Identity and Toxicity of Off Gases in Thermolysis Lithium Battery Recycling Schemes.

[NNadir]

The paper I'll discuss in this post is this one: Toxicity Identification and Evolution Mechanism of Thermolysis-Driven Gas Emissions from Cathodes of Spent Lithium-Ion Batteries (Fang Hu et al, ACS Sustainable Chem. Eng. 2019, 7, 22, 18228-18235).

Over the decades, I've encountered many members of the awful class of human beings to which I belong, "Baby Boomers" - a class that never really escaped from the "Baby" designation - who, when confronted with either an environmental disposal issue or to a limited resource issue, engage in hand-waving coupled with the magic word, "recycle."

I am not immune from this mentality of course; much of what I write on the internet is about recycling, in particular, the recycling of the components of used nuclear fuels, and recovery of the valuable components therein.

Of course, there really isn't much used nuclear fuel in the world - certainly less than would be desirable in a safe and sustainable world - and in pure terms of mass they physical transport of these materials would be, were we sane (and we're not) relatively trivial. In the United States, for example, the world's largest producer still of nuclear energy, after over 60 years of operations, less than 80,000 tons of used nuclear fuel exists. We may compare this with the hundreds of billions of tons of the dangerous fossil fuel waste carbon dioxide the United States has released in the last 60 years, and the hundreds of millions of tons of waste plastic, which despite all the rhetoric about "recycling" is clogging the guts of fish and other marine, lacustrine, and fluvial organisms and will soon, in terms of mass, exceed the mass of all the living marine, lacustrine and fluvial higher organisms.

The "recycling" of plastics did not work, is not working, but I think could work, albeit only with entirely new thinking of a type that isn't fashionable.

Nevertheless, despite our obvious failure to be responsible, we Boomers like to declare ourselves "green." We Baby Boomers like to tell lies, to ourselves and to others, witness that awful orange Baby Boomer creature sliming the White House with his insipid and criminal presence, who is, in some ways, the avatar of our generation. He is often portrayed and mocked using a giant orange plastic balloon, inflated with some of the last helium on Earth, wearing a diaper, which is amusing and perhaps proper in terms of marketing, but unfortunate in ways we often don't consider.

Even wit has environmental consequences.

If I differ from other Baby Boomers in magical thinking about recycling, it is only because I work to make myself aware of the practical aspects or recycling, many of which are far less "green" than we like to imagine, because first of all "recycling" requires significant amounts of energy and although a few of us know how to make clean energy, in general, as a practical matter, we don't do so.

One of the most intractable forms of waste is electronic waste. It turns out that when we engage in magical "recycling" of electronic waste, the actual performance of the task is consigned to poor people in areas about which we neither know or care to know, precisely because the risk and toxicology of the recycling technologies are dangerous to health of those performing the task and destructive to the environment, and as such, is not permissible in countries with sensible environmental regulations, regulations that diaper Don and his denizens are working to eliminate.

One of the big Boomer lies we tell ourselves and others is that we can make so called "renewable energy" viable if only we had enough batteries to store the energy generated by this pixilated scheme. So called "renewable energy" has not been viable, is not viable and won't be viable, and we will never have enough batteries to make it so. Nevertheless, we are accumulating batteries at an accelerating pace, and it is that which this paper discusses.

For the record, until recently, China was the most prolific electronic recycling nation in the world; the concentration of polybrominated diphenyl ether and other types of flame retardants, heavy metals like lead and cadmium, and similar substances in the plasma and other tissues of large numbers of Chinese children reflects the results of that "green" industry. As China is becoming rich and powerful, it has banned the import of electronic waste from other countries, and presumably we in the Western world will need to find other poor countries about which we couldn't care less to bear the environmental and health costs of our "green" ways.

Nevertheless, China, now becoming a rich country, has its own endogenous electronic waste problem, and it also has lots of practicing scientists to evaluate the consequences of the practice of recycling electronic waste.

