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Sekisui Chemical develops high-capacity film-type Lithium-ion battery with silicon anode; triple the capacity

Sample of the film-type Li-ion battery developed by Sekisui Chemical. Click to enlarge.

Sekisui Chemical Co., Ltd. has developed a high-capacity film-type lithium-ion battery with a silicon anode using a coating process that has simultaneously tripled the battery capacity (900Wh/L) compared to other Sekisui Chemical products; increased its safety (as shown by nail penetration tests or crush tests); and sped up production by ten times (compared to other Sekisui Chemical products).

The new cells feature high lithium-ion conductivity (approximately ten times compared to other Sekisui products) with enhanced safety through the use of a high-performance gel-type electrolyte. Sekisui Chemical used its original materials technology to enable the application the novel high-performance gel-type electrolytes using a coating process instead of the standard vacuum infusion process.

By further adding its newly developed high-capacity silicon anode material in this process, the company can provide high-capacity film-type lithium-ion batteries with high productivity while being flexible, slim, long and covering a large area. (The company has not yet discussed cycle life for the Si anode battery.)

The cells can offer large savings in terms of space (a third the size of previous products for comparable density) and can be installed in any shape or form, giving rise to a large number of applications in automobiles, houses, appliances and so on, according to the company.

The assumed size of film-type lithium-ion batteries is currently 200cm long, 30cm wide, and 0.3-5mm thick, however, the size will differ according to the design capacity and application.

The process technology was developed with support from the Advanced Technology Research Project for the Application and Commercial Use of Lithium-Ion Batteries being run by the New Energy and Industrial Technology Development Organization (NEDO).

Sekisui said that it will be exploring mass production with these film-type lithium-ion batteries, aiming at quickly realizing products for a variety of uses, including electric vehicles. The company will begin providing samples starting around next summer (2014).

The company will present the research at Eco-Products 2013 in Tokyo, 12-14 December.

(A hat-tip to RK!)



What will HarveyD write about this one?


he will say : "Will this be the solution for EV in 2020" ?

I understand that these guys don't make batteries but just component for battery. So let's see what comes out.


Finally, somebody is going to start sampling their new battery tech. I'm tired of hearing about all these new battery advancements, and never actually having anything for people to test.
I am curious about the cycle life though. Common problem for silicon anodes is poor cycle life.


If this claim is true, it may very well have the potential to mass produce 5-5-5 EV batteries by 2020 or so. It will certainly NOT be the only technology available.

By that time (2020 or so), my Camry Hybrid will have 120,000+ Km and I'll be shopping for a new Camry extended range BEV.


if these people have the perfect solution for batteries they will just make batteries because the potential market is phenomenal based on their claim. So I skeptical that their material is more than for demo of higher capacity than real commercial applications


This sounds very promising. I assume that cycle life and Wh/kg are not great or they would have bragged about those as well. That's not a criticism, simply an observation. Even if I'm right, there will be markets where this type of battery (safe and high Wh/l) is still desirable.

They also didn't talk about cost but it is just a I'm not sure that's a bad sign but possibly them just being prudent until they know what a full cell cost would be???


900 Wh/l, that would give you a 60 kWh battery for the size of an average petrol tank (European petrol tank, not US ;)

It would conveniently fit below the rear seat as a petrol tank. Or spread out under the floor a la Tesla, it would be merely 3 cm thick.

The only thing that pops into my mind is the phrase: "If it sounds too good to be true, it probably isn't true" There have been so many wild claims from small, unknown companies that my skept-o-meter is deep in the red zone. Did anyone say Envia, EESTOR, DBM? So I'll restrain my enthousiasm for now.

DaveD, as a reference: the average 18650 cell weighs 45 g, and the volume is 16.5 cm³. That works out to roughly 3 kg/l. I don't see this battery containing large amounts of a heavy metal, so it'll be in the same ballpark. That would give this battery a gravimetric energy density of around 300 Wh/kg. That is not too far off the best Panasonic 18650 cells today (~250 Wh/kg), so the claim becomes a little less wild. My skept-o-meter just dropped a bit into the orange zone :)

Much will indeed depend on the other properties like price, heat tolerance, cycle life, calendar life, max (dis)charge rate.


4. Future Business Development

In the future Sekisui Chemical intends to further improve the batteries toward realizing actual products, beginning the provision of samples from around summer 2014, to reach the markets in FY2015 after testing and evaluation.


In other articles Sekisui claims that their new rugged ultra thin flexible battery has 3 to 4 times the energy density, 10 times the power density and cost 3 to 5 times less to produce (in various sizes and shapes).

If all those claims are true, it would come close to the 5-5-5 future battery but more fine tuning would be required.

Secondly, Sekisui is one of 3 partners (including NEC) developing this technology.


Arne/Anne.."Did anyone say Envia, EESTOR, DBM?"....

EXACTLY, & what gets to me is that THESE several-fold higher energy density/better batteries ARE certified BY NATIONAL GOVERNMENT LABS - YEARS AGO.

