I Am the President of the University

  Chapter 487 Lithium-air battery?

  Currently 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 with lithium-ion batteries, lithium-air batteries have a higher energy density because their cathodes (mainly porous carbon) are light, and oxygen is obtained from the environment instead of being stored in the battery.

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

  "Study on the preparation and performance of key materials for lithium-air batteries."

  Chen Hao is now in front of the poster, watching the title and reading it again, only this time it has attracted the attention of the stall owner.

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

  Chen Hao looked at the other party, wearing a polo shirt and jeans, in a typical engineering man's outfit.

  Her beard, dark circles around the eyes, looking like thirty or forty.

   "I'm interested." Chen Hao nodded slightly, and continued to look at the other party's paper.

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

"me?"

  Chen Hao's mouth turned up, "I am studying polymer materials."

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

  At first, Chen Hao was a bit contemptuous. After all, the technology of lithium-air battery is far from mature.

  It was still in 2012 when the lithium-air battery field published a paper on Nature and Science for the first time, which represented 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.

  It's just that the more I look back, the contempt in Chen Hao's eyes gradually recedes.

  The expression in his eyes became serious.

"interesting."

  This paper unexpectedly surprised him.

  Twenty minutes later.

  Chen Hao roughly scanned the full text. Before he said he wanted it, 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 inception. This is also an important reason why it was not envisaged at the beginning of the establishment but has not been realized so far, which affects the effect of this experiment. The purpose of this experiment was to establish a general education system similar to that of the top American liberal arts colleges, but after more than ten years of operation, this goal was not achieved. You can find many commentary articles on Peking University Yuanpei General Education on the Internet, with mixed reviews. But in a word, this experiment was not successful.

2. Peking University Yuanpei College focuses on general education, but its current training model is not to offer general education courses by itself, but to adopt a platter-style general education method. Whether this method is good or not remains to be discussed, but at present domestic It is difficult to set up independent general education courses in the educational environment of China. This may be the "experimental failure" mentioned upstairs.

The so-called platter-style general education means that students of Yuanpei College can take all the 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. In the sophomore year, students are divided into majors. Students can freely choose any major in Peking University as their major (of course, the right to change directions and take other professional courses), or choose Yuanpei’s special majors: such as PPE (Politics) , Economics and Philosophy), Foreign Languages ​​and Foreign History, Paleontology, Integrated Science, etc. As the name suggests, these majors combine the relevant courses of various faculties and departments as your compulsory courses.

  This century is a banner of undergraduate education and teaching reform. Yuanpei College has been exploring a thick foundation and wide-calibre talent training model for 13 years, and it is the first batch of domestic colleges and universities to test the waters of general education. The accidents, frustrations, embarrassments and even controversies encountered by "Yuan Pei" in this talent experiment fully reflect the difficulty and pain of general knowledge.

  Beijing University Yuanpei is the earliest and relatively mature model in the domestic general education reform. Now general education is spread in various universities, but the current results are not particularly good-but at least one step has been taken.

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

  "Spiritual freedom, academic freedom, and learning freedom." Almost all students' first feeling is "freedom" after entering Yuanpei, but after that, most people will start to be "lost".

  A student who enrolled in 2004 once published an article on the Internet complaining about Yuanpei’s "free system." For example, the "tutor system" that should be responsible for tutoring students in choosing courses and majors has limited effect. In fact, the freshmen of Yuanpei's 04 freshmen can't even get a course plan from the department and must 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 classes in the whole school, but what do you listen to?

  At Peking University, the undergraduate course plan is mainly divided into two parts: professional 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 in his sophomore year and chooses his or her major, the courses of other faculties previously elective can replace the general elective courses~www.wuxiahere.com~ and can graduate after completing the credits.

  For students, such regulations are tantamount to the shackles other than "free treatment": choose courses according to their interests, and once the exam results are not satisfactory, they 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 to directly convert the generated energy into electrical energy.

  This is like burning wood or burning coal. As the most common way for humans to obtain energy, the direct reaction of raw materials with oxygen results in extremely high energy release. According to calculations, 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 entire order of magnitude!

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

  (End of this chapter)