Automotive Electrochemical Power Systems

Vehicular Batteries Are Widely Used; Vehicular Fuel Cells Are Widely Discussed All batteries contain the anodic reactant, but not necessarily the cathodic reactant, which can be O 2 In fuel cells, the anodic reactant is stored in an external reservoir The apparent, but not the true, power density of fuel cells is higher than that of batteries When the weight (or volume) of the reactant- reservoir, plumbing and fuel pumps are added, fuel cells loose their apparent advantage –The successful fuel-efficient hybrid cars have batteries, not fuel cells

Why GM Lost Market Share Because of the low taxation of gasoline in the US and its high taxation in Japan – While engineering-led Honda (with Sanyo) and Toyota (with Matsushita-Panasonic) engineered the nickel-metal hydride battery for hybrid cars, – Marketing-led GM aimed, through its Hy Wire/Sequel project, at sustaining its image as the advanced engineer, building a hydrogen fueled, fuel cell-powered dream car GM Hy-Wire PEFC car

GM’s Statement (Verbatim ) “While GM is serious about delivering innovative solutions for the environment and safety, we’re just as serious about performance. And we haven’t forgotten that cars should still be fun. People are passionate about driving. And nothing could be more fun to drive than the Sequel. Wheel hub motors deliver unprecedented torque and instant acceleration, providing a unique driving experience. As GM chairman and CEO Rick Wagoner puts it, “Sequel excites the driving enthusiast within us.” How’s that for reinvented?”

Problems of Vehicular H 2 /O 2 Fuel Cells Because of poor mass transport in the cold cell, starting and restarting require pre- heating Response to increase or decrease in power demand is slow Cost – the membrane, the platinum alloy catalyst, the seals and the containment are much too expensive There is no hydrogen fuel infrastructure

Electrode Reactions of the Hybrid Car Batteries Anode (metal-hydride) (LaNi 5 lattice structure) MH ↔ M + H + + e - M= (rare earth) (transition metal) 5 Transition metal= Ni 3.2 Co 1.0 Al 0.2 Mn 0.6 Cathode (hydrated nickel oxide with carbon) NiOOH + H + + e - ↔ Ni(OH) 2 Cell: Ni(OH) 2 + M ↔ NiOOH + MH

Design Principles of Hybrid Vehicle Battery Materials Cycle-life: To prolong the cycle life, only protons and electrons (hydrogen atoms) are added or stripped in the reduction/ oxidation cycles. Adding or stripping hydrogen atoms does not change the phase or the morphology Power density and rapid charging: High proton (hydrogen) permeability provides for rapid charging and discharging (i.e. power)

Current RD&E Objectives of the Hybrid & Electric Vehicle Consortia Lower the cost of the electrode materials Lighter electrodes for a higher energy density battery

A High Risk, High Payoff Research Option: An Air Cathode for a Vehicular Battery Proposed approach: Improve the efficiency, lessen the sensitivity to poisoning and reduce the cost of the O 2 -electroreduction catalysts by replacing the platinum alloys with nature-mimicking synthetic 3-Cu atom (or 3-Ag atom) cluster-based catalyst Impact: Air cathode would provide for a much lighter, much lower cost power system