Starting from a top student and marching towards the sea of ​​stars

Chapter 102 Your guess came true

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

"Mr. Xu, I think the number of charge-discharge cycles done before is a bit small. 50 charge-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 to the actual use of lithium batteries, the 50 charge-discharge cycles in the experiment must be relatively small.

However, the first thing we are studying now is to first 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 anode material is cycled the same number of times, such a comparison is relatively scientific. "

"Mr. Xu, I understand what you mean. This kind of experimental idea is naturally no problem. It's just that I hope to set up another set of experiments to test the limit of a porous silicon-metal composite material. 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, it will definitely be no problem to complete this experiment."

Because this experiment does not require too many details, as long as the lithium battery is charged and discharged continuously, and the reversible capacity change of the lithium battery is recorded after each cycle.

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

"Okay, then leave it to Sui Feng to do it. Then this experiment will still use the porous silicon-copper composite material I made before?"

"Well, let's use that one, because we've already done 50 cycles, and then we'll start counting directly from 51."

After making the 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 further advice.

Using brain simulation skills, although it is possible to predict the experimental phenomenon in advance, the number of simulations is very limited after all, and it is not yet the time when Ning Chen feels that it is necessary to 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.

The various theorems and proofs involved in it amounted to dozens of pages, and on each page, Ning Chen used the most concise language to describe and prove the theorems.

If Ning Chen thinks it goes well, he may finish the remaining work within a few weeks.

On the other hand, on the side of the material laboratory, some new progress has been made in the progress of the experiment.

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 lithium battery undergoes the same number of charge and discharge cycles, and the reversible capacity of the battery increases by several percentage points.

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.

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...how did the reversible capacity of the lithium battery drop so much when the lithium battery was cycled for the 208th time?"

Originally, the relationship between the reversible capacity of a lithium battery and the number of cycles was close to a linear function, but the experimental data this time 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 in mind, Sui Feng continued with the next experiment.

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

"No... from the 208th cycle, the reversible capacity of the lithium battery has dropped very rapidly. No, I have to tell Teacher Xu about it."

After all, Sui Feng is also a qualified master of materials science. Knowing that this kind of experimental phenomenon is contrary to their theory at the beginning, he quickly found Xu Zhou and explained the phenomenon he 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, now you take this anode material to do a scanning electron microscope, and I'll help you to say hello to the testing center."

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

It is necessary to make an appointment in advance for normal scanning electron microscopy, but some teachers occasionally use the rest time to test a few samples, and the testing center is generally accommodating.

What's more, Xu Zhou has just published a paper on "Nature" as the corresponding author. Although the main credit for the paper is on Ning Chen's side, Xu Zhou has indeed improved his status in the college and school.

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

After dealing with the matter here, Xu Zhou hurriedly called Ning Chen to explain what happened in the experiment just now.

Ning Chen also frowned slightly after hearing this, it seems that his worries before were not superfluous.

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 biggest possibility is that some reactions occurred during the contact between the electrolyte and the electrodes, and the substances produced by the reactions affected the reversible capacity of the lithium battery. This reaction may have been going on all the time. When the reactants When the quantity is large enough, the quantitative change leads to a qualitative change. Of course, there may be some reason for this kind of reaction to appear suddenly.”

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

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

(End of this chapter)