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A rapid charge

Commentators are talking about a tipping point in the electric vehicle (EV) sector. Sales of EVs have pushed past the 5% mark (in adoption rates) in the US, Europe and China, which means they are starting to go mainstream in the market. But another of the milestones getting mention is the five-minute rule – or being able to recharge your EV in the same time that it takes to fill up a car with petrol.

That’s one of the thresholds being targeted by Greater Bay Technology (GBT), a battery tech spin-off from Guangzhou Automobile Corp (GAC), one of China’s largest state-owned carmakers. Established in 2020, GBT caused a stir last year when its latest design of graphene batteries was introduced in a new sports utility vehicle launched by its parent firm.

With charging power of 480 kilowatts, the battery was taking no more than eight minutes to power up to the desired 80% level, it was claimed. The company this month reached unicorn status when it raised Rmb1 billion of funds from Tencent and other investors giving it a valuation of Rmb8 billion ($1.19 billion). With its latest fundraising it says it will add battery capacity at its factory able to power 120,000 new energy vehicles next year.

The Guangzhou-based firm specialises in research and development for fast-charging batteries, a crucial frontier in bringing briefer stops to car-charging and shorter queues at charging stations.

Analysts say that battery breakthroughs like these will also help to reduce so-called ‘range anxiety’ about the distances that vehicles travel on a single charge, encouraging manufacturers to install smaller batteries and thus make EVs more affordable.

Another of the holy grails is the spread of a larger network of DC, or direct current, stations that charge vehicles at much higher voltages. Rebooting an EV from empty through a standard socket at home can take more than two days but the fast-charging stations can cut that down to a few minutes.

To speed things up the batteries need to be able to accept the power at higher voltages, however, which can be a problem for the lithium-ion formats that dominate the sector. They risk overheating at higher charging speeds, degrading their performance, and there have been explosive flame outs in extreme cases.

Because of these dangers battery makers have installed speed limits on the charging process. But there’s also a growing focus on alternative materials like graphene that allow for faster rates of energy transfer.

Graphene is a very thin form of carbon (and relatively newly discovered) that offers superior electrical conductivity and chemical stability. In the longer run it might even emerge as an energy-storage medium in its own right. But most of the current generation of designs are still based on lithium-ion formats that deploy graphene as a wrapper for the battery’s anodes and cathodes. The main disadvantage of graphene is its cost, with critics warning that that there won’t be a fuller breakthrough until production costs fall dramatically. And while firms from China have been grabbing a growing share of lithium supply, they don’t have the same grip on the graphene market. The world’s biggest producer of graphene nanotubes is Luxembourg’s OCSiAl (it unusual name consists of four chemical elements) with 97% of global capacity, while Canada’s NanoXplore is the main player in graphene powder, with 70% share of the market.

Read More at https://www.weekinchina.com/2022/07/a-rapid-charge/

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