The US battery hub is budgeted to 5X energy, 1/5th cost batteries in 5 years and we're well into the second year of the expenditures.

Our borders, currency, the return of DECADES of our money "contributions" to our old age Social Security, .. all ride on government departments and labs that seem proven to be LYING through their teeth.

Concerning Envia, battery firms backed by GM have a clear track record.

Still, for instance - were/are the Envia battery claims(US Navy lab tested from a China battery assembly line 22 months ago) physically achieved?

GM and EV battery technology being shelved isn't a surprise.


I found additional info

Battery recharge cycles(400 cycles/72% remaining capacity) is the stated problem.

Then again, IF there's still twice the initial capacity and half the cost - it's a better value - except GM is in the IP rights.

If nano tech/coatings can stabilize electrode deterioration.. it's a winner.

Perhaps this is like GM crushing EV1s and selling NiMH EV battery patents to an oil company.

While Toyota grandfathered small NiMH battery rights into the hybrid Prius family - best mpg and third best selling car model/plate in the world.

Leopards and spots..


"400 cycles/72% remaining capacity" At $160 kwh, the Envia battery would a good choice for GM even at that cycle lifetime, but only for a BEV. Probably they only want to put it into a Volt, which relies on 100% DOD every day. Therefore, of course it's not good enough. But if it's put into a BEV, with 200 mile range, a 100% DOD would be once a week on average and it would last about ten years. But most likely the BEV's 200 mile battery would be kept between 70% and full charge by charging every night.


Actually a 100% DOD each week might give only a five year lifetime. But, keeping a 200 mile Envia battery at near full charge by plugging it in every night might allow a ten year lifetime. Why do 99% of battery articles only talk about deep discharge lifetimes and not small discharge lifetimes?



"Probably they only want to put it into a Volt, which relies on 100% DOD every day"

This is not the case. The Volt uses only 10.5 kWh of a 16 kWh capacity, so it cycles over only ~65% of capacity. Even full EV's like the LEAF or Zoe only cycle over ~85% of capacity to prolong battery life.

Roger Pham

Actually, existing battery technology is already very good to advance PEV (PHEV) to mass market level.

Take, for example, the Panasonic NCA 18650 cells used in the Tesla Model S. I've read somewhere that this cell is capable of 5000 cycles with 80% capacity remaining. This is truly incredible, at ~250Wh/kg? Tesla uses the 85kWh battery at 3.5C maximum discharge rate, warranty the pack for 8 years and unlimited mileage, while charging $12,000 for the replacement pack after 8 years. At 265 mi range after 5000 charging cycles, this pack would cover 1.3 million miles of driving!!! At 15,000 miles/year, this would cover 80-90 years of driing. But too bad and so sad, it ages significantly after 8-10 years such that Tesla only warranty it for only 8 years. 8 years of driving at 15,000 miles/yr will get only 120,000 miles, or 30,000 miles/yr will get only 240,000 miles, thus wasting over 1 million potential miles of the pack! Incredible waste of battery potential!!!

If a 20-kWh pack of NCA 18650 is to be used on a PHEV at the same consumption rate of the Volt, it will be capable of 50 miles of AER, that can satisfy 80-90% of total driving without fuel. The pack will last for 300,000 miles of driving on AER, or 400,000 miles overall driving. At 3.5 C, this pack is capable of 70 kW of power, added to the power of a 2-cylinder engine of 40 kW to get 110 kW of total power. At 250 Wh/kg, the pack would weigh only 80kg or 176 lbs, and would cost under 1/4th that of the Tesla 85 kWh pack, or under $3,000. A 2-cylinder engine of 40 kW is really inexpensive, probably costs under $1,000 and weighing about 100-150 lbs. No transmission needed. Emission control will be minimum since only 10-20% of the time on ICE power, meaning very low emission per mile driven. Savings in cost and weight of the motor and power electronics also, now that the electric power is reduced to 70-80 kW.

Now, let's look at the ramification of all the above numbers: It is possible to make a PHEV with similar curb weight, cost, and similar luggage space to a comparable ICEV, NOW. NO need to wait til 2020 or a 5/5/5 magical battery to appear!


The world may need short range, mid-range and affordable extended range BEVs.

More efficient batteries will not necessarily weight and cost more. It may very be the opposite. Using less lower cost materials and more efficient mass production methods will, by 2020 or so, produce 5-5-5 batteries for future affordable extended range EVs.

People satisfied with 20-40 kWh packs will be able to use less modules. The average majority may want 60-100 kWh packs and may be able to buy them. The rest may want 120 to 200 kWh packs and may buy them.

The same happened with 3 cyls to 12 cyls IVECs.

Let end users decide what size of packs and e-range they want.


@Arne - "cycles over only ~65% of capacity" But this is deep discharge. My point is that a large battery gives at the same time a long range and long lifetime by discharging only a little each day, with normal driving.

The Li Iron Phosphate battery gets about four times the cycle lifetime at 20% DOD as it does with 65% DOD. Between 65% and 100% the curve is pretty flat, meaning 65% DOD lifetime is only 15% greater than 100% DOD. 80% DOD doesn't extend the lifetime more than 5%.


