The truth about graphene batteries

After NIO's solid-state battery, GAC has once again pushed the controversy over new power battery technology to a new height.

According to an official poster released by GAC Aion last Friday, vehicles equipped with graphene-based super-fast charging batteries can be fully charged to 80% in 8 minutes and have a NEDC range of 1,000 kilometers.

The next day, Ouyang Minggao, an academician of the Chinese Academy of Sciences, said at an industry conference: "If someone tells you that this car can run 1,000 kilometers, can be fully charged in a few minutes, is very safe, and has a very low cost, based on current technology, he must be a liar."

There is a war of words going on around graphene battery technology. How should we understand "graphene battery" from a technical perspective?

First of all, we need to clarify what graphene batteries are. This starts with the industry naming rules. It is understood that in the power battery industry, the general rule is "which component plays the main role, which component is used to define it". Since the performance of power batteries is most related to the positive electrode material, the names are generally distinguished by the positive electrode material, such as ternary batteries, lithium iron phosphate batteries , lithium manganese oxide batteries , etc.

In this sense, the term "graphene battery" should mean: a battery whose positive electrode material is mainly graphene.

According to GAC, the full name of this technology is "graphene-based super-fast charging battery". Although there is only one more word "base", it is far from the so-called "graphene battery".

The correct name for what GAC calls "graphene battery" should be "graphene-doped silicon-based negative electrode lithium battery ." This battery technology is more consistent with the general direction of graphene commercialization in batteries in recent years.

In 2016, Dongxu Optoelectronics announced the launch of the world's first graphene-based lithium-ion battery product "Ene King". Subsequently, Huawei also announced the launch of the industry's first high-temperature and long-life graphene-based lithium-ion battery. The Xiaomi 10 Extreme Edition released by Xiaomi in August last year also claimed to use a new graphene-based material battery with built-in third-generation conductive agent graphene, whose conductivity is 1,000 times that of traditional carbon black materials.

In the above three examples, the so-called "graphene-based" refers to graphene as the battery conductive material, rather than graphene as the positive electrode material. Therefore, it can be roughly inferred that the "graphene-based super-fast charging battery" mentioned by GAC is also a lithium battery that uses graphene as a conductive agent. The correct expression should be "graphene-based lithium battery."

In addition, the "super fast charging" emphasized in GAC's statement also indirectly illustrates the role of graphene as a conductive agent in its batteries - stronger conductivity leads to faster charging speed. It should be made clear that graphene-based lithium batteries improve charging speed rather than driving range, which is an important means to alleviate consumers' "battery anxiety" from another dimension.

Secondly, we need to understand the technical direction of graphene integration into batteries. Graphene has the characteristics of thin texture and high hardness. The emergence of graphene materials has made it possible for lithium-ion batteries to achieve breakthroughs in high performance, high capacity, high rate and long life.

There are two main directions to integrate graphene technology into the battery industry: one is as a conductive additive, and the other is as a negative electrode material.

If it is used as negative electrode material, high cost will be a big barrier. According to analysis, if power batteries use graphene as the main negative electrode material, the cost of electric vehicles will be very high. If it is used as an additive, its cost can be accepted.

However, if it is used as a conductive additive, its essence is still a lithium battery. Moreover, at room temperature, graphene cannot achieve superconductivity, and compared with cheaper additives, it does not have much advantage.

Finally, we need to clarify the problems that graphene mass production faces. The graphene preparation process is relatively complicated, and the cost is much higher than conventional graphite, and even the widely favored silicon anode. It is also more difficult to ensure the stability of multiple batches of graphene.

How to solve the problems of low-cost high-quality graphene preparation and graphene blocking lithium ion channels has become an important issue for the implementation of graphene batteries. However, if it is to be applied to mass-produced vehicles, there are still many problems that need to be tested on the ground.