Chevy Bolt; defects in LG lithium cells from two different plants

It will be interesting to see what happens as people become aware of other choices. Anyone else notice the split now taking place with Tesla? They recently began offering the choice of LFP batteries, a chemistry that eliminates cobalt & nickel. It sacrifices energy & weight for the benefit of being far more robust, including fire resistance. Offering significantly more recharging cycles and greatly reduced cost will be the highlights though. And yes, this is what we expect Toyota to use for their first dedicated-platform BEV, the upcoming bZ4X.

 

I have a friend who found a leak when the Bolt was new, The dealer was able to fix the issue in a few days even though there was serious disassembly involved. I hope the fix has been identified. When the recall first came out a month or two ago I read they still didn't know exactly what was wrong with the packs.

 

The positives of LFP are great, but the negatives do have a big impact. LFP is only available for the Model 3 SR+ because a LFP pack for the long range model wouldn't fit into the car.

The defects have been identified. The OP article covers them. There is two, and they have to appear in the same cell to cause an issue. The causes hadn't been identified by when it was printed.

This isn't the first battery recall for the Bolt. There were two early on. Those defects resulted in performance issues, not fires. The defects were identified(IIRC, one was microscopic) and fixed. No reason to not expect the same outcome here.

 

Know your audience. There is clearly a market for low-cost, long-life batteries, as LFP offers. In fact, the benefit of them being more robust is rapid-charging becomes far less of a longevity concern. Shorter charging-sessions more often... which ironically is what BEV tend to recommend anyway... work out just fine.

Turns out, Tesla can only cater to their niche for so long. That market will become saturated and it would be idiotic not to diversify... a mistake GM continues to repeat. You neglect a market-segment for too long, someone else will step in. Remember, that "nicely under $30,000" target is still vital. GM just recently reaffirmed it. Tesla must finally acknowledge it. Toyota never took their eye off that ball... despite endless efforts from antagonists.

No cobalt. No nickel. Both have been problematic battery materials. Elimination of them by LFP chemistry not only addresses those political/social, environmental, and safety issues, it also opens up the market for low-cost vehicles. This is exactly why some Chinese BEV have thrived and why Toyota simply focused on their component advancement in the meantime. Initial offerings we have seen so far really were just qualification laps. The actual race has yet to begin.

In other words, drawing a conclusion of "big impact" really doesn't equate to much. Sales to mainstream consumers is something we must still wait for. The entire industry is still just preparing for the countdown lights, since cost isn't quite there yet. LFP is one of the opportunities to achieve what the early-adopter market could not.

 

wait - what?
I thought based on your own definition of niche market, that the niche threshold had been surpassed some time ago, maybe ½ million vehicles ago - no?
.

 

Know your audience. GM failed with both Volt & Bolt because they didn't. Volume is a component of success, but not the only criteria required to achieve it.

 

I see Mitsubishi and Honda are doing local market testing with LTO chemistry cells in the iMiEV and Honda in the Fit hybrid .... although it looks like Honda may be abandoning the Fit for the export market due to poor sales.
Energy density is their down side, but ultra fast recharging coupled with a long cycle life might change just how people use their EV. For instance, if there was a rapid charging facility every 200 miles, that nature stop and stretch the legs could include a recharge for the next 200 miles ...... the 55Ah LTO cells I recently bought claim to have 10 min recharging capability. A 700v nom. 55Ah LTO battery would give 38kWh capacity and recharged in 10 mins .... well, as long as the cables didn't melt :lol:

T1 Terry

 

So our trip to the Mississippi Gulf Coast:

• Start 100% SOC and drive ~3 hours.
• Subsequent segments, 2 hrs and 20 min charging break.

It is easy with our Tesla and SuperChargers.

Bob Wilson

 

Around the turn of the century, cars that use other batteries along with the 12volt , it seems to me, the very basic reason for most owners was Fuel Economy (cost of operation/maintenance) and Reduction of Fossil Fuel use. Most of those who started driving cars with extra batteries are still driving some kind of a car with extra batteries.
To try to get more interest from the masses who still drive ICE only vehicles, manufactures have tried all kinds of combinations of fuels, sizes of vehicles and battery packs, to get more business in a, currently fairly small in comparison, market that governments are trying to regulate and promote due to climate change. It hasn't been all that successful so far.
Why? Is waste something that gets past governments, businesses and individuals in equal proportions?

