Written by Elissa Yao, edited by Carson Riar
Electric vehicles and clean energy grids promise emission-free transportation and energy, an urgently needed transition to reduce the acceleration towards a climate catastrophe. However, that new Tesla and all other electric vehicles rely on a battery that has environmental impacts of its own.
Lithium-ion batteries were the miracle invention that won M. Stanley Whittingham, John B. Goodenough and Akira Yoshino the joint 2019 Nobel Prize in Chemistry [1]. An invention that was deadly at first (due to a short-circuit formed by a needle-like growth from a reaction between the electrolyte and lithium metal anode), now shapes the world's renewable energy landscape. Thankfully, they don’t short-circuit and combust anymore since Akira Yoshino discovered that graphite is a safer anode alternative to lithium metal [2]. In contemporary times, lithium-ion batteries (LIBs) can power everything from your smartphone, laptop, and car, and have ambitious, yet also feasible plans, to soon power our cities. They provide high energy density, high discharge power and last multiple decades. Additionally, they will be a key player in the endeavor to reduce global emissions and move away from the world’s reliance on fossil fuels. Regrettably, this miracle does not come without environmental and sustainability challenges. With plans to mass manufacture large utility-scale batteries for grid storage (most notably Tesla Megapacks) and the fast-growing electric vehicle (EV) market, there is urgency in seriously evaluating the impacts of our batteries.
Lithium-ion batteries work by moving positively charged lithium ions back and forth between the cathode and the anode through liquid electrolyte. While charging a battery, the electricity applied rips the lithium out of the cathode where they flow through the electrolyte and insert into the graphite anode. To get electricity out of a battery, the ions need to flow back into the cathode, where electrons will be drawn towards a metal current collector. Over a lifetime of use, the structure of the cathode can change slightly, reducing the amount of lithium that can intercalate thereby reducing the capacity of the battery. Nowadays, the reduction in capacity for most commercial batteries however is low with most electric vehicle’s batteries retaining around two-thirds of the original capacity by the time the car is ready for the junkyard.
It was only 1991 when lithium-ion batteries were first commercialized [3]. In the thirty years since then, performance improved, and demand increased. Currently batteries are capable of large-scale energy storage with excellent energy density for grid storage and substantial power for electric cars. We will increasingly rely on these batteries as more of the energy we use is generated from clean sources that produce intermittent electricity such as solar and wind power [4]. While renewable energy sources have a lower environmental impact, a grave downfall is the unreliability of the power generation. To transition relying on these greener energy sources, adequate storage infrastructure must be present.
In September 2016, South Australia was affected by several severe storms, damaging part of the wind energy infrastructure that the region had grown to depend on [5]. This resulted in 850,000 customers losing power for several days. The Australian Energy Regulator (AER) took several wind farm facility operators in the Hornsdale area to court with accusations of “not performing” properly during this time. Alberto Boretti writes in Energy Storage that “This court action thus evidences once more the lack of any understanding of the way renewable energy, wind, or solar, works”. Boretti argues that “Without the adoption of massive energy storage systems, for every wind energy facility, it is therefore wrong to expect a production of wind energy that is independent of the variability of the wind energy resource, as it is wrong to expect a production of wind energy that is independent of the presence of a grid collecting that energy produced”. Neoen, one of the wind facility operators in the Hornsdale area agrees. In 2017, the installation of the biggest lithium-ion battery energy storage reserve at the time took place. Rows and rows of big white boxes holding batteries that make up the Tesla Megapack now store energy from the nearby wind farm. These batteries are huge, big enough to be impractical for any use other than utility storage, weighing 23,000 kg having a capacity of 129 MWh [6]. As the adoption of renewable energy increases, more LIB storage reserves are built. In December 2020, Vistra’s Moss Landing battery energy storage in California was installed surpassing the Hornsdale Power Reserve in size. Battery storage has already started to become a key player in the energy transition.
Battery storage projects are needed most in places where the key energy sources are unreliable because batteries can help stabilize the times of peak demand or low supply. Solar and wind energy generation relies heavily on whether the sun shines or the wind blows at the right rate, while consumption relies on the demand and capacity of the power grid. Energy is often abandoned in situations where there are power grid issues such as the power constraints, insufficient storage in the lines, and scarce capacity of peak shaving [7]. Lithium-ion batteries can help alleviate this problem as unused energy can charge the batteries which then can be discharged when needed. These storage facilities that minimize the disruptions of intermittent renewables can have the potential to ease the transition away from fossil fuels.
