Non-metal anode alkali and alkaline-earth ion batteries with hexacyanometallate cathode

Abstract

A battery structure is provided for making alkali ion and alkaline-earth ion batteries. The battery has a hexacyanometallate cathode, a non-metal anode, and non-aqueous electrolyte. A method is provided for forming the hexacyanometallate battery cathode and non-metal battery anode prior to the battery assembly. The cathode includes hexacyanometallate particles overlying a current collector. The hexacyanometallate particles have the chemical formula A.sub.nA.sub.mM1.sub.xM2.sub.y(CN).sub.6, and have a Prussian Blue hexacyanometallate crystal structure.

Claims

1. A method for forming a non-metal battery anode, the method comprising: providing a dried non-metal electrode powder; mixing the dried non-metal electrode powder with a binder and an electronic conductor powder in a low boiling point solvent selected from a group consisting of amyl acetate, acetone, diethyl carbonate, dimethyl carbonate, and n-methyl-2-pyrrolidone (NMP); forming a paste; coating a metal current collector with the paste, forming an anode; drying the paste; soaking the anode in a first organic electrolyte including a salt with metal ions; accepting a first electric field in the electrolyte between the anode and a metal first counter electrode; in response to the first electric field, forming a metal ion-containing solid electrolyte interphase (SEI) layer overlying the anode; subsequent to forming the metal ion-containing SEI layer, accepting a second electric field, opposite in polarity to the first electric field between the anode and the first counter electrode; and, removing metal ions from the anode while maintaining the metal ion-containing SEI layer intact.

2. The method of claim 1 wherein soaking the anode in the first organic electrolyte includes the metal ions being selected from a group consisting of Na, K, Mg, and Ca; and, wherein accepting the first electric field includes accepting the electrolyte between the anode and a first counter electrode with the selected metal ions.

3. The method of claim 1 wherein forming the metal ion-containing SEI layer overlying the anode includes forming the metal ion-containing SEI layer with additional elements selected from a group consisting of carbon, oxygen, hydrogen, and combinations of the above-mentioned elements.

4. The method of claim 1 wherein soaking the anode in the first organic electrolyte includes soaking in a first organic electrolyte with A cations selected from a group consisting of Na, Ka, Mg, and Ca; wherein accepting the first electric field includes accepting the first electric field between the anode and a metal first counter electrode additional with the selected A cations; and, wherein forming the metal ion-containing SEI layer includes additionally forming the anode from a composite with the selected A cations.

5. A method for forming a non-metal battery anode, the method comprising: providing a non-metal anode soaked in an organic electrolyte including a salt with metal ions; accepting a first electric field in the electrolyte between the anode and a metal first counter electrode; in response to the first electric field, forming a metal ion-containing solid electrolyte interphase (SEI) layer overlying the anode; subsequent to forming the metal ion-containing SEI layer, accepting a second electric field, opposite in polarity to the first electric field between the anode and the first counter electrode; and, removing metal ions from the anode while maintaining the metal ion-containing SEI layer intact.

6. The method of claim 5 wherein soaking the anode in the first organic electrolyte includes the metal ions being selected from a group consisting of Na, K, Mg, and Ca; and, wherein accepting the first electric field includes accepting the electrolyte between the anode and a first counter electrode with the selected metal ions.

7. The method of claim 5 wherein forming the metal ion-containing SEI layer overlying the anode includes forming the metal ion-containing SEI layer with additional elements selected from a group consisting of carbon, oxygen, hydrogen, and combinations of the above-mentioned elements.

8. The method of claim 5 wherein soaking the anode in the first organic electrolyte includes soaking in a first organic electrolyte with A cations selected from a group consisting of Na, Ka, Mg, and Ca; wherein accepting the first electric field includes accepting the first electric field between the anode and a metal first counter electrode additional with the selected A cations; and, wherein forming the metal ion-containing SEI layer includes additionally forming the anode from a composite with the selected A cations.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 depicts the framework for an electrode material with large interstitial spaces in a metal-ion battery (prior art).

(2) FIG. 2 demonstrates the crystal structure of Prussian blue and its analogues (prior art).

(3) FIG. 3 is a partial cross-sectional view of a battery with a hexacyanometallate cathode and non-metal anode.

(4) FIG. 4 is a partial cross-sectional schematic view of a Na-ion battery in the discharge state, with a Na.sub.xM.sub.1M.sub.2(CN).sub.6 positive electrode and a non-metal negative electrode separated by a Na.sup.+-ion permeable membrane.

