As we transition towards green energy and renewables, one question on everyone’s mind is about the climate cost of materials used in all of this new technology.
We have already started hearing about the environmental impact and carbon footprint of lithium, cobalt, nickel and manganese; metals used to power batteries used in electric vehicles and so many of our other technological instruments. These metals are used on the cathode side of the battery (conventional current flows from cathode to anode outside of the cell or device, with electrons moving in the opposite direction, regardless of the cell or device type and operating mode).
But what about the anode?
The other part of the cell – the anode – has been largely ignored in all of this. In a conventional battery, anodes were originally made from lithium metal. When the battery is powered up, lithium ions move towards the anode, which is the positively charged end and take residence there till energy is needed. But there was a problem because lithium metal is unstable and frequently explodes when in contact with air and water. In an effort to try out other metals, carbon was selected and refined into a hexagonal lattice, which could attract a large number of ions without exploding. This new carbon material was graphite (naturel as well as synthetic), and it prescribes the amount of energy a battery can hold, as well as how fast it can be charged.
Problem solved. Except that it wasn’t because we have not been paying attention to the carbon footprint of graphite for the anode.
Two studies that came out in 2022 suggest that the estimates of graphite’s environmental cost and carbon footprint, spanning its complete global journey (from mine to finished product) have been grossly underestimated. Till now, we have been concentrating on the materials used for the cathode, ignoring the graphite used in the anodes, the production of which goes through very energy intensive processes. The graphite used in EV batteries is either produced synthetically or mined naturally and then is heavily processed before being baked onto a copper foil to serve as anodes.
If we are ignoring this crucial source of carbon emissions, we are not really looking at the complete picture of the production of electric vehicles. Our climate change panacea may yet need a lot more work.
There is no doubt that electric vehicles are greener than using fossil fueled cars, although we do contribute to global carbon emissions when we charge them, but with more and more sources of energy being renewable and green, this problem can be solved. However, the raw materials needed to manufacture these vehicles, especially their batteries, are still a long way away from being green. The minerals used in cathodes are now widely acknowledged to not only have detrimental environmental impacts but are also a source of major human rights violations because they are mined in countries with unsatisfactory or abusive human rights practices. In fact, child labour is used to mine many of these minerals. As this information has become common, companies have tried to (or at least said that they have tried to) move away from controversial mining areas. They have even tried to incorporate new materials into the cathode.
But what about graphite? One of the two studies, “demonstrates that some upstream, downstream, and peripheral processes—including important processes associated with mining, calcination, and other steps—are often omitted, leading to greatly underestimated impacts.” Basically, if we look at the whole supply chain, gaps in how corporations estimate their carbon emissions become glaringly obvious.
The first study therefore “proposes a new rigid framework for comparing different graphite production routes and a corresponding indicative inventory for synthetic graphite production”.
The second study begins by saying, “Graphite manufacturing is characterized by energy intense production processes (including extraction), mainly being operated in China with low energy prices and a relatively high greenhouse gas emission intensity of electricity generation.” So, a lot of dirty energy is being used by manufacturers in China, which has a monopoly over graphite production.
According to this study, “Industrial scale primary data related to the production of battery materials lacks transparency and remains scarce in general. In particular, life cycle inventory datasets related to the extraction, refining and coating of graphite as anode material for lithium-ion batteries are incomplete, out of date and hardly representative for today’s battery applications.”
Basically, manufacturers used old and incomplete datasets, as well as estimates from processing other materials to measure the carbon impact of their graphite production, clearly giving an inaccurate picture of climate impacts.
Although the two studies arrived at different numbers of the overall effects of graphite production due to different datasets, the end result was the same (up to 10 times higher carbon emissions for synthetic graphite and between 4 – 8 times higher carbon emissions for natural graphite), showing without any doubt that the estimates used by manufacturers to measure climate impacts are vastly underestmated.
And the problem does not stop there. Recycling graphite by scraping it off anodes is an expensive process; it is much cheaper to just produce new graphite for battery use, even though it uses prodigious amounts of energy (for both natural and synthetic graphite). According to estimates this can be up to 1500 celsius for natural graphite and up to 3000 celsius for synthetic graphite for just one step of the process. Perhaps using greener energy can be part of the solution but we are a long way away from that too. So, for now at least we are stuck with dirty graphite adding to our carbon footprint, without even knowing how much that footprint is.