Chapter 486： Lithium-air battery?

Chapter 487 Lithium-air battery?

The current commercial batteries are mainly lead-acid batteries and lithium batteries, and lithium batteries are currently roughly divided into four categories: lithium-ion batteries, lithium-sulfur batteries, lithium-air batteries and lithium-oxygen batteries.

As for the lithium-air battery, it is a battery that uses lithium as the negative electrode and oxygen in the air as the positive electrode reactant.

Compared to Li-ion batteries, Li-air batteries have higher energy density because their cathodes (mainly porous carbon) are light and oxygen is taken from the environment instead of being stored in the battery.

sounds better than common lithium-ion batteries, but the development of lithium-air batteries is still in the early research stage, and there are still many technical difficulties that cannot be solved before practical application and commercialization.

"Preparation of key materials for lithium-air batteries and research on their properties."

Chen Hao was now in front of the poster, looked at the title and read it again, but this time it caught the attention of the stall owner.

"Hey, mam, are you interested in lithium-air batteries?" The other party stood up happily and asked Chen Hao.

Chen Hao looked at each other, wearing a polo shirt and jeans, very typical of engineering men.

Beard, some dark circles around his eyes, he looks like he is in his 30s or 40s.

"A little interested." Chen Hao nodded slightly and continued to look at the other party's paper.

"What direction are you researching?" The other party didn't seem to recognize Chen Hao, but asked curiously,

"me?"

Chen Hao's mouth twitched, "I study polymer materials."

"Polymer materials are also very good." The man replied, but he noticed that the other party was carefully reading the paper, so he didn't speak.

At first, Chen Hao was a little contemptuous, after all, the technology of lithium-air batteries is far from mature.

In 2012, the first paper in the field of lithium-air batteries was published in Nature and Science, which means that the lithium-ion-air battery was officially recognized by the world's top journals.

Prior to this, lithium-air batteries were not recognized by the scientific community.

Just looking back, the contempt in Chen Hao's eyes gradually disappeared.

His eyes became serious.

"interesting."

This paper took him by surprise.

Twenty minutes later.

Chen Hao roughly scanned the whole text. Before he could say yes, the man beside him couldn't wait to ask:

"how is it going?"

…

Peking University Yuanpei General Education Curriculum System

1. It has not been established since its establishment. This is also an important reason why it was not envisaged at the beginning of its establishment and has not been realized so far, thus affecting the effect of this experiment. The purpose of this experiment was to establish a general education system similar to that of the top liberal arts colleges in the United States, but after more than ten years of operation, this purpose has not been achieved. You can find many commentary articles on the general education of Yuanpei at Peking University on the Internet, with mixed reviews. But in a word, this experiment was not successful.

2. The Yuanpei College of Peking University focuses on general education, but its current training model is not to set up general education courses by itself, but to adopt a platter-type general education method. Whether this method is good remains to be discussed. It is difficult to set up independent general education courses in the educational environment in which the above mentioned "experimental failure".

The so-called platter-type general education means that students of Yuanpei College can elect all professional courses in Peking University. Therefore, Yuanpei does not offer general education courses, but students can freely combine professional courses from different departments to achieve general education. the result of education. Students will be divided into majors in their sophomore year. Students can freely choose any major in Peking University as their major direction (of course, they reserve the right to change their direction and study other professional courses), or they can choose Yuanpei’s characteristic majors: such as PPE (politics). , Economics and Philosophy), foreign languages ​​and foreign history, paleontology, integrated science, etc., as the name suggests, these majors are a combination of related courses from various departments as your required courses.

A banner that started the reform of undergraduate education and teaching in this century, Yuanpei College has been exploring a broad-based and broad-caliber talent training model for 13 years. It is one of the earliest institutions in China to test the waters of general education. The accident, setback, embarrassment and even controversy that "Yuanpei" encountered in this talent experiment fully reflected the difficulty and pain of general knowledge.

Peking University Yuanpei is the earliest and relatively mature model in the reform of general education in China. Now general education is rolled out in various colleges and universities, but the current results are not particularly good - but at least a step has been taken.

3. According to the talent training plan of Yuanpei College, after admission, freshmen can theoretically choose any course offered by the whole school, and listen to whatever they want. The course study plan is all made by themselves; You can freely choose the direction of study according to your own interests, and there is no limit in theory.

"Spiritual freedom, academic freedom, and study freedom." After entering Yuanpei, almost all students feel "freedom" at first, but then most of them start to be "confused".

A student who entered the school in 2004 once published an article online complaining about Yuanpei's "free system". For example, the "tutor system" that should be responsible for guiding students to choose courses and majors has a limited effect. In fact, the freshmen of Yuanpei 04 can't even get a course plan of a department, and they have to go to the academic affairs department of each department. "Look at it".

Compared with these trivial matters, the freedom of course selection has become a bigger obstacle - you can listen to the whole school's classes, but what are you listening to?

At Peking University, the undergraduate course plan is mainly divided into two parts: specialized courses and general elective courses. Generally speaking, professional courses are more difficult than general elective courses. It is envisaged that after any Yuanpei student is a sophomore and chooses his or her major, the courses taken by other colleges and departments before can replace the general elective courses can graduate with full credits.

For students, such regulations are tantamount to the shackles of "free treatment": choosing courses according to interests, once the test scores are not satisfactory, you will lose a certain degree of freedom when choosing a major.

…

Although the names are similar, "lithium-ion battery" and "lithium-air battery" are two completely different systems, and the principles involved are also quite different.

The concept of "lithium-air battery" was first seen in the 1970s. Its core principle is to allow lithium to react with oxygen in the air, converting the generated energy directly into electricity.

This is like burning wood or burning coal. As the most common way for humans to obtain energy, the raw material reacts directly with oxygen, which brings about a very high energy release. It is calculated that the energy density of lithium-air batteries can reach 12,000 watt-hours per kilogram, which is almost 10 times that of lithium-ion batteries, and even close to the energy level of gasoline (13,000 watt-hours per kilogram) [1].

This seemingly simple combination of lithium and air has raised the physical ceiling of battery technology by an order of magnitude!

Moreover, the oxygen it uses comes from air, and this part of the raw material is almost infinite.