Batteries are the engine room for so much of the modern world, from smartphones to laptops and weird new scooters to the emerging fleets of autonomous trucks. So there are plenty of folks with an interest in pushing battery technology forward, and 2017 brought a raft of exciting breakthroughs aimed at making them safer, longer-lasting, faster-charging and more cost effective. Here's the best of the bunch.
Safety first
The chances of lithium-ion batteries failing is very low, but with so many of them in use everyday the chances of something going wrong somewhere in the world are very real. Flaming Samsung smartphones and exploding "hoverboards" (we're still reluctant to call them that, but whatever) are evidence of that.
Today's batteries already come with chips embedded that track voltage, temperature and the charge they are holding, allowing for warning systems like the one you'll see on an iPhone screen when the handset gets too hot. But researchers are always looking for ways to keep them cool, and one way of achieving this could be to substitute the combustible electrolyte, the liquid that carries the ions, with something less flammable.
Back in 2015, scientists at the University of Maryland and the US Army Research Laboratory came up with a saltwater electrolyte recipe that promised safer batteries for everything from pacemakers to large-scale grid storage. While their battery design carried less risk of fire, it only had a maximum voltage of 3 V.
In September this year, the researchers were able to bump this up to 4 V, packing it with enough voltage for regular applications, like laptop computers. They achieved this by developing a new gel polymer coating that can be applied to the battery's anode and better repel water from the surface. The team is now focused on increasing the number of full performance cycles the battery can complete, from 100 to 500 or more, to make it competitive.
Another way the fire danger can be averted is by integrating a flame retardant into the battery that is automatically released when things start to heat up. A built-in fire extinguisher, if you will. Researchers have been chipping away at this problem for years, looking at using flame-retardant materials to build the membrane separator, or incorporating ceramics. But their efforts have tended to compromise the battery's performance in one way or another.
In January, Stanford University scientists came up with a better way forward. Their design packs a common flame retardant called triphenyl phosphate (TPP) into shells made from polymer microfibers. These melt when the mercury hits 160° C (320° F) and release the retardant into the electrolyte, before or at the early stages of combustion.
The design has been tested in a coin cell battery, and the team found that when combustion occurred, the TPP was able to quickly extinguish the flame. Testing is now being carried out to see how it stands up under greater mechanical pressures on a larger scale.
Fast-charging
Would you be more likely to buy an electric car if you could plug it in for six minutes and drive 320 km (186 mi) without stopping? Batteries that allow for this kind of fast-charging would be a game-changer not just for electric vehicles, but all kinds of devices, and they mightn't be as far away as they seem.
In October, Toshiba announced the next generation of its Super Charge ion Battery (SCiB0). This uses a new material for the anode called titanium niobium oxide, which is able to store lithium ions more efficiently, so much so, that the energy density has doubled. Toshiba plans to put the battery into practical applications in 2019, and says that if incorporated into an electric vehicle, it would offer around three times the range of current batteries on a six-minute charge.
Toshiba isn't the only electronics giant making waves in the fast-charging space. In November, researchers at the Samsung Advanced Institute of Technology reported what they described as graphene balls. By using these popcorn-like clumps of wonder material as the anode, along with a protective layer for the cathode, in a lithium-ion battery, the team was able to contain nasty side reactions and create more conductive pathways.
The researchers say that if these graphene balls were worked into a full-sized lithium battery, they could cut charging times for smartphones from over an hour to just 12 minutes. What's more, they could also boost battery capacity by 45 percent and maintain stable operating temperatures, a handy attribute when it comes to electric vehicles.
Capacity
The high capacity of lithium-ion batteries saw them take the lead over other variants and come to power so much of our everyday lives, but ask a smartphone user if they could do with some extra juice and they'll probably say "sure, that'd be great." So stretching the capacity of lithium batteries to hold more charge is another key focus for scientists around the world.
For researchers at Rice University, this meant zeroing in on a byproduct of the charging process called dendrites. These microscopic lithium fibers build up on the anodes and spread like a rash, hindering battery performance and eventually causing it to short-circuit.
