Featured Solid-state battery wars

Pricing is not an issue. When they get the chemistry right lower cost and more sustainable will materials will make sodium batteries less expensive. The problem is energy density. CATL is talking about hitting 160 wh/kg and moving it to 200 wh/kg. Tesla's battery cells are now 260 wh/kg and they expect next gen ones to be 380 wh/kg. Lithium metal anodes whether in solid state or hybrid batteries promise over 500 wh/kg.

Now small batteries like those used in hybrids may be better as sodium batteries, these chemistries are more energy dense than toyota's nimh batteries but may not have the power density. The bigger part of CATL's press release for plug-ins was talk about combining them with Lion or higher energy density batteries. A more expensive bms is needed but this could lower total cost and increase cold weather performance at the battery pack level. Solid metal anode batteries have worse performance in the cold than today's Lion, but put some sodium cells in the pack and they could be used at start up and could warm the rest of the pack.

Tesla hybrid battery technology could add 20% more range - Plugboats
Sodium-Ion Batteries Poised to Pick Off Large-Scale Lithium-Ion Applications - IEEE Spectrum

 

Tesla Semi 4680 Battery Pack Engineering Analysis

"We estimate that the 500-mile pack will be approximately 875 kWh and 900 Volts DC. Total pack weight (not just cells) of 9243 pounds taking credit for reduced weight of current collectors from the higher voltage."

4680s. 875kWh. 9243 pounds. That works out to 208Wh/kg for the pack.

 

Yes - Which is really good pack overhead is down to less than 1 kg/kwh if that is accurate. If they used sodium @160 wh/kg at the cell level it would be over 2 tons heavier. If they can get energy density up to 380 wh/kg as they have in the lab for lithium ion it will drop by over 1 ton.

 

I'm not following how going from 260 to 208 is "really good". 208Wh/kg stinks big time. Frankly, so does 380 compared to other energy sources which tend to be in the 800-1000Wh/kg range.

I thought structural packs were supposed to make this overhead negative.

 

A battery pack is going to weigh less than cells that it contains. Where did you get such an idiodic idea.

Perhaps you understood that a BEV will not gain as much weight as its structural battery pack since the the pack itself can be used as part of the structure.

Gen 2 prius battery pack 22 wh/kg
First gen prius phv 4.4 kwh battery pack 55 wh/kg. This is much better than the hybrid pack but adds over 7kg/kwh
Prius prime 8.8 kwh battery pack 73 wh/kg

Of course a bigger pack makes a difference
Tesla model 3 long range 82 kwh battery pack is 170 wh/kg. this includes components that are not in the prime's battery pack, but a bigger pack means less over head. It also is using more energy dense cells than toyota. This pack adds about 2 kg/kwh. increasing energy density to 208 wh/kg would mean 100 kwh instead of 82 kwh with the same cell chemistry and weight, or more likely, a weight savings of 86 kg on the pack and more on the car with tesla keeping the long range model 3 awd at 350 miles aer

The semi's battery pack adds less than half of this weight or less than 1 kg/kwh if your figures are correct. The cell design and pack design are responsible for shaving this extra material. This is a great figure. My guess is they are still working on manufacturing, otherwise we would have seen the plaid + with structural battery packs.

What battery packs are you thinking of that weigh only 1 kg/kwh? Can they last in an automotive environment? I have not heard of any. In the lab there are cells that meet this but not packs and the cells do not have the cycle life required for automotive applications.

 

Because the battery cells will act as structure to replace structure that would be there without the cells.

They aren't my figures (I provided the reference) and the final result of 208Wh/kg is still terrible.

The ICE + fuel tank in my Prius Prime and a H2 fuel cell + H2 tank. Both are around 1000Wh/kg.

 

But you were arguing the pack should weigh less than the cells. Yes the car will gain less weight than the battery pack because it replaces part of the structure. Your math only was for the battery pack, so it ignored this entirely and stated the weight was terrible.

There you go again. If 208 wh/kg is terrible then what do you think of the battery in your prime that has only 1/3 the energy density? Please don't be so judgemental. If you are talking about progress, and can't even follow simple numbers. Why do you even care about batteries if you can't even muster a consistent idea about them. That means a prime with 208 wh/kg could have 16 kwh instead of 8.8 kwh and it could be used to reduce the structures weight meaning even a lighter car.

Well yes if you ignore everything else. How many kg of fuel do you use a year? Is that a good metric. Does a prime provide the same power as a semitruck? You have a battery and a fuel tank and fuel and ice and pollution control. No one is trying to argue gasoline and a fuel tank has lower energy density than batteries. But how much is good enough? To most consumers 208 wh/kg is great, it means you can build a 200 mile bev at about the same weight as a similar powered ice vehicle. VW and tesla are moving to lithium iron phosphate for these lower priced bevs as less energy density is good enough. Lower price is more important. On the semi though all the weight savings is needed.

That hydrogen tank, well you need to protect it, you need something to be around it. That is why you can build a 300 mile aer bev with similar weight as a fuel cell vehicle. Then when you realize how many hundreds of billions in subsidies would be required to make fueling as convient as a tesla even on just the west coast of the US, you realize what a terrible metric the weight of just that hydrogen and fuel tank are.

If you have something to add that isn't just some crazy judgemental crap against phevs and bev batteries please add it, but think about your numbers.

 

No, I didn't. I said the overhead would be negative. Not the same thing if the cells replace structure that would be there without them.