Tech is changing our world at an alarmingly quick rate presently, and the human condition that effect most all of us is doing everything in it's power to keep the status quo. Just who's getting it right and who's getting it wrong in every sector is currently based on one controlling quantity, profit or survival of the species. We can't all be getting it wrong, can we?

 

But Tesla is starting to put LFP into the standard range Model 3 in order to get to a lower price point.

No, wait. They are doing it to reduce customer wait times for cars while netting more profit from their price increase.

The Model 3 still has some ways to go before catching the Camry, but it might surpass the Accord in US sales soon. Not bad for a more expensive sedan.

What does GM have to do with Tesla?

Took a look at the Wiki article for LTO. https://en.wikipedia.org/wiki/Lithium-titanate_battery

In addition to a specific energy* lower than LFP, the chemistry replaces carbon for titanium for the anode, while keeping the cobalt and nickel at the cathode. They likely cost more per cell than Li-ion, and the lower specific energy means more cells needed to reach a pack capacity. A lower capacity battery could be put into an EV, if there is a network of ultra fast chargers to support the car. Otherwise, buyers will want longer range or lower price.

The better heat tolerance, better safety, and longer life are nice features. We just get those with LFP. Maybe the LTO is even better, but LFP gets them with lower cost by swapping the cobalt and nickel for iron. Then again, I don't think Li-ion is actually any more dangerous than a car with a gas tank, and many car fires start from the 12V system of the car.

The iMiEV offered TFO early on; 2011/12 for Toshiba's TFO, brand named SCiB. The TFO pack gave the car longer range over the Li-ion pack, but the car used an air cooled pack. The heat tolerance of the LTO meant the cells could be packed tighter in the battery case. The majority of EV use liquid cooling because it works better than air, and it allows the pack to smaller overall. Even the Escape and Explorer hybrids use liquid cooling now. I remember an article mentioning the SCiB battery working better in the cold than Li-ion.

*Specific energy is what people actually mean when saying energy density in these discussions. It is the amount of energy per unit of weight of the battery or other fuel. Energy density actually refers to the energy amount per unit of volume. Which is also important for EV cars because of limited space in the frame.

 

Li-ion is just the title for all lithium type rechargeable batteries, just like lead acid covers all the range from flooded cell, AGM, Gel and lead crystal.
The LTO cell uses lithium lithium titanate nano crystals inplace of the carbon to increase the area for lithium ion exchange, that is why they can be recharge and discharges at a much higher rate than other chemistries, yet still hold the voltage better through the discharge curve.

Energy density can be misleading, the energy density of petrol will not reach its full potential in an inefficient engine, at best 1/3rd of that energy goes into propelling the vehicle, the rest goes into the cooling system and out the exhaust.
A high energy density battery cell that drops its voltage under load will not deliver the advertised energy on anything but light load, where an LTO cell can deliver that advertised energy under a much higher load.
A quality LTO cell can be discharged at 10CA (10 times the advertised capacity) so a 700vdc nom battery could supply 200kW of electrical energy from a 300 x 30Ah cell LTO battery.
200kW on the ground at zero wheel speed would be like side stepping the clutch on a top fuel dragster because even those monsters slip the clutches to get off the line and right through the 60 ft mark or longer so they can get the revs to develop the power and avoid spinning the tyres.


There is a saying amongst the EV owner community, you just can beat the EV grin as you launch off from the lights and leave the ICE powered vehicle in the rear view mirror.

T1 Terry

 

From a previous post by Trollbait:
In addition to a specific energy* lower than LFP, the chemistry replaces carbon for titanium for the anode, while keeping the cobalt and nickel at the cathode.

