Five minute battery charging and long-lasting fuel cell technology is providing new impetus for EV powertrain development

New developments in battery and fuel cell technology is promising to dramatically improve the performance and longevity of both. For the former, charging times of five minutes and far higher energy density from lithium-ion cells is on the horizon, whilst a domestic breakthrough should improve the viability of hydrogen fuel cells for the latter.

Breast implants and fried food improve battery performance

The first piece of news comes out of the Korean Institute of Science and Technology (KIST). Scientists there have been working on ways of improving battery charging performance and longevity – both of which are seen as stumbling blocks for traditional lithium-ion setups. The headline is that the new tech can store up to four times more energy and be charged far more quickly and many more times than a standard battery cell.

According to the research, the keys to their discovery rest in silicon – often associated with breast implants – and a similar process to that which we see when frying food.

Delving beyond the headline of boobs and burgers and into the science, we’ve long known that graphite is a weak link within lithium-ion batteries. Used as an anode material, it has a relatively low capacity compared to other materials, but it has the benefit of remaining stable during charging and discharging cycles. Silicon has a capacity around ten-times greater, but it has a propensity to swell in and shrink volume (insert innuendo here) during charge and discharge. Stabilising it is possible, but until now has been expensive and commercially unviable.

What the scientists at KIST, led by Dr Hun-Gi Jung, have done is concentrate their efforts on finding a way of keeping silicon stable enough to work within an anode by using materials that are common in everyday life. The materials in question were water, oil and starch – basically the constituent ingredients of a chip (or French fry for our American cousins).

Dr Jung and his team dissolved the silicon with starch in water and oil, then mixed and heated them to produce a carbon-silicon composite. According to KIST: “A simple thermal process used for frying food was employed to firmly fix the carbon and silicon, preventing the silicon anode materials from expanding during charge and discharge cycles.”

In the simplest of terms, combining silicon with carbon prevents it from expanding when charged, and therefore heated up. Furthermore, with carbon being such a conductive material, the team found that not only was the material stable when discharged, it could do so at a fast rate. A capacity of 1530mAh/g was observed, which is around four-times more than with a graphite anode, and capacity remained stable over 500 charging cycles. The team could even charge to more than 80 per cent capacity in five minutes.

The beauty of the work by Dr Jung and the team at KIST is in the way it has kept potential costs very low, and therefore the potential for rapid commercialisation very high. Dr. Jung, the lead researcher of the KIST team, said: "The simple processes we adopted and the composites with excellent properties that we developed are highly likely to be commercialised and mass-produced. The composites could be applied to lithium-ion batteries for electric vehicles and energy storage systems (ESSs)."

This isn’t the first time we’ve seen the potential of silicon unlocked to improve the efficiency of future EV technology. Last year, Bosch revealed a silicon carbide semiconductor which, when used in little things like windscreen wiper and heater relays, could increase the range of a Renault ZOE by 15 miles thanks to its efficient conducting properties.

“Needle in a haystack” discovery for fuel cell technology

While new and vibrant battery technology seems to be coming on leaps and bounds with every passing week, fuel cells are like the plucky and capable, but often overlooked older sibling. Despite this, whichever way you look at it the technology will almost certainly make up an important part in our future fuel mix if we are to hit net zero by 2050.

If you fancy a long read on this subject, our hydrogen feature will tell you everything you need to know.

Researchers from the University of Aberdeen believe they have discovered chemical compounds that will make ceramic fuel cells cheaper and longer lasting. It’s important to note that the fuel cells in question are subtly different to those used in most hydrogen fuel cell applications such as fuel cell electric vehicles (FCEVs). Where most hydrogen fuel cell electric vehicles are powered by proton exchange membrane fuel cells, we’re talking about protonic ceramic fuel cells.

Protonic ceramic fuel cells can run on hydrogen, but they can also run on hydrocarbon fuels such as methane and in order to achieve high electrical conversion efficiency, operate at very high temperatures. They typically ‘come on song’ at between 800 and 1000 degrees Celsius, which means the lifespan of some of the materials is relatively short.

Scientists from the University of Aberdeen have been researching the potential for a new compound that might overcome these issues for a number of years. What they have come up with are collectively called hexagonal perovskites, and these exhibit high conductivity at lower temperatures.

Professor Abbie McLaughlin, Director of Research in the University’s Department of Chemistry, explained: “Ceramic fuel cells are highly efficient, but the problem is they operate at really high temperatures, above 800 degrees Celsius. Because of that they have a short lifespan and use expensive components.

“What we have discovered here is a dual proton and oxide ion conductor that will operate successfully at a lower temperature – around 500 degrees Celsius – which solves these problems. You could say that we’ve found the needle in a haystack that can unlock the full potential of this technology.” 

Lowering the cost of fuel cells is one of the biggest barriers to their adoption, and utilising lower cost ceramic fuel cells that run on hydrogen could offer a way into FCEVs for manufacturers. The researchers are also keen to point out that compared to internal combustion ceramic fuel cells are far more efficient when running on hydrocarbon-based fuels. This could make them a ‘bridging technology’ between low- and zero-emissions vehicles.

Discover EV’s take

Both of these advancements in technology are great news in principle, but as with any breakthrough, it’s only any use when put to work in a practical application. This requires a lot of jumping through hoops to upscale the ideas to make them workable for EVs, then to get large-scale component manufacturers on board, and then for the car manufacturers themselves to adopt the technology. With BEVs being the focus for most car brands, the carbon-silicon tech from Korea would seem to be the most likely of the two schemes to reach mass-market any time soon – just don’t hold your breath.

#batteries #battery-developments

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