Composite Anode Structure for Aqueous Electrolyte Energy Storage and Device Containing Same

• US 20140159668A1
• Filed: 08/21/2013
• Published: 06/12/2014
• Est. Priority Date: 12/12/2012
• Status: Active Grant

• Current Assignee: Aquion Energy, Inc. (Juline-Titans Holdings Group Co. LLC)
• Original Assignee: Aquion Energy, Inc. (Juline-Titans Holdings Group Co. LLC)
• Inventors: Whitacre, Jay, Mohamed, Alex, Shanbhag, Sneha, Polonsky, Andrew, Carlisle, Kristen
• Granted Patent: US 8,945,756 B2
• Time in Patent Office: Days
• US Class Current: 320/130
• CPC Class Codes: H01G 11/04 Hybrid capacitors
• CPC Class Codes: H01G 11/06 with one of the electrodes allowing ions to be reversibly doped thereinto, e.g. lithium ion capacitors [LIC]
• CPC Class Codes: H01G 11/28 arranged or disposed on a current collector; Layers or phases between electrodes and current collectors, e.g. adhesives
• CPC Class Codes: H01G 11/30 characterised by their material
• CPC Class Codes: H01G 11/32 Carbon-based
• CPC Class Codes: H01G 11/50 specially adapted for lithium-ion capacitors, e.g. for lithium-doping or for intercalation
• CPC Class Codes: H01G 11/60 characterised by the solvent
• CPC Class Codes: H01G 11/62 characterised by the solute, e.g. salts, anions or cations therein
• CPC Class Codes: H01M 10/44 Methods for charging or discharging circuits for charging H02J7/00
• CPC Class Codes: H01M 2004/027 Negative electrodes
• CPC Class Codes: H01M 2300/0002 Aqueous electrolytes
• CPC Class Codes: H01M 4/364 as mixtures
• CPC Class Codes: H01M 4/5825 Oxygenated metallic salts or polyanionic structures, e.g. borates, phosphates, silicates, olivines
• CPC Class Codes: H01M 4/583 Carbonaceous material, e.g. graphite-intercalation compounds or CFx
• CPC Class Codes: H01M 4/587 for inserting or intercalating light metals
• CPC Class Codes: H01M 4/625 Carbon or graphite
• CPC Class Codes: H01M 50/209 adapted for prismatic or rectangular cells H01M50/216 takes precedence
• CPC Class Codes: H01M 50/244 Secondary casings; Racks; Suspension devices; Carrying devices; Holders characterised by their mounting method
• CPC Class Codes: H01M 50/271 Lids or covers for the racks or secondary casings
• CPC Class Codes: H01M 50/289 characterised by spacing elements or positioning means within frames, racks or packs spacing elements inside cells other than separators, membranes or diaphragms H01M50/471
• CPC Class Codes: Y02E 60/10 : Energy storage using batteries
• CPC Class Codes: Y02E 60/13 : Energy storage using capacitors
• CPC Class Codes: Y02P 70/50 : Manufacturing or production processes characterised by the final manufactured product

Abstract

An anode electrode for an energy storage device includes both an ion intercalation material and a pseudocapacitive material. The ion intercalation material may be a NASICON material, such as NaTi₂(PO₄)₃ and the pseudocapacitive material may be an activated carbon material. The energy storage device also includes a cathode, an electrolyte and a separator.

Claims

1. An anode electrode suitable for an aqueous electrolyte energy storage device, the anode electrode comprising both an ion intercalation material and an electrochemical double layer capacitive and/or pseudocapacitive material.

2. The electrode of claim 1, wherein the ion intercalation material comprises a NASICON material able to reversibly intercalate and deintercalate alkali ions from the aqueous electrolyte.

3. The electrode of claim 2, wherein the electrochemical double layer capacitive and/or pseudocapacitive material comprises an activated carbon material.

4. The electrode of claim 2, wherein the NASICON material formula is A_xB_y(PO₄)₃, where A is an alkali ion, or combination of alkali ions, B is a multivalent metal ion, P is at least 80 atomic percent phosphorus, O is oxygen, 0.95≦

x≦

3.05, and 1.95≦

y≦

2.05.

5. The electrode of claim 4, wherein the NASICON material formula is AB_2±

δ

1(PO₄)<sub>3±

δ

2</sub>, where A comprises at least 5 atomic percent Na, B comprises at least 50 atomic percent Ti, and δ

1 and δ

2 each independently vary between zero and 0.05.

