I know I said I would not do any further reviews on Redwood Materials, but after I was flooded with emails and DMs with their latest blog post: Building the Most Sustainable (and Scalable) Battery Materials Process. I figured a quick fisking was in order, plus their blog post gives me a reason to rant about a aspect of the industry that annoys the heck out of me, well ok a couple aspects.
If you were to take the amount of misinformation that says the recycling of lithium-ion batteries is to expensive and that it is not viable and convert it into a weight, the metric tonnage that it equals would stun a team of oxen in their tracks. These misconceptions are compounded by the common practice of companies, exemplified in Redwood’s blog post, to omit or twist data in order to paint themselves as the greenest and most advanced recyclers around. While promoting themselves they create a picture that all other companies are as environmentally sound as a oil tanker that just ran aground at a nature preserve. It’s this arrogance, that sours the general public’s perception of the industry, a industry that will require at least 10 more companies alongside Redwood Materials by 2035 in order to make all this work.
However It would be disingenuous of me not to mention Redwood Materials has been involved in local and nationwide programs to help educate and promote recycling for years. And more than any other company in the sector they’ve brought the discussion of lithium-ion battery recycling to America’s dinner tables. But while doing this the company’s CEO has continuously overinflated or misrepresented the capabilities of his company. While testifying in front of a Senate subcommittee he dismissed the need for further advancements and research in lithium-ion recycling by referring to it as a very mature technology. Instead of a recycling infrastructure, after all his company has that covered, he suggested the main focus needs to be on creating a lithium-ion battery manufacturing industry.
Billions of dollars is being spent on the lithium-ion battery industry every year. The creation of new chemistries, the advancements and optimization of the subcell components, and the efficiency of manufacturing is continuing to accelerate. While at the same time only a fraction of that funding is being spent on the recycling technologies. There is a mindset that once a recycling process has been created, everyone can celebrate, turn off the lights and head home, nothing can be further from the truth. Without constant advancements in recycling to mirror what is happening on the manufacturing side the transition to a sustainable energy infrastructure might as well be abandoned.
Ascend Elements while not perfect, there are things that the CEO has said in interviews and during panels that are pretty cringeworthy, come on Mike you can’t repurpose the term “Closed Loop” and use it in place of the actual term “Contract - Fee” when describing one of the business models that a manufacturing facility will use for the processing of their production waste, without the rest of the panel participants giving you the side eye. But as a whole are the only lithium-ion recycling company out there that has taken a real active role in combating misinformation. American Battery Technology Company (ABTC) used to be active in these efforts, but that was indirectly through my drone videos of their Fernley facility. On the lithium primary resource side, companies should take a page from Cornish Lithium’s playbook when it comes to promoting themselves.
After saying all that, and placing my opinion of Redwood Materials’ CEO aside, If they were a public company I would most likely invest in them because I do believe in what they are trying to accomplish. My main grievance with them is the bull-larkey they constantly publish and post on social media platforms, they are not the worst offenders of this in the lithium industry however, some of the feldercarb that EnergyX and Altilium have been posting…
Now on to the Fisking:
“Our reductive calciner is the only calcining facility for battery recycling in North America and is crucial for processing all types of live battery feedstocks efficiently. This thermal pre-process allows us to handle live battery cells, consumer electronics, and electric vehicle modules – and can process over 40,000 metric tons (about 15-20 GWh) annually.”
Low temperature calcination or pyrolysis are common pyrometallurgical components that can be found in many modern lithium-ion battery recycling platforms and is included in the module systems produced and sold in China. Thermal pre-treatment usually takes place at 160°C at the low end and can reach temperatures as high as 700°C; and unlike direct reduction smelting, it will have various stages that include mechanical size reduction and separation. The goal is not to create alloys and slags but rather to accomplish 3 tasks.
Transition the battery to a inert status: The organic compounds and plastics found in batteries are decomposed, this normally occurs in a reducing atmosphere and if the separators are sufficiently decomposed, the battery will short circuit triggering a exothermic reaction, which can be used to supplement the heat in the kiln.
Breaking down the binder in the CAM: The organic binder typically polyvinylidene fluoride (PVDF) is used adhere the cathode active material to the aluminum foil used for the current collector. By thermally decomposing this compound the active material will be released from the aluminum. Depending on the pressure and atmosphere composition in the kiln this process typically starts at 300°C and will peak around 550°C.
Thermal reduction: During this stage, starting at 500°C, the active material is converted into a more soluble form that decreases the time and agents needed for the extraction of the metals.
A couple of companies in North America have incorporated thermal pre-treatments into their system, Cirba Solutions and Lithion are two of the closest to deploying at the commercial scale that I can think of.