The team built a battery prototype that uses a two-dimensional graphene sheet grown on metal combined with carbon nanotubes as the anode. With its low density and high surface area, this 3D nanotube forest creates lots of space for particles to slip in and out during charge and discharge cycles, and it completely prevents the growth of dendrites.
In testing, the team found its anode material was capable of a lithium storage capacity of 3,351 milliamp hours per gram, which is close to pure lithium's theoretical maximum of 3,860 milliamp hours per gram and 10 times that of standard lithium-ion batteries.
And graphene features prominently in another of 2017's promising energy advances. The material's ability to conduct energy is well established and has prompted countless research projects around that capability, but in November scientists at the University of Arkansas discovered that it could actually generate its own.
The team came up with a way of tapping into the minute energy generated by what they called graphene ripples. This is when the carbon atoms on a sheet of graphene rise and fall like waves in the ocean in response to the ambient temperature.
By suspending the graphene sheet in between two stacked electrodes, the team was able to create a positive charge when groups of atoms rise and touch the top electrode, and then an alternating current when they fell and touched the lower electrode. Using a device called a Vibration Energy Harvester, the team was able to harness an alternating current strong enough to power a wristwatch.
In theory, this technology never needs charging and never wears out, so does raise the prospect of using graphene as a limitless energy solution. Getting it into watches and other small electronics like pacemakers and hearing aids remains a challenge, but the researchers are continuing their experiments with a view to moving it beyond the lab.
Speaking of capacity, we must mention that just last month South Australia switched on the world's largest lithium-ion battery. Provided by Tesla and taking just 100 days to install, the 129-MWh Powerpack aims to address some of the state's recent energy woes, and provide on-demand power delivery for more than 30,000 homes.
Going green
This year we saw some advances that not only promise to boost the capacity of batteries, but do so in ways that are friendly to the environment.
Researchers at Japan's Tohoku University and Osaka University made use of a big byproduct of electronics manufacturing – the silicon sawdust created when silicon is cut from large sheets. Pulverizing this sawdust into porous nanoflakes and coating them in carbon, the team was able to fashion a new kind of battery anode.
The resulting lithium-ion battery not only featured recycled materials, it also achieved a constant capacity of 1,200 mAh/g (milliamp hours per gram) over 800 cycles. The team claims this to be 3.3 times greater than that of a conventional graphite anode.
Another example of recycled materials being put to use in advanced batteries came from researchers at the University of California, Riverside back in April. The scientists collected discarded glass bottles, crushed them into powder and reduced the silicon dioxide within it to nanoparticles before coating them in carbon.
Silicon as a battery anode has the potential to store up to 10 times more energy than a typical graphite anode, and by taking this approach the team was able to produce a coin cell battery that demonstrated a capacity of around 1,420 mAh/g (milliamp hours per gram), a marked improvement on the typical 350 mAh/g capacity of graphite anodes. The team has filed a patent for its eco-friendly, low-cost technology.
It makes sense to use widely available materials where we can. In August, scientists at the University of Sydney revealed a zinc-air battery that does just that, while overcoming some of the problems plaguing devices of this kind.
Zinc-air batteries are good because by using air around the cell to drive the chemical reactions, you can fit more zinc in and increase the energy density. But zinc-air batteries are bad because this oxidizes the zinc anode and renders it pretty much useless, requiring expensive, precious metals as catalysts to keep them operational.
The research team in Sydney came up with a low-cost alternative, by instead fashioning catalysts out of more common elements like iron, cobalt and nickel. The result is a zinc-air battery that can be more easily recharged and, in testing, lost less than 10 percent of its efficacy over 60 discharge and charging cycles of 120 hours.
Looking forward
Better batteries hold the key to smartphones that keep us connected longer, cars that drive further, cameras that capture more photos, wireless speakers that keep the party going and e-bikes that take you all the way across town, so there is no shortage of interested parties pumping money into moving things forward.
It's been a big year for batteries, but with new materials being developed all the time, and scientists learning more and more about the capabilities of those materials (we're looking at you, graphene), things certainly won't be slowing down as we head into 2018. Who knows, maybe in years to come you'll be reading New Atlas on a Samsung phone powered by batteries with graphene balls, while you travel in an electric car with a battery that hardly ever needs to be plugged in (both would pack their own fire extinguishers of course, just in case).