From the introductory text of the paper:

Lithium-ion batteries (LIBs) are a technical and commercial success that has enabled a wide range of everyday applications like electronics and energy storage, and, more recently, electric vehicles (EVs).(1,2) The increasingly growing consumptions of LIBs, coupled with their end of service life, is leading to the generation of considerable quantities of end-of-life (EoL) LIBs; for instance, it is predicted that China alone will produce about 500 000 t of spent LIBs by 2020.(3,4) In general, a commercial LIB cell typically consists of plastic and metallic shells, a cathode (lithium metal oxide on Al foil), an anode (graphite on Cu sheet), an electrolyte (composed of solvents like ethylene carbonate (EC) and methyl ethyl carbonate (EMC)), as well as electrolyte lithium salts like LiPF6, a polyvinylidene fluoride (PVDF) binder and separator.(5) It was estimated that 4000 t of LIBs would contain approximately 1100 t of critical metals and more than 200 t of electrolyte, which poses a significant potential threat to both the environment and human health.(6,7)

Nowadays, many pyrometallurgical, hydrometallurgical, and bioleaching approaches have been proposed in order to recover valuable metals from the EoL LIBs.(8?11) In a typical pyrometallurgical process, valuable metals are enriched into alloy phases before being subsequently recovered via hydrometallurgical refining processes. Nonetheless, in recent years, state-of-the-art hydrometallurgical processes have increasingly become the preferred industrial method for recovery of a majority of valuable metals within the EoL LIBs cathodes.(12) Pretreatment, either via mechanical or chemical means, is required in order to make the different waste battery streams ready for the leaching operations that follow. Of these, thermal-based pretreatment processes have become widely adopted and have been the subject of numerous research in recent years.(13,14) For instance, Sun and Qiu(15) and Yang et al.(16) have suggested that heat treatment of the cathodes can lead to the active powder being completely separated from Al foils. Hanisch et al.(17) have proposed that the thermal decomposition of organic compounds like PVDF binder can reduce the cohesion of the coated particles and weaken the adhesion between the particles and Al foils. In our previous investigation, it was found that thermal pretreatment not only promoted the removal of the organic compounds but also benefited the subsequent leaching of valuable metals.(18) Nevertheless, the risks associated with the toxic off-gas emissions generated during thermolysis remain poorly investigated, and consequently, more detailed information on on the nature of such gas emissions is essential for the development of a more sustainable EoL battery recycling process.

Currently, a number of studies have been undertaken to illustrate the thermal runaway event of LIBs under abusive conditions, whether mechanical, electrical, or thermal.(19,20) During the thermal runaway, battery components, especially the electrolyte, are usually subjected to uncontrolled exothermic reaction chains, which can cause severe safety issues.(21,22) Consequently, the gas emission during thermal runaway of LIBs and its associated mechanisms are relatively well documented, whereas in contrast the gas emissions from a conventional EoL LIBs recycling process has received limited research. Recently, Diaz et al.(23) measured the generated off-gases during thermal and mechanical pretreatment of spent LIBs and found that the thermal pretreatment had superiority to avoid disordered dispersal of the organic substances into the subsequent processing steps. On the other hand, their results also suggested that the off-gases—composed of HF, COF2, acrolein, CO, formaldehyde, HCl, and electrolyte—were of acute toxicity...

COF2 is fluorophosgene. In my career I worked with chlorophosogene, most commonly called simply "phosgene." Phosgene is a war gas that was used to kill tens of thousands of soldiers in the First World War; flourophosgene is more reactive, and more toxic than the phosgene I know so well. HF is hydrofluoric acid. I worked with that too. The safety videos for working with HF include examples of where this acid burned right through to the bone of people who unknowingly had drops of HF solutions on their skin. It is advisable to wear a lot of protective clothing when working with it.

Apparently though, we need more batteries to be "green."

