Samsung Global Research Lab Discusses Potential Lithium-Ion Battery Breakthrough

JUL 11 2015 BY MARK KANE 15

SiC-free graphene growth on Si NPs (a) A low-magnification TEM image of Gr–Si NP. (b) A higher-magnification TEM image for the same Gr–Si NP from the white box in a. (Insets) The line profiles from the two red boxes indicate that the interlayer spacing between graphene layers is ~3.4 Å, in good agreement with that of typical graphene layers based on van der Waals interaction. (c) A high-magnification TEM image visualizing the origins (red arrows) from which individual graphene layers grow. (d) A schematic illustration showing the sliding process of the graphene coating layers that can buffer the volume expansion of Si.

SiC-free graphene growth on Si NPs
(a) A low-magnification TEM image of Gr–Si NP. (b) A higher-magnification TEM image for the same Gr–Si NP from the white box in a. (Insets) The line profiles from the two red boxes indicate that the interlayer spacing between graphene layers is ~3.4 Å, in good agreement with that of typical graphene layers based on van der Waals interaction. (c) A high-magnification TEM image visualizing the origins (red arrows) from which individual graphene layers grow. (d) A schematic illustration showing the sliding process of the graphene coating layers that can buffer the volume expansion of Si.

Samsung, lithium-ion battery supplier for companies like BMW, is working through its global R&D hub (Samsung Advanced Institue of Technology) on new generation batteries.

Recently scientists at SAIT released a paper on a new silicon anode with graphene, which when paired with a commercial cathode (LiCoO2), gave them volumetric energy density of 972 and 700 Wh L−1 at first and still at the 200th cycle. On the gravimetric densities they achieved 242.0 and 169.6 Wh kg−1.

The volumetric energy density, which corresponds to the size of the pack, is very high. According to the article, 1.8 and 1.5 times higher than those of current commercial lithium-ion cells (graphite//LiCoO2).

“Silicon is receiving discernable attention as an active material for next generation lithium-ion battery anodes because of its unparalleled gravimetric capacity. However, the large volume change of silicon over charge–discharge cycles weakens its competitiveness in the volumetric energy density and cycle life. Here we report direct graphene growth over silicon nanoparticles without silicon carbide formation. The graphene layers anchored onto the silicon surface accommodate the volume expansion of silicon via a sliding process between adjacent graphene layers. When paired with a commercial lithium cobalt oxide cathode, the silicon carbide-free graphene coating allows the full cell to reach volumetric energy densities of 972 and 700 Wh l−1 at first and 200th cycle, respectively, 1.8 and 1.5 times higher than those of current commercial lithium-ion batteries. This observation suggests that two-dimensional layered structure of graphene and its silicon carbide-free integration with silicon can serve as a prototype in advancing silicon anodes to commercially viable technology.”

This new concept of dealing with large volume change of silicon over charge–discharge cycles, could in next few years enable Samsung to produce more capable batteries.

The volumetric energy density of 5 wt%-Gr–Si (a) The volumetric capacities of pure Si film (calculation, cal.), theoretically packed Si NP film (calculation), 5 wt%-Si–Gr electrode (experimental) and graphite electrode (experimental). The value of theoretically packed Si NP film (calculation) was obtained by consideration of the gravimetric theoretical capacity of Si at room temperature (3,580 mAh g−1), the density of Si (2.2 g cm−3), the void portion in the theoretical particle packing (body centred, 0.32) and the binder content (~20 wt%). (b) Cross-sectional SEM images of the 5 wt%-Gr–Si and commercial graphite electrodes (left). Top (right) and front (blue inset box) views of the 5 wt%-Gr–Si//LiCoO2 and graphite//LiCoO2 full cells with the same total energy (9.0 Wh). Both cells were wound into 18650 cylindrical cases with an identical winding tension. (c) The cycling performance of the 5 wt%-Si–Gr//LiCoO2 and graphite//LiCoO2 full cells. The 5 wt%-Gr–Si electrode in b and c is the one with 3.0 mAh cm−2 shown in Fig. 4c.

The volumetric energy density of 5 wt%-Gr–Si
(a) The volumetric capacities of pure Si film (calculation, cal.), theoretically packed Si NP film (calculation), 5 wt%-Si–Gr electrode (experimental) and graphite electrode (experimental). The value of theoretically packed Si NP film (calculation) was obtained by consideration of the gravimetric theoretical capacity of Si at room temperature (3,580 mAh g−1), the density of Si (2.2 g cm−3), the void portion in the theoretical particle packing (body centred, 0.32) and the binder content (~20 wt%). (b) Cross-sectional SEM images of the 5 wt%-Gr–Si and commercial graphite electrodes (left). Top (right) and front (blue inset box) views of the 5 wt%-Gr–Si//LiCoO2 and graphite//LiCoO2 full cells with the same total energy (9.0 Wh). Both cells were wound into 18650 cylindrical cases with an identical winding tension. (c) The cycling performance of the 5 wt%-Si–Gr//LiCoO2 and graphite//LiCoO2 full cells. The 5 wt%-Gr–Si electrode in b and c is the one with 3.0 mAh cm−2 shown in Fig. 4c.

