Chapter 102 Your guess came true
"Well, Ning Chen, if you have any ideas, just tell me directly."
"Teacher Xu, I think the charge and discharge cycle we did before The number is 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 said with a smile:
"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 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 negative electrode material undergoes the same number of cycles, this comparison is relatively scientific. "
"Teacher Xu, I understand what you mean. There is no problem with this 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 experimental phenomena after multiple charge and discharge cycles. "
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 sufficient manpower. Ning Chen, do you plan to do this experiment yourself or leave it to 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 constantly tested Just perform charging and discharging operations and record the reversible capacity changes of the lithium battery after each cycle.
Ning Chen did not want to put his experiment on this 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, just use that one. , because the cycle has been done 50 times, and then the calculation starts 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, after all, the number of simulations is very limited. It is not yet time for Ning Chen to feel that he must use the number of simulations.
……
As the research work continued, Ning Chen continued to make a number of important progress in the second phase of research work to solve 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, there are more and more experiments recently.”
While doing the experiments, 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.
While 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 when the lithium battery was cycled for the 208th time?"
The original reversible capacity and cycle of the lithium battery The relationship of degree is 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."
Sui Feng After all, he 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 lithium batteries suddenly dropped significantly? What's going on?"
Recalling 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 take this negative electrode material for scanning electron microscopy now, and I'll help you go to the testing center to say hello."
"Okay, Teacher Xu, I’ll go over there.”
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 credit for the paper lies with Ning Chen, Xu Zhou has indeed improved his reputation in the academy. and the status of the 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, Xu Zhou 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 before were indeed unnecessary.
Ning Chen temporarily stopped what he was doing and came to Xu Zhou's laboratory.
"Teacher Xu, what do you think is the cause of this phenomenon?"
Xu Zhou thought for a while and said:
"I think the most likely reason is During the contact between the electrolyte and the electrode, certain reactions occur, and the substances generated by the reaction affect the reversible capacity of the lithium battery. This reaction may be ongoing. When the amount of reactants is large enough, the quantity changes. Of course, this reaction may have occurred suddenly for some reason."
Xu Zhou immediately gave his analysis of the experimental phenomenon, and Ning Chen also felt what Xu Zhou said. Both reasons are 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.”
(End of this chapter)