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Samsung Ventures invests in Li-poly battery company Seeo; targeting 400 Wh/kg product

Seeo, a developer of advanced lithium polymer batteries, has closed its largest funding round to date, and added Samsung Ventures Investment Corporation. Earlier investors Khosla Ventures and GSR Ventures also participated in the round. The invested capital will be used to accelerate the commercialization of Seeo’s high energy density advanced lithium polymer batteries. (Earlier post.)

Seeo enables the production of safer batteries by replacing the flammable liquid electrolytes of conventional lithium-ion cells with Seeo’s DryLyte solid polymer electrolyte that is non-flammable and non-volatile. These enhanced safety characteristics, combine with high energy density. Currently, Seeo has cells cycling with an energy density of 350 Wh/kg, with a future target of 400 Wh/kg, roughly twice the level of batteries used in today’s EVs.

Among its current products, SEEO offers DryLyte Automotive Packs employing the Seeo DryLyte 1.6 kWh module as the basic building block. Scalable in voltage and capacity, the DryLyte Automotive Pack can be configured to meet a variety of requirements. The pack achieves 130 Wh/kg.

Originally developed at Lawrence Berkeley National Laboratory with sponsorship from the US Department of Energy, DryLyte products are safer, lighter and longer lasting than competitive Lithium ion batteries. Seeo has an exclusive license to core patents from Lawrence Berkeley National Laboratory and has more than 40 issued, exclusively licensed and pending patent applications.



Between this and the announced tie in between QuantumScape and VW, interest in solid state batteries is obviously high.

The increase in energy density depends what you are comparing it with though.

At the cell level those in the Nissan Leaf are around 140Wh/kg, so these are obviously a large advance on that.

The NCA Panasonics in the Tesla S run at around 270Wh/kg at the cell level though, so for the moment at least the increase in energy density although worthwhile is limited, and even 400Wh/kg is around a third more, not a doubling.

OTOH solid state may be more robust and less flammable than the tricky NCA chemistry.

Increasing energy density much compared to the Panasonics is proving tough indeed.


Yes, but those 350Wh/kg batteries would give a Leaf a real world range of 183 miles. If they hit 400Wh/kg then the Leaf would be ~210 miles. So for everyone outside of Tesla, it's a hell of an advance.



Even for Tesla a move from 270WHrs/Kg to 400Whrs/Kg would be a big deal in weight and cost reduction, 30%.


In the same time what they claim is really huge, so let's see what's come out next...I am still unconvinced that they can make it even with the fundin of Samsung...


I'm with you on this one; doubling a Leaf's range would sell lots of BEVs for Nissan, especially if the batteries will tolerate fast charging and they can maintain the current prices or better them.

Patrick Free

Sounds great, but 400WH/KG is how much WH/L here ?

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For all we know Tesla uses a 3.1Ah battery cell from Panasonic that has 243wh/kg (=3.1Ah*3.6V*(1000g/46g)). These cells are going into Tesla's cars at least until 2017 until the Giga factory starts up. However, in 2017 that factory will probably only do battery pack assembling and not actual cells. My expectation is that Panasonic and Tesla has a 4Ah cell ready sometime 2015 so that Tesla can add a larger battery pack to customers that want to pay for that. That 4Ah cell has = 252 wh/kg (=4Ah*3.4V*(1000g/54g)) and more importantly a very high 800Wh/L. Do not expect anything better on this side of 2020 from Tesla and Panasonic.

Tesla and Panasonic supply contract

Panasonic 4Ah cell


For general info., Just at this very moment, I weighed a Panasonic 18650 Cell.
- weight = 46.2g
- nom. V = 3.6
- Ic max = 3300 mah; 3.6V x 3.3A = 11.88wh per cell
1kg = 1000g or 1000g/46.2g = 21.645 (cells)
11.88wh x 21.645 = 257.14 wh/kg

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The 4Ah cell is still better than the 3.3Ah cell since Tesla as far as I know can fit 7600 of them into their pack. Use the 3.1Ah cell and you get a 85kwh pack (7600*3.6*3.1), use the 4Ah cell and you get a 103 kwh pack (7600*3.4*4.0), and use the 3.3Ah cell and you get a 90 kwh pack (7600*3.6*3.3).

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I just read at wiki that the Model S battery is composed of 7104 cells. I quote "The 85 kWh battery pack contains 7,104 lithium-ion battery cells in 16 modules[55] wired in series (14 in the flat section and two stacked on the front).[56] Each module contains six groups[57] of 74 cells[58] wired in parallel; the six groups are then wired in series within the module."

That is different from the about 7600 cells and a 3.1Ah cell that has otherwise been written on the web. I think the wiki reference is the correct one because it is so detailed with sources and that would also imply that Tesla use the 3.3Ah cell you are talking about as 3.3Ah*3.6V*7104 = 85kWh. I now guess you work at Tesla and simply picked up a cell and weighted it. Therefore now I assume that the 3.3Ah cell is a modified version of Panasonics 3.4Ah cell. This is interesting because it means any future battery pack upgrade from Tesla will have to be based on the 4Ah Panasonic cell and that it could result in a 4.0Ah*3.4V*7104 = 97kwh battery pack. That pack could become available for Model X next year and maybe also Model S.


Isn't this (about +30% or 400 Wh/Kg) what Tesla-Panasonic will produce in their mega-factory sometime in 2017? Model S110 could than approach 400 miles per charge. The Leaf could get close to 200 miles per charge.

By 2020 or so, 600+ batteries could be available and most BEVs could become range competitive with ICEVs. PHEVs (if still required) could go 100+ miles on electricity and use very little liquid fuel.

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