Emerging Technologies in Transportation Casebook/Electric Vehicle Battery Developments

One of the first Porsches was an Electric Vehicle (EV) built sometime in 1889. Despite the vehicle's performance of 21 mph and a 49 mile range the EV did not out compete the gas powered vehicles. Porsche's batteries weighed some 1,110 pounds and availability of infrastructure for charging simply did not exist. It failed to capture the market because the energy source was not abundant. Today, society has embraced the EV as a potential solution for reduction in greenhouse gases (GHG) such as CO₂. We now debate the merits of providing public space for solar powered charging stations for EVs to charge while parked along city streets. At the heart of the discussion concerning the promise of EV is the battery. This case study is dedicated to discussing the advancements in battery technology for EVs and their associated political, environmental, and infrastructure barriers to widespread use.

LIST OF ACTORS

1. Consumers – The owner/operators of Electric Vehicles (EV).
2. Battery Manufacturers – Gigafactory (Tesla), Brownstown Battery Pack Assembly Plant (GM), Rockwood Holdings
3. EV Manufacturers- Tesla, GM, BMW, Mercedes, Porsche, Toyota, Volvo, Nissan, Ford
4. National Highway Transportation Safety Administration (NHTSA) – “NHTSA was established by the Highway Safety Act of 1970 and is dedicated to achieving the highest standards of excellence in motor vehicle and highway safety. It works daily to help prevent crashes and their attendant costs, both human and financial.”
5. Mining Industry - Sociedad Quimica y Minera (SQM), Western Lithium, Lithium Americas, FMC Corp, Talison Lithium Ltd., Rockwood Holdings
6. Wall Street – Lithium is trade as a commodity in the futures market.
7. Major Lithium Producing Countries – Chile, China, Bolivia, United States, Australia, Argentina, Portugal, Brazil, Zimbabwe, Russia

TERMINOLOGY

1. Range Anxiety – Consumer apprehension to purchase EV vehicles based on the limited distances the vehicle can travel based on a single charge.
2. Standardization – Common specification for charging equipment and battery pack design.
3. Minerals Extraction – Lithium, Sodium, Zinc, Copper, Cobalt
4. Oxidation/Reduction – a type of chemical reaction in a battery that creates electricity.
5. Electrolyte – typically an aqueous solution with positively and negative charged minerals such as sodium, lithium, Zinc, Oxygen, Sulfur, etc. The solution tends to be very caustic and harmful to organic tissue.
6. AC – Alternating Current
7. DC – Direct Current
8. Fast Charging – Usually refers to charging cycles of 30–90 minutes requiring 240 volt plug-ins.
9. Kilowatt Hours (kWh) – unit of measurement for energy usage and production.
10. Electrical shock protection – Grounding of vehicles to prevent electrocution.
11. EV Charging- EV charging has three categories, residential, work, & public. The infrastructure to build this is costly.
12. HEV – Hybrid Electric Vehicles like the Toyota Prius that do not plug into the electrical grid.
13. PEV/PHEV- “Plug-in electric vehicles (PEVs), which include battery electric vehicles (BEVs) and plug-in hybrid electric vehicles (PHEVs). The common feature of these vehicles is that their batteries are charged by being plugged into the electric grid. BEVs differ from PHEVs because they operate solely on electricity stored in a battery (that is, there is no other power source); PHEVs have internal combustion engines that can supplement the electric power train.”
14. SAE – Society of Automotive Engineers
15. Memory Effect – effect produced when a battery is improperly discharged or charged, wherein the battery ceases to discharge properly and gives improper voltage readings, so that full charging becomes sporadic. Long thought to not be a concern with lithium-ion batteries, a small effect was recently documented in them.
16. FMVSS - Federal Motor Vehicle Safety Standards are regulated by NHTSA.

POLICY ISSUES

Environmental Issues

EVs will affect increased demands for power generation from CO2 producing sources like natural gas and coal facilities. Consideration of alternative sources of electrical generation may need to be considered. Nuclear energy has costs that may outweigh the benefits, while renewables such as wind and solar are not developed enough to meet future needs. Additionally, they both have production gaps due to availability of the resource

Economic and Infrastructure Issues

Alternative revenue streams will be required to offset losses to Highway Trust Fund due to PHEV and PEVs. “Washington and Virginia have imposed special registration fees.” Other issues resulting from EV diffusion include the costs to fund the EV charging infrastructure required for optimization of the availability of electricity at peak times. Charging units will need to be placed in residences, at work, and in public areas including parking and in-road induction charge strips. Many strategies for this implementation have been identified to meet the growing demand for energy attributed to EVs.

International Harmonization of EV Battery Standards

Safety standards for the transport of Lithium and other toxic materials have been in place for a long time. Standardization of requirements for battery packs once installed are another matter. Standards that do exist vary from region to region. Exposure to electrolyte and toxic materials during an accident is a concern as is exposure to electrical discharges for emergency personnel and crash victims. Also, “Standardization of Charging Infrastructure is critical to standardize the many components of the charging infrastructure. Multiple plugs for fast chargers and the lack of standardization of payment methods for various charging networks are particularly problematic.”