It is terrible.

It's better, because the combined system weighs less and can produce 160kWh while refueling in under 2 minutes.

In the last year, about 6kg.

More power-to-weight ratio.

For an ICE car, 400 miles is good enough (the last ICE car I owned that had less than 400 miles of range was built in 1972). For a BEV, 750 miles is good enough with today's charging infrastructure. That's for road trips. For in-town, 60 miles is good enough. That's the problem with BEVs - they have way too much range (and therefore too much cost and weight) for in-town and not nearly enough range for road trips.

 

Huh. Why would you use the full weight of the pack in your calculation and ignore the structual weight savings on the rest of the car. This is your full quote. Why don't you not pretend that you are trying to use the structual weight savings when it clearly is not there.

Clearly you are stating a figure of the battery pack. Again just retract it. Say it was 400 wh/kg when weight savings are taken into account. Why would you use 208? Again I have nothing to do with the figures you used, and will wait for a production car to know what the real net wh/kg.

 

You aren't following.

The pack is 208Wh/kg using 4680s.

Separately from that, you said that 1kg/kWh of overhead is good. I'm saying it should be negative. I don't know what it is on this truck but the overhead should be zero or negative on a structural pack.

Highly unlikely unless it replaced structure that weighs as much as it does.

 

Let me take this real real slow.

Let's say you have a battery pack whose weight is P. It contains cells whose weight are C. You are saying that in a good pack.

C > P.

Lets define the weight of balance of pack as B, that is the stuff not in the cells. This is cooling loops and bms and other stuff. This is the figure that was greatly reduced down to 1 kg/kwh.

P = C + B.

You are saying these components should weigh less than 0. That makes no sense.

Now in the case of the semi the structural nature of the pack can enhance structural rigidity and replace or allow lighter weight components. Let's call this weight savings S.

The net effect of the structural pack is going to be P-S versus a truck designed with

Yes
P - S < P
But you included no weight savings S in your calculations. Pretty simple. Now I have no idea how big S is in the Cyber Truck, and you need that to jump to your conclusion.

It is pretty simple. I am not sure why you are having such trouble with the concept.

Now lets look at the prime. It's battery pack

 

No, I didn't say that. I just explained that to you.

 

Sure. For the 1% of the population that has a need similar to yours. Most people who drive 70mph for 10 hours will want to stop once for a break...maybe even twice.

And when/if there is a BEV with such a range it will be declared silly since most of the battery capacity will rarely be used.

Mike

 

Prove it's 1%.

I did the analysis and I found it was closer to 90-95%. Since around 2% of cars are EVs, there's no evidence to support your guess.

Which is fine. I stop more than that. I stop every 2-3 hours. But 90+% of the places I stop don't have chargers. I need 750 miles of range because I drive places that don't have chargers along the route or at the destination. It's not hard to get this.

750 miles total range.
Only charge to 85% to preserve battery longevity - start at 637.5 miles of range.
Drive at 75 mph - range reduced by 30%. 446.25 miles of range.
Always preserve 100 miles of range minimum for emergencies - 346.25 miles of range.
No charger at the destination so round trip range is halved - 173 miles of range.

Now try that for a 300 mile range car.

Which is the same as now. 99% of my in-town driving is met by the 30ish miles of range in my Prius prime. Even including many out-of-state road trips I've taken in that car, all of which had at least one leg that no Tesla could have managed, my overall electric usage is 78% of my miles driven. So, having a 300 mile range is means I'll only use 10% of the battery range when I'm in town, and 200% of the range when I'm on road trips (which have gotten rare in the last year thanks to the pandemic).

 

I did a survey of people at my office. None would drive 750 miles without stopping in a place with no chargers.

Mike

 

It's not without stopping, it's between charging locations.

Right now, there's basically a gas station in virtually every town. If chargers were that plentiful, this wouldn't be as big an issue because you could stop anywhere to charge. It's still an issue because charging takes so long but at least you could charge. But as it is now, if you aren't on the main highways, you can go many hundreds of miles with little or no charging infrastructure to speak of. I know because I've done it many times.

 

Let me make sure I understand you correctly.
Are you saying that 90-95% of car drivers require a minimum of 750 mile range out of a BEV?

or

Are you saying a 750 mile range BEV would meet the needs of 90-95% of drivers?

 

They are called 120 VAC outlets. Not fast, my car gets 5 miles extra range per hour. Overnight, easily 35-40 miles of range.

Bob Wilson

 

I'm saying that it would take 750 miles of range with today's charging infrastructure to accomplish 100% of the drives of 90-95% of the drivers in the US. The other 5-10% can do it with less.

If we're really going to have today's low-range "long range" EVs (every one of which has less range than a typical ICE car), we're going to need a huge improvement in charging infrastructure to meet the needs of everyone, and there are a few applications where even that won't work (i.e. heavy equipment on construction sites).

It's the last few percent of drives that are the problem. 90+% of drives could be met with 60 miles of range since most drives are to the store, to the school, to work, etc. A few people have insane commutes but the big problem is going off the beaten path in rural areas away from today's on-highway charger networks. I'm going to a place in a couple weeks that just got its first fast charger recently, and it's a 50kW CCS - one for the entire town. Zero Tesla infrastructure. One public L2 in the town. The round-trip between Superchargers is 257 miles, not including any driving I do in the town. Since a good bit of that is 75mph, I don't think that would work in a 300 mile range Tesla. I could do it in any other EV because of the CCS.