## Penn State team develops thermally modulated LFP battery; fast-charging, inexpensive, long-life for mass-market EVs

##### 19 January 2021

A team of Penn State engineers has demonstrated a thermally modulated lithium iron phosphate (LFP) battery to offer an adequate cruise range per charge that is extendable by a 10-minute recharge in all climates, essentially guaranteeing EVs that are free of range anxiety.

Such a thermally modulated LFP battery—designed to operate at a working temperature around 60 °C in any ambient condition—could support a well-rounded solution for mass-market EVs, the researchers said. Furthermore, they found that the limited working time at the high temperature presents an opportunity to use graphite of low surface areas, thereby prospectively prolonging the EV lifespan to greater than two million miles.

A paper on their work is published in Nature Energy.

We developed a pretty clever battery for mass-market electric vehicles with cost parity with combustion engine vehicles. There is no more range anxiety and this battery is affordable.

—Professor Chao-Yang Wang, corresponding author

The researchers said that the key to long-life and rapid recharging is the battery’s ability to heat up quickly to 60 ˚C for charge and discharge, and then cool down when the battery is not working.

The very fast charge allows us to downsize the battery without incurring range anxiety.

—Professor Wang

The battery uses a self-heating approach previously developed in Wang’s center. The self-heating battery uses a thin nickel foil with one end attached to the negative terminal and the other extending outside the cell to create a third terminal. Once electrons flow it rapidly heats up the nickel foil through resistance heating and warm the inside of the battery. Once the battery’s internal temperature is 60 ˚C, the switch opens and the battery is ready for rapid charge or discharge.

Wang’s team modeled this battery using existing technologies and innovative approaches. They suggest that with this self-heating method, they can use low-cost materials for the battery’s cathode and anode and a safe, low-voltage electrolyte. The cathode is thermally stable, lithium iron phosphate, which does not contain any of the expensive and critical materials such as cobalt. The anode is made of very large particle graphite, a safe, light and inexpensive material.

Because of the self-heating, the researchers said they do not have to worry about uneven deposition of lithium on the anode, which can cause lithium dendrites that are dangerous.

This battery has reduced weight, volume and cost. I am very happy that we finally found a battery that will benefit the mainstream consumer mass market.

—Professor Wang

According to Wang, these smaller batteries can produce a large amount of power upon heating—40 kWh and 300 kW of power. An electric vehicle with this battery could go from zero to 60 miles per hour in 3 seconds and would drive like a Porsche, he said.

Other Penn State researchers working on this project were Xiao-Guang Yang, assistant research professor of mechanical engineering, and Teng Liu, doctoral student in mechanical engineering.

The US Department of Energy’s Office of Energy Efficiency and Renewable Energy and the William E Diefenderfer Endowment supported this research.

Resources

• Yang, XG., Liu, T. & Wang, CY. (2021) “Thermally modulated lithium iron phosphate batteries for mass-market electric vehicles.” Nat Energy doi: 10.1038/s41560-020-00757-7

Sounds good but a few questions:
a: How long does it take to warm up the battery from say ambient 5 degrees?
b: Can you drive off with the battery in a cold condition (with lower power)?
It's "end of range anxiety" is based on the ability to charge at 300 kW, but there are very few 300 kW chargers around.
You would probably end up with 140 miles range (3.5 miles / kWh), so if you had to charge every 2 hours and it took 10-20 minutes, (300-150 kW charging), it would be tolerable.
However, if you rarely did long runs, it would be perfect.

It would take a while to heat a 600 pound pack,
if you were commuting and it was well insulated
that should not be a problem.

The heating step is at the cell level using nickel strips and is fast, around 30 seconds based on this article.
Asymmetric Temperature Modulation for Extreme Fast Charging of Lithium-Ion Batteries,
"we introduce a heated-charge protocol that adds a heating step to warm up the cell from ambient temperature (Tamb) to a high temperature (TH) prior to the conventional constant-current constant-voltage (CCCV) charging (Figure 1B)."

(Ref: https://www.sciencedirect.com/science/article/pii/S2542435119304817).
Also, the Penn State team is working with EC Power Group (www.ecpowergroup.com). Professor Wang is also the Chief Technology Officer and founder of the startup EC Power.
This makes LFP batteries look like the best low cost EV approach, particularly since Tesla also will come out a $25K LFP auto. Tesla has not said their$25K car will be with LFP. It could be that by then they will be up to full production on their own 4680 batteries.

Man it sounds hokey to me. You've got to use battery energy, reducing your range, to heat u the battery. Using that energy to heat the pack also increases charge time.
I don't see how this helps. I have driven DFW to Phila and back twice with no problems using Tesla's network. Most of those are only 150 kW. Drive ~3hrs, charge 25-45 min and drive again. Drive 4 legs sleep and drive 4 more. Done.
I have family in Kerrvile , Tx and can drive there with one charge stop. Honestly most of us do not make that many road trips. Charging at home (house) is super convenient. For our schedule my wife just charge once a week.

From Tesla Battery DayPresentation and InsideEVS,
Check this out: https://insideevs.com/news/446245/tesla-slide-25000-car-lfp-batteries/.

Three Points about the Penn State system:
#1: Self Heating only uses 2% of the battery's total energy and completes this process in 40 seconds (reference:https://ecpowergroup.com/acb/). Note: if your Tesla has the new "Octovalve Heat Pump", you can gain 5% efficiency.