Lentis/Lithium-Ion Batteries in Electric Vehicles

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Introduction[edit]

The global climate change crisis has prioritized the transition from fossil fuels to renewable energies in the transportation sector. In recent years, there has been a surge in electric vehicle development from major manufacturers such as Tesla, Inc., General Motors, Nissan Motor Co., Ltd., and Bayerische Motoren Werke AG (BMW). This Lentis casebook chapter will provide historical background on electric vehicles and analyze the environmental and societal impacts associated with the production, usage, and disposal of lithium-ion batteries found in popular electric vehicles.

History[edit]

Electric Vehicles Through Time[edit]

Electric vehicles first came into existence in the late 1800s, as scientists experimented with early batteries and electric motors. [1] In the United States, William Morrison of Des Moines, Iowa is credited with developing the first successful electric vehicle in 1890, securing patents on electric current regulators and improved processes to manufacture storage battery plates. The Morrison Electric Vehicle had six seats, 24 batteries, and 4 horsepower, with a top speed of 14 mph and a range of 50 miles. [2] The 1890's to the early 1900s was the golden age for electric vehicles. Steam engines required long startup times, while gasoline cars required gear changes and produced exhaust. The decline of electric vehicles started in 1908 with the invention of the cheaper Ford Model T, as well as improved roadways and the Texas oil boom. Electric vehicles made a comeback in the 1970s due to increased gas prices and environmental concerns. This eventually resulted in the development of modern electric and hybrid vehicles. [3]

Lithium-Ion Battery Development[edit]

Early electric vehicles in the late 1800s used rechargeable lead-acid batteries invented by Gaston Planté in 1859. Advancements in battery technology increased lead-acid battery performance and charging rates, but their poor specific energy led to alternative solutions. Lighter batteries such as nickel-cadmium batteries were implemented in the 1960s, but lithium-ion batteries eventually became the modern-day standard due to their superior performance and low weight. [4] John B. Goodenough, M. Stanley Whittingham, and Akira Yoshino made discoveries that led to early commercial lithium-ion batteries and were awarded the Chemistry Nobel prize in 2019. Goodenough experimented with cobalt as a key component that is still used today. Yoshino used petroleum coke in place of lithium metal, greatly increasing stability. Scientists today seek to make lithium-ion batteries safer, longer-lasting, increase energy density. [5] In 2008, the Tesla Roadster was the first electric vehicle to use lithium-ion batteries and the first to have a range over 200 miles. [6]

Fundamentals of Lithium-Ion Battery[edit]

Components[edit]

A lithium-ion battery consists of an anode, cathode, electrolyte, separator, and two current collectors (positive and negative). The anode and cathode store the lithium; the cathode releases lithium ions when the battery is charging while the anode releases them when discharging. The electrolyte is a liquid that serves as a transporter of lithium ions. The separator allows for the ions to flow freely from the anode to the cathode and vice versa. The positive current collector receives electrons from the circuit during discharging while the negative current collector receives the electrons during charging. [7]

In terms of materials, the cathode consists of a layered oxide, usually containing cobalt and nickel because of their high stability. However, cobalt is toxic and the mining of it is fraught with human rights violations. The anode is usually made of lithium which has good charge density but has problems with cycling and short circuiting. The electrolyte has many variations but the best performing solvents are flammable and pose safety risks. [8]

Chemistry[edit]

Lithium-ion batteries are the most common battery in EV due to their high power to weight ratio. There are many different derivatives of lithium-ion batteries, each with varying cathode materials to increase efficiency, power output, and lifetime. Currently the most common lithium-ion batteries are Lithium-Nickel-Manganese-Cobalt-Oxide (NMC), Lithium-Nickel-Cobalt-Aluminum-Oxide (NCA), and Lithium-Manganese-Oxide (LMO). The Chevy Bolt uses an NMC battery with a total capacity of 60 kWh. The Tesla Model 3 uses an NCA battery with added Manganese for increased efficiency that stands at 75 kWh capacity. [9] The Nissan Leaf and BMWi3 both use a combination of LMO and NMC to optimize performance and their capacities are 30 kWh and 42 kWh respectively. [10] [11] [12]