However, nothing comes for free and there is a cost to these “mega” batteries. The environmental impact of lithium-ion batteries has become a scholarly concern in recent times [8; [9]. Lithium, primarily from Argentina and Chile is extracted using massive quantities of water and then treated at extremely high temperatures to produce battery-grade lithium. It takes on average 520 MJ to produce 1 kg of lithium (GRANTA EduPack) Most of the lithium in the world is produced from brine. This process entails drilling in the salt flat and pumping the lithium-rich solution to the surface, depleting the water tables of the area. In Chile, mining accounts for 65% of regional water usage [10]. Newer techniques utilize geothermal energy to drive much of the extraction process. No matter how much energy it takes to process the lithium, the mining and use of lithium is still greatly favourable as it displaces the much worse fossil-fuel extraction and burning process. A gasoline powered car is expected on average to have a carbon dioxide emission of about 220 grams per kilometer [11]. The emissions from an electric vehicle relies on the energy source of the grid and can range from as low as around 50 grams per kilometer on a hydroelectricity grid to as high as 260 grams per kilometer on a coal powered grid [11].
The supply chain for an invention that the world relies on so heavily has some incredibly weak links. A popular cathode for lithium-ion batteries are nickel-manganese-cobalt (NMC) materials, with the biggest weakness being the dependence on cobalt for stability. Over 70% of the world’s cobalt is mined in the Democratic Republic of Congo [12]. The low wages of the population there (less than $1200 USD annually) and the high demand for cobalt worldwide result in individuals working at any cost alongside industrial mines to supply cobalt. These “artisanal miners” are no strangers to child labour, fatal accidents, and violence between miners. As a result, many companies are trying to reduce or eliminate cobalt from their battery’s designs, for both cost and ethics concerns. However, it is a complex dilemma as millions of Congolese rely on these jobs and the cobalt industry for their livelihood.
Batteries are at an all-time high demand and all-time low prices dropping from $7523 per kilowatt in 1991 to below $181 per kilowatt in present day [13]. The lowering costs of electricity is what the electric vehicle market depends on. The International Energy Agency estimates there will be between 148 million and 230 million battery-powered vehicles on the road worldwide by 2030. In 2017, the sales of electric vehicles exceeded 1 million, a remarkable milestone for the electrification of transportation. When those cars are at the end of their life, there will be 250,000 tonnes of unprocessed battery waste to contend with. The march towards a fleet of electric vehicles displacing gasoline automobiles is a very positive trend and understanding how to ensure the sustainability steadies the beat of the march, moving us towards a carbon neutral future.
Dead batteries are essentially hazardous waste with precious metals inside. Recycling costs are high for LIBs but is worth it if the cobalt extracted is worth more than the cost of recycling and mining more cobalt. One of the reasons that batteries are expensive to recycle is the lack of standardization of their design [14]. Many lithium-ion batteries adopt a “jelly-roll” form factor where the cathode, electrolyte-soaked separator and anode are layered on top of each other and rolled into a can with current collectors on each side of the final anode and cathode. This maximizes the energy that one could get by maximizing the area of active materials. The adhesive polyvinylidene fluoride (PVDF) is often used to hold the cathode material on the thin film. Unfortunately, PVDF only dissolves in a solvent called NMP (N-Methyl-2-pyrrolidone), a substance that poses an environmental hazard during disposal but necessary in both the production and disassembly of LIBs. The components are stored in a can or pouch that is then glued or laser welded shut, making disassembling again in a safe way difficult to navigate. This design eases customer’s anxieties about the capacity and safety of their batteries, especially the ones in electric vehicles where range is an important selling feature, and the batteries need to operate safely under harsh environments. These designs are optimizing for many positive features, but recyclability is certainly not one of them.
