A newly published patent from Tesla aims to bring the company’s idea for a one-million mile battery to life by using numerous electrolyte additives to increase the longevity and performance of its lithium-ion cells.
Tesla submitted the patent for “Dioxazolones and Nitrile Sulfites as Electrolyte Additives for Lithium-Ion Batteries” in August 2018. The patent is focused on improving the company’s rechargeable battery systems by adjusting the cells’ chemistry.
The patent claims that the addition of electrolyte additives, like lithium salt, can drastically improve the longevity and performance of battery systems when combined with a nonaqueous solution. A nonaqueous solution does not include water as the solvent, but rather another liquid.
The patent states:
Electrolyte additives have been shown to be operative and increase the lifetime and performance of Li-ion-based batteries… To further progress the adoption of electric vehicles and grid energy storage applications, it is desirable to develop lithium-ion cell chemistries that offer longer lifetimes at high temperatures and high cell voltages, without significantly increasing cost. The introduction of sacrificial electrolyte additives on the order of a few weight percent is a practical method to form protective solid-electrolyte interphase (SEI) layers that limit electrolyte decomposition during cell storage and operation. In recent years, significant efforts have yielded a large number of such additives that may be used to improve cell performance for various applications. Examples are vinylene carbonate (VC), fluoroethylene carbonate (FEC), prop-l-ene-l,3-sultone (PES), ethylene sulfate (1, 3, 2-dioxathiolane-2, 2-dioxide, DTD), and lithium difluorophosphate (LFO)
Tesla recognizes that increased temperatures are detrimental to the lifespan of a battery system. In a previous patent, Tesla outlined a cooling system that could lead to longer-lasting energy storage systems. While heat is unavoidable as it is a key player in the use of lithium-ion batteries, especially when owners of Tesla vehicles are operating in performance modes, engineers realize the solvents and solutions could be a way to improve performance and lifespan without significantly increasing cost.
In a way, a good part of Tesla’s lead in the electric car industry lies in the company’s batteries, or more specifically, its cell chemistry. It is these factors that allow Tesla to maximize its vehicles’ battery packs, and a key reason why the Model S Long Range is able to travel 373 miles on one charge with a 100 kWh battery, and why the Porsche Taycan can only go 201 miles per charge on a pack that’s nearly as large. This patent confirms that Tesla continues to work on improving its batteries, allowing the company to maintain or even increase its lead in the EV segment.
At Tesla’s Autonomy Day in April 2019, Elon Musk promised owners that the company would soon power its vehicles for upwards of one million miles over the span of the vehicle’s life. While the claim seemed enthusiastic and somewhat unrealistic, critics soon realized Tesla may be closer to this than many think. In September, a team of researchers led by Jeff Dahn at Dalhousie University published a research paper that claimed they had developed a lithium-ion battery capable of one million miles of driving, or 20 years of use in an energy-storage system.
Tesla’s battery technology continues to advance thanks to developments from its engineers. It appears Tesla is aiming to create a line of products that will last decades. In terms of automobiles, it would be groundbreaking to have a car that could run for 20 or 30 years with relatively no annual maintenance. Convenience, performance, and longevity are three things Tesla’s products are aimed toward, and the patent for an advanced and more affordable battery system thanks to an electrolyte solvent could alleviate any concerns some owners may have.