Recently, a new aluminum-graphene battery developed by the Gaochao team of the Department of Polymer Science and Engineering of Zhejiang University. This battery can work in the environment from minus 40 degrees Celsius to 120 degrees Celsius, which is both high temperature resistance and cold resistance. In the minus 30 degrees Celsius environment, this new type of battery can achieve 1,000 times of charge and discharge performance, while in the 100 degrees Celsius environment, it can achieve 45,000 cycles of stability.
This new type of battery is flexible. After bending it for 10,000 times, the capacity is fully maintained; and even if the battery is exposed to fire, it will not catch fire or explode.
On December 15, the related paper Ultrafast all-climate aluminum-graphene battery with quarter-million cycle life was published in Science Advances. The first author was Dr. Chen Yu of the team.
The battery does not burn at high temperatures
Heat-resistant, freeze-resistant and bendable "longevity" battery
A piece of dark gray film with metallic luster is the team's newly developed graphene-aluminum battery. Its positive electrode is a graphene film, and its negative electrode is aluminum metal. Connecting two batteries in series will light up a group of LED lights. After testing, the graphene cathode has a specific capacity of 120 mAh/g (milliampere-hours per gram), and can maintain 91% capacity after 250,000 charge-discharge cycles; at the same time, its rate capability is excellent, and the rapid charge can be filled within 1.1 seconds. Electricity still has a reversible specific capacity of 111 mAh/g.
Aluminium-graphene battery light up LED string with "ZJU120" printed
Compared to lithium batteries, the aluminum-graphene battery developed by the High-Research Group shows obvious advantages: As the battery is repeatedly charged and discharged, the specific capacity will continue to decrease. This is the so-called 'durable'.
However, this lengthy “unconspicuous†aluminum-graphene battery performed well at this point. If one cycle of charge-discharge is used as a cycle, the battery will experience 250,000 cycles, and the specific capacitance will still be as high as 91%, with almost no loss.
If a smart phone uses such a battery, it can be used for nearly 70 years even if it is charged 10 times a day.
"This aluminum-graphene super battery has much higher rate performance and cycle life than other batteries and has higher energy density, comparable rate performance and cycle life than supercapacitors," said Gao Chao.
Aluminum battery system takes a big step
Aluminum is the most abundant metal element in the earth's crust. It is cheap and safe. It is an ideal negative electrode material in battery preparation. But over the years, the overall performance of aluminum batteries is still inferior to lithium-ion batteries and supercapacitors. The key issue is to design a positive electrode material that can be matched with aluminum and work efficiently, in order to truly exert excellent electrochemical performance.
In 2015, Stanford University's Dai Hongjie team published a work in Nature magazine. It used high-temperature pyrolysis graphite foam to make positive electrodes. For the first time, it achieved high specific-capacity and long-cycle aluminum ion batteries. Inspired by this, the Gaochao Group tried to use graphene films to make electrodes for aluminum batteries.
After a year and a half of exploration and accumulation, the team of Gaochao proposed the "three high and three continuous" design principles for graphene cathode materials.
"Three high three consecutive" design principles
"Battery performance depends critically on the 'running' state of electrons and ions between the positive and negative electrodes." Supersonic said that the electrode material must allow as many electrons and ions as possible to run smoothly, or quickly 'retreat'. If there are not enough roads or the road is crowded, performance will suffer. "Three highs" refers to the high quality, high orientation, and high cell rate of the microstructure; "triple continuous" refers to the continuous conductive network, continuous ion transport channels, and continuous ion channel in the macro structure.
This design principle has taken a big step forward in the performance of aluminum-graphene batteries. Before, the specific capacity of aluminum batteries has been around 60mAh/g, and the number of repeated charge and discharge times is also within thousands of times.
Commercialization still has challenges
“Some smart phones now have a fast charge function. It seems that the battery is very full and the actual battery life is not long.†Gao Chao said, and the new laboratory battery data is 1.1 seconds to fully charge the current laboratory capacity. Minor loss.
This shows that if you use a mobile phone in the future, it is entirely possible to charge for 5 seconds for 2 hours. However, Gao Chao said that it is still facing great challenges from real commercialization, and it requires the efforts and input of more scientists to achieve it.
Gao Chao said that the current cathode specific capacity, output voltage and surface load have a larger room for improvement, energy density is not enough to match with lithium-ion batteries, in the future also need to maintain a high power density based on further increase energy density. In addition, the current classical ionic liquid electrolyte is more expensive, and if cheaper electrolytes can be found, the commercial prospects of aluminum ion batteries will be broader.
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