Energy

Enevate's silicon-anode batteries promise ultra-fast EV charging

Enevate's silicon-anode batter...
Enevate's silicon anode technology massively boosts charging speeds, and also delivers a 30% bump in energy density for EV batteries
Enevate's silicon anode technology massively boosts charging speeds, and also delivers a 30% bump in energy density for EV batteries
View 1 Image
Enevate's silicon anode technology massively boosts charging speeds, and also delivers a 30% bump in energy density for EV batteries
1/1
Enevate's silicon anode technology massively boosts charging speeds, and also delivers a 30% bump in energy density for EV batteries

Battery advances are starting to come thick and fast as massive investment in the segment begins to bear fruit. California's Enevate has been chipping away at silicon anode technology since 2005, and now the company says it's managed not only to achieve an incredibly fast charging solution for lithium-ion EV batteries, but one that handily boosts energy density as well.

The typical current-gen lithium battery anode is made of graphite. Replacing it with silicon, says Enevate founder and CEO Benjamin Park, would give you an instant boost of 25% in energy density and enable super-quick charging if you could just get around the fact that it swells by 400% when it charges up, eventually cracking and degrading the battery surfaces. This kills the battery within a few hundred cycles.

Enevate's solution can be conceptualized as a hard, porous, conductive film, with each pore having its own small "balloon" of silicon inside. Thus, the silicon can swell and deflate as much as it likes without causing any of the cracking issues, and you get yourself a silicon anode that gives your battery some pretty impressive properties and a lifespan that's no longer a deal-breaker.

Those properties include an energy density boost of around 30% over current-gen tech, up to 350 Wh/kg, as well as the ability to charge extremely quickly, at rates that could effectively put 400 km (250 mi) of range into your battery in five minutes. That's not far off how fast it is to fill a tank with gasoline, and it'd be a game-changing leap forward if the infrastructure was there to move that amount of energy.

They also charge well at temperatures well below freezing, something other lithium-based batteries can struggle with, and the company says its electrodes don't suffer from the kinds of lithium deposits that can lead to the dangerous dendrite formation that can short out batteries and lead to them catching fire. So they'd appear to be safer than the status quo, as well.

With some US$111 million in investment from major companies, including LG, Samsung, Mitsubishi, Renault and Nissan, Enevate now says its cells are ready for the big time. In an interview with Charged EVs, Park said Enevate is designing packs for the 2024 and 2025 model years to get its cells into consumer products with major manufacturers. There are no announcements around who or what exactly they're making packs for, but the list of companies above may be instructive.

As far as we're aware, though, the infrastructure to support blast-charging at the kinds of rates we're talking about here simply doesn't yet exist. Tesla's V3 superchargers are currently capable of blast-charging a Model 3 at 250 kilowatts, which would give you around 133 km (83 mi) of range in five minutes.

These batteries would charge three times faster, at around 0.75 megawatts, which is a huge power draw. An alternative method might involve trickle-charging massive supercapacitors all day at slower rates so they've got enough energy to supply the cars super-quickly when they need it, but we're yet to see anything like that in action, and the size of those supercapacitors might end up being prohibitive.

Still, there appear to be a number of potentially viable solutions crystallizing out of the vast amounts of battery research that is underway, and it seems clear that EVs will be jumping significantly both in range and charging speed in the next few years.

