The trend toward long-range electric vehicles has motivated researchers to find ways to improve existing battery cell chemistries.
Lithium batteries are characterized by the chemistry used in the cathode. The first successful lithium batteries used a lithium-cobalt-oxide chemistry, often just called a lithium battery or LiCo. Later, oxides of nickel, manganese, and iron were used. Lithium chemistries are assigned names like NMC (Nickel Manganese Cobalt), NCA (Nickel Cobalt Aluminum), or LiFePO (Lithium Iron Phosphorus) to distinguish one another. Often, lithium is dropped from the designation.
Up until now, Tesla has used NCA cell chemistry for its long-range vehicles. NMC has been used for high-lifecycle uses like Tesla’s utility storage products. As NMC has recently gained improved energy density, however, it is now poised to be used more frequently in long-range EVs.
NMC 111 means equal parts nickel, manganese, and cobalt. The relative amounts of those elements determines the characteristics of the battery.
The effect is noted in the triangle diagram above. Researchers are targeting 250 Wh/kg and beyond for long-range electric vehicles using nickel-rich cathodes to increase energy density, while reduction in cobalt is also helpful since it lowers costs. Companies have switched from NMC 111 to NMC 442 to NMC 622, and now NMC 811 is slated for introduction in the next two years.
Jeff Dahn of Dalhousie University has shown NMC improvements in a relatively fresh video. These improvements have shown increased cycle life and he states that cells show only 5% capacity reduction after 1200 cycles. That indicates a cell cycle life of over 4000 cycles.
If you want to get into some weeds, check out the various charts below.
Other researchers have also noted improvement in NMC characteristics with the addition of aluminum.
NMC chemistry patents have come from Michael Thackeray at Argonne and from Jeff Dahn working with 3M. Argonne has licensed its patent to BASF and 3M has made agreements with Johnson Matthey.
The planned increases in NMC 811 energy density brings it to levels higher than the current Tesla/Panasonic NCA batteries used in the Model S and X. But NMC performance does not need to go that far to have an impact. The NMC cycle life shown is greater than NCA and potentially also lower cost.
SK Innovation has already started production of NMC 811 cells, with LG Chem hot on their heels.
It is possible Panasonic/Tesla is already using NMC 811 for high-cycle-life products such as the Powerpack and Tesla Semi. 300 Wh/kg slated for NMC 811 cells compares well with 265 Wh/kg available from NCA. The Powerpack operates at full discharge for over 10 years of daily cycling, equivalent to a cycle life of over 3,650 cycles with over 70% capacity retention.
Battery manufacturers source components from chemical providers like Johnson Matthey and 3M using cathode, anode, separator, and electrolyte materials to form a finished product. The goals set for NMC 811 are 300 Wh/kg and $100/kWh. NMC 811 is a step along the way to advanced, lower cost, longer range electric vehicles — with other advances further down the pipeline, including solid state batteries and metal anodes. The secrecy of this industry as well as the complexity of the batteries makes it hard to know what exactly is going on behind closed doors, but it looks like NMC 811 is poised to launch electric vehicles and grid storage into new territory.
Perhaps this is the underbelly of what led Elon Musk to say: “Tesla Semi Truck unveil to be webcast live on Thursday at 8pm! This will blow your mind clear out of your skull and into an alternate dimension. Just need to find my portal gun …”
Don't want to miss a cleantech story? Sign up for daily news updates from CleanTechnica on email. Or follow us on Google News!
Have a tip for CleanTechnica, want to advertise, or want to suggest a guest for our CleanTech Talk podcast? Contact us here.