Improved Electric Vehicle Powertrain Incorporating a Lithium-Ion Battery and a Range Extender Zinc-Air Battery, plus Associated Health and Economic Benefits

Abstract

As the world confronts the serious challenge posed by anthropogenic climate change, electric vehicles have emerged as a serious candidate to displace gasoline-burning vehicles. In spite of the environmental and operational advantages of electric vehicles, however, and in spite of billions in investment, electric vehicles have not attained meaningful market share in the main national vehicle markets. This is a serious problem not only for climate change mitigation but also for air pollution mitigation, given the substantial air pollution generated by vehicles. The inability of electric vehicles to attain market share may be due to the inadequacies of the lithium-ion batteries which power electric vehicles, and which are heavy and expensive.

In this work an electric vehicle with a novel powertrain is designed, optimized and modelled. The novel powertrain uses a lithium-ion battery as the primary energy storage system and a lighter and cheaper zinc-air battery as a range extender. The first objective of this work is to compare this novel powertrain to a conventional electric vehicle powertrain and quantify the benefits. The optimized two-battery electric vehicle achieves 400 km of range, over 12 years of zinc-air battery life and an MSRP of $26,300 – over $5000 lower than that of the conventional electric vehicle. As part of this work, it is necessary to create a zinc-air cell model based on academic literature, since there are no commercially available rechargeable zinc-air cells that are suitable for use in vehicles. The cell model achieved 10% greater specific energy to the lithium-ion cell at a much lower price. An improved cell model achieved even greater specific energy – 65% greater than the lithium-ion cell.

The second objective of this work is to analyze the air pollution impacts of electric vehicles in a local context. Specifically, the air pollution impact of increasing levels of electric vehicles on Highway 401 is simulated. Using Ontario Ministry of Transportation data for traffic flows on Highway 401, pollution modelling software and Transport Canada guidance it is estimated that pollution from Highway 401 costs $18.5M per year, and that replacing all the light passenger vehicles with electric vehicles could reduce these costs by 45.6%. The modelling demonstrates that NOx and PM2.5 are the costliest pollutants, and that PM2.5 experiences the least relative reduction in emissions with increased electric vehicle penetration.