In other words, if GM is testing the Envia battery in a volt, at 65% DOD and gets 400 cycles, this doesn't reflect the cycle lifetime if it were put into a BEV. If they put a large Envia battery, with a 200 mile range, in a BEV, they will get about 1,600 cycles. That would probably give more than 1000 weeks (20 years) of average driving.


Actually, 1,600 cycles, at five cycles per week, would be 330 weeks, or 6.5 years.

However, I believe I greatly underestimated the increase in lifetime. According to the graph on page 20-4 of this LFP battery study -, the lifecycle at 65% is 2,000. At 20% it is 20,000 cycles. So, what is the lifetime of the Envia battery at 20% DOD? If expansion of the silicon in the anode is what causes the degradation, maybe there would be a lot less expansion and much greater lifetime at smaller DOD.

Roger Pham


Aye, there's the catch. Shallow DOD will greatly increase cycle life, however, smaller battery for PHEV can't do that. Larger battery packs for BEV can do shallow DOD, but the batteries of BEV like the Panasonic NCA 18650 will last for 1.3 million miles, or 4-5 times the mileage that the car will travel during its lifetime, so who cares about cycle life of BEV battery packs with that type of battery? Shelf life is a more important attribute in BEV's battery.

At 5,000 cycles with capacity reduction to only 80%, and at $150/kWh as Tesla is charging for the battery pack, and at 250 Wh/kg, and at 8 years warranted shelf life, what is the automotive industry is waiting for, before producing the kind of PHEV's that most people will buy, you know, those more practical-minded people, after the market for early adopters is saturated?

Of course, at the time that the Volt and the Fusion Energie was developed, perhaps the NCA 18650 battery was not commercially available, so we can't really blame GM and Ford for not trying harder to make more appealing PHEV's.

The near future is indeed exciting for future PHEV shoppers. Just imagine having a PHEV-30 on the market using 10 kWh of the NCA 18650 battery, having 40 kW of electric power (motor and inverter) to keep cost down, in a smaller and lighter vehicle, with a 2-cylinder 40 kW ICE for a total of 80 kW, the ICE will kick in with stronger acceleration without gear-change transmission. It can be charged at home for those with commuting distance of under 30 miles, or charged at work also for those with up to 60 miles of commute. The day-time charging can help soak up excess daytime solar PV electricity, to make at-work solar PV installation much more cost-effective. THis PHEV will cost under $20,000, which is well below the $31,000 median price of a 2013 new car.

Alternatively, this modern and ultra-affordable 5-seat PHEV may have embedded solar PV's cells at over 20% efficiency to give substantial proportion if not all of daily driving distance on solar power alone in sunny seasons. Look, Ma, no need for plugging in!


There is such thing as social conscience when it comes to GHG reduction. Why hogging up so much battery capacity in one BEV that travels 15,000 miles /yr, when that battery capacity can be divided to make 8 PHEV-30 that can travel 10-12,000 miles yearly on electricity. Multiply 12 x 8 = 96,000 miles, vs. 15,000 miles, or 6-fold difference in GHG reduction per a given amount of battery capacity. The world's resources are limited, both in natural and human resources that can be exploited. Battery, motors, inverter, etc. can be produced only so fast. One Tesla having 315 kW of power and 85 kWh battery pack is hogging up resources to make 8 PHEV-30 that can travel 6 times further on electricity power. Shortages of any of EV materials or components will drive up prices of future EV's (BEV, PHEV, HEV, and FCEV) and that will impact the rate of efficiency gain and GHG reduction in the transportation sector.


$150/kWh actual cost or covered by the cost of the car? Could you buy a battery pack from Tesla for that price, without buying the car too?


Already, <50 mile battery range can do 80-90% of typical urban travel.

"A 2-cylinder engine of 40 kW is really inexpensive, probably costs under $1,000 and weighing about 100-150 lbs." genset could be a standardized "plugable" in the trunk area.

The i3, with optional genset in axle space, is on the road and a Wankel power genset could be even smaller, lighter, and 'one man' lug-able ( )

With a 10-20% constant speed duty cycle, gas use and emissions would be very low.


We used to talk about this genset style hybrid about twenty years ago. The key is constant speed duty cycle, which keeps the efficiency high. This is old technology and I'm surprised never to read that somebody has done it.


One more item about the Envia battery. Their web site shows 400 cycle lifetime at 80% DOD. But they don't have any info about lifetime at 20%DOD.

In addition, it seems obvious that GM is testing at deep discharge in a small battery designed to have high current output. The high current per kg also degrades the lifetime.

So if they test a 200 mile battery, as designed for BEV, instead of a short-range battery designed for the Volt, the average current draw would be much smaller. Therefore, the lower current and the small DOD would extend the battery lifetime very much.

I wouldn't give up on Emvia's battery yet, especially at $125/kwh, except there are plenty of competitors like CalBattery.


...and the copyright lawsuits against Envia don't help them much.

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