(5) FIGS. 5A through 5C depict three types of battery configurations.

(6) FIG. 6 is a flowchart illustrating a method for forming a hexacyanometallate battery cathode.

(7) FIG. 7 is a flowchart illustrating a method for forming a non-metal battery anode.

DETAILED DESCRIPTION

(8) FIG. 3 is a partial cross-sectional view of a battery with a hexacyanometallate cathode and non-metal anode. The battery 100 comprises a cathode 102 with hexacyanometallate particles 104 overlying a current collector 106. The hexacyanometallate particles 104 have the chemical formula A.sub.nA.sub.mM1.sub.xM2.sub.y(CN).sub.6, and have a Prussian Blue hexacyanometallate crystal structure (see FIG. 2). The A cations may be either alkali or alkaline-earth cations. Likewise, the A cations may be either alkali or alkaline-earth cations. For example, the A and A cations may be Na.sup.+, K.sup.+, Mg.sup.2+, or Ca.sup.2+. Note: the A and A cations may be the same or a different material.

(9) M1 is a metal with 2+ or 3+ valance positions. Likewise, M2 is a metal with 2+ or 3+ valance positions. For example, the M1 and M2 metals may be Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ca, or Mg. The M1 metal may be the same metal as the M2 metal, or a different metal than the M2 metal.

(10) From the hexacyanometallate formula above, m is in the range of 0.5 to 2, x is in the range of 0.5 to 1.5, y is in the range of 0.5 to 1.5, and n is in the range of 0 to 2. In one aspect, the cathode hexacyanometallate particles 104 have the chemical formula A.sub.mM1.sub.xM2.sub.y(CN).sub.6, where n=0.

(11) The battery 100 further comprises an electrolyte 108 capable of conducting A cations 110. An ion-permeable membrane 112 separates a non-metal anode 114 from the cathode 102. Some examples of anode materials include carbonaceous materials, oxides, sulfides, nitrides, silicon, composite material including metal nanoparticles with carbonaceous materials, and silicon nanostructures with carbonaceous materials. The electrolyte 108 may be a non-aqueous, organic, gel, polymer, solid electrolyte, or aqueous electrolyte.

(12) In one example of the battery, the A cations are Na.sup.+ cations, the ion permeable membrane 112 is a Na.sup.+-ion permeable membrane, and the electrolyte 108 is a Na.sup.+ soluble non-aqueous electrolyte. The general expression for the cathode may be: Na.sub.2M.sub.1M.sub.2(CN).sub.6, NaM.sub.1M.sub.2(CN).sub.6, NaKM.sub.1M.sub.2(CN).sub.6, or M.sub.1M.sub.2(CN).sub.6. M.sub.1, M.sub.2=Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ca, Mg, etc. The ratio of M.sub.1 and M.sub.2 can be an arbitrary number. For example: Na.sub.2Fe.sub.2(CN).sub.6, NaFe.sub.2(CN).sub.6, NaKFe.sub.2(CN).sub.6, and Fe.sub.2(CN).sub.6.

(13) In another example, the A cations are K.sup.+ cations, the ion permeable membrane 112 is a K.sup.+-ion permeable membrane, and the electrolyte 108 is a K.sup.+ soluble non-aqueous electrolyte. The general expression for the cathode materials may be: K.sub.2M.sub.1M.sub.2(CN).sub.6, KM.sub.1M.sub.2(CN).sub.6, NaKM.sub.1M.sub.2(CN).sub.6, or M.sub.1M.sub.2(CN).sub.6. M.sub.1, M.sub.2=Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ca, Mg, etc. The ratio of M.sub.1 and M.sub.2 can be an arbitrary number. For example: K.sub.2Fe.sub.2(CN).sub.6, KFe.sub.2(CN).sub.6, and NaKFe.sub.2(CN).sub.6.

(14) In another example, the A cations are Mg.sup.2+ cations, the ion permeable membrane 112 is a Mg.sup.2+-ion permeable membrane, and the electrolyte 108 is a Mg.sup.2+ soluble non-aqueous electrolyte. The general expression for the cathode materials may be: MgM.sub.1M.sub.2(CN).sub.6, Mg.sub.0.5M.sub.1M.sub.2(CN).sub.6, or M.sub.1M.sub.2(CN).sub.6. M.sub.1, M.sub.2=Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ca, Mg, etc. The ratio of M.sub.1 and M.sub.2 can be an arbitrary number. For example: MgFe.sub.2(CN).sub.6, Mg.sub.0.5Fe.sub.2(CN).sub.6, or Fe.sub.2(CN).sub.6.