HF, by the way, is a useful reagent for recycling nuclear fuels, but the mass of nuclear fuels is much, much, much, much lower than the mass of batteries when one compares their existing inventory.

The authors used some wonderful analytical chemistry instruments to study the thermal recycling of lithium ion battery cathodes:

In this work, the chemical composition and evolution mechanism of the off-gases generated from the thermal treatment of spent electric vehicle LIBs were investigated during the whole thermolysis period. A system of thermogravimetry (TG)-differential thermal analysis coupled with mass spectrometry (MS) equipped with skimmer-type interface and with electron ionization (TG-DSC-EI-MS), which was based on the operating principles of a TG-MS system, was established as a real-time, on-site measurement technique that could be used to record the MS signals. The solid thermolysis products were characterized by chemical analysis, X-ray diffraction (XRD), and scanning electron microscopy (SEM). Based on the above analytical results, a correlation between emission characteristics of the generated off-gas and the thermolysis behavior of the cathodes was established.

Beautiful stuff, although the reality is that all of these wonderful instruments will all some day be electronic waste in their own right, although I have personally been in laboratories featuring workable instruments that are many decades old, although usually these instruments are of a very special type.

Here's a graphic of the schematic of one analytical system:



The caption:

Figure 1. Schematic diagram of thermolysis experiments of off-gas emitted from cathodes with an online TG-DSC-EI-MS measuring system.

The batteries used in this study were real electronic waste, obtained from a real plant:

obtained from a hazardous waste disposal factory in Anhui Province, China. The spent LIBs were initially placed in a 10 wt % NaCl solution for 24 h to discharge the remaining capacity before being manually dismantled into cathode, anode, separator, and shell. The composition and physio-chemical properties of the relative organic compounds contained in the cathodes are shown in Table S1.25.

Here is a graphic of the DSC/TGA curves. The inflections and peaks represent points at which decomposition chemistry is observed:



The caption:

Figure 2. TG-DSC-DTG curves of the cathodes plotted against temperature.

The mass spectra gives information about the chemical composition of these gases:



The caption:

Figure 3. Ion current intensities of the species within the off-gases at the low channel: (a, b) 3D mass spectrum graph plotted against temperature and m/z. (c) Characteristic peaks of mass spectrum of the main emitted gaseous species.

The caption:

Figure 4. Ion current intensities of the species within the off-gas at the high channel: (a) 3D mass spectrum graph plotted against temperature and m/z. (b) Characteristic peaks of mass spectrum of the emitted gaseous species.

Ion current loosely corresponds to the concentration of the gases, but is a function of the ionization efficiency of the gases and thus the response factor, and is therefore not entirely quantitative without an internal standard.

The following graphic gives some idea of the elemental composition of the solid residues:



The caption:

Figure 5. Chemical (sic) analysis of solid thermolysis products at different temperature.

There is a considerable amount of fluoride ion present, which is a good thing, since the volatile fluoride species are surely nasty. These fluoride ions are almost certainly present as the salts of the metals. Note that this data is in weight percent, and thus reflects the atomic masses of the elements in question. The conflict metal cobalt has an atomic weight of 58.933 grams per mole; lithium an atomic weight of 6.93 grams per mole. Thus on a molar basis, the lithium portion of the graphic, in green should be 8.5 times larger when normalized to the conflict metal cobalt, in purple.

Not all of the fluorine remains behind in the solid however; which is unsurprising, since the hexafluorophosphate ion that serves an electrolyte in lithium batteries (as the lithium salt) is made by reacting toxic pentafluorophosphorous gas with hydrogen fluoride (hydrofluoric acid) gas.

The following sets of equations show the reversal of this inorganic synthetic reaction, present as off gases in the thermolysis of the cathodes:





Nasty.

Flow rates of the off gases:



The caption:

Figure 6. Comparison of the flow rate curve of calibrated gaseous species and DTG curve of the cathodes.