Source: Samsung Advanced Institue of Technology via Green Car Congress

Categories: Battery Tech

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15 Comments on "Samsung Global Research Lab Discusses Potential Lithium-Ion Battery Breakthrough"

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Surya

Nice, but what about 2000 cycles?

mr. M

500-700 is enough for automotive. 2000 is still to few for storage.

Lensman

Surya is correct. 2000 cycles is the target for a plug-in EV. An auto maker might be able to get away with as little as 1500, but certainly not 500.

przemo_li

On the contrary.

When we are talking about ‘cycles’ in research papers those mean full charge/discharge cycles.

Car oems do not want even single of those in their batteries, as those are MOST damaging to the battery.

So everybody do what they can to make those unneeded.

Increasing ‘unusable’ battery capacity. Improving charging management. Adding active and passive cooling/heating of battery.

All are used to increase number of not-so-full cycle batter can go through.

No reason why those could not be applied to this particular chemistry.

PS Tesla S can do 100 000 miles with minimum battery degradations… With charge cycles far exciding expected ~500 for Li-on. So its doable, with battery packs big enough(and cheap enough)

Lensman

przemo_li said:

“When we are talking about ‘cycles’ in research papers those mean full charge/discharge cycles.”

You are correct — and kudos to you for knowing the subject well enough to debate the point.

Yes, it’s true that the average “cycle” in PEV (Plug-in EV) charging isn’t a (near-)complete discharge followed by a (near-)complete charge cycle.

Nonetheless, you’ll find that in practice, 2000 cycles is what PEV makers tell battery cell suppliers they want, as a minimum. Remember that if a cell is rated for X number of cycles, that means it will experience approximately a 20% drop in capacity in that many cycles. PEV owners don’t like having a significant drop in capacity. PEV makers don’t generally guarantee battery capacity against loss, but in their descriptions of the cars they generally say a PEV owner should expect the car to maintain at least 80% capacity after X number of years or X number of miles.

That “at least” is an important consideration here. That’s the minimum that a PEV owner should expect. More is better, both for the owner and the PEV maker.

Nix

If I were selling a 75 mile range EV, I certainly would want a 2000 cycle battery.

Here is a bit of unscientific math, just for the sake of comparison. (NOT hard numbers at all!!)

2000 cycles times 75 miles per complete cycle == 150K miles, but when you lose 20% of range, it puts the range at around 60 miles, which can really start limiting usability. Losing another 20% after that, and it really hurts usability!

For an EV with 300 miles of range, the number of cycles isn’t as important. Even if it is 500 cycles * 300 == the same 150K miles, but when you lose 20%, you still have 240 miles of range to work with. You can still stand to lose another 20% a couple more times and still have a perfectly functional vehicle.

So it really comes down to what kind of range the battery is used for. A 700 cycle battery in a 300+ mile EV would likely outlive the rest of the vehicle before the battery wore out enough where the vehicle wasn’t usable anymore.

Lensman

Look at it this way: If you have a plug-in EV like a Leaf, with an approx. 80 mile range, that’s about twice the average daily driving range. So the average driver would need to cycle the pack every 2nd day. If the pack is only good for 500 cycles, then that’s only 1000 days… which is only 2.7 years. Who wants to buy a PEV that has a battery pack which needs to be replaced in less than three years?

2000 cycles would yield 11 years before the pack is notionally worn out.

Ambulator

I suspect that Tesla batteries would be better after 300 or so cycles. In any case, this is not much improvement for an experimental cell.

Lensman

I agree. This may be an incremental improvement over what has been previously demonstrated in lab experiments, but it appears to be still some distance from being ready for commercial production.

It’s good that Samsung is working on lithium-silicon battery tech, but so are a lot of other companies and university research teams. That’s a good thing, as competition is driving advances in rechargable battery tech.

Micke Larsson

This seem to be great for cell phones and laptops where space is relevant.

In EV’s there is more than enough space so unless this battery comes with more cycles/less degradation and/or a lower price it will not be interesting for EV’s.

But there might be a slight reduction in weight anyway for the total batterypack with the batteries occupying lesser space, the question is how much/little it will save.

Dave K.

I’ll debate that one, use the Leaf as an example, battery under the front seats, rear floor and back seat. If you increase volumetric density a larger battery will fit in the same space, no problem, you may have to adjust the suspension but that’s all. If the gravimetric density increases but the volumetric doesn’t you have to redesign the car to fit a larger battery, bummer.

Martin

Silicone batteries are nothing new. They yield much higher density then current batteries. The problem with Si batteries has always been durability, This might be slightly better but has not solved the problem. Si is not for automotive applications and this certainly will not be, it needs to be 1500 cycles minimum. Tesla is correct to work on durability and cost reduction rather then size and weight reduction. P85D with batteries that last 30 years and at a cheap price is what people really need, not tiny batteries like most people think, even though it would be nice.

Ambulator

Silicon, not silicone. There is no silicone being used here.

Kosh

This is great! So it turns out the key to ridding ourselves of oil dependence from the middle east is to use silicon? Now we just need to find a large source of sand….. oh, shoot.

(for the aspergers humor impaired, that’s a joke, and yes I realize middle east sand may not be the kind of silicon they need).

Steven

I think 1000 would suffice for the cellular phone market, who holds onto a phone for four years anymore?