STABLE ELECTROLYTE FOR LITHIUM AIR BATTERY AND LITHIUM AIR BATTERY INCLUDING THE SAME

Abstract

Provided are electrochemical cells that include a compound having the general formula

##STR00001##

wherein R.sub.1 is moiety associated with a lithium ion, X.sub.1 and X.sub.3 are unsubstituted methylene moieties, X.sub.2 and X.sub.4 are each independently selected from a substituted or unsubstituted methylene moiety, X is a substituted or unsubstituted C.sub.1-C.sub.10 alkylene moiety, arylene moiety or heteroarylene moiety, R.sub.2 is selected from Li, H, an alkyl moiety, or a heteroalkyl moiety, 0<m1, 0n1, and m+n=1.

Claims

1. An electrochemical cell, comprising: a cell container, containing therein a negative electrode, a positive electrode, and an electrolyte in electrochemical contact with negative and positive electrodes; and a compound having the formula ##STR00006## wherein R.sub.1 has a formula selected from ##STR00007## and further wherein X.sub.1 and X.sub.3 are each an unsubstituted methylene moiety, X.sub.2 and X.sub.4 are each independently selected from a substituted or unsubstituted methylene moiety, X is a substituted or unsubstituted C.sub.1-C.sub.10 alkylene moiety, arylene moiety or heteroarylene moiety, Pf is C.sub.1-C.sub.10 alkyl moiety, R.sub.2 is selected from Li, H, an alkyl moiety, or a heteroalkyl moiety, 0<m1, 0n1, and m+n=1, and the compound has an average molecular weight of about 1000 g/mol to about 1,000,000 g/mol.

2. The cell of claim 1, wherein the compound is located in the electrolyte.

3. The cell of claim 1, wherein the compound is located at an interface between the negative electrode and the electrolyte.

4. The cell of claim 1, wherein the compound is located at an interface between the positive electrode and the electrolyte.

5. The cell of claim 1, wherein an interfacial layer is formed on an electrode surface by the compound.

6. The cell of claim 5, wherein the interfacial layer is formed upon charging of the cell.

7. The cell of claim 5, wherein the interfacial layer is formed upon discharging of the cell.

8. The cell of claim 5, wherein the interfacial layer is formed upon assembling of the cell.

9. The cell of claim 5, wherein the interfacial layer is formed upon the filling of the cell container.

10. The cell of claim 1, wherein the negative electrode comprises carbon.

11. The cell of claim 10, wherein the negative electrode comprises a layered form of carbon.

12. The cell of claim 1, wherein the negative electrode comprises a metallic material.

13. The cell of claim 1, wherein the negative electrode comprises a negative electrode material capable of reversible Li insertion.

14. The cell of claim 13, wherein the negative electrode material is capable of reversible Li intercalation.

15. The cell of claim 1, wherein O.sub.2 serves as an electroactive material at the positive electrode.

16. The cell of claim 1, wherein the electrolyte consists essentially of the compound in a solid form.

17. The cell of claim 1, having an open circuit voltage of at least about 3.0 volts when charged.

18. The cell of claim 1, X.sub.2 and X.sub.4 are each independently selected from CH.sub.2, CHF, and CF.sub.2.

19. The cell of claim 1, wherein Pf is a C.sub.1-C.sub.10 fluoroalkyl moiety,

20. The cell of claim 19, wherein Pf is C.sub.1-C.sub.10 perfluoroalkyl moiety.

21. An alkali metal/air cell that includes a compound having the formula ##STR00008## wherein R.sub.1 has a formula selected from ##STR00009## and further wherein X.sub.1 and X.sub.3 are each an unsubstituted methylene moiety, X.sub.2 and X.sub.4 are each independently selected from a substituted or unsubstituted methylene moiety, X is a substituted or unsubstituted C.sub.1-C.sub.10 alkylene moiety, arylene moiety or heteroarylene moiety, Pf is C.sub.1-C.sub.10 alkyl moiety, R.sub.2 is selected from Li, H, an alkyl moiety, or a heteroalkyl moiety, 0<m1, 0n1, and m+n=1, and the compound has an average molecular weight of about 1000 g/mol to about 1,000,000 g/mol.

