The most common criticism of electric vehicles (EVs) and smartphones is that they take too long to charge.
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Why would anyone want to drive a car requiring more than a minute of recharging? Imagine, however, an electric vehicle with a battery that charges extremely quickly and has a long driving range, or visualize a smartphone that sets in under a minute. Although it might seem impossible, the advancements in graphene batteries are bringing these possibilities to life.
The Downfall of Lithium-Ion Batteries
Lithium-based batteries are acknowledged as one of the promising substitutes for applications in energy storage due to their high energy density. These batteries power our computers, smartphones, and even our cars.
One issue that lithium-ion battery continues to have is safety. The liquid contained within a lithium-ion battery is highly flammable. Any damage to the battery's outer layers can result in a short circuit, leading to fire and explosion. For example, in 2016, a sudden burst of smartphones caused first-degree burns to several users worldwide.
Over the last few years, lithium-ion batteries used in electric vehicles have received an extensive cooling system. However, this cooling system takes up lots of space that could be utilized for energy storage.
Another problem with lithium-ion batteries is recyclability. Most of the parts in lithium-ion batteries are not biocompatible, making the recyclability process very expensive.
Lastly, the battery suffers from low power density. Take an example of a smartphone: because of its high energy density, the battery will last most of the day; to recharge the device, it must be connected to another power source for an hour or more.
The Promise of Graphene
Graphene is a one-atom-thick sheet of carbon atoms with a relative surface area of 2,630 m2/g, which is superior at storing charges with almost no degradation over long-term cycling. The bonds in graphene give graphene more than four times the tensile strength of steel while being super transparent, flexible, and an excellent conductor of electricity and heat. These properties make graphene a suitable candidate for not only battery but also supercapacitor
However, the graphene supercapacitor cannot store as much energy as a battery, but it can be fully recharged within minutes. Hence, to overcome the low energy density of graphene supercapacitors, scientists started working on the coupling of supercapacitors and batteries as hybrid energy storage systems.
Graphene-Aluminium Hybrid Battery
In collaboration with Graphene Manufacturing Group, researchers at the University of Queensland Australia have developed a graphene-based hybrid battery prototype. This battery uses graphene and aluminum as electrode materials and is generally referred to as a graphene aluminum battery. The battery has an energy density of 150-160 Wh/kg, and it can be charged extremely fast within 1-5 minutes.
Furthermore, graphene aluminum-ion batteries offer significant advantages in terms of battery safety, recyclability, and longer battery life (over 2000 cycles) with almost no degradation in performance.
As per the latest information, the Graphene Manufacturing Group (GMG) has announced that it has manufactured its graphene aluminum-ion batteries in pouch cell format for use in smartphones, tablets, laptops, and more.
According to GMG, the theoretical energy limit of these batteries is about 1050 Wh/Kg. Thus, with further development, we can soon expect to reach the energy of graphene batteries more than commercial batteries.
Graphene Enhanced Lithium-Sulfur Battery
The watershed moment in the development of graphene hybrid batteries came at the end of 2021, when California-based company Lyten announced that they had developed a graphene battery for electric vehicles with an energy density three times the energy density of traditional lithium-ion batteries.
These batteries are lithium-sulfur (Li–S) batteries which have long been touted as the next generation of rechargeable batteries. However, the challenge with real-world applications of Li-S batteries is the formation of soluble polysulfide species during discharge cycles. These intermediate species diffuse between the anode and cathode and cause internal short circuits. This phenomenon is commonly referred to as the shuttling effect, and it is responsible for the poor efficiency and quick capacity fading of the Li-S cells.
Lyten incorporated a 3D graphene membrane into the sulfur cathode to overcome this issue, which acted as an effective separator and reduced the cyclic capacity decay rate.
The product is named LytCell EV and was reported to deliver 900 Wh/kg energy density. Tests have apparently shown that a LytCell prototype can sustain more than 1,400 charge-discharge cycles.
Graphene Enhanced Polymer Battery
PolyJoule, a Massachusetts Institute of Technology (MIT) spin-off company, recently announced a new battery technology for high-power data center backup and power grid applications. The device is a two-electrode electrochemical cell with a carbon-graphene hybrid and a conductive polymer. The battery can discharge up to 1 MW of power in less than 10 seconds and recharge in less than five minutes. It has a voltage range of 158 V to 972 V and can operate continuously at temperatures ranging from -40 °C to 50 °C with minimal capacity loss.
Graphene Non-Flammable Li-Battery
When a Li-ion battery is shorted, it causes the battery to catch fire, which has raised concerns about its use in consumer products. This is due to the flammable electrolyte contained within the Li-ion battery. Nanotech Energy, based in the United States, has created a non-flammable graphene-based Li-ion battery pack that is both safe and environmentally friendly. They used graphene as an electrode material in their Li-battery and developed an inexpensive nonflammable electrolyte called OrganoLyteTM.
The battery is said to have an energy density of 162.5 Wh/kg and can withstand more than 1400 cycles (almost 10 years) at 80 percent capacity.
The battery is entirely fire resistant and suitable for all weather conditions. For comparison, traditional Li-batteries can only withstand 300-500 cycles (about two to three years). According to the latest updates, the company has begun taking pre-orders, and the battery may be customized for use in electric vehicles, computers, and military applications.
The Future of Graphene Batteries
Tesla recently announced that their Model 3 battery has an energy density close to 260 Wh/kg. Still, it requires a complicated cooling system to prevent overheating and thus takes up a lot of space. On the other hand, because graphene batteries do not overheat or explode, there is no need for a cooling system, and the space could be used for energy-storing batteries in electric vehicles.
A breakthrough in graphene battery technology occurred when GAC Motor Co. Ltd, a Chinese automobile company, announced the launch of the AION V car, which features a graphene battery with a range of 1000 km and can be recharged to 80 percent capacity in 8 minutes. Undoubtedly the ongoing commercialization of graphene batteries will soon outperform conventional batteries for its wider adoption.
References and Further Reading
Graphene Manufacturing Group (2021). Aluminum ion battery. [online] graphenemg.com Available at: https://graphenemg.com/energy-storage-solutions/aluminum-ion-battery/
PolyJoule (2022). Graphene enhanced polymer battery. [online] www.polyjoule.com Available at: https://www.polyjoule.com/
Lyten (2022). Lithium-Sulfur Battery. [online] www.lyten.com Available at: https://lyten.com/products/batteries/
GAC Motors (2021). AION V. [online] https://www.gac-motor.com/en/index Available at: https://www.carandbike.com/news/gac-aion-v-has-a-battery-that-can-achieve-80-charge-in-8-mins-2497866
Nanotech Energy (2020). Nonflammable Graphene Battery. [online] www.nanotechenergy.com Available at: https://nanotechenergy.com/press/press-releases/
A. Urade. (2022). Applications of MXenes in Lithium Sulfur Batteries. [online] AzoNano. Available at: https://www.azonano.com/article.aspx?ArticleID=6129
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