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

6 December 2013

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!)

December 6, 2013 in Batteries | Permalink | Comments (30) | TrackBack (0)


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I heard rumor that Tesla got their current batch of battery for $170/kWh at cell level, which may translate to ~$200/kWh at the pack level. The future deal with Panasonic of 2 Billion cells perhaps may lower the cost down to $150/kWh. Of course, Tesla will take back the old battery pack and will likely recycle the electronics, so they won't lose any money.

So, why even consider Envia's unproven technology when current and superior technology exists at $150/kWh that can by cycled 5,000 times and at a light weight of 250 Wh/kg?

Much is being said and unsaid about future batteries. Many $$B are at stake. Major technology changes are always challenged and so will every new higher performance battery.

Future 5-5-5 batteries will come by 2020 or so and will meet major resistance (disclaimers) from many interest groups including major Oilcos.

It's not to surprising that a battery of $150 is available. But the 250 Wh/kg capacity is "not there yet". For a BEV, people need much more range. At 4 miles per kwh, you need about 50 kwh battery for a respectable 200 miles. But that's a big battery - 200 kg (440 lb) and still costs a lot, if you want good range.
I think Envia's battery is "proven' because GM engineers say it has 400 Wh/kg ( 125 kg or 275 lb/50kwh), but the lifetime is a little less than advertised. I don't know how the weight affects milage, but I still think they are testing it for deep discharge. Anyway, the Envia problem is more about who stole the anode formula. They are using Argonne Lab's cathode, but the silicon composite anode is what the law suit is about and when that's settled, another battery maker will already have a similar anode on the market.

What's the advantage of 5,000 cycles over 1,000? Tesla is pushing long-range vehicles, which means a big battery. This means most of the time the battery is being discharged only 20% and recharged every night.

The 1,000 cycle battery on 20% DOD would have a practical lifetime of about 20,000 cycles / 365 = 54 years! But the 5,000 cycle battery on 20% DOD would have a real lifetime of about 100,000 cycles / 365 = 274 years! I don't see a practical advantage of 5,000 cycles for a long-range BEV.

Envia's battery's performance is not reproducible by GM, therefore, GM cancelled the contract. Kinda like EEstor many years ago.

Range is not a problem in a PHEV. Energy density above 250 Wh/kg is of little advantage in a PHEV 30-50. The high life cycle is of advantage when a PHEV has high DOD daily and is charged twice daily. If a PHEV-30 is charged 12x/week at 70-80% DOD, in one year, the battery will be charged 600 times, so will reach 5000 cycles in 8 years or so. This is just perfect, because of shelf life of 8-10 years. So, the battery size, cycle life, and shelf life must all match in order to take the most out of a battery pack.

What's more important is to raise the 3.5 C of the NCA 18650 to about 5-6 C in order to get more power in the all electric mode. However, if 3.5 C is maximal continuous discharge, then burst discharge for 5-10 seconds may be higher, perhaps to 6 C, and this will allow a PHEV-30 with a 10 kWh pack to deliver 60 kW in short burst of 5-10 seconds or so for quick acceleration. Combined with a 40 kW ICE, total power will be 100 kW, which is totally adequate for a 5-seat compact or even mid-size vehicle.

Battery performance of today's commercially-available batteries is very adequate to make a PHEV-30 that is competitive with comparable ICEV's in term of purchasing cost, curb weight, performance, load capacity, and internal space! We simply hope that auto MFG's see this and put it into practice!

BEV's will be a niche market of BEV purists, who do not want anything to do with ICE, and are willing to pay premium price for a much larger battery pack that most of its life-time capability will be wasted due to shelf-life limitation. For the luxury auto market, cost saving is not primary consideration. Rather, it's the lifestyle, personal image, or status symbol. A car is more than just merely personal transportation. For this reason also, SUV's and sport cars will continue to sell well, no matter how impractical they are.

Envia had to go for Chapter 11 when GM dropped them?

Over powered extended range EVs are required for the same reasons as we are all driving overpowered 200+ HP extended range ICEVs.

We all want to accelerate like a rocket, drive faster and go for 300+ miles without having to stop for fuel?

Our 'wants' dictate a 120+ kWh battery pack and it will be available by 2020 or shortly thereafter.
For short daily trips (40 to 60 miles), only about 20% of the battery pack capacity will be used. That is very positive to extend the potential batteries life to 10+ years.

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