(15) If the A cations are Ca.sup.2+ cations, the ion permeable membrane 112 is a Ca.sup.2+-ion permeable membrane, and the electrolyte 108 is a Ca.sup.2+ soluble non-aqueous electrolyte. The general expression for the Ca-ion battery is the same as the Mg-ion battery, just replacing Mg with Ca in the formulas above.

(16) In one aspect, the cathode hexacyanometallate particles 104 have the chemical formula A.sub.nM1.sub.xM2.sub.y(CN).sub.6, where m=0. The anode 114 includes A cations, and the ion-permeable membrane 112 is permeable to A cations. More explicitly, the ion-permeable membrane 112 is permeable to the A cations used in the anode 114. As used herein, an anode is defined as being a non-metal anode if it is a composite material that includes a metal.

(17) Thus, sodium-ion, potassium-ion, magnesium-ion, and calcium-ion batteries are disclosed with positive (cathode) electrodes of A.sub.xM.sub.1M.sub.2(CN).sub.6, negative (anode) electrodes of a non-metal material, an ion-permeable membrane separating the cathode and anode, and an electrolyte. The material, A.sub.xM.sub.1M.sub.2(CN).sub.6, demonstrates a framework that consists of a M.sub.1-NC-M.sub.2 skeleton and large interstitial space as shown in FIG. 2. M.sub.1 and M.sub.2 are the same or different metal ions (M.sub.1, M.sub.2=Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ca, Mg, etc.) and their ratio can be an arbitrary number. A-ions (Na, K, Mg and Ca) can easily and reversibly move in the interstitial space. The anode is a non-metal material. It can be one of carbonaceous materials, oxides, sulfides or nitrides. In order to obtain a high voltage for the battery, a non-aqueous electrolyte, such as organic electrolyte, gel electrolyte, polymer electrolyte, solid electrolyte, etc., may be used in the battery.

(18) FIG. 4 is a partial cross-sectional schematic view of a Na-ion battery in the discharge state, with a Na.sub.xM.sub.1M.sub.2(CN).sub.6 positive electrode 102 and a non-metal negative electrode 114 separated by a Na.sup.+-ion permeable membrane 112. In order to obtain a high voltage, a Na.sup.+ soluble non-aqueous solution 108, polymer, or solid electrolyte is used in the Na-ion battery. The non-metal negative electrode 114 is the carbonaceous material, oxide, sulfide, and so on. In the charge/discharge process, Na.sup.+ ions rock back and forth between the positive electrode 102 and negative electrode 114. Similarly, a K-ion battery would have of K.sub.xM.sub.1M.sub.2(CN).sub.6 positive electrode, a non-metal negative electrode, and a K.sup.+-ion permeable membrane separating the cathode and anode electrodes. The battery charge reactions at the cathode and anode are shown below.

(19) For sodium-ion battery, the positive electrode:

(20) Na.sub.xM.sub.1M.sub.2(CN).sub.6.fwdarw.xNa.sup.++M.sub.1M.sub.2(CN).sub.6+xe.sup.; and,

(21) the negative electrode:

(22) Na.sup.++e.sup.+.fwdarw.(Na); =non-metal negative electrode material.

(23) For potassium-ion battery, the positive electrode:

(24) K.sub.xM.sub.1M.sub.2(CN).sub.6.fwdarw.xK.sup.++M.sub.1M.sub.2(CN).sub.6+xe.sup.; and,

(25) the negative electrode:

(26) K.sup.++e.sup.+.fwdarw.(K); =non-metal negative electrode material.

(27) For magnesium-ion battery, the positive electrode:

(28) Mg.sub.xM.sub.1M.sub.2(CN).sub.6.fwdarw.xMg.sup.2++M.sub.1M.sub.2(CN).sub.6+2xe.sup.; and,

(29) the negative electrode:

(30) Mg.sup.2++2e.sup.+.fwdarw.(Mg); =non-metal negative electrode material.