22. The cell of claim 21, wherein the cell is a lithium air cell.

23. A rechargeable cell, comprising: an anode for lithium ion insertion and deinsertion; a cathode comprising oxygen as a cathode active material; and a lithium ion conductive electrolyte disposed between the anode and the cathode, wherein the electrolyte comprises a compound having the formula ##STR00010## wherein R.sub.1 has a formula selected from ##STR00011## and further wherein X.sub.1 and X.sub.3 are each an unsubstituted methylene moiety, X.sub.2 and X.sub.4 are each independently selected from a substituted or unsubstituted methylene moiety, X is a substituted or unsubstituted C.sub.1-C.sub.10 alkylene moiety, arylene moiety or heteroarylene moiety, Pf is C.sub.1-C.sub.10 alkyl moiety, R.sub.2 is selected from Li, H, an alkyl moiety, or a heteroalkyl moiety, 0<m1, 0n1, and m+n=1, and the compound has an average molecular weight of about 1000 g/mol to about 1,000,000 g/mol.

24. The cell of claim 23, wherein the anode includes an anode active material that is capable of reversibly intercalating lithium ions.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0009] Overview and Definitions

[0010] The invention provides useful, novel and nonobvious electrochemical cells that include a chemical compound having a formula as generally described herein. The compound may include a moiety associated with a lithium ion, which may be dissociated upon interaction with a negative ion and/or upon application of an electrical potential

[0011] Before describing the invention in detail, it is to be understood that this invention, unless specifically noted to the contrary, is not limited to any particular cells, batteries, electrically powered device, or the like, as such may vary. In addition, numerous electrochemical cell configurations may be used to form embodiments described herein. It is also to be understood that the terminology used herein is for the purpose of describing particular embodiments only, and is not intended to be limiting.

[0012] In this specification and in the claims that follow, reference is made to a number of terms that are defined to have the following meanings, unless the context in which they are employed clearly indicates otherwise:

[0013] As used herein, the singular forms a, an, and the include both singular and plural referents unless the context clearly dictates otherwise. Thus, for example, reference to a battery comprising a cell includes one or more batteries that may include plurality of cells as well as a single battery consisting of a single cell, reference to a compound includes a combination of compounds as well as a compounds, and the like.

[0014] The term and/or when used in a list of items, refers to the any of the items singly or in combination, unless the context clearly dictates otherwise. For example, Z1, Z2 and/or Z3 refers to Z1, Z2, Z3, Z2 and Z3, Z1 and Z3, Z2 and Z3, or Z1, Z2, and Z3, or any permutation of the foregoing.

[0015] The terms anode and cathode are interchangeably used with the terms negative electrode and positive electrode, respectively.

[0016] The terms electronic, electronically, and the like are used in their ordinary sense and relate to structures, e.g., semiconductor microstructures, that provide controlled conduction of electrons, holes, or other charge carriers.

[0017] The term electrolyte is used herein to refer a material through which ions may, under an electric potential gradient, diffusion forces, and/or the like, migrate. Electrolytes may be solid, liquid and/or gaseous. Typically, an electrolyte exhibits high ionic conductivity and low electronic conductivity.

[0018] The term moiety is used in its ordinary chemical sense and refers to a part or functional group of a molecule. Similarly, the terms substituted, unsubstituted, methylene, X.sub.2, X.sub.4, X, independently selected, C.sub.1-C.sub.10, alkylene, arylene, hetero R.sub.1, R.sub.2, Li, H, and the like are to be interpreted in their ordinary chemical sense as well.

