Flouride Ion Batteries Could Be Ten Times Better and Cheaper Than Lithium Ion

Researchers at Caltech, the Jet Propulsion Laboratory, the Honda Research Institute, and Lawrence Berkeley National Laboratory and others are working together to develop rechargeable batteries based on fluoride, the anion (negatively charged form) of elemental fluorine.

Fluoride batteries can have a higher energy density, which means that they may last longer—up to eight times longer than batteries in use today. But fluoride is corrosive and reactive. Iron fluorides already have more than double the lithium capacity of traditional cobalt- or nickel-based cathodes. Iron is 300 times less expensive than cobalt and 150 times less costly than nickel.

Researcher team made a new type of cathode from iron fluoride active material and a solid polymer electrolyte nanocomposite. They tested several variations of the new solid-state batteries to analyze their performance over more than 300 cycles of charging and discharging at elevated temperature of 122 degrees Fahrenheit, noting that they outperformed previous designs using metal fluoride even when these were kept cool at room temperatures.

They will make new and improved solid electrolytes to enable fast charging and also to combine solid and liquid electrolytes in new designs that are fully compatible with conventional cell manufacturing technologies employed in large battery factories.

Nature Materials – Cycle stability of conversion-type iron fluoride lithium battery cathode at elevated temperatures in polymer electrolyte composites

Metal fluoride conversion cathodes offer a pathway towards developing lower-cost Li-ion batteries. Unfortunately, such cathodes suffer from extremely poor performance at elevated temperatures, which may prevent their use in large-scale energy storage applications. Here we report that replacing commonly used organic electrolytes with solid polymer electrolytes may overcome this hurdle. We demonstrate long-cycle stability for over 300 cycles at 50 °C attained in high-capacity (over 450 mAh g−1) FeF2 cathodes. The absence of liquid solvents reduced electrolyte decomposition, while mechanical properties of the solid polymer electrolyte enhanced cathode structural stability. Our findings suggest that the formation of an elastic, thin and homogeneous cathode electrolyte interphase layer on active particles is a key for stable performance. The successful operation of metal fluorides at elevated temperatures opens a new avenue for their practical applications and future successful commercialization.

Science – Room-temperature cycling of metal fluoride electrodes: Liquid electrolytes for high-energy fluoride ion cells (Dec 2018)

Fluoride ion batteries are potential “next-generation” electrochemical storage devices that offer high energy density. At present, such batteries are limited to operation at high temperatures because suitable fluoride ion–conducting electrolytes are known only in the solid state. We report a liquid fluoride ion–conducting electrolyte with high ionic conductivity, wide operating voltage, and robust chemical stability based on dry tetraalkylammonium fluoride salts in ether solvents. Pairing this liquid electrolyte with a copper–lanthanum trifluoride (Cu@LaF3) core-shell cathode, we demonstrate reversible fluorination and defluorination reactions in a fluoride ion electrochemical cell cycled at room temperature. Fluoride ion–mediated electrochemistry offers a pathway toward developing capacities beyond that of lithium ion technology.

Journal of the Electrochemical Society – An Aqueous Rechargeable Fluoride Ion Battery with Dual Fluoride Electrodes (2019)

An anion flow battery has recently emerged as an option to store electricity with high volumetric energy densities. In particular, fluoride ions are attractive for these batteries because they have the smallest size among anions, which is beneficial for charge transport. To date, reported fluoride ion batteries either operate with an ionic liquid, organic electrolyte or solid-state electrolyte at high temperatures. Herein, an aqueous fluoride ion flow battery is proposed that consists of bismuth fluoride as the anode, 4-hydroxy-TEMPO (TEMPO) as the cathode, and NaF salt solution as the aqueous electrolyte. During the charging process, bismuth fluoride electrochemically releases fluoride ions with the formation of bismuth metal, while TEMPO captures the fluoride ions. A reversible and stable discharge capacity of 89.5 mAh g−1 was achieved at 1000 mA g−1 after 85 cycles. The fluoride ion battery possesses excellent rate performance. To the best of our knowledge, this is the earliest demonstration that fluoride ion batteries can work in aqueous solutions, which can be used for future clean energy applications.

26 thoughts on “Flouride Ion Batteries Could Be Ten Times Better and Cheaper Than Lithium Ion”

  1. It doesn’t have to be flammable if it is Hazmat worthy, any number of interactions could poison passengers after a crash, not to mention the surrounding area, soil and groundwater – or water supply if a water source is close enough to be directly affected.

