corresponding author. Although the main contribution of the paper lies with Ning Chen, Xu Zhou has indeed improved his status in the college and school.

After Xuzhou called the testing center to explain the situation, the testing center quickly said that it would help Xuzhou arrange a scanning electron microscope testing experiment as soon as possible.

After handling the matter here, Xuzhou hurriedly called Ning Chen to explain what happened in the experiment just now.

Ning Chen frowned slightly after hearing this. It seemed that his worries were not unnecessary.

Ning Chen temporarily stopped what he was doing and came to Xu Zhou's laboratory.

Teacher Xu, what do you think is the reason for this phenomenon?

Xu Zhou thought for a while and said:

I think the most likely possibility is that some reaction occurred during the contact between the electrolyte and the electrode, and the substances generated by the reaction affected the reversible capacity of the lithium battery. This reaction may be ongoing. When the reactants When the quantity is large enough, quantitative changes lead to qualitative changes. Of course, this reaction may suddenly appear for some reason.

Xu Zhou immediately gave his analysis of the experimental phenomenon, and Ning Chen also felt that the two reasons Xu Zhou mentioned were possible.

As for the specific reason, we have to wait for the results of the scanning electron microscope to be analyzed more specifically. But Ning Chen, fortunately you proposed to conduct experiments in this direction before. Otherwise, I don't know when we will discover this question.