NARRATIVE

EV Battery Types

Lithium Batteries

Modern rechargeable batteries are typically lithium ion. These batteries are characterized by a high voltage, high energy capacity, high drain rate, are low pollution and high safety due to a lack of heavy metals in the battery, have a high cycle life (around 1000-2000 charges for the dominant EV variety, LiNiMnCoO2, depending on depth of charge and temperature), low self-discharge, very low memory effect, and a fast charge rate.

Lithium-air

Lithium-air batteries have the potential for enhanced energy storage that could remove range anxiety as a consideration related to electric cars. They can be aqueous (in which case they can be acidic or alkanline) or nonaqueous. In the case of electric cars, nonaqueous batteries would be required (largely for density reasons), limiting the potential electrochemical reaction to the formation/decomposition of dilithium dioxide. They are very energy dense, as the material that makes up the cathode reaction is not stored in the battery itself but rather simply taken out of the air. Potential nonaqueous Li-air batteries could store 3-5 times as much energy as modern lithium-ion batteries, enough for a 300 mile drive, but ensuring their rechargability is crucial; many components currently do not allow for this on a practical level.

Lithium-sulfur

Lithium-sulfur batteries operate by converting lithium and sulfur to lithium sulfides. They also have the potential for greatly enhanced energy storage, with an estimated energy density in excess of 3000 Wh/kg. However, the discharge reaction products tend to dissolve in common, liquid organic electrolytes, and the cathode material's capabilities are limited To this end, phosphorus pentasulfide may be a promising compound to use as an electrolyte Should improvements occur, primarily in these two areas, the technology will become markedly more viable. They are further in development than lithium-air battery technology is, however

Sodium-ion (e.g. Sodium-sulfur)

Sodium-ion batteries, such as sodium-sulfur, originally were developed with systems that ran at very high temperatures for the express purpose of ensuring that the sodium ion remained dissolved in solution “so the electrodes remain...molten..., and so the battery convert[s] electrical energy to chemical potential..” According to Slater, Lee & Johnson, they “utilize solid ceramic electrolytes[, and possess] high energy density, [long life, and high efficiency]” but despite natural abundance and resulting low cost of sodium, they are expensive due to the costs associated with running them at high temperatures. Recent efforts have focused on forms that operate at ambient temperatures and in solid state environments

Flow Batteries

Flow batteries, or redox flow batteries, are comprised of three separate tanks. Two hold redox compounds in separate tanks; these compounds (electrolytes) are pumped to a third tank, where a medium in the center prevents them from mixing. Chemical energy from the pumping is then converted to electrical energy or potential energy (discharging and charging, respectively) upon reaction with one of the two electrodes on either side of the medium. One of their primary advantages is the fact that used electrolyte fluids can be easily replaced, combined with a lifespan of greater than 10 years . Among the major issues at play are low solubility; low energy density; the membrane not being 100% impermeable – leading to electrolyte mixing – and electrolyte quantity stability. Also, they require more additional parts relative to other types (e.g. pumps)

List of EVs and Ranges

Plugin cars

Environmental Realities

Widespread use of PHEVs, PEVs, and BEVs have the potential to reduce Green House Gas emissions worldwide. Some 14% of the worlds GHGs are attributed to motor vehicles burning fossil fuels. As the market for the EV increases many expect corresponding reduction in GHG production as motor vehicle numbers decline. Skeptics of these GHG reduction benefits quickly point out that any reductions attributable to EVs will be offset by production of the EVs and the increased power generation requirements needed for an EV fleet. This seems to be supported by the Energy Administration’s report that shows PEVs could double the energy requirements for the average household ranging from 3-19 kilowatts. However, a closer examination of the issue by Daniel J. Berger and Andrew D. Jorgensen, shows that issues lies with the type of power generation facility. The researchers point out that some 40% of all power generation in the U.S., as of 2011, comes from coal fired plants. Coal fire generation produces the some of the highest amounts of CO2, the primary GHG. In states where coal burning generation facilities operate, the PEVs do not operate with a net reduction in CO2. On the other hand, the study did show that PHEV vehicles in these coal burning states were able to operate with a net reduction in CO2. Hypothetically, generation facilities that burn coal will, therefore, need to use clean coal technologies to reduce CO2 emissions or be phased out in order to achieve the GHG emission targets. Clean coal technologies exist, but are costly, and have some environmental externalities of their own. This is perhaps the greatest policy issue surrounding the EVs because of the regulation needed to require CO2 scrubbing technologies. There is no easy answer, lower CO2 emission power generation alternatives such as wind, solar, natural gas, and nuclear all have impacts to the environment and varying levels of efficient energy production.

The pre-eminence of lithium based batteries in EVs presents another environmental reality. One that comes with impacts associated with any resource extraction industry including socio-geo-political ramifications. Lithium, like all natural resources, must be mined and processed for use. The potential exists for irreparable impacts to water based ecosystems like those found in Chile and Bolivia where the prized form of Lithium (Lithium Carbonate) are typically found. The “brine” mining process includes dewatering of lakes for dredge operation for collection of raw ore where it is usually processed (purified) for commercial use either on site or at another repository prior to shipping to markets in the U.S. The process used in mining has led to concern for environmental health of local communities due to contaminants getting into food and water supplies. This is not to say the extraction cannot be done safely. However, mining regulation varies from region to region and could be lacking in the poorest of countries.