A nice cartoon of the entire study's results:



The caption:

Figure 7. Correlation between emission characteristics of the off-gas and thermolysis behaviors of the cathodes.

An excerpt from the paper's conclusion:

This research outlines a comprehensive investigation of the evolution behaviors and mechanisms of the toxic off-gas generated from the thermolytic treatment of spent LIBs cathodes...

...…detailed characterization of the gaseous thermolysis products in conjunction with the quantitative changes of the solid products taking place as temperature was increased allowed the evolution mechanisms of the gas emissions from the cathodes to be determined. Also, the evolution mechanisms of the gas emissions driven by thermolysis under various temperatures were established. The solvent EC/EMC was found to volatilize and decompose into gaseous hydrocarbons, CO2, and H2O at around 177 °C. The electrolyte was the main source for the release of fluoridecontaining gases which are mainly composed of POF3 and HF over the same temperature range. The PVDF binder decomposed as H2O, CO2, and fluoride-containing gases with maximum emission peaks at 522 °C, whereas the generation of CO2 above 600 °C was attributed to the oxidation of acetylene black. The analytical data gained about toxic gas species and the evolution mechanism of gas emissions during the thermolysis process provide fundamental knowledge and useful guidance for the continuing investigation of sustainable battery recycling strategies.

The most recent Nobel Prize in Chemistry was awarded for the development of lithium ion batteries. It was well deserved. These batteries have proved to be useful tools in many areas.

Nevertheless it is a lie we tell ourselves to say that batteries will save the world.

They will not.

As this research shows, the idea that this particular type of battery is infinitely sustainable is dubious.

History will not forgive us, nor should it.

I hope you will have a pleasant weekend and enjoy the upcoming Thanksgiving holiday.

[cstanleytech]

1. So are there any promising potential replacements for lithium that are safer for the environment?

[NNadir]

2. A lot of work is being done on batteries.

The main journals I read usually have one or two battery papers every issue.

A class that sticks in my mind is sodium sulfur type batteries, but there are many others.

I sometimes skim these papers, but they are not among my chief scientific interests, so I'm not qualified to say what might be cleaner.

A battery is by definition, a device that wastes energy: One can never recover the energy input entirely. The idea that they are environmentally sustainable is absurd on its face, but some batteries are safer than others. The second law of thermodynamics cannot be circumvented.

The environmental impact of lithium battery recycling is easy to ignore, since they are still on the small scale. It is disturbing that people look to them to store otherwise useless so called "renewable energy." This would be a worse environmental disaster than the "renewable energy" itself, which is a pretty awful thought.

I do believe that there is a place where energy storage on a macroscopic scale might be desirable and sustainable; I'm talking on the industrial power plant level. This is in the form of compressed air which, properly utilized can actually recover some energy losses represented by waste heat. It would offer the additional benefit on a very very very large scale of allowing the processing of air to recover and possibly destroy some intractable greenhouse gases, notably the very disturbing gas nitrous oxide, some organofluorides and sulfur fluoride pollutants, and possibly even carbon dioxide.

Chemical batteries, except for portable devices where they are a necessary evil, don't cut it in my view.

[moniss]

3. Apparently

you have a thing against wind and solar etc. Your statement that renewable energy "is not and never will be viable" is pure horsecrap. These technologies have been deployed and expanded successfully for several decades now in states in the US and in countries around the world. Iowa, Germany etc. have a long track record of success. Even on a smaller scale solar has made great advances and powers many devices without using any battery storage technology and in fact is able to replace existing battery use. I know a gentleman who goes camping, as an example, and he powers with solar and no battery needed. There are millions and millions of solar panels that are being used in various applications large and small and the development of the efficiency marches ever onward. I do not disagree with your article about gases emitted etc. but your statement about renewable energy is simply false.

[NNadir]

4. It should be apparent, since I clearly do have a lot against solar and wind.

It's because I give a shit about the environment and because I give a shit about future generations.

