Electrochemical energy cell system

Abstract

A metal halogen electrochemical energy cell system that generates an electrical potential. One embodiment of the system includes at least one cell including at least one positive electrode and at least one negative electrode, at least one electrolyte, a mixing venturi that mixes the electrolyte with a halogen reactant, and a circulation pump that conveys the electrolyte mixed with the halogen reactant through the positive electrode and across the metal electrode. Preferably, the positive electrode comprises porous carbonaceous material, the negative electrode comprises zinc, the metal comprises zinc, the halogen comprises chlorine, the electrolyte comprises an aqueous zinc-chloride electrolyte, and the halogen reactant comprises a chlorine reactant. Also, variations of the system and a method of operation for the systems.

Description

BACKGROUND OF THE INVENTION[0001]1. Field of the Invention[0002]The present invention relates to metal halogen electrochemical energy systems.[0003]2. Related Art[0004]One type of electrochemical energy system uses a halogen component for reduction at a normally positive electrode, and an oxidizable metal adapted to become oxidized at a normally negative electrode during the normal dispatch of the electrochemical system. An aqueous electrolyte is used to replenish the supply of halogen component as it becomes reduced at the positive electrode. The electrolyte contains the dissolved ions of the oxidized metal and reduced halogen and is circulated between the electrode area and a reservoir area and an elemental halogen injection and mixing area, to be consumed at the positive electrode. One example of such a system uses zinc and chlorine system.[0005]Such electrochemical energy systems are described in prior patents including U.S. Pat. Nos. 3,713,888, 3,993,502, 4,001,036, 4,072,540, ...

AI Technical Summary

Benefits of technology

[0008]complexity and inefficiency of requiring active cooling systems during discharge, which can further reduce capacity;

[0013]mal-distribution of zinc metal from internal shunt currents between cells of differing potential further reduces available capacity;

[0014]a long length of small diameter channels required for minimizing shunt currents during operation further reduce system capacity due to pumping losses;

Problems solved by technology

There are certain weaknesses or disadvantages in prior electrochemical energy systems for standby applications.

These include, but are not limited to, the following:an inability to store sufficient energy without requirement to charge the system, precluding availability while in a discharged condition;complexity and inefficiency of requiring active cooling systems during discharge, which can further reduce capacity;ambiguities in diagnosing symptoms of failure, which can significantly increase a probability of failure; andhydrogen generation, which can be a significant and costly safety issue.

Specific weaknesses or disadvantages in prior metal halogen systems for standby applications also include, but are not limited to, the following:inability to maintain a state of readiness without significant capacity loss due to self-discharge;mal-distribution of zinc metal from internal shunt currents between cells of differing potential further reduces available capacity;a long length of small diameter channels required for minimizing shunt currents during operation further reduce system capacity due to pumping losses;metallic dendritic growth during the charge mode can permanently damage a metal halogen system and lead to premature and hazardous failure conditions.

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