(31) For calcium-ion battery, the positive electrode:

(32) Ca.sub.xM.sub.1M.sub.2(CN).sub.6.fwdarw.xCa.sup.2++M.sub.1M.sub.2(CN).sub.6+2xe.sup.; and,

(33) the negative electrode:

(34) Ca.sup.2++2e.sup.+.fwdarw.(Ca); =non-metal negative electrode material.

(35) In the discharge process, all reactions take place in the reverse direction.

(36) The positive electrode fabrication process flow is as follows. Dried A.sub.nM.sub.1M.sub.2(CN).sub.6 (A=Na, K, Mg, or Ca) powder with a particle size of 5 nm-1 m is mixed with binder, such as polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), etc., and an electronic conductor powder, in a low boiling point solvent to form a paste. The electronic conductor powder may be carbon black, carbon nanotube, carbon nanowire, grapheme, etc., with particle size of 5 nm-10 m. The A.sub.nM.sub.1M.sub.2(CN).sub.6 (A=Na, K, Mg, or Ca) powder contains crystal water even after the drying process. The water is not shown in the formula. The composition of the paste is 60 wt. %-95 wt. % A.sub.nM.sub.1M.sub.2(CN).sub.6, 0 wt. %-30 wt. % electronic conductor powder, and 1 wt. %-15 wt. % binder. The paste is coated on a metal foil or mesh (Al, Ti, etc.) that is used as the current collector for the positive electrode. After drying, the electrode undergoes forming process. The forming process includes two steps: the first step is to remove the ions (A.sub.n) and residual water from the A.sub.nM.sub.1M.sub.2(CN).sub.6 lattice. The second step is to fill Na-ions, K-ions, Mg-ions, or Ca-ions into the A.sub.nM.sub.1M.sub.2(CN).sub.6 lattice. The Na ions and K ions (Mg ions and Ca ions) occupy the A site and these ions are moved in/out of the A.sub.nA.sub.mM.sub.1M.sub.2(CN).sub.6 lattice during the discharge/charge cycles. Additional details of the 2-step forming process are provided in parent application entitled, ELECTRODE FORMING PROCESS FOR METAL-ION BATTERY WITH HEXACYANOMETALLATE ELECTRODE, invented by Yuhao Lu et al., Ser. No. 13/432,993.

(37) The forming process can be summarized as follows. For simplicity, it is assumed that the ions at the A site are all removed in the first step.

(38) In the first step:

(39) A.sub.nM.sub.1M.sub.2(CN).sub.6.fwdarw.nA+M.sub.1M.sub.2(CN).sub.6+ne.sup.;

(40) Residual water is removed: 2H.sub.2O=4H.sup.++O.sub.2+4e.sup..

(41) In the second step:

(42) M.sub.1M.sub.2(CN).sub.6+me.sup.+mNa.sup.+.fwdarw.Na.sub.mM.sub.1M.sub.2(CN).sub.6 (m1) for the sodium-ion battery; or,

(43) M.sub.1M.sub.2(CN).sub.6+me.sup.+mK.sup.+.fwdarw.K.sub.mM.sub.1M.sub.2(CN).sub.6 (m1) for the potassium-ion battery; or,

(44) M.sub.1M.sub.2(CN).sub.6+2me.sup.+mMg.sup.2+.fwdarw.Mg.sub.mM.sub.1M.sub.2(CN).sub.6 (m0.5) for the magnesium-ion battery; or,

(45) M.sub.1M.sub.2(CN).sub.6+2me.sup.+mCa.sup.2+.fwdarw.Ca.sub.mM1M.sub.2(CN).sub.6 (m0.5) for the calcium-ion battery.

(46) All steps are operated in a water-free environment. After the forming process, the electrode is ready for battery assembly.

(47) Note that the A ions in cathode material A.sub.nM.sub.1M.sub.2(CN).sub.6 before the forming process, and the A ions in A.sub.mM.sub.1M.sub.2(CN).sub.6 after forming process may be a different material. For example, K.sub.xM.sub.1M.sub.2(CN).sub.6 is used before the electrode forming process, and the materials change to Na.sub.xM.sub.1M.sub.2(CN).sub.6 or Na.sub.xK.sub.yM.sub.1M.sub.2(CN).sub.6 after forming process for a Na-ion battery application.