Reclamation of lithium and other battery types is critical to the long term sustainability of the EV. Lithium battery reclamation is perhaps the most critical due to the growing demand for it. Secondly, finite lithium reserves supply many other industries including aviation, pharmaceuticals, glass, and other battery intensive tech industries involving cell phones and computers. Some reclamation processes have similar impacts on the environment as mining. The process of cleaning and repurposing the lithium in batteries can involve hydro metallic processing or "leaching" to extract metals from solution. Leaching facilities tend to be highly toxic and require regulation similar to mining.

As to the socio-geo-political issues, according the 2015 USGS Lithium reserves information, other sources of lithium occur around the world, just not in the quantities found in South America, particularly Bolivia. The top lithium reserves by country include Chile, China, Argentina, Australia, Portugal, Brazil, Bolivia, Portugal, United States, Russia, and Zimbabwe. It important to note that Russia is a top producer of Lithium but the reserves are not reported. Worldwide reserves total some 14 million metric ton. The overwhelming majority (75%) of the world wide reserves exist in South America. China also has large reserves as compared to the U.S. As a result, Lithium has been dubbed as the “new oil” due to the fact that the U.S. is the main user of lithium based products yet has some of the smaller reserves when compared worldwide.

Safety

Safety is a major concern due to the high capacity of EV batteries, regardless of battery chemistry. Such batteries operate with a much higher capacity and in more extreme conditions than personal electronics do. The National Renewable Energies Lab (NREL) notes that "High rates of both discharge and charge can occur at extreme temperatures...[and] fire safety is a primary concern. Batteries with flammable electrolytes present challenges when designing the safety of a vehicle's energy storage device...[particularly] for PHEV and EV applications where vehicles may be charged in confined garage spaces of private residences and commercial businesses.

NREL identifies thermal stability as the most important component that affects battery safety, and also points out that "batteries contain both an oxidizer (cathode) and fuel (anode [and] electrolye)...Combining fuel and oxidizer is rarely done due to the potential of explosion (other examples include high explosives and rocket propellant), which is why the state of charge is an important variable. Lower SOCs [reduce the potential of redox reactions occurring at each battery node]...However, if electrode materials are allowed to react chemically in an electrochemical cell, the fuel and oxidizer convert the chemical energy directly into heat and gas. Once started, this chemical reaction will likely proceed to completion...becoming a thermal runaway. Once thermal runaway has begun, the ability to quench or stop it is nil.

Liu, et al, further observes that batteries “are expected to operate without active cooling...[so] thermal management becomes more critical because the surface area/volume ratio...decreases with increasing battery, resulting in a lower heat transfer per unit rate of [irreversible] heat generation” Because of these risks, strenuous abuse tests are required to ensure that a battery design will not fail in this manner, regardless of the conditions that it is forced to operate under; NREL conducts tests related to “thermal (...stability, fire, storage temperature, rate of charge, [etc.])...electrical (...overcharge...short circuit, overdischarge, [etc.])...[and] mechanical abuse (...crush, penetration, drop, immersion, roll-over, vibration, and mechanical shock” Each battery type discussed previously shares some safety concerns. Flow batteries raise concerns of chemical handling and leakage, for example, while lithium-ion require advanced monitoring due to flammability However, flow batteries have several major advantages in safety over other types; as Wang, Li, & Yang point out, “the major constituent is a liquid...and the reactive materials are stored separately...A major catastrophe resulting from an internal shorting is very unlikely [because] the flowing electrolytes carry away the heat generated during the redox reaction...”

Conclusion

Lithium batteries dominate personal electronics and vehicles today. Future batteries are likely to be one of several types: lithium-air, lithium-sulfur, sodium-ion, or so-called “flow” batteries. Each has its advantages and disadvantages. Lithium sulfur batteries are high in energy density, but if the cathode (containing sulfur) is not prepared exactly right from a chemical standpoint, capacity loss and charge rate become major issues due to the low solubility of lithium sulfide in organic solvents and other intrinsic phenomenon. Further research is required to resolve these concerns, although the addition of other compounds, such as phosphorus pentasulfide, holds promise to resolve them. Sodium ion batteries have numerous advantages in the long term. Chief among them are the fact that sodium is far more abundant, and the extraction process and product more environmentally friendly. This means less ecological impact from mining the resources to manufacture batteries, limiting the amount of mining that must be done to extract the resources to manufacture the batteries. They also hold longer charges, and, should they be developed, would likely cost substantially less due to the greater abundance of the raw materials. However, the substantially greater size of the sodium ion means that, despite the similar chemistry of the sodium and lithium reactions, it is much harder to move the sodium ion in the reactions than the lithium ion. Current research is focused on resolving this particular issue.

DISCUSSION QUESTIONS

1. Will EV battery charging generate more or less CO2 than current levels?
2. What are the Infrastructure costs associated with expansion of electrical vehicles?
3. What happens when we run out of Lithium?

REFERENCES