Prototype electric New Flyer transit bus powered by 120 kWh MHI MLiX Li-ion pack in operational testing in Manitoba, Canada
8 June 2012
An all-electric, battery-powered prototype demonstration bus under joint development by Mitsubishi Heavy Industries, Ltd. (MHI), the government of Manitoba, Manitoba Hydro, Red River College and New Flyer Industries Canada ULC has been completed and was recently unveiled in Manitoba, Canada. (Earlier post.) The bus will be demonstrated on the streets of Winnipeg over the next two years.
The 40-foot “E-Bus” is based on New Flyer’s 40-foot Xcelsior heavy-duty transit bus and is powered by a 120 kWh lithium-ion rechargeable battery pack developed by MHI. The $3-million electric bus project costs are split equally between the Government of Manitoba, Manitoba Hydro and Mitsubishi Heavy Industries.
The cells are MHI’s MLiX prismatic 50Ah, 3.7V cells (185 Wh-class). The MLiX batteries use lithium compound oxide (nickel, manganese, and cobalt) for the cathode material, along with a graphite anode, high-strength separator, electrolyte, and electrolyte additives to attain high voltage and high capacity, a high energy density to volume and weight, a high charge/discharge rate, and long life (3,500 cycles or more, 80% DOD @ 1C.)
Gravimetric energy density of the cells is 132 Wh/kg; volumetric energy density is 266 Wh/L.
The flat-plate stacked structure of the electrode achieves high charge/discharge rates, long life, and a high-level of safety by eliminating the stress difference generated at the inner/outer spiral electrode, and at small radius positions caused by electrode expansion/shrinkage, and the directional heat transfer (rolling direction only; seen in a spiral electrode), according to MHI.
MHI also makes a 20Ah cell using the same chemistry. The 50 Ah battery was designed to have a high energy density through the use of a conductive network with a proper dispersion of conductive materials, while the 20 Ah battery was designed to have a high power density for hybrid vehicles by reducing the internal resistance with an optimized electrode thickness.
Other steps taken to augment the capacity of the battery were adjusting the separator porosity, diffusing the lithium-ion in the electrolyte, and easing the insertion to the negative electrode through optimization of the conductive materials, electrolyte composition, and electrolyte additives.
The E-Bus project is being implemented under the Memorandum of Understanding (MOU) on Renewable Energy Development signed in December 2010 between the Government of Manitoba and MHI, under which the two parties agreed to collaborate towards realizing an advanced low-carbon society.
The agreement created the structure for a series of potential collaborative projects between Manitoba and MHI in eight areas: electrification of transportation and recharging infrastructure projects; battery-storage technologies; heat-pump technologies; advanced biofuels technologies; wind-energy technologies; energy-efficiency technologies and systems; solar technologies and silicon processing; and integrated energy production, storage and utilization demonstrations.
As the first step of the initiative, the partners have been working since April 2011 to develop and demonstrate a lithium-ion rechargeable battery-powered bus and recharging technology.
Going forward, the project will test the E-Bus’s compatibility in cold weather through actual operation. Also, it will contribute to the study of promoting electrification of transportation using electric powertrains such as lithium-ion rechargeable batteries, and establishment of recharging infrastructure, aiming to respond to the need for environmental burden reduction in the transportation field.
MHI views this project as a very important step for popularizing lithium-ion rechargeable batteries in the North American electric bus market, a market which the company expects to grow.
Daisuke Mukai et al. (2012) Development of Large High-performance Lithium-ion Batteries for Power Storage and Industrial Use. Mitsubishi Heavy Industries Technical Review Vol. 49 No. 1
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