Battery Yarn Could Knit Power Into Fabrics
Wei Wang, Fudan University
The battery yarn is as flexible as any other woven material.
Debate still rages on thebest way to sell electric cars
. Should automakers be boasting of their environmental credentials? Or should they talk in a language people understand -- money -- and highlight the economic benefits? Maybe it's all about silence and refinement? Rarely mentioned is just how funelectric cars
can be to drive. So we've taken a primal, quantitative measure of driving fun -- the 0 to 60 mph acceleration sprint -- to rank each battery-electric vehicle on sale today, or on sale soon. At the very least, this gallery will serve as a handy list of whichcars
not to try and beat from the next green light.
You probably aren't surprised by this one. The Model S is comfortably the most powerful electriccar
on sale, and while it's also the heaviest, it still offers super-sedan performance. If you like that airliner-on-takeoff feeling on your commute, this is the car to offer it.
Another car with Tesla influence (though not for much longer
) and apparently Tesla-style performance, the RAV4 is a Toyota product. With a 115 kW (154 hp), 220 lb-ft electric motor and a Sport mode, the RAV4 EV will see off most other crossovers andSUVs
at the lights. A 103-mile EPA-rated range isn't bad, either.
BMW's electric city car has attracted attention for its styling more than anything else, but with a 130 kW (170 hp) electric motor driving the rear wheels and a lightweight carbon fiber reinforced plastic chassis, it's also brisk. It's worth noting that the extra weight of the range-extended model does dull performance a little.
The key figure for the Spark EV isn't the 97 kW (130 hp) power output -- though that's not bad for such a small car. No, it's the incredible 400 pounds-feet of torque, more than a Ferrari 458 Italia. Okay, so the Ferrari is still quicker and perhaps a little more attractive too, but the Spark comfortably sees off its combustion counterparts, which is much more interesting.
Mercedes-Benz is pitching itsupcoming B-Class Electric Drive
as a rival to the BMW i3, and pricing is near-identical. It's got a little more interior space, but isn't quite as innovative in its construction and in terms of both acceleration and cornering, the BMW driver will be having more fun.
The best demonstration of the Fit EV we've yet seen hasn't really called for outright acceleration; there's a limit to how much you can usesliding around on a frozen lake
. But 8.5 seconds to 60 mph is still better than most compact cars, let alone subcompacts. And you still get all the other Fit benefits -- an agile chassis and spacious interior.
TheFiat 500E is a hoot to drive
whether you're going in a straight line or zipping around city streets, and a 0-60 dash of 9.1 seconds is similar to that of its gasoline counterparts. But let's be honest, you'd prefer to have that performance with a quiet, clean electric motor, wouldn't you?
Volkswagen's entrant into the electriccompact
sector isn't yet on sale, but it's not too bad a performer. "Around 10 seconds" is VW's estimate for the e-Golf (to 100 km/h, or 62 mph, it's 10.4). More pertinently, it's good over those first few yards too--proving fun to drive around the streets of Berlinon the car's recent launch
Like the Golf and Leaf, few will regularly do a full 0-60 mph sprint on their daily commutes, but the Focus is par for the course for acceleration performance. The Focus's main trump card is handling though -- the gasoline Focus is already widely praised, and the Electric model is also a neat handler.
The Leaf lags its compact rivals here but many owners are content to cruise around using as little energy as possible. Like allelectric vehicles
, it's pretty good over those first few feet anyway -- thank the 80 kW (110 hp) and 210 lb-ft electric motor's instant torque characteristics for that.
We've driven the electric Smart Fortwo on several occasions, andconsistently deem it a better vehicle
than its jerky gasoline siblings. It's also quicker, hitting 60 mph in the same time as the Leaf -- quite an experience in the Fortwo's upright body shape.
If you're a speed freak with a penchant for electricvehicles
, the i-MiEV probably won't be on your shopping list. The 15-second sprint has been bettered by some drivers, but as the official figure that's the one we have to run with, and it does the i-MiEV no favors. Luckily, low lease rates make it one of the cheapest electriccars
to get your hands on.
Could your car seats become large, comfortable batteries? If experiments by scientists at Fudan University in Shanghai, China become reality, perhaps they could, as the group has developed battery technology that can be woven into fabrics.
According to Phys.org, researcher Wei Weng and his colleagues have designed and fabricated carbon nanotube composite yarns, wound around lithium-ion battery fibers and combined them with a cotton fiber. MUST SEE: BMW, Tesla Are Only Electric-Car Makers 'To Build A Business': Really??
At 1 mm in diameter, these fibers can be woven into flexible textiles or cloth, like strands of any other material.
The main aim is to develop the technology into a generation of wearable electronics, since devices would then have a power source that wouldn't require pockets and compartments specially developed for existing solid batteries. But naturally, where there is material, there's a potential battery -- so automobile trim panels, seats, carpets and more are all potential batteries using the tech.
Some may be uncomfortable with the idea of sitting on a big battery, and Gizmag reveals the team is looking to ensure resulting battery fibers are safe. Weng says it's "the most important thing for wearable electronics," and that the team is investigating the "battery structure, the electrolyte and the packaging."
The battery yarn also needs to be flexible -- like any other woven material. It needs to stretch, and be easy to fold -- particularly for other functions the team sees as useful, such as materials used in hiking and camping where an extra source of power could be very useful indeed.
Further issues include measures to limit the expansion of silicon in the battery chemistry during charge and discharge cycles. It's already a problem in existing battery experiments -- the silicon's expansion damages the battery's internal structure -- but even more of a problem in a woven material, that relies on certain important characteristics.
The team thinks it's got around this particular problem by incorporating those carbon nanotubes, which help clamp the expanding silicon in place. The battery so far exhibits impressive electrochemical properties, 0.75 mWh/cm energy density and capacity retention of 87 percent after 100 cycles.
Improvements are ongoing, and the team already has several goals: improving performance, developing large-scale production and adding color-changing and stretchable characteristics.
Get more from Green Car Reports
How Hard Is Lithium-Air Battery Research? Pretty Tough, Actually
Lithium-Ion Batteries For Lighter, Compact Jump-Starting Pack
Tesla Model S Electric Car: What Has Changed Since 2012?
This article originally appeared on Green Car Reports, a High Gear Media Company. All rights reserved.