To compound the problem for those looking to recycle LIBs, the design of electric vehicle batteries is not standardized making the process much slower, as optimization becomes harder. Companies like Spiers New Technologies store used batteries that belong to automotive manufactures because the uncertain market may make recycling the batteries economically sensible someday. The batteries of the Chevrolet Bolt, a vehicle that had to be recalled quickly due to a few spontaneous fires that had occurred when drivers were charging their vehicles overnight, are now sitting in a (fireproofed) warehouse in Oklahoma City waiting to be recycled [15]. As many battery-makers are looking to move away from LCO due to the ethics issues with cobalt, and towards using cheaper metals, the financial incentive to recycle batteries will become virtually non-existent as cheaper metals like iron would not be worth extracting. Despite the challenges, the sheer volume of spent batteries that need to be handled will be met with a growing industry to meet the demand.
Another end-of-life option for electric vehicle batteries may be to perform the role that the Tesla Megapack and other utility scale battery energy storages are hoping to do: replace the “peaker power plants”. These are plants that generate extra energy to fill the gap between demand and supply [4]. Even when the range on an EV drops or the vehicle is decommissioned for other reasons, the capacity of the battery may still be sufficient, in some cases only losing 20% of their original capacity. There are certainly challenges with assessing the condition of various kinds of EV batteries and determining whether the cost to transport and repurpose the old batteries outcompetes making new ones. From an energy consumption and environmental perspective, reusing an old EV battery is a no-brainer compared to making new ones which demand more resources notably cobalt and water. However, cost will be the major driver of what the post-vehicle life will look like for the millions of EV batteries that will be coming off the road in the next few decades. Afterall, why bother using old batteries that might have to be changed more often when new batteries are so cheap to make? In May 2020, B2U deployed a second life battery storage using batteries from Nissan Leafs as a proof of concept in California [16]. Hopefully the success of this project inspires other companies and investors to consider the potential value of used batteries. Developments in other kinds of batteries, notably the sodium ion batteries which utilize the extremely abundant sodium instead of lithium, also reduce the environmental impact of LIBs.
Utility-scale storage and EV are both engineering marvels that the three founding fathers of the LIB should be proud of today. Their invention has been and will continue to be key in the green energy transition, pushing burning fossil fuels to obsolescence. There are still important questions that are largely unanswered that dictate the impact of LIBs in our world such as: who is responsible for recycling or disposing of the batteries after use? Who is responsible for the ethical mining of the materials in the batteries? The consensus is that there are various improvements that need to be made for LIB recycling at sufficient scale to be economically viable, such as better sorting method of different types of batteries, methods for separation of electrodes, flexibility in the process and greater standardizations in the manufacturing of the batteries. When there is little current economic incentive to undergo the process of recycling and stockpiling long term is dangerous, the imperative to recycle large LIBs arises solely from the desire to keep them out of the landfills.
A realistic future where the adoption of renewable energy can sufficiently displace fossil fuel reliance requires a sincere and in-depth discussion about the reliability and sustainability (both environmentally and economically sustainable) of the infrastructure being developed. The role of batteries in this future cannot be overstated or overlooked. This electrochemical energy storage is genuinely a Nobel Prize-winning discovery, but it is not magic. As innovations are made daily from the scientific and engineering side, policy and business discussions are also being had. Only when all consumers know that they can reliably and safely recharge their cars and power their homes consistently without fossil fuels can the energy transition be considered a success.
References
1) 2022, N. P. O. A. (2019). The Nobel Prize in Chemistry 2019. [Press release]. Retrieved from https://www.nobelprize.org/prizes/chemistry/2019/press-release/
2) Yoshino, A. (2012). The birth of the lithium‐ion battery. Angewandte Chemie International Edition, 51(24), 5798-5800.
3) Schipper, F., & Aurbach, D. (2016). A brief review: past, present and future of lithium ion batteries. Russian Journal of Electrochemistry, 52(12), 1095-1121.
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13) Ritchie, H. (2021). The price of batteries has declined by 97% in the last three decades. Retrieved from https://ourworldindata.org/battery-price-decline
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15) Barber, G., & Marshall, A. (2021). Cars Are Going Electric. What Happens to the Used Batteries?
16) Marshall, A. (2021). These Batteries Can't Power a Car—but They Can Light Up a City. Retrieved from https://www.wired.com/story/batteries-cant-power-car-light-city/#intcid=_wired-bottom-recirc_394d2742-51a0-487b-aa93-1e93f2c20483_text2vec1