Moli Energy (1990) Limited

Moli Energy Limited

Ballard Power Systems Corporation

E-one Moli Energy (canada) Limited

Her Majesty the Queen in Right of the Province of British Columbia As

David S Wainwright

David P Wilkinson

Jeffery R Dahn

Jean St-Pierre

Shanna Denine Knights

Jeffrey R Dahn

James A Stiles

Klaus Brandt

Wu Li

Keith Cheuklap Lee

Jared L Taylor

Huanyu Mao

An integrated fuel cell and pressure swing adsorption system is disclosed for operating a solid polymer fuel cell on an enriched reactant stream. The fuel and/or oxidant streams may be enriched; for example, air and reformate streams may be oxygen and hydrogen enriched, respectively. The system may advantageously combine periodic reversal of the reactant flows through the fuel cell with use of an integrated pressure swing adsorption system.

Integrated fuel cell and pressure swing adsorption system

In a solid polymer fuel cell series, various circumstances can result in a fuel cell being driven into voltage reversal by other cells in the series stack. For instance, cell voltage reversal can occur if that cell receives an inadequate supply of fuel (for example, fuel starvation). In order to pass current during fuel starvation, reactions other than fuel oxidation may take place at the fuel cell anode, including water electrolysis and oxidation of anode components. The latter may result in significant degradation of the anode. Such fuel cells can be made more tolerant to cell reversal by promoting water electrolysis over anode component oxidation at the anode. This can be accomplished by enhancing the presence of water in the anode catalyst layer through modifications to the anode structure or anode composition near or in the catalyst layer. For instance, water electrolysis during voltage reversal is promoted through the use of different or additional ionomer, polytetrafluoroethylene, or graphite in the anode catalyst layer, or through the use of certain sublayers between the anode catalyst layer and the anode substrate.

Fuel cell anode structures for voltage reversal tolerance

Rechargeable batteries based on the 'rocking chair' principle and alkali or alkaline earth insertion compounds are disclosed that employ aqueous electrolytes. Batteries of the invention can have energy densities comparable to conventional aqueous batteries. Embodiments of the invention include aqueous lithium ion batteries.

Aqueous rechargeable battery

After undergoing overcharge abuse, non-aqueous rechargeable lithium batteries can be left in a relatively hazardous state of charge, representing a safety concern with respect to subsequent thermal or mechanical abuse. Electrolyte additives which electrochemically form conductive polymers can be used to create a short circuit inside the battery as a result of overcharge abuse and automatically discharge the battery internally. The invention is particularly suitable for batteries equipped with electrical disconnect devices which cannot be discharged externally after the disconnect has activated. Aromatic compounds such as biphenyl are particularly suitable additives.

Polymerizable additives for making non-aqueous rechargeable lithium

Greater energy densities can be obtained in aqueous rechargeable batteries based on the `rocking chair` principle by the use of certain polymer insertion compounds as an electrode material. Aqueous lithium ion batteries using poly(carbon disulfide) polymer as an anode have energy densities comparable to nickel metal hydride batteries.

A novel battery construction which incorporates a disconnect safety device which is hydraulically activated by an increase in solid volume upon abusive overcharge of the battery to disconnect the cathode or anode. A rechargeable battery which comprises: (a) a Li.sub.x MO.sub.2 cathode wherein x, is equal to or less than 1.1, and M is Ni, Co, Mn or combinations thereof; (b) a carbonaceous anode; (c) an electrolyte of one or more lithium salts dissolved in one or more non-aqueous organic solvents; and (d) an internal disconnect device which activates by hydraulic means on overcharge.

Battery incorporating hydraulic activation of disconnect safety device

Nonaqueous electrolyte rechargeable cells may contain an excess of negative electrode material to improve the rechargeability. This excess of negative electrode material can form brittle alloys with noncorrosive current collector metals in positive electrodes at low cell voltages. The invention discloses that an excess of current collector material in the positive electrode directly opposite to the negative electrode improves the safety characteristics of the rechargeable cells during overdischarge and multiple voltage reversal abuses.

Electrode composition and design for high energy density cells

An electrode precursor for lithium batteries includes a layer of an electrochemically active particulate material and a binder. The binder is soluble in the cell electrolyte so that the electrolyte extracts the binder from the particulate material after assembly, leaving a particulate layer substantially devoid of binder. Thus, the binder does not significantly decrease electrical conductivity of the layer in the cell and does not impede the ionic access to the layer. The soluble binder may be present in the electrode precursor in an amount sufficient to protect particulate which would otherwise react with the atmosphere.

Electrochemical cells, electrodes and methods of manufacture

A battery cell and a method for preparing a battery cell are disclosed in which a substantially fixed volume container includes the cell components therein in voltaic relationship, with the cell components including an anode comprising lithium metal, a non-aqueous electrolyte and a cathode in a spatial relationship to the anode within the fixed volume container, wherein the cathode comprises cathode active material which upon discharge intercalates lithium and undergoes a phase transition to a distinct structural phase in which phase the cathode active material can reversibly operate and which phase provides a cathode expansion greater than the anode volume decrease upon discharge, and wherein the spatial relationship and the cathode expansion within the substantially fixed volume are sufficient to produce a compressive load on the anode which inhibits the formation of a porous deposit of exterior, irregularly oriented, amalgamated lithium grains on the anode when the cell is reversibly operated with the cathode in said phase.

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Vancouver, Canada

David S Wainwright