[0019] The terms substantial and substantially are used in their ordinary sense and mean of considerable importance or to a great or significant extent, but that trivial or insignificant counterexamples may be found. For example, a substantially solid-state battery is to be interpreted to mean a battery comprising entirely or consisting essentially of solid components, but that the battery does not have to exclude components that are entirely devoid of fluids as long as the operation of the battery is not hindered. In addition, a substantially stable compound for use in an electrochemical cell may mean a compound that is considered stable electrochemically and/or chemically given the electrochemistry within the cell under ordinary circumstances, but that the compound does not have to be completely stable when exposed to abusive or unintended operational conditions.

[0020] The term solution is used in its chemical sense and refers to one or more solutes in a solvent. A solution may be fluid or solid in nature. For example, a solid-state solution differs from a solid-state compound in that the crystal structure of the solvent remains unchanged by addition of the solutes and that the solution may remain in a single homogeneous phase.

[0021] The term stable, as in a stable compound, is generally used in its chemical and/or electrochemical sense and refers to something, e.g., a compound, that is not likely to change, fail, or undergo and undesirable chemical change that renders the invention completely inoperative.

[0022] An Exemplary Electrochemical Cell

[0023] In general, the invention provides an electrochemical cell in combination with the stable compounds described herein. Any of a number of electrochemical cell constructions may be used. Typically, the inventive cell includes a negative electrode, a positive electrode, and an electrolyte in electrochemical contact with the electrodes. In some instances, an anolyte may be provided that serves as a dual purpose, i.e., as both the anode and electrolyte. Similarly, a catholyte may be provided, in the alternative or in addition, that serves as both the cathode and the electrolyte.

[0024] The anode, cathode, and electrolyte are located within a cell container. Depending on the desired chemistry, the container may be sealed or be at least permeable to certain but not other electrochemical reactants. For example, when the invention takes the form of a lithium-air cell, the container may be constructed ensure that potentially undesirable compounds such as water, does not generate uncontrolled hydrogen gas.

[0025] A polyacrylate compound having the following general formula may be used.

##STR00004##

[0026] Typically, R.sub.1 has a formula selected from

##STR00005##

[0027] Also typically, X.sub.1 and X.sub.3 are each an unsubstituted methylene moiety, X.sub.2 and X.sub.4 are each independently selected from a substituted or unsubstituted methylene moiety, X is a substituted or unsubstituted C.sub.1-C.sub.10 alkylene moiety, arylene moiety or heteroarylene moiety, Pf is C.sub.1-C.sub.10 alkyl moiety, R.sub.2 is selected from Li, H, an alkyl moiety, or a heteroalkyl moiety, 0<m1, 0n1, and m+n=1, and/or compound has an average molecular weight of about 1000 g/mol to about 1,000,000 g/mol. Optionally, X.sub.2 and X.sub.4 are selected from CH.sub.2, CHF, and CF.sub.2, and/or Pf is a C.sub.1-C.sub.10 fluoroalkyl moiety, e.g., a perfluoroalkyl moiety. In some cases, the Li.sup.+ ions associated with polyacrylate compound can be substituted with H.sup.+, Na.sup.+, and/ or K.sup.+ ions

[0028] Typical, the compound is located within the cell container. For example, the compound may be located in the electrolyte. In addition or in the alternative, the compound may be located at an interface between the negative electrode and the electrolyte and/or at an interface between the positive electrode and the electrolyte.

[0029] In some instances, an interfacial interfacial layer may be formed on an electrode surface by the compound. The interfacial layer may be formed in any of a number of ways. For example, the interfacial layer may be formed upon charging and/or discharging of the cell. In addition or in the alternative, the interfacial layer may be formed upon assembling of the cell and/or upon the filling of the cell container.

[0030] The invention may be used with any of different anode materials. For example, the negative electrode may comprise carbon, optionally in a layered form, e.g., as a mesophase or graphitic carbon. In addition or in the alternative, a metallic material, e.g., metallic Li may be used. Optionally, the negative electrode material may be capable of reversible Li insertion and/or intercalation.

