Can you dare 1.1 seconds to fully charge the battery? Pick up a scientific scalpel dissect an aluminum ion battery

[China Aluminum Network] A while ago, the team of the Zhejiang University Gaochao teacher has made excellent work, namely the use of graphene as a cathode for high rate performance, high cycle life of aluminum ion batteries, both flexible functions. The work was published in the journal "SCIENCE ADVANCES."

Once launched, it has received extensive industry attention and discussion. Many friends are asking about the technology's impact on the battery industry. Everyone is very concerned about this type of battery technology. That is exactly what we are talking about today. We will start with a simple analysis of the prospects for the development and application of aluminum-ion batteries.

1, aluminum ion battery - how much energy density?

First look at the author's own summary of the introduction of the battery.

The innovation of this work is to create a novel structure of 3H3C graphene film cathodes with high quality, orientation and local channels, which can ensure electron, ion conduction and sufficient active substance quality. . The capacity of the positive electrode is 120 mAh/g at the charging time of 1.1 s, the capacity guarantee rate is 91.7% after 250,000 cycles, the working performance is excellent at high and low temperatures, and it is flexible.

It is not difficult to see that the graphene-aluminum metal aluminum ion battery is excellent in high-low temperature, flexibility, and rate performance, which of course is of great benefit to the prepared graphene electrode. However, the summary is a highlight, highlighting the results will be reflected here, but here are several important parameters of the battery did not say: such as volume energy density, mass energy density.

1) When the volumetric energy density is low, cell phones and automobiles are basically hopeless for applications in important fields. The space is very limited and must be fully utilized. Mobile phones and cars are also pursuing long-term voyages. At this time, high energy density must be required.

Turn to page 5 of the article and see the author's introduction to his battery performance: 66Wh/kg (mass energy density).

First of all, 66Wh/kg is still the typical energy density range of aluminum ion batteries 40-65Wh/kg, this data is much lower than lithium-ion batteries: Lithium iron phosphate 100+Wh/kg, three yuan near 200Wh/kg. With the energy density of aluminum ion batteries used in the mobile phone and automotive fields, the basic can only be aimed at hybrid vehicles, and the insertion and mixing are somewhat suspended, the mobile phone is even more difficult to have hope.

2) The bigger problem is that the full text does not mention volumetric energy density related data. Considering that the mass energy density of the battery is not high, the materials used are bulky (graphene, etc.), and their volumetric energy density may also be difficult to achieve. One-third of lithium batteries. Because the author of this article did not mention this data, so I can only infer based on the existing data and common sense: volume energy density data is likely to be difficult to see.

Here again emphasizes the significance of volume energy density: if the battery is not heavy, but the volume is large, carrying the load will also have a big problem, especially in mobile energy storage applications (mobile phones, cars) is difficult to practical. For a fixed energy storage with less stringent requirements, a bulky energy storage method may be more appropriate, such as a typical flow battery.

Actually, at present, it is difficult for an aluminum ion battery system to find a suitable positive electrode material. The capacity and voltage of the vanadium compound are not good, and the graphene can only be used as a general from the dwarf, and the electrolyte (only an ionic liquid can be used), etc. The limitation also makes no sign of breakthrough in the energy density of aluminum-ion batteries, so the current energy density performance greatly limits the possibility of wider application of the technology.

2. Cost analysis

Based on the data reported by the above two performance authors and the analysis, it can be seen that the battery may be more suitable for power type applications. The potential for replacing the existing lithium-ion battery is not too large, and the threat to the capacitor is not small, if the cost can be made It is also possible to compete with lead-acid, which has a similar energy density.

After Zui, the author also gave his own evaluation - mainly for capacity-dominant high-power density energy storage system. In short, it is aimed at the high power field.

The volumetric energy density is not known from the current point of view. It has also been said that if the cost can be made, there may be a certain potential. However, the system uses several materials: graphene, ionic liquids, and aluminum metal.

The raw material of the graphene positive electrode is graphene oxide GO, which is coated with an oriented film and then reduced. After zui is processed at 2850° C., the final required material can be obtained, which is similar to the processing temperature required for producing graphite. Therefore, the graphite raw material-graphene electrode preparation used in this process route is equivalent to two times of 2850°C treatment, which will definitely increase the requirements for the furnace body and energy consumption.

Some people may ask: Why can't reduce the temperature when processing graphene twice? The answer is simple: if graphene is a redox route, the degree of material structure will be affected by the oxidation, and mild reduction conditions are insufficient to solve the problem, and high temperature is needed to make it recover effectively; if graphene is used, Other methods such as CVD, mechanical stripping, the quality of the prepared materials will be high, and high temperature processing may not be used, but the mass production capacity of these methods is often very limited. The dilemma is here.

In addition, ionic liquids are indeed important and promising technologies. However, for the aluminum ion battery, at present its technology seems to rely heavily on ionic liquids, which currently has a series of problems of high viscosity and high cost, which greatly increases the cost of the aluminum ion battery. Of course, with the joint efforts of the scientific research community and the industrial sector, ionic liquids will indeed have much room for improvement in the future, and the application prospects are promising.

Therefore, in general, compared to the current common battery systems: Lithium-ion batteries, lead-acid materials are used more conventionally, and stable mass production can be achieved. This has played a significant role in reducing battery costs (especially in recent years). The supporting role. However, for the aluminum ion battery system, there is still a lot of work to be done in the industrialization of raw materials and economic practical work.

3. Did you really dare 1.1s to fully charge the battery?

In fact, the pitfalls of this type of article are common: If you really want 1s to be fully charged, it is natural for a small-capacity laboratory-grade battery. And if it is a mobile phone battery? According to 10Wh 1s full, the charging power is 36kW, we recall the Joule's law of calorie calculation of physics learning, and take a look at their own home appliances, and then consider whether it is feasible.

to sum up

Aluminum-ion battery technology does have its own characteristics, but the disadvantages are obvious. It is hoped that in the future development, it will be able to achieve breakthroughs in terms of energy density and cost reduction potential, thus accelerating its practical application.