Cirba Solutions: Formerly a subsidiary of KBI, a traditional metal recycler located in California, is now a conglomerate of 3 different recycling entities. The original process patented in 1998 was expanded on in 2013 with a patent that describes a lithium-ion battery recycling process that will use calcination to breakdown the binders in black mass and other organic compounds after the mechanical size reduction. They are taking the kitchen sink approach to recycling and will be employing cryogenic, mechanical, thermal pre-treatment, ESRL using LiOH and pH adjustments, electro-chemical, and precipitation. In 2022 Cirba Solutions was awarded a grant from the DOE to build out their lithium-ion battery recycling operations.
Lithion: Are a Canadian based company that have a platform that will shred a battery in a organic solvent to prevent thermal runaway and also dissolves the electrolyte. The pulp is then washed using the same solvent to create a liquid that is dried to create a slurry that contains the lithium from the electrolyte. Their system has a very extensive recovery and distillation stage to fully recover the chemicals used in the electrolyte at battery grade. The process will use different stages between 300°C and 500°C to decompose and remove the organic compounds found in the battery prior to magnetic and density/size based separation stages.
Redwood’s reduction calcination however sounds a lot like a process patented by Accurec Recycling GmbH who are operating at commercial scale in Germany. Lithium-ion batteries are placed in a kiln where the atmosphere is evacuated to achieve a pressure of less than 10mbar. The batteries are then heated to a temperature (160 to 200°C) which is sufficient enough to cause the electrolyte to evaporate. The resulting vapor pressure causes the batteries to open and the gases created by the evaporation of the electrolyte are pumped out and collected.
In the second step the batteries are heated in a reducing atmosphere while at the same time the pressure is simultaneously increased to no more than 700mbar. Through precise control of the pressure in the kiln during the second step temperatures produced by the exothermic reaction of the batteries during thermal runaway are regulated. The temperature in this stage will be limited by the lowest oxidizing point for the metals in the battery, in the case of a lithium-ion battery that would be aluminum at 600°C. The heat generated by the exothermic reaction in this stage is used to offset the fuel needed to heat the batteries through indirect means.
By using a two stage process, Accurec is able to collect and remove the gases from the electrolyte separately from the hydrofluoric acid gas created during the thermal decomposition of components including the binder in the CAM. After thermal treatment the batteries are cooled and sent on for further processing using mechanical separation to create a black mass and secondary product streams containing the metallic foils and steel from the casings.
Some of, what I would call next generation recyclers accomplish this first stage using proprietary, and that word is important when it comes to the availability of their data; methods of non-thermally assisted comminution of end-of-life battery either in a inert atmosphere (vacuum or non combustible gas) or in a aqueous medium. This allows for the safe mechanical disassembly and possible recovery of the electrolytes, a component normally lost in the use of a thermal pre-treatments before the mechanical disassembly and size reduction stage. There are also recyclers that have developed systems that store the residual energy from batteries as they discharge them to power the recycling system, Volkswagen has created the most known example of this technique.
The breakdown of the binder in the CAM can be preformed before the foil separation phase of the mechanical stage or included in the hydrometallurgical stage using organic solvents that are later stripped and regenerated. There are a few companies, Ecobat and ABTC are two of them, that have developed ways to do this process as a pre-treatment before the main mechanical stage to avoid the costs associated with thermal pre-treatments and are able to lower the amounts of solvents needed for the chemical delaminating of the cathode.
“Redwood’s proprietary reductive calcination technology is powered by the residual energy in end-of-life batteries and uses no fossil fuels.”
Small nitpick here, while not a fossil fuel, the Air Quality II Operating Permit lists biodiesel as the fuel source for the burners. But during operations the heat for the kilns are further supplemented by the thermal runaway caused by the batteries shorting out.
“Stanford helped us identify that the peroxide in our hydrometallurgy process contributed significantly to our total CO2 footprint, and today we’ve redesigned our hydrometallurgy process to use no peroxide at all, an industry first.”
Peroxide commonly in the form of H2O2 acts as a reducing agent to increase the yield of metals during extraction. Using a reducing agent in combination with a acid is standard in reductive leaching, yes even for that company that uses chromatography that have a CEO posting they do not use hydromet. But not all platforms use a peroxide, I have at least 5 papers/patents on this iPad alone that I am using to write this that covers platforms that do not use a peroxide for lithium-ion battery recycling. One interestingly included a process that replaced hydrogen peroxide with the waste from green tea and was able to maintain a extraction rate of 99%, however this was not practical due to the difficulties of applying the reducing agent at larger scales.
But If one wants to get technical and say first in the industry to not use a peroxide at commercial scale, that would be true if it was limited to the United States. Off the top of my head I know of one that has their process included in a Korean recycling facility,