Electrochemical systems with precipitated reactants and related methods

Patent metadata

Field	Value
Publication number	US-2020119384-A1
Application number	US-201916597329-A
Country	US
Kind code	A1
Filing date	Oct 9, 2019
Priority date	Oct 10, 2018
Publication date	Apr 16, 2020
Grant date	—

Abstract

Electrochemical apparatuses containing electrolytes that include redox-active reactants that may be present as both a dissolved species and as a solid during a charging and/or discharging process, and related methods are generally described. The redox-active reactant may contain an active species, and the electrolyte may contain a total concentration of the active species that is greater than if the redox-active reactant were completely dissolved during an entire charging and/or discharging process. The electrochemical apparatuses described may provide relatively high energy storage capacity.

First claim

1 . An electrochemical apparatus comprising:
a first electrolyte comprising a liquid solvent and a redox-active reactant, the redox-active reactant having a reduced state and an oxidized state and comprising an active species; wherein solubility of the redox-active reactant in the reduced state, and solubility of the redox-active reactant in the oxidized state are each greater than or equal to 0.1 M in the first electrolyte at 22.5° C., and wherein during a charging process and/or a discharging process of the electrochemical apparatus that causes interconversion between the reduced state and the oxidized state of the redox-active reactant, at least 10 mole percent of the active species in the first electrolyte is present as a solid.

2 . The electrochemical apparatus of claim 1 , wherein the liquid solvent is an aqueous solvent.

3 . The electrochemical apparatus of claim 1 , wherein the total concentration of active species in the first electrolyte is greater than or equal to 0.5 M.

4 . The electrochemical apparatus of claim 1 , wherein greater than or equal to 20 mole percent of the active species is present in the first electrolyte as a solid during the charging process and/or the discharging process.

5 . The electrochemical apparatus of claim 1 , wherein less than or equal to 90 mole percent of the active species is dissolved in the solvent of the first electrolyte during the charging process and/or the discharging process.

6 . The electrochemical apparatus of claim 1 , wherein the electrochemical apparatus can be charged and discharged reversibly.

7 . The electrochemical apparatus of claim 1 , wherein the first electrolyte is an anolyte.

8 . The electrochemical apparatus of claim 1 , wherein the first electrolyte is a catholyte.

9 . The electrochemical apparatus of claim 1 , wherein the redox-active reactant comprises a sulfur-containing compound.

10 . The electrochemical apparatus of claim 1 , wherein the redox-active reactant comprises a polysulfide.

11 . The electrochemical apparatus of claim 1 , wherein the reduced state of the redox-active reactant comprises S 2 2− or a salt thereof, and the oxidized state of the redox-active reactant comprises S 4 2− or a salt thereof.

12 . The electrochemical apparatus of claim 1 , wherein the active species of the redox-active reactant is sulfur.

13 . The electrochemical apparatus of claim 1 , wherein the redox-active reactant comprises vanadium, iodine, titanium, chromium, manganese, and/or iron.

14 . (canceled)

15 . The electrochemical apparatus of claim 1 , wherein the solid is a nonmetallic compound.

16 . The electrochemical apparatus of claim 1 , wherein the solid is an electronically insulating compound.

17 . The electrochemical apparatus of claim 1 , further comprising a first electrode in contact with the first electrolyte.

18 . The electrochemical apparatus of claim 1 , wherein the first electrode comprises a suspension of conductive particles, optionally comprising carbon.

19 - 25 . (canceled)

26 . The electrochemical apparatus of claim 1 , wherein the electrochemical apparatus is configured to operate as a flow battery cell.

27 - 34 . (canceled)

35 . A method of operating an electrochemical flow cell, comprising
charging and/or discharging the electrochemical flow cell, wherein the electrochemical flow cell comprises a first electrolyte comprising an aqueous solvent and a redox-active reactant, and wherein a portion, but not all of the redox-active reactant is present as a precipitate during at least a portion of either the charging or the discharging.

36 - 40 . (canceled)

41 . A method, comprising:
cycling an electrochemical apparatus having a cell potential of at least 0.35 V and a charge capacity of at least 70 Ah/L for at least 100 charge/discharge cycles, wherein the electrochemical cell comprises a redox-active reactant, and wherein a portion, but not all of the redox-active reactant is present as a precipitate during at least a portion of either the charging or the discharging.

Assignees

• Massachusetts Inst Technology

Inventors

• Chiang Yet-Ming
• Li Zheng
• Su Liang
• Pan Menghsuan Sam

Classifications

• H01M4/58

  of inorganic compounds other than oxides or hydroxides, e.g. sulfides, selenides, tellurides, halogenides or LiCoFy; of polyanionic structures, e.g. phosphates, silicates or borates · CPC title

• H01M8/08

  Fuel cells with aqueous electrolytes · CPC title

• H01M8/225

  Fuel cells in which the fuel is based on materials comprising particulate active material in the form of a suspension, a dispersion, a fluidised bed or a paste · CPC title

• H01M12/08

  composed of a half-cell of a fuel-cell type and a half-cell of the secondary-cell type · CPC title

• H01M4/96

  Carbon-based electrodes · CPC title