6. The electrode of claim 5, wherein the NASICON material is Na_xLi_(1-x)Ti₂(PO₄)₃, where 0.05≦

x≦

1 and the activated carbon has a surface area between 400 and 1500 m²/g.

7. The electrode of claim 6, wherein the anode electrode comprises a mixture of a NaTi₂(PO₄)₃ NASICON material and the activated carbon, the mixture having a NaTi₂(PO₄)₃:

activated carbon mass ratio ranging from 0.5;

9 to 9.5;

0.5.

8. The electrode of claim 1, wherein the anode electrode has a specific capacity of at least 50 mAh/g in aqueous electrolyte with alkali ions as functional ions.

9. The electrode of claim 1 wherein the anode has a physical and electrochemical stability of at least 500 cycles in which a state of charge swing is at least 75% without displaying any loss in energy storage function.

10. An energy storage device, comprising:

a plurality of electrochemical energy storage cells connected electrically in parallel or series, wherein each cell comprises;

a negative anode electrode of claim 1;

a positive cathode electrode;

a separator; and

an aqueous electrolyte,

wherein the charge storage capacity of the anode electrode is less than the charge storage capacity of the cathode;

wherein water in the electrolyte locally electrolyzes to form hydrogen and OH⁻

species at the anode electrode of at least one of the plurality of cells when the charge storage capacity of the ion intercalation material resident in the anode electrode is exceeded upon charging of the device; and

wherein alkali cation species from the electrolyte intercalate and deintercalate into and out of the NASICON material regardless of what kind of alkali species is resident in the NASICON material.

11. The device of claim 10, wherein:

the device comprises a hybrid energy storage device;

the cathode electrode in operation reversibly intercalates alkali metal cations; and

the anode electrode stores the hydrogen species capacitively or pseudocapacitively and stores the metal cations through a combination of ion intercalation and at least one of capacitive and pseudocapacitive storage.

12. The device of claim 11, wherein the double layer capacitive or pseudocapacitive material comprises an activated carbon material having an electrical resistivity greater than 0.001 ohm-cm and a surface area of 600-3000 m²/g as determined by the BET method, the intercalation material comprises NaTi₂(PO₄)₃, and in use, the activated carbon protects the NaTi₂(PO₄)₃ material from corrosion by gettering corrosive species comprising at least one of OH⁻

and hydrogen species that evolve during charging.

13. The device of claim 10, wherein the device comprises a plurality of cells grouped and connected in parallel, where the groups of parallel connected cells are then connected electrically in series with no cell-level battery management system.

14. The device of claim 10, wherein:

the storage capacity of the anode electrode available before water begins electrolysis at the anode electrode/electrolyte interface is 50-90% of the charge storage capacity of the cathode electrode;

a mass ratio of the anode electrode to the cathode electrode is less than 1; and

an ion storage capacity of the anode in mAh is less than an ion storage capacity of the cathode in mAh.

15. The device of claim 11, wherein:

the cathode electrode comprises a material having a formula A_xM_yO_z, where A is one or more of Li, Na, K, Be, Mg, and Ca, where x is within a range of 0 to 1, before use and within a range of 0 to 10, during use;

M comprises any one or more transition metals, where y is within a range of 1 to 3, and z is within a range of 2 to 7;

the anode electrode comprises a combination of activated carbon and NaTi₂(PO₄)₃; and

the electrolyte comprises one or more of 0.1 to 10 M SO₄²⁻

, NO₃⁻

, ClO₄⁻

, PO₄³⁻

, CO₃²⁻

, Cl⁻

, CH₃COO⁻

or OH⁻

anions, one or more of 0.1 to 10 M Na⁺, K⁺, Ca²⁺ or Mg²⁺ cations, and a pH of 4-10.

16. The device of claim 15, wherein the cathode electrode comprises a doped or undoped cubic spinel λ

-MnO₂-type material or a Na_0.44MnO₂ tunnel structured orthorhombic material, and the electrolyte comprises at least one of Na₂SO₄, Li₂SO₄, NaClO₄, LiClO₄, NaNO₃, LiNO₃, or MnClO₄ solvated in water.

17. The device of claim 15, wherein:

the cathode electrode comprises a doped or undoped cubic spinel LiMn₂O₄;

the electrolyte comprises at least one of Li₂SO₄, LiClO₄, LiNO₃, or MnClO₄ solvated in water; and

the electrolyte is sodium free and contains no solvated sodium ions, but contains one or more of Li, K, Ca, Mn, and Mg solvated cations.