The manganese component of a LMO battery has very good thermal stability, which improves the batteries’ safety. It offers high discharge/recharge rates but has a lower capacity and lifetime. [13] NMC batteries are designed for high specific energy or power with high density. [10] These batteries are usually made with the cathode with a 1-1-1 ratio of nickel, manganese, and cobalt, but this ratio can vary between manufacturers. [13] NMC batteries are often combined with LMO and the combination results in a battery with high power (LMO) and long driving range (NMC). [10] NCA batteries have similar properties to NMC batteries, offering high specific energy and power and a long lifespan. However, it is not as safe as other battery types and more costly to manufacture. [10]

Environmental Impacts[edit]

Production[edit]

The Congo produces 60% of the worlds’ cobalt. Although the majority comes from large strip mines, 10 - 25% of the global cobalt production comes from the Congo’s artisanal mines. [14] Because of the lack of regulation and quantity of artisanal mines in the Congo, heavy metal contamination is widespread even in areas outside of mining districts. Cobalt is often found with other toxic heavy metals, such as lead and cadmium, which leach into waterways and the atmosphere when brought up to the surface. There is a lack of research on the long-term health effects of cobalt exposure; however, current studies found the urinary concentrations of cobalt of individuals living near the mines to be 43 times more than the average US citizen, the highest ever reported concentrations. [15] With the global demand for cobalt increasing, heavy metal concentrations are expected to rise and its consequences to become apparent. Eighty percent of the global lithium supply is located in Argentina, Bolivia, and Chile: the ABC’s of lithium. To mine the “white gold”, miners pump brine into sectioned out portions of the salt flats that contain lithium. The water dries over a few months and the concentrated liquid is pumped to processing plants. [16]

The water for the brine comes from aquifers underneath the desert region, which greatly strain the local groundwater supply. It takes roughly 500,000 gallons per tonne of lithium produced, consisting of 65% of the water usage for the Salar de Atacama: Chile’s most important region for lithium mining. [17] As water is pumped out the aquifers more than it can be recharged, conflicts over water use have developed as local farmers struggle to raise animals due to the declining meadows. [18]

Disposal[edit]

Due to the complexity and weight of Lithium-Ion batteries in electric vehicles, most battery maintenance is done at dealerships. The centralized management allows for proper collection of spent batteries for disposal. Even though they are considered “spent”, the batteries still maintain 70-80% of their charge. They are often repurposed by their respective car manufacturers for various projects such as backing up data centers and powering street lamps. Recycling batteries is not currently economical because using raw materials for batteries is cheaper than recycled materials (5x cheaper for lithium). [19]

Life Cycle Analysis[edit]

Electric vehicles are more harmful to the environment than regular gasoline vehicles during production (a midsized electric vehicle produces 8.8tCO2e while a similar-sized gasoline car produces 5.6tCO2e). [20] However, gasoline produces more greenhouse gas emissions than typical grid power. Although coal burns dirtier than gasoline, it only makes up 27% of the US grid. Over 40% of the grid is powered by nuclear and renewable energy that produces very little to no greenhouse gasses. In 2018, an average electric vehicle produced the same amount of greenhouse gas emissions as a gasoline car getting 80MPG. [21] In the majority of the US, electric vehicles only take 2-3 years to match similar-sized gasoline cars in overall CO2 emissions. Since the average lifespan of cars is roughly 8 years, the vast majority of electric cars are more environmentally friendly than their gasoline counterparts.

