- Engineers made a new battery that works in a temperature range from -40°C to 120°C, and can be charged within 5 seconds.
- It can retain 91% of its capacity after 250,000 charge-discharge cycles.
- The battery is extremely flexible, bearing 10,000 times of folding.
Engineers at Zhejiang University, China have developed ultra-fast, all-weather, long-cycle aluminum graphene battery that boasts a superior performance, especially in terms of charging time. Once the commercial production starts, the battery could be fully charged in 5 seconds and then last for two hours.
Material and engineering researchers who developed the battery claim that it is more cold-resistant, less flammable and can work in a temperature range from -40°C to 120°C. However, few industry experts have cast a dubious eye one these claims.
The negative pole of the battery is made of aluminum and the positive pole of graphene. It is capable of retaining 91% of its capacity after quarter million charge-discharge cycles – a lot better than today’s lithium battery. It’s built for all-climate energy device and has remarkable flexibility bearing 10,000 times of folding.
If integrated with smartphones, it could be charged in 5 seconds and used as long as two hours. Also, the battery lasts up to 70 years without losing its capacity, even if the phone is charged 10 times every day.
Design And Performance
To built cathode material of aluminum-ion battery, they chose graphite, graphene, sulfur and metal sulfide. Graphitic carbon provides features like fast charging and stable cycling. For such carbon-based cathode, engineers took care of 4 requirements –
- Highly crystallized graphene lattice.
- Continuous electron-conducting matrix for large current transportation and internal polarization mitigation.
- High mechanical strength and Young’s modulus to prevent material collapsing.
- Interconnected channels, facilitating high electrolyte permeability and ion diffusion.
To fulfill these requirements they’ve built an ideal graphene film fabricated by either wet-spinning or cast-coating graphene oxide (GO) liquid crystal solution into GO film, followed by chemical reduction to form reduced GO (rGO) film and high temperature annealing.
A perfectly aligned graphene sheet leads to higher electrical conductivity and mechanical properties than graphene foams composed of non-oriented graphene sheets. The rGO film further annealed at 2850 degree Celsius to restore atomic defects, converting into long continuous slivery graphene film.
The performance of a battery primarily depends on the state of how fast electrons and ions run between negative and positive electrodes. The electrode material must enable as many electrons and ions to run freely as possible. If the road is over-crowded, performance will be affected. That’s the reason one needs to take care of quality, orientation and porosity of microstructures. And conductive networks, ion transport channels and ionic channels in a macrostructure.
Reference: Sciencemag | DOI: 10.1126/sciadv.aao7233 | Zhejiang University
This design principle enables aluminum-graphene battery to take a big step forward and deliver astonishing performance. Previously, the aluminum battery’s capacity has been hovering around 60mAh/g, with charge-discharge cycle less than thousands of times.
Battery lighted the ZJU-120 LED | Image credit: Zhejiang University
After testing, graphene positive electrode capacity of 120mAh/g, after 25 million charge-discharge cycles still maintained the capacity of 91 percent. At the same moment, fast charging could be filled within 1.1 seconds, maintaining reversible capacity of 111mAh/g.
Some Experts Aren’t Fascinated by The Findings
According to an industry expert, Zheng Jiatu, deputy managing director of the China Electric Vehicle Charging Technology, the results published by the team don’t look promising. “The figures should be read with caution”, even testing a quarter million charge-discharge cycle would itself take a very long time. These results are more likely experiments performed on a simulated data model instead of prototype testing.
Moreover, commercialization would require several things that are not clear. Some of the key factors include cost performance, particular type of battery’s energy intensity, safety, reliability and a mature business model. There are many other proven and ready technologies that haven’t been commercialized yet.
However, the research team said, they still have a long way to cover with numerous obstacles to overcome. They believe “super” battery is much better than lithium ion batteries, but still there are a lot of things needs to be improved. In addition, the conventional ionic liquid electrolyte is quite expensive, if one can find cheaper electrolytes, the business opportunities for aluminum ion batteries would be broader.