18. The device of claim 11, wherein the cathode electrode comprises a material having a formula KMFe(CN)₆ and a Prussian blue type crystal structure, and the electrolyte comprises at least one of Na₂SO₄, K₂SO₄ or Li₂SO₄ solvated in water.

19. The device of claim 10, wherein:

the OH⁻

species increase a pH proximal to the anode electrode surface and wherein the increase in pH lowers the voltage stability window of the electrolyte locally, thereby reducing or eliminating further hydrogen evolution; and

the hydrogen species formed on charging of the at least one cell combines with the OH⁻

species upon discharging of the same at least one cell.

20. The device of claim 19, wherein at least a portion of the hydrogen species formed on charging of the at least one cell is stored in, on or at the anode electrode.

21. The device of claim 20, wherein the anode electrode further comprises a hydrogen storage material.

22. The device of claim 10, wherein:

a first cell of the plurality of cells in the device comprises a lower charge storage capacity as manufactured than a second cell of the plurality of cells in the device;

the first cell experiences overcharge and undercharge conditions during discharging and charging; and

the device lacks a cell level voltage monitoring and a current control circuit.

23. A method of operating the energy storage device comprising a plurality of electrically connected electrochemical energy storage cells, wherein each cell comprises a negative anode electrode comprising both an ion intercalation material and an electrochemical double layer capacitive and/or pseudocapacitive material, a positive cathode electrode, a separator, and an aqueous electrolyte,

the method comprising charging and discharging the plurality of electrochemical energy storage cells, wherein the electrochemical double layer capacitive and/or pseudocapacitive material protects the ion intercalation material from corrosion by gettering hydrogen species that evolve during the charging step.

24. The method of claim 23, wherein:

on charging, water in the aqueous electrolyte electrolyzes to form hydrogen and OH⁻

species at an anode electrode of at least one of the plurality of cells when a charge storage capacity of the anode electrode of the at least one cell is exceeded on charging the at least one cell, the OH⁻

species increase a pH proximal to the anode electrode surface, and the increase in pH lowers a voltage stability window of the electrolyte, thereby reducing or eliminating further hydrogen evolution; and

on discharging, the hydrogen species formed on charging of the at least one cell combines with the OH⁻

species.

25. The method of claim 24, wherein the steps of charging and discharging have a cycle time of greater than 1 hour, and wherein the step of charging comprises the storage device at a voltage 1.5 times greater or 0.8 volts higher than a voltage at which electrolysis of the water at the anode electrode is initiated under pH 7 conditions.

26. The method of claim 24, wherein the double layer capacitive and/or pseudocapacitive material comprises an activated carbon, the intercalation material comprises NaTi₂(PO₄)₃, and the activated carbon material protects the NaTi₂(PO₄)₃ material from the corrosion by gettering the hydrogen species that evolve during the charging step.

27. The method of claim 26, wherein during the steps of charging and discharging the NaTi₂(PO₄)₃ material reversibly intercalates and deintercalates alkali metal cations from the electrolyte and the activated carbon material undergoes a partial non-Faradaic charge transfer surface interaction with the alkali metal cations while also having an ability to store hydrogen species upon overcharge without substantial decrease in capacity over at least 100 cycles.

28. The method of claim 23, further comprising maintaining the plurality of electrochemical energy storage cells at temperatures ranging from 30 to 90°

C. during the steps of charging and discharging.

29. The method of claim 23, wherein the electrolyte is saturated with one or more of Na₂SO₄, Li₂SO₄, NaClO₄, LiClO₄, NaNO₃, LiNO₃ and MnClO₄ salts solvated in water such that no manganese ions dissolve into the electrolyte from the cathode during the steps of charging and discharging.

30. The method of claim 23, wherein:

the intercalation material comprises a NASICON material having a formula Na_xLi_(1-x)Ti₂(PO₄)₃, where 0.05≦

x≦

1;

the double layer capacitive and/or pseudocapacitive material comprises an activated carbon having a surface area between 400 and 1500 m²/g; and

during the charging step, the NASICON material intercalates at least one of Li, Na and K alkali cations from the electrolyte regardless of which alkali species is resident in the NASICON material depending on alkali cation availability in the electrolyte and intercalation affinity, such that one or more of Li, Na and K intercalate and reside in the host NASICON material structure to form a fully charged intercalation material that has a formula A₂Li_xNa_(1-x)Ti₂(PO₄)₃, where A is one or more of Li, Na and K.