Battery500 project has achieved 350 Wh/kg and more than 350 cycles
28 May 2020
EV battery costs have declined significantly over the past ten years, from more than $1,000 per kilowatt-hour (kWh) to less than $200/kWh. Increasing cell energy is one way to decrease cost even further, as a higher specific energy value will result in fewer materials needed for the same total battery energy. However, it is difficult to increase the energy density beyond that of today’s cells, which are approximately 220 Wh/kg using graphite anodes.
Li-metal anodes deliver almost 10 times the storage capacity of graphite anodes, thus enabling much higher cell energies. However, Li-metal anodes suffer from poor cycle life (typically 10 cycles or less, compared to the 1000 cycle EV battery requirement).
Announced in 2016, the Battery500 consortium, led by the US Department of Energy (DOE) Pacific Northwest National Laboratory (PNNL), is working to to develop next-generation Li-metal anode cells delivering up to 500 Wh/kg. (Earlier post.)
In the first two years of this program, the Consortium made significant progress developing novel cell materials and integrating these materials in industry relevant pouch cells. At the beginning of the program, a Li-metal pouch cell delivered 300 Wh/kg but only cycled approximately 10 times.
Currently, the team has increased that energy density to 350 Wh/kg and extended the cycle life to more than 350 cycles. Specifically, they developed new electrolytes with enhanced stability against Li-metal, optimized the use of thick cathodes against a thin lithium foil, and applied cell-stack pressure to extend cycling life.
Stable Cycling of 350 Wh/kg Li/NMC622 Pouch Cell. Source: DOE.
Recent research on even thicker cathodes and more stable electrolytes shows a path to a 500 Wh/kg cell. Current focuses include increasing rate capability and extending cycle life.
The Battery500 team is composed of world-class scientists and engineers from four National Laboratories and five universities. Notably, two of the researchers on the team, Professor Stanley Whittingham of Binghamton University and Professor John Goodenough of the University of Texas at Austin, received the 2019 Nobel Prize in Chemistry for their work in Li-ion batteries.
Coated lithium anode with better solvent
should be able to get higher energy density.
Posted by: SJC_1 | 28 May 2020 at 07:55 AM
Actually 350 Wh/kg energy density at the pouch level is very good.
Most research typically reports energy density at the component (anode or cathode) or better at the cell level. In this study on Lithium metal anode batteries (https://www.cell.com/iscience/pdf/S2589-0042(20)30027-4.pdf) done by LG Chem R&D and others shows 679 Wh/kg at the cell level (anode, cathode, and separator) results in 288 Wh/kg at the pouch level (current collectors, anode, separators, electrolyte, cathode, and pouch packaging, sealant taps). At the full Battery this would be significantly less.
However, there is good news as reported here: Specifically, they developed new electrolytes with enhanced stability against Li-metal, optimized the use of thick cathodes against a thin lithium foil, and applied cell-stack pressure to extend cycling life.
Tesla and others are using "Dry Processing" of electrodes to reduce process time and costs that will create cathodes up to 1 mm with no binders. Electrolytes and single crystal cathodes are extending battery life greatly.
Companies like Soteria (https://www.soteriabig.com) are replacing the copper and aluminum current collectors with polymer that also reduces fire risk. Finally, CATL, BYD, SVolt, and Tesla are going to Cell-to-Pack technology eliminating hardware in the Battery Pack.
So looking forward to 2021 or 2022, actual production batteries should be at the 400 Wh/kg Battery Pack level (for reference the Tesla Model 3 Battery pack is at the 170 Wh/kg level), and with no Cobalt at a cost less than $100/kWh.
Posted by: Account Deleted | 28 May 2020 at 11:04 AM
I think there is to much obsession with higher energy density, meanwhile existing technology is still incrementing slowly in energy density, but more importantly it's also surpassing 2000 cycle life and getting to 4000 cycles.
What is more beneficial? Battery that will last 15 years in a car and then also have second life in storage for additional 15 years. Or super high energy density battery that will last "only" 10 years in an EV or 1000 cycles as stated in this article? And still currently this Technology is at 350 cycles, there is still long path to get to 1000.
Posted by: GasperG | 28 May 2020 at 11:08 PM
While this is a Lithium Metal battery, being a little more critical one should compare this to the SVOLT NMx L6 cobalt-free long cell which has a 1.2 million km warranty (using single crystal tech similar to Jeff Dahn's ,i.e.Tesla million mile battery that still has a NMC532 cathode).
The SVOLT battery is ready for use in EV next year and currently has 240 Wh/kg, with Cell to Pack battery design this will be better than the Tesla Model 3 battery pack density and costs less than $100/kWh at the pack level. SVOLT is already a member of the Soteria Innovation Group so expect mostly polymer current collectors.
We can see what Tesla shows on "Battery Day", However Chinese manufacturers appear to be making big headlines today.
Posted by: Account Deleted | 30 May 2020 at 09:24 AM
Gasper,
I agree battery life is important,
but if it weighs 1200 pounds and cost $20,000 maybe not.
Posted by: SJC_1 | 31 May 2020 at 09:31 AM