While many of us worry about sulfates in shampoo and sulfites in wine, I recently learned about the terrible impact of using sulfates in the manufacture of battery cathodes. It appears that the method used to create most lithium-ion cathodes for the past 30 years produces a huge quantity of trash. Fortunately, I came across this issue when investigating a potential fix.
The positive electrode of a battery, or cathode, is where charging energy is applied. Lithium-nickel-manganese-cobalt is the primary component of the majority of lithium-ion batteries used today (NMC). Mining the metals, reducing them into metal salts or sulfates, converting lithium carbonate into lithium hydroxide, and then delivering these materials to the cathode producer where they are combined with water are the steps involved in making these. In order to create the powder precursor that is combined with the lithium hydroxide and baked in a furnace to form grains of lithiated cathode material, a caustic substance, such as sodium hydroxide, is added. Then, a distinct procedure is used to apply a particular coating.
At least 1.8 times as much sodium sulfate trash is produced during the process as cathode material. Although it poses little risk to both people and the environment, there isn't much of a market for it, thus it usually ends up being diluted with water and disposed of or landfilled. This arrangement was manageable when processing 10,000 tons annually to power personal devices and a small fleet of electric vehicles, but it is unsustainable at projected levels of EV production. More than 2 million tons of sodium sulfate waste will be produced if a terawatt-hour of batteries are produced using this method, which is enough for 10 million battery packs with an average capacity of 100 kWh. Need a picture? 500 NFL football fields worth of trash are sprawled out there. Even China, which tolerates pollution, is running out of options for getting rid of this waste stream. To make matters worse, metal sulfates have a five times greater shipping expense and environmental impact than metal powders.
Using no sulfates, Nano One Materials Corporation suggests a superior solution. When fired in a furnace, the One-Pot Metals to Cathode Active Ingredients (M2CAM) process combines pure metal, lithium-carbonate, and coating materials to create coated lithiated particles. With less energy and capital investment needed, this easier, more direct approach is already more affordable than the historical method and has the potential to become much more affordable with additional development. Nano One says the sulfate-free M2CAM process occurs in water (consuming 60% less of it) at room temperature and atmospheric pressure, but it won't reveal all its secrets because patents are pending. The chemistry produces no waste, is ecologically friendly, and reduces the cost of shipping raw materials by a factor of four or five.
By changing formulas, coatings, and process settings, Nano One claims it can alter the method to produce different cathode chemistries for use in conventional or solid-state battery designs. Additionally, because the cathode materials are coated during the One-Pot Process as they are being created, each crystal within the bigger particle receives a coating. Durability is increased by reducing adverse reactions like lithium spikes, which can short a battery. You question, what about getting those pure metals? Depending on the mine and the metal ore, a refiner may plate the metal out with electricity to attain battery-grade purity, or they may crystallize the metal using a procedure involving chemical reactions, filters, membranes, and various electrochemical technologies.
Although it may seem pricey, we're assured that these methods are usually less expensive than making metal salts—and keep in mind that pure metal powders are lighter and less expensive to send. When might these "greener" no-sulfate cathodes become commercially available? While aggressively looking for a possible licensee or joint-venture production partner, Nano One is collaborating with automobile manufacturers and suppliers to generate demand for its cathode materials. By 2024, the business wants to start up a pilot production facility. Let's hope it can stay on schedule for those 500, foot-deep football fields.