[0031] The electrolyte may comprise a fluid phase that includes a salt in solution. The fluid phase is more typically substantially aprotic, but electrolyte materials such as polyethylene oxide (PEO, also known as polyethylene glycol with terminal hydroxyl moieties from which H ions may be liberated) may be sparingly used. In any case, the fluid phase typically contains a salt or salt-like moieties that easily, dissociates positive ions such as H, Li, Na, and/or K. However, the electrolyte may, alternatively or additionally, be solid, liquid or gel. In some instances, a ceramic electrolyte may be used. The electrolyte may comprise or consist essentially of the ion-conductive polyacrylate material, as discussed above, which may not exhibit a high electronic conductivity.

[0032] The inventive cell typically has an open circuit voltage of at least about 3.0 volts when charged. However higher or lower voltages may occur depending on the specific chemistry involved

[0033] Numerous alternatives and equivalents exist which do not depart from the invention set forth above. For example, the cathode material may include a substance other than O.sub.2. For example, the invention may use a cathode material, the solid electrolyte material, an electronically conductive material and a binder. Cathode active materials suitable for a solid-state lithium battery are typically highly Li-conductive and exhibit a relative high voltage against metallic Li. In contrast, cathode materials may be ionically nonconductive but electronically conductive

[0034] Microstructurally similar materials used in known Li-ion electrochemical cells may be used here. For example, FeS.sub.2, MnO.sub.2, spinel LiMn.sub.2O.sub.4, LiCoO.sub.2, LiNiO.sub.2 may serve as electroactive cathode materials. Examples of electronically conductive materials for use in the cathode include acetylene black and graphitic materials. The cathode active material layer may also contain a binder. Exemplary binders include fluorine-containing polymers such as polytetrafluoroethylene (PTFE) and polyvinylidene fluoride (PVDF). Examples of current collector materials for the cathode layer include aluminum, nickel, iron, titanium and carbon.

[0035] The anode layer includes an anode material and optionally includes the solid electrolyte material, an electronically conductive material, and a binder material. Examples of the anode materials include but are not limited to metallic Li, alloys thereof, and metal active materials in combination with carbon active material. Examples of anode active material include metals such as In, Al, Si, and Sn. On the other hand, examples of the carbon active material include mesocarbon microbeads (MCMB), high orientation property graphite (HOPG), hard carbon and soft carbon.

[0036] The electronically conductive material and a binder used for the anode active material layer may be the same as or similar to those contained in the cathode layer. Exemplary anode current collector materials include copper, nickel and carbon.

[0037] Although the examples of embodiments described herein relate to room-temperature batteries, embodiments may be used in elevated temperature environments, e.g., human body temperature or greater. It should be apparent that liquid anode and cathode materials may be used as well.

[0038] It is to be understood that, while the invention has been described in conjunction with the preferred specific embodiments thereof, the foregoing description merely illustrates and does not limit the scope of the invention. For example, while the bulk of the disclosure focuses on Li or Li ion chemistry, the invention is not limited to Li batteries. The invention may be adapted for H, Na, or K chemistry. That is, the above-identified polyacylate polymer was tested with respect to K.sup.+ ions because neither K nor Li affects the stability of polyacylate structure. Thus, carrier ions such as Li, H, K and Na can be selected according to the battery system of interest, e.g., Li-Air, Na-Air, etc. In addition, the invention may be used to avoid detrimental dendritic growth. Furthermore, when a numerical range is recited, the range is to be interpreted to as if every number within the numerical range is individually recited. Other aspects, advantages, and modifications within the scope of the invention will be apparent to those skilled in the art to which the invention pertains.

[0039] All publications, patent applications, and patents mentioned herein are hereby incorporated by reference in their entireties to an extent consistent with the above disclosure.