Source: Enevate via IEEE Spectrum

14 comments
MemoriaTechnica
This would definitely be a game changer. It seems incredible now, however, I have to keep reminding myself that EV tech is still pretty much in it's infancy. Things will change quickly in the coming years, and like the smart phone, I suspect improvments in power storage will open up new applications no one has even considered yet. The future looks bright... If we don't screw it all up some how.
zr2s10
Good to see something that's not vaporware, lol. But you hit the nail on the head with concerns over infrastructure. Look at a busy gas station (not at the moment), and imagine a dozen cars all charging at these rates, all at once! There is no way our current grid can handle that kind of charging. Infrastructure (design/compatibility/cost) is a way bigger issue that we're nowhere near solving.
Catweazle
250 kilowatts at 250 volts is 1,000 amps, that's serious current. What happens if the connector contacts aren't scrupulously clean?
guzmanchinky
I still think it will be easier to fix the power to the pump problem than it was to fix the rapid charging battery problem. SO many naysayers were 100% sure we would never see this kind of charging time, and they are now 100% sure that we can't fix the whole thing.
zr2s10
I think that these would almost have to be used in conjunction with fuel cell technologies of some sort when placed in vehicles. Like in my previous comment, there's no way we can support this rapid of charging currently, no pun intended. But in combination with a fuel cell, this could allow for lighter packs and more range. Hydrogen presents its own problems, but at least when transferring to a vehicle at high rates, it will cool things off, instead of heating the heck out of them. As Catweazle implies, that's going to be dangerous with bad connections. Heck, even just the switch gear is going to hum like crazy, lol
KD4MNI
There are practical limits in the "BEV charging wars" to be considered:
- BEV charging station installers are frequently adding Tesla Powerpacks (and PV solar panels) to provide supplemental reserve power in addition to the local power grid for high-demand situations.
- To fully charge a large 100kWh, 400Vdc EV battery pack in 5 minutes would require 3000A - the size of the cables and connectors required to safely deliver this dangerous amount of current would be ridiculous/impractical, completely unmanageable (current EVSE equipment is rated for 400A max).
- Stepping up the battery pack voltage to 800Vdc (Porsche, Audi, etc) drops the current to 1500A, which would still be ridiculous/impractical.
- Current EV charging connectors (for non-commercial uses) are rated for a maximum of 400A (dc), and this typically requires active cable and connector cooling to prevent overheating if you want the cables and connectors to remain reasonably-sized.
- Some EU CCS-2 rapid dc charging stations can provide up to 350kW (920Vdc/400A max)
- Tesla Generation 3 Superchargers (with actively-cooled cables) provide up to 250kW (400Vdc)
- All of this is academic, actual BEV drivers don't completely charge a "dead" battery pack just as most drivers don't wait until their gas tank is almost completely empty, and BEV drivers typically charge to 80%-90% since charging to 100% takes much longer (due to tapered charging) and reduces the longevity and capacity of their expensive battery pack). More importantly, dc rapid charging is primarily used on trips and for topping off, BEV drivers prefer convenient, economical overnight charging for everyday driving.
- This said, long-life hybrid supercapacitor/battery cells are coming (Tesla, others) that promise to be able to charge much faster - perhaps with less tapering required - which should significantly shorten charging times. Tesla Battery & Drivetrain Investor Day is coming in April 2020, stay tuned.
paul314
So the supercapacitors would have to be what, 10x the volume of the battery packs they're intended to charge? That seems plausible for the scale of a gas station.
KD4MNI
The hybrid supercapacitor/battery cells are rumored to be a development based partly on Maxwell Technologies R&D and dry film process technology, they would be used to build new, improved power packs for Tesla BEVs:
Tesla Next-Gen Battery Could Use Dry Cell And Supercapacitor Technologies
www.tesmanian.com/blogs/tesmanian-blog/tesla-next-gen-battery-dry-cell-supercapacitor-semi
Supercapacitors Could Accelerate Electric Car Revolution
www.cleantechnica.com/2020/02/23/super-duper-supercapacitors-could-accelerate-electric-car-revolution/
High-density hybrid powercapacitors: A new frontier in the energy race
www.newatlas.com/energy/toomen-powercapacitors-kurt-energy-high-density-supercapacitors/
KD4MNI
The point is that with improved BEV battery packs and 250-350kW rapid charging stations, most long-trip charging stops will take 15-25 minutes, providing 200+ miles of range (3+ hours of driving). Once you've owned a BEV for a while, this becomes part of life, you simply plan accordingly, and more and more fast-charging stations are being built every day, making long-distance travel easier. The tradeoff is that you never have to visit a gas station, the convenience and economy of overnight charging far outweighs the relatively minor inconvenience of rapid charging on long trips, particularly if you drive a Tesla BEV and have access to the Tesla Supercharger network.
Expanded Viewpoint
Yes, the electrical cables needed for charging will be pretty stout for sure! The contacts at the ends will have to be taken into consideration more than most people realize. If plated with a gold alloy to avoid possible corrosion, it will wear away in a short span of time due to all of the abrasion of making and breaking the connection. The best way then to avoid that problem at first glance would appear to be induction coil charging, but then that has problems all its own too, like high inefficiency/ waste of power as not all of what is in the induction coils goes into the batteries. If a system of draining and replacing a charged up electrolyte could be invented, that might be the best way to go. Have a suction line to draw out the electrolyte that has most of its electrons depleted, and then refill the battery with fresh, charged up electrolyte. Remember, it's the electrolyte (acid) in current lead/acid batteries where the charge is stored up, not in the plates.