Human Impacts[edit]

Cobalt Mines[edit]

Global cobalt sourcing is dominated by the Democratic Republic of Congo and is saturated with violence, corruption, and human rights abuse. Large-scale mines face problems with proper contracting and subcontracting documentation, while artisanal mines exploit child labor, have dangerous working conditions, and are often controlled by corrupt military forces. Even though high global demand for cobalt should be beneficial to the people of the Congo, government corruption led by president Joseph Kabila, in office from 2001-2019, money is taken away from the needy. Around 90% of cobalt mining is artisanal. While salary is lucrative in comparison to the national average, individual miners often dig deeper than 30 meters beneath the surface to find higher grade cobalt, leading to frequent cave-ins and landslides. The few women miners found in industry experience sexual abuse and lesser pay. [22] Unregulated and unsafe mining procedures leave big impacts on human health, including children as young as 4 years old. Exposure to cobalt particles results in "hard metal lung disease", a serious lung disease known as pneumoconiosis. Pneumoconiosis starts with shortness of breath and cough, but with long-time exposure and inadequate personal protective equipment (PPE), lung scarring and asthma can develop, leading to hypoxemia (low blood oxygen levels). Congolese miners are rarely provided with face masks, proper clothing, and gloves, which are the bare necessities. Not only does hazardous materials impact miners, but local water supplies and living areas have found to be contaminated with dust and toxic materials such as uranium. [23]

Claude Kebemba, executive director of Southern Africa Resource Watch seeking alternative means of work for artisanal miners, stated, "People know it’s very harsh conditions, to go underground, you either have to be on drugs or be drunk.” [24]

User Safety[edit]

Since lithium-ion batteries have flammable components, safety is a big concern for their many applications. Highly exothermic reactions can take place resulting in dangerous fires putting the lives of drivers, passengers, and firefighters at risk. External short circuits, internal short circuits, cell overcharging, cell over-discharging, physical damage, or exposure to high ambient temperatures can each potentially cause overheating of a cell and initiate thermal runaway events. [25]

Recent fires in EVs has sparked anxiety about the safety of these vehicles. Of the 14 known fires involving Tesla vehicles, the majority occurred after a collision, but there have been a growing number of blazes in which its products appear to spontaneously ignite. Three of the most recent cases were sedans catching fire while parked; investigations concluded they were due to thermal runaway. [26]

Future Developments[edit]

Technology[edit]

Advances in using different materials to increase efficiency, lifetime, and safety, while decreasing cost and environmental impact by phasing out cobalt are currently in progress to further develop lithium-ion batteries for EVs.

Li-air has huge potential to have energy densities comparable to gasoline, which would provide a Tesla Model S to have a range of 20,000 miles per charge. Only half of the battery materials are required to store the same amount of energy in the air medium and therefore can reduce the battery weight by up to 50%. However, there are problems with poor cycle life and low specific power at low temperatures. [27]

Li-S batteries are also promising for the future of EVs, due to the low cost of sulfur, Li-S batteries could be much less expensive than current batteries. [27] Sulfur is also environmentally benign compared to cobalt infused batteries. They also have high specific energies, and a high specific power. Drawbacks include low cycle life and stability issues. [8]

Policy[edit]

EV Everywhere is the umbrella effort of the U.S. Department of Energy to increase the adoption and use of plug-in electric vehicles. It was introduced in 2012 and its goal is to enable plug-in electric vehicles to be as affordable and convenient as gasoline-powered vehicles by 2022. [28] DOE R&D has reduced the cost of EV batteries by 50% in the last four years and investments topped $225 million to address key issues in EV deployment. [29] In Europe, the creation of a European Union Battery Alliance to support battery manufacturing is part of an effort to transition to clean mobility in the EU. The focus of this is to target innovation in cell chemistries, formats, and manufacturing technologies/processes. [30]

Conclusion[edit]

Just because something is "green" doesn't mean that it is inherently better. Although electric vehicles are better for the environment in CO2 emissions, the unmeasurable human impacts complicate the ability to compare gasoline and electric vehicles. Lithium-ion batteries should be looked at from a cradle-to-grave perspective, from the mining of the materials used in these batteries to emissions in production and use (emissions from charging from the often fossil-fuel powered grid) and finally the environmental impacts of disposal. A wholistic view of lithium-ion batteries is needed for a complete picture as to how they impact the planet.

References[edit]

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