  2. Fluoride isn’t flammable, or is it? That alone makes it order of a magnitude safer than jet fuel. I.e. of all US air-crash accidents, 22% of victims died because of firesmoke.

    -“Grandma, your teeth are ok even at age of 90 – how come?”
    -“Fluoride. I have have survived an air-crash in 20205”

  3. I don’t know about that – it’s bad enough having aircraft with flammable fuel flying over inhabited areas, it will be much worse with batteries using more dangerous chemical compositions in a crash, having collateral damage extending much further from the impact area.

  4. I never heard an exact composition mentioned, Dallas only mentions that he hadn’t seen anything like it except “molecular acid” – which could be anything, typical ambiguous sci fi wonder stuff.

  5. Your post points to another post called “Removing Chemical Used to Make Teflon-like Coatings Has Led to Fewer Low Birth Weights and Less Brain Damage“. That points to a source paper “Perfluorooctanoic acid and low birth weight: Estimates of US attributable burden and economic costs from 2003 through 2014” which implicates perfluorooctanoic acid specifically.

    It’s not just used in teflon manufacturing”

    PFOA is used for several industrial applications, including carpeting, upholstery, apparel, floor wax, textiles, fire fighting foam and sealants. PFOA serves as a surfactant in the emulsion polymerization of fluoropolymers and as a building block for the synthesis of perfluoroalkyl-substituted compounds, polymers, and polymeric materials. PFOA has been manufactured since the 1940s in industrial quantities. It is also formed by the degradation of precursors such as some fluorotelomers. PFOA is used as a surfactant because it can lower the surface tension of water more than hydrocarbon surfactants while having exceptional stability due to having perfluoroalkyl tail group. The stability of PFOA is desired industrially but is a cause of concern environmentally.

  6. That high reactivity is exactly why you can get high energy density though, isn’t it? If you want high energy density batteries, you pretty much have to work with highly reactive materials. Their high chemical energy content is what makes them reactive. Then the engineers have to figure out how to make it safe enough for public use, which isn’t easy.

  7. When I see “Could” in the headline my hopes go down to zero. I mean a Pepperoni Pizza “Could” be 10 times better than Li-ion too. Could? Feh.

  8. The main thing we need high energy density batteries for are electric aircraft and flying drones. The 500 mile range Tesla is going to have with its solid lithium batteries is reasonably adequate and does not require going to these potentially dangerous compounds. But we need 3-5x the energy density in current generation batteries for aircraft that have reasonable/good flying range. Aircraft could have some sort of foam that gets released to neutralize the stuff after an aircraft crashes. You don’t want survivors and first responders to be killed by chemicals in ruptured batteries. Electric aircraft should have less issues but there is always the unexpected, bozos, and suicidal sociopaths.

  9. It’s bismuth fluoride BiF5 anode, 4-hydroxy-tempo cathode, sodium fluoride aqueous electrolyte.
    The 4-hydroxy-tempo is a concern if a fire starts from freed fluorine gas (creating hydrofluoric acid). Free fluorine in multi-kg quantities (like in an EV) could become a serious hazmat incident.
    BiF5 is super reactive.
    Maybe it could be used in grid-scale storage relatively far from people. Fluorine gas is so reactive it can burn oxides by displacing the oxygen.
    An EV wreck that burns could release enough fluorine to potentially kill dozens or even more, unfortunately. Like 20kg in an EV battery of fluorine.

  10. It’s not clear what the chemical form is. It might be quite harmless. After all there is sodium fluoride in my toothpaste.

  11. It’s called ‘The Devil we Know’ on Netflix. Every article that I’ve read about the potential for flouride batteries has stated that the chemical is corrosive and toxic. Maybe it can be manufactured and recycled safely, but who knows? They call the chemical that makes up teflon the devil’s piss, because it can’t be broken down by any known chemical or heat-based reaction. Although the prospect for better batteries is always tantalizing, obviously.

  12. In hydrogen fluoride form it is especially bad (hydrofluoric acid).

    It’s spill 6-60% of a teaspoonful on your skin and have a 50% chance of dying.

    As little as 5mg/kg to have a 50% chance of killing you ingested or on skin, but also up to 10x that. So like 350mg if you are 70kg. 10x that is 3.5 grams (60% of a teaspoonful). So also 50% chance of killing you if you spill that much on your skin. Not that you’ll be fine if you survive.

  13. If people stopped doing stuff just because it could all go horribly wrong with death and maiming and injury… then we would never have even started riding horses.

  14. I really doubt using flouride for batteries is a good thing. The damage teflon manufacturing alone has caused to the world is pretty serious. Birth defects, environmental contamination, etc.

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