Chapter 153: Beautiful and deadly dendrite

Lu Zhou replied, "I'll come."
The system does not stipulate who must perform the experiment, as long as the experiment is done once, and then collect the data that needs to be collected. But not for the purpose of learning, Lu Zhou still wants to do it by himself.
After all, the paper has to be superficial, and the books handed to him are all theory. Only by implementing them can the legendary black technology be turned into a real guy.
Putting on a white coat with great ritual sense, Lu Zhou took out the momentum of the scientist a little, took a deep breath, reached for the sample box containing the experimental materials.
However, before his hand was touched, he was snatched away by Brother Qian, an eye-wrenching hand.
"I'll come and watch."
Without saying a word, Brother Qian took over the initiative of the experiment and hung Lu Zhou with a grim expression on his side.
Looking at Brother Liu, Brother Liu holding his arms shrugged helplessly.
"Don't mind, this is the old money. The equipment here is like his wife. It is more important than his life. For the first time, you should watch him do it."
Brother Qian was not at all, and then said, "It is not mathematics to do an experiment. You can calculate a wrong decimal point and then you can continue to calculate. An error in a small detail of the experiment may cause the entire experiment to be abolished. Of course, I am more afraid You abandon the experimental equipment and show me the experimental process of your design. "
"Here." Lu Zhou quickly took out the a4 paper.
He has written the experimental steps required by the system and the experimental data to be collected.
Brother Qian took a glance at the a4 paper and nodded: "The design is quite professional."
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After all, it's system design.
Lu Zhou had a subtle expression and did not speak.
The experimental process is simple, starting with making the battery and observing the phenomenon.
7% graphite was used as the negative electrode material, the binder was sodium carboxymethyl cellulose (cmc) and styrene-butadiene rubber (sbr), and the current collector was copper foil. The graphite layer has a thickness of 90 m, the positive electrode active material uses lifepo4, and the current collector is aluminum foil.
As for the diaphragm, a three-layer diaphragm of celgard2325 is used, and the thickness is about 25m.
To prevent material oxidation, everything is done in an argon-filled glove box.
Of course, not only to prevent the material from oxidizing, but also to prevent the lipf6 component in the electrolyte from reacting with water in the air to generate hydrofluoric acid.
Hydrofluoric acid is known to anyone who has studied high school chemistry.
And how dangerous this gadget is, everyone who has been in the silicon-based microelectronics laboratory should also be very clear. Wipe a little with either hand, and basically you can't see anyone with this hand.
From the point of view of Brother Qian's operation process, he is obviously more professional than Lu Zhou, a theorist.
Soon, the samples were made.
To prevent sample damage, an edge-to-edge assembly method is used. Brother Qian fully covered the lifepo4 material with a layer of diaphragm in the glove box, and carefully left the free ends of the positive and negative electrodes with a 2mm gap.
This step is critical and is related to the safety of the experiment.
Taking the sample out of the glove box, Brother Qian closed the air valves of each way and exhaled.
"Get it."
Looking at the sample in Brother Qian's hand, Lu Zhou asked, "Is this a battery?"
"A simple and unsafe lithium-ion battery," Brother Qian introduced concisely.
Lu Zhou was nervous: "Will it explode?"
Brother Qian shook his head: "It will not explode, but improper operation may cause a fire."
And it was a fire on a digital microscope.
Burning out the sample is a trivial matter, and baking the lens of a digital microscope is a big deal.
Lu Zhou estimates that this is also one of the reasons Brother Qian does not let himself be a novice to experiment.
The sample was connected to the bk6808 rechargeable battery tester, and then placed on a digital microscope. Brother Qian set a few parameters to the computer, repeating the steps on the paper in a whisper to himself: "Collect once every 2 minutes Image, the data collection frequency is 1hz, the battery is discharged to the cut-off voltage ok after the battery is first charged to 400min. "
The rest is a long wait.
Looking at the unchanging instrument, Lu Zhou couldn't help asking: "Do you have to wait so long for battery material tests?"
Four hundred minutes, it's almost seven hours.
Brother Qiang pushed his glasses and said, "Seven hours are the basic operation, and sometimes you have to wait a few days to see the results. Generally, you will stay in the lab on duty. Basically, I and Liu Bo take turns. "
"Yes," Liu Bo said with a smile, "I did more than forty shows last year, I did it when I was on duty in the laboratory. Would you like me to recommend something?"
Lu Zhou: "This is not necessary anymore."
Even if it was recommended, he probably didn't have much time to see it.
After all the operations needed to be done, Brother Qian simply taught Lu Zhou some methods to deal with unexpected situations.
For example, when you see the sample smoke, you smell something wrong, how to clean up the damaged sample, how to protect the instrument, and how to protect yourself most importantly.
No matter how expensive the instrument is, it is less important than humans.
Of course, this experiment was not so dangerous, so Brother Qian threw the key into Lu Zhou's hand with ease.
He and Brother Liu had something to do, and it was impossible to stay here all the time, and Lu Zhou was embarrassed to be so troublesome. After all, doing this experiment has delayed them a lot of time.
Taking out the quantum chromodynamics, Lu Zhou was sitting next to the digital microscope, and while he complemented the knowledge of theoretical physics, he looked at the situation on the digital microscope from time to time.
Later, he found that he didn't need to be so careful. The sample stayed under the microscope for so long, and there was no change outside.
It can be seen that Brother Qian's experimental technique is still quite reliable.
From 10 o'clock in the morning, I stayed in the laboratory until almost 6 o'clock in the evening, during which Lu Zhou also ordered a takeaway and had lunch.
Finally, the set time was up and charging and discharging were over. According to Brother Qian, Lu Zhou kept the circuit open for 10 minutes and then cut off the power.
Almost after he finished the finishing work, footsteps came from outside the laboratory. Brother Liu, who had just had dinner in the cafeteria, almost stepped into the laboratory.
"Done?" Looking at the sample, Brother Liu skillfully operated the computer and clicked the print button. "Then collect the data."
The printer buzzed.
Soon, Lu Zhou got what he wanted.
A group records the microscopic growth of lithium dendrites, and charts such as the cyclic voltage curve collected by the system.
While collecting these data, Brother Liu said in a chat.
"Lithium is the most ideal anode material, but it is also the most difficult to serve. When charging, the lithium ions to the anode will never be as you wish. The lithium metal layer will be flat and flat, but will bloom like To form a beautiful and deadly tree branch. "
Waiting for the printer to print the chart, Lu Zhou asked casually: "Fatal?"
"Yes, once this kind of thing called dendrite is formed, it will continue to grow with constant charging and irresistible, and eventually it will pierce the diaphragm and contact the positive electrode like a fork."
Having said that, Brother Liu paused and said in a joking tone: "Imagine what happens if you use a wire with the positive and negative electrodes of the battery? Yes, it is a short circuit. And organic electrolytes are easy Burning things, have you heard of moli? "
"no, what happened?"
Brother Liu shrugged ~ EbookFREE.me ~ handed the printed a4 paper to Lu Zhou, "their product almost made history, but because lithium was used as the negative electrode, a major safety occurred The accident led to the call of the NTT mobile phone, and finally the company went bankrupt and was acquired. In contrast, Sony was very smart, using graphite as the negative electrode and launching the lithium-ion battery to quickly occupy the market. "
Lu Zhou couldn't help asking: "Did they not do a safety test?"
Brother Liu sighed: "Yeah, it's a personal question, but things may not be so simple. Maybe they didn't find the problem at all? Maybe they think they have found the perfect solution? Who knows? Sometimes , Reality is so magical. "
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