Just had a look at what the chemical make up of the two compounds involved in an LTO cell, and I have no idea just what the chemical names mean :lol:

Its anode material is Li4+aTi5O12, the cathode material is LibFePO4 and the carrier is Li+

For the cathode, I know the Li part is lithium, the Fe part is iron (ferrous) and the P04 part is phosphate. No idea what the small b means.
As far as the annode, would Li4+ be 4 parts lithium? The Ti part is the titanate but no idea where the small a and the 5012 come into it .... tried to do a google search but the head started to explode .... seems something to do with how the crystals are grown ..... but I couldn't find any reference to cobalt or nickel .....

T1 Terry

 

Interesting. A recent article from Toshiba Toshiba Clip | Toshiba’s Lithium-Ion Batteries – driving the future of a decarbonized society (Part 3) dated around March this yr seem to suggest the NTO chemistry is still in the lab stage and later in the article it seems to suggest they would be suited to robotics and mobility scooters, so maybe they don't scale up well to make them suitable for EV use.
LTO has been around since 2008 but it has taken 15 yrs for it to become the new kid on the block for EV use, let's hope if NTO does have EV capabilities it won't take another 15 yrs for it make it out into the market place.

Cost wise for the LTO cells I just bought compared to LFP and LYP chemistry cells, not a big increase in cost per cell for the same capacity in AH, but more cells are required so that ups the cost a bit, but the fact they hold their voltage under high load and accept a much faster charge rate than LFP or LYP, make them a better choice for the fast recharge multiple charging type of use. The Tesla battery can be rapid charged, but not all the time, the computer actually slows the charge rate the more times the rapid charging is used until it drops back to the standard rate charging ..... something Tesla doesn't mention in their specs, so even their proprietary chemistry cells and special cooling can't really handle the high rate recharging.

T1 Terry

 

this does not sound good for the future of the electric Hummer

 

Ahh yes, decisions, decisions. The (current) EV innovators dilemma: powerful, weight, cost. Pick two.

 

The iMiEV got LTO cells in 2012, maybe late 2011. Mitsubishi never offered outside of Japan though. Of course, the reason for doing doesn't have to be related to the batteries performance. Cost was likely the issue. Even though LTO gave a range boost, the range was short to begin with, and that increase was the result of more cells being packed in.

I'd think LTO will have a role where battery size is limited, and that is mitigated by having ultra fast charging, or in top end performance cars or motorcycles. It seems a LTO anode means lower energy capacity than a graphite one. So likely won't see use in a long range EV like Tesla. For shorter range EVs, LFP has similar benefits with a graphite anode. How often will such an EV need the better benefits by using the LTO anode? Is it often enough for a reduction in range?

BEVs now are designed around the idea that most charging will be slow, overnight charging at the owner's home. LTOs will have an advantage when the market focuses more on apartment dwellers and others without home charging access. If the infrastructure moves to ultra fast charging. These chargers will cost more, and be a larger burden on the grid. If slow chargers become available for overnight charging on a large scale, that cost for the ultras may not be needed.

Today's batteries do take abuse from fast charging, but for most owners, the trips where they are required are far from an everyday occurence. For others, PHEVs are an option, with renewable fuels being possible.

 

The mighty Tesla battery doesn't handle fast charging well and the on board computer reduces the charge rate each time a fast charge is used to the point it could be slower than a standard rate charge.
LFP cells can not handle fast charging, that does not suit regen charging because that is generally high current. The only fix is either an intermediate storage system that can handle the high current, then pass it on at a lower rate to the traction battery for recharging purposes, or a much bigger capacity LFP battery so the CA charging rate is within the parameter the LFP cell can still return a decent cycle life. The specs do say you can charge them at 5CA, they just don't mention the cycle life if you try that, or the cell's internal rapid temperature increase that leads to boiling off the electrolyte.
I have been working with this chemistry for the last 10 yrs on a much larger scale than basic laboratory testing, charge faster than 0.5CA and you can expect a shortened cycle life, keep it below that rate and the cells have a very long life ... we have a number of sets in systemsat over 10 yrs continuous service to prove it.

T1 Terry

 

Curious, my 2019 Std Rng Plus Model 3 charges faster than some of my biology breaks. I had to move car to avoid idle fees.

Bob Wilson