EV Charging Series, Part 1: The Future of EV Charging - Revolutionary Developments are Closer Than You Think
Electric vehicles (EVs) are big business – you only need to look at Tesla’s share price to see just how big. Imagine how much more valuable the market would be if EVs could charge in a few seconds, not minutes or hours.
According to Reuters, the world's major car companies expect to spend nearly $1.2 trillion between now and 2030 to develop and produce electric vehicles, along with the batteries and raw materials for them [1]. This level of investment means they need consumers to buy into the product without hesitation.
But charging speed is a problem. A recent study carried out by EVBox found that 42% of Europeans said that taking too long to charge was a reason they would not buy an electric car [2].
Faster charging is more convenient, reduces range anxiety, and means each shared charger can power more vehicles in a day. This is significant as the growing number of electric cars on the road puts strain on the infrastructure of chargers – leading to frustrating queues for chargers at peak times.
How can we give car buyers the super-fast charging they want, and why is this even a problem?
This article looks ahead to some of the new technologies being developed for quicker EV charging, with the promise of top-ups in only a few seconds, and what their impact might be.
Why battery charging has a speed limit
Lithium-ion batteries have become the norm in EVs, providing enough capacity to deliver a usable range to consumers. In terms of their specifications, the batteries are typically compared on how quickly they can charge from zero to 80%. With the fastest chargers today, this takes something like 30 to 40 minutes.
To understand why there is a limit on how fast the charging process can go, let’s look at how batteries are charged.
A lithium-ion battery has a positive cathode and a negative anode, with these two electrodes separated by a liquid electrolyte. When the battery is charging or discharging, lithium ions can move through the electrolyte between the two electrodes.
During charging, these lithium ions reach the anode, made of graphite, which is of course just carbon. The lithium ions enter the structure of the anode, in a process called intercalation.
But if the battery is being charged too quickly then this process can’t keep up – and crystals of lithium form on the anode’s surface. These crystals, called dendrites, reduce the battery’s capacity, and in the worst case can short circuit the battery and even cause a fire.
Fast, faster, fastest
To overcome this limit on fast charging, there are many companies and academic institutions trying to find new solutions.
One example is StoreDot, which is developing what it calls extreme fast charging (XFC). The company claims this will reduce the time to reach 80% charge from 30 minutes to less than ten. StoreDot also says its batteries can handle over 1,200 cycles of fast charging, well above the industry norm of 700 cycles.
To achieve these results, StoreDot has replaced the graphite in the battery’s anode with tiny silicon particles, incorporated proprietary compounds in the anode and the electrolyte, and redesigned the physical structure of the battery cell.
A different approach to overcome the problem of dendrite formation, and thus to speed up charging, is to add a binder material to improve the rate of lithium ions joining the graphite anode. For example, a team from the Japan Advanced Institute of Science and Technology (JAIST) has developed a binder that includes lithium borate, which improves lithium-ion diffusion in the anode [3].
Another new technology on the horizon is solid-state batteries. These use a solid electrolyte, instead of the liquid or polymer in existing EV batteries. This means that no dendrites are formed during charging, which can mean there is less degradation of the battery’s capacity over multiple fast-charge cycles. However, commercialisation of the technology is proving difficult, and it seems likely there will be no major breakthrough in their usage before 2030, or even later [4].
Looking further ahead, Korea’s Institute for Basic Science (IBS) has proposed what it calls ‘quantum charging’, which could achieve a 200-fold acceleration of charging speed, reducing the time needed to just a few seconds [5]. This is based on a concept of charging all the cells in a battery collectively as a whole, rather than the cells being charged independently, as in conventional systems.
Microturbines and local power generation
Of course, the electricity used to charge EVs must come from somewhere. Ideally, this would all be from renewables, but right now it will always include a proportion generated from fossil fuels.
To help overcome this, several companies are exploring ways of making electricity locally, directly at the EV charging point – for example, Wingardium Energy is developing wind turbines that would provide electricity for battery vehicles on site, as well as using any surplus power to produce hydrogen to fuel hydrogen-powered cars [6].
Another innovative local power idea is to use small wind turbines, called microturbines, which can be sited at the roadside to harness the airflow from passing traffic. Charging EVs is just one possible use of the electricity generated in this way.
Alpha 311, a UK start-up, has developed microturbines that can produce up to 2kW. This can be used to power streetlights next to the microturbines, with any excess power fed back to the grid. Alpha 311’s wind turbines are being trialled at the roadside in the UK [7], with 2,000 of the turbines set to be deployed in Manchester [8].
Look, no hands
What if drivers could avoid the annoyance of plugging in altogether?
French start-up Gulplug has developed a hands-free charging system for EVs, which means the driver no longer needs to manually plug in a cable [9]. As soon as the vehicle is parked in its usual slot, the charging cable is automatically connected by the system.
There’s no requirement for the driver to take a bulky cable out of the car, to plug it in, to unplug it and then to store it back in the car full of dirt or moisture.
As well as improving convenience for the driver, this system also means the car will be plugged in for much longer durations. Instead of just plugging in for a few minutes to charge up, the driver will leave the car connected – which massively increases the potential for its battery to be useful to return electric energy to the grid. It also means the battery can be kept at an optimum charge level for much more of the time, therefore extending its usable life by up to two years.
Gulplug EV charging solution
Conclusions
Electric vehicles are rapidly taking over the world, and in the not-so-distant future, we’ll all be driving around in battery-powered cars.
While the speed of charging is an irritation for EV drivers right now, we can see there are multiple technological solutions being developed. These promise to cut charging times, increasing the convenience of driving an electric car, and making range anxiety a thing of the past.
This article is part one of a three-part series of articles. You can find part two and part three below:
- Part two: Integrating EV Charging with Matter and the Smart Home
- Part three: V2G Benefits Drivers and Electricity Suppliers
See EV Charging Solutions from Avnet Silica