To be qualified to speak about what is and is not "horse crap," one would be advised to look at data rather than repeat mindless dogma.

We have spent over two trillion dollars on this toxic nightmare, so called "renewable energy" in the last ten years alone, this on a planet where billions of people lack access to basic access to any kind of improved sanitation.

How about I share something called "references" as opposed to mindless chanting about that gas and coal burning hellhole Germany?

Expenditures on so called "renewable energy," from the UNEP:

This information is here, in the UNEP Frankfurt School Report, issued each year: Global Trends In Renewable Energy Investment, 2018

Lack of access to basic sanitation, WHO, where that two trillion bucks might have been more worthily spent:

Key facts, WHO Sanitation

Key facts

In 2017, 45% of the global population (3.4 billion people) used a safely managed sanitation service.

31% of the global population (2.4 billion people) used private sanitation facilities connected to sewers from which wastewater was treated.

14% of the global population (1.0 billion people) used toilets or latrines where excreta were disposed of in situ.
74% of the world’s population (5.5 billion people) used at least a basic sanitation service.

2.0 billion people still do not have basic sanitation facilities such as toilets or latrines.

Of these, 673 million still defecate in the open, for example in street gutters, behind bushes or into open bodies of water.

Now, let's get down to what this so called "renewable energy" provided for humanity:

I have prepared this table from the 2019 IEA World Energy Outlook, published just a few days ago:



(In this table I have converted MTOE in the original table to the SI unit exajoules in this text. An original table from page 38 of the 2019 edition is here:

2019 Edition of the World Energy Outlook Table 1.1 Page 38]

Additional tables with my commentary are here:
World Energy Outlook, 2017, 2018, 2019. Data Tables of Primary Energy Sources.

In this century, world energy demand grew by 179.15 exajoules to 599.34 exajoules.

In this century, world gas demand grew by 50.33 exajoules to 137.03 exajoules.

In this century, the use of petroleum grew by 34.79 exajoules to 188.45 exajoules.

In this century, the use of coal grew by 63.22 exajoules to 159.98 exajoules.

In this century, the solar, wind, geothermal, and tidal energy on which people so cheerfully have bet the entire planetary atmosphere, stealing the future from all future generations, grew by 9.76 exajoules to 12.27 exajoules.

12.27 exajoules is slightly over 2% of the world energy demand.

You know what we got for all this horseshit about so called "renewable energy?"

The rate of growth for carbon dioxide concentrations hit the highest level ever observed, 2.4 ppm per year. We hit 415 ppm in 2019, and are sure to hit 418 this year. Seven million people die every year from air pollution. The seas are rising. Extreme weather is tearing up the planet.

That's what we got.

Are we tired of winning yet?

Don't tell me about horseshit, OK? I'm an old man. I've been hearing about how wonderful so called "renewable energy" would or could be my whole adult life. When I was a kid I used to believe it.

But I grew up.

You see the OP? It's about a paper in the primary scientific literature, not from some shit for brains web page on the internet where "renewable energy" advocates quote each other.

I have spent on average, about 10 hours a week in academic libraries for the last 30 years. Do you know why? Because I care, and I'm not into horseshit, or chanting horseshit, although I can certainly recognize it when I see it.

I'm a scientist. This means, to me, facts matter.

It is a fact that we are failing all future generations with misplaced faith in so called "renewable energy," which was, by the way, abandoned by humanity in the 19th century because it didn't work with 1/7th the population we have now.

So called "renewable energy" didn't work; it isn't working; and it won't work. The reason is physics, specifically low energy to mass ratios.

The longer we squander limited resources on it and the expense of the world's poorest citizens, the longer we chase after this silly unicorn, the less likely we are going to qualify for forgiveness by history.

There are young people calling us out for what we have done. They will write the history of our generation. It's not pretty.

