Tesla Motors Canada has filed a patent for a lithium-ion pouch cell containing ‘fewer operative, electrolyte additives’ with the potential to be used in energy storage applications including vehicle and grid-storage— Tesla’s key markets.
The new technology using a nickel manganese cobalt (NMC) chemistry was filed under the title ‘Dioxazolones and nitrile sulfites as electrolyte additives for lithium-ion batteries’.
The patent— whose inventors include Jeffery Dahn— claims to enhance performance and lifetime of lithium-ion batteries, while ‘reducing costs from other systems that rely on more or other additives’.
The patent application claims: “Certain embodiments described herein include a nonaqueous electrolyte for a lithium ion battery comprising at least one lithium salt, at least one nonaqueous solvent, and an additive component comprising at least one operative additive.
“This work characterises the high temperature storage and long-term cycling performance of lithium-ion NMC/graphite pouch cells prepared with a recently developed electrolyte additive, MDO, and two new additives, PDO and BS.”
Last September, Dahn and his colleagues published results for a pouch cell that could last a million miles in The Journal of The Electrochemical Society.
The results, the authors claimed, were more representative of modern lithium-ion cells and followed three years of testing, including include long-term charge-discharge cycling at 20, 40 and 55°C, long-term storage at 20, 40 and 55°C, and high precision coulometry at 40°C.
Several different electrolytes, including those that can promote fast charging, were considered in the LiNi0.5Mn0.3Co0.2O2/graphite chemistry.
The abstract read: “We conclude that cells of this type should be able to power an electric vehicle for over 1.6 million kilometers (one million miles) and last at least two decades in grid energy storage. The authors acknowledge that other cell format-dependent loss, if any, (e.g. cylindrical vs. pouch) may not be captured in these experiments.”
The month before, Dahn and his team revealed research they claimed outperformed solid-state technology in the journal Nature Energy.
The research abstract read: “Cells with lithium-metal anodes are viewed as the most viable future technology, with higher energy density than existing lithium-ion batteries.
“Many researchers believe that for lithium-metal cells, the typical liquid electrolyte used in lithium-ion batteries must be replaced with a solid-state electrolyte to maintain the flat, dendrite-free lithium morphologies necessary for long-term stable cycling.
“Here, we show that anode-free lithium-metal pouch cells with a dual-salt LiDFOB/LiBF4 liquid electrolyte have 80% capacity remaining after 90 charge–discharge cycles, which is the longest life demonstrated to date for cells with zero excess lithium.
“The liquid electrolyte enables smooth dendrite-free lithium morphology comprised of densely packed columns even after 50 charge/discharge cycles. NMR measurements reveal that the electrolyte salts responsible for the excellent lithium morphology are slowly consumed during cycling.”