Rather than repeat platitudes about those dangerous fossil fuel dependent hellholes like Germany and Denmark, it would be better to open a science book.

OK?

Have a wonderful Thanksgiving week.

[moniss]

8. I don't care if you include the

entire Encyclopedia Britannica. You say that Germany is this "hellhole " of fossil fuel consumption but fail to point out (most likely didn't know) that last year for several hours Germany met it's power demands 100% with renewables. You also don't know, apparently, that Germany has exceeded it's target for renewables last year by being over 35% for the whole year. They are committed to 100% renewables by 2050 and there is little doubt they'll make it. So you don't want renewables, you don't want coal, you don't want fossil fuel etc. I guess you just want to go back to killing your prey with a tree branch. Those of us who have worked in technical fields see problems as things to be solved. Not to run from. You on the other hand have your jogging shoes all laced up with nowhere to go.

[moniss]

5. Furthermore

you seem to want to knock those of a certain age and/or self denigrate. It seems that it is now fashionable in pseudo intellectual circles to use the term "Boomers" as a knock on everything about those of a certain age. I'm tired of this false notion being spread here and elsewhere that the people of that demographic have contributed little to nothing positive to society and are merely a big drain and are in the way. I will name just a few things that the Boomers like me brought about through our efforts. Civil rights legislation, voting rights legislation, environmental legislation, open expression, stopping the draft, ending the war in Vietnam and the list goes on and on. I'm sure you will find a way to brush aside these things and any others as insignificant (most likely as you stare at your phone) but what we did took the courage to face the certainty of beatings and death. The kids who fell at Kent State and Jackson State were Boomers. The kids in the streets of Chicago in 1968 trying to stop a war were Boomers. You may not like being one but I am proud to be from that generation warts and all because I remember how it was and what we went through to change it. As soon as you find that perfect generation that has no faults then you go join it because frankly I'm sick of thinking that you are part of mine.

[NNadir]

6. Whatever.

I've made very clear what I think, and I'm not going to apologize for it. I work at what I think. I don't issue tiresome platitudes. I have every right to reflect on my generation and it's idiotic self congratulations.

In this country we, the shit for brains Boomers, are a generation of mindless consumers who were against wars until we didn't have to fight them any more. Then many of us were as pleased as purring pussies to invade Iraq to secure oil. We are a generation that thought being productive was about trading stocks and driving SUV's, on which we piled horseshit worship for awful people like Elon Musk.

The Civil Rights act was passed in 1964, when most baby boomers were in elementary school. The clean air act was passed in 1970, when most Baby Boomers were still in high school or in early college and had no power.

I'm sure that you claim responsibility, but I actually believe it was the generation that came of age in the 1940's, who fought a real war against racists, might have had more to do with human rights legislation than a bunch of Hippies smoking dope and listening to Grace Slick sing "White Rabbit" for the billionth time.

We're summed up, in my view, with "Sex, Drugs and Rock and Roll." We have no sense of decency, and never did.

Since you obviously disagree with this assessment, you and I have nothing to say to one another, nothing at all.

In general, when confronted with people on this website to whom I have nothing to say and who clearly nothing to say to me that I will value, I expand my "ignore list."

Have a nice life, OK Boomer?

[moniss]

9. Did

I say the Civil Rights Act of 1964? Are you ignorant enough to believe that piece of legislation was the only Civil Rights legislation passed? Probably so since it fits your need. The environmental legislation passed because of pressure not only because of elected officials but also the pressure from millions of demonstrators that you ignore as powerless. Nowhere do I claim sole responsibility for the Boomers in bringing change. You ascribe some of the ills of society such as greed upon a whole generation. I'm sure you think yourself to be a "science" type but that glaring generality has nothing scientific about it. Your sign off let's us all know where you're at. Actually I doubt whether you're a Boomer in reality. Not a Boomer at all. Just plastic.

[gibraltar72]

7. Amen.