(48) The negative (anode) electrode is fabricated as follows. A dried non-metal negative electrode powder (e.g., carbonaceous material, oxides, or sulfides) is mixed with binder such as PTFE or PVDF, etc., and an electronic conductor powder (carbon black, carbon nanotube, carbon nanowire, grapheme, etc., with particle size of 5 nm-10 m) in low boiling point solvent to form a paste. The composition of the paste is 60 wt. %-95 wt. % non-metal anode, 0 wt. %-30 wt. % electronic conductor powder, and 1 wt. %-15 wt. % binder. The paste is coated on a metal foil or mesh (Cu, Ti, Ni, etc.) that is used as the current collector for the negative electrode. The negative electrode has a very low potential that can reduce the organic electrolyte to form an ion-permeable layer on the negative electrode so-called solid electrolyte interphase (SEI). The SEI improves the stability of the negative electrode in the ion battery. However, the reduction reaction exhausts the metal-ions (Na.sup.+, K.sup.+, Mg.sup.2+, or Ca.sup.2+) from the positive electrode, which decreases the capacity of the positive electrode. So a process of forming the electrode is applied to the negative electrode prior to the electrode slitting and battery assembly. The forming process is performed in a water-free environment. The negative electrode (anode) is paired with a counter metal-electrode (e.g., Na, K, Mg, Ca) in an electrochemical cell that includes an organic electrolyte with metal-ions (Na.sup.+, K.sup.+, Mg.sup.2+, Ca.sup.2+). Upon receiving the electrical field in the electrochemical cell that moves the metal ions toward the negative electrode, the metal-ions insert into or react with the negative electrode. At the same time, the electrolyte reacts with the negative electrode to form a SEI layer that contains metal ions, carbon, oxygen, and hydrogen on the negative electrode surface. Next, in the same electrochemical cell, an opposite electrical field is applied and the metal-ions are de-inserted from the negative electrode. However, the SEI layer is intact. For example, if a Na-ion battery is being formed, the counter electrode in made with Na, and the electrolyte includes Na ions. After the process, an-ion permeable inner layer forms on the electrode.

(49) FIGS. 5A through 5C depict three types of battery configurations. After the positive electrode and the negative electrode are prepared, the battery can be assembled. A membrane separates the positive and negative electrode. The membrane can be one of polymer, gel, or solid materials. The sandwich electrode assembly can be configured according to the container shape of the battery. The electrode assembly is put into a container. If a liquid solution is needed to help the ion transport, it can be injected into the container. After all the electrodes are thoroughly soaked in electrolyte, the container is sealed.

(50) An all-solid sodium ion-battery or potassium-ion battery, uses a different composition for the electrode fabrication. The all-solid ion battery consists of the positive electrode and the negative electrode separated by an ion-conduct solid electrolyte. For example, in the sodium-ion battery, -Al.sub.2O.sub.3, NaZr.sub.2(PO.sub.4).sub.3, Na.sub.4Zr.sub.2(SiO.sub.4).sub.3 and their derivates can be used as the Na.sup.+-ion solid electrolyte. In order to improve the ions transport in the electrode, the 5 wt. %-60 wt. % solid electrolyte powder can be added into the pastes of the positive electrode and the negative electrode to prepare the electrode. After obtaining the electrode, they can be assembled into a battery as described above.

(51) FIG. 6 is a flowchart illustrating a method for forming a hexacyanometallate battery cathode. Although the method is depicted as a sequence of numbered steps for clarity, the numbering does not necessarily dictate the order of the steps. It should be understood that some of these steps may be skipped, performed in parallel, or performed without the requirement of maintaining a strict order of sequence. Generally however, the method follows the numeric order of the depicted steps. The method starts at Step 600.

(52) Step 602 provides dried hexacyanometallate particles having a chemical formula A.sub.nM1.sub.xM2.sub.y(CN).sub.6 with a Prussian Blue hexacyanometallate crystal structure, including impurities and H.sub.2O. A is either an alkali or alkaline-earth cations, and M1 is a metal with 2+ or 3+ valance positions. Likewise, M2 is a metal 2+ or 3+ valance positions, n is in the range of 0.5 to 2, x is in the range of 0.5 to 1.5, and y is in the range of 0.5 to 1.5. For example, the A cations may be Na.sup.+, K.sup.+, Mg.sup.2+, or Ca.sup.2+. The M1 metal may be Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ca, or Mg for example. Likewise, the M2 metal may be Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ca, or Mg. The M1 may be the same metal as the M2 metal or a different metal than the M2 metal. The dried hexacyanometallate particles typically have a size in the range of 5 nm to 10 microns.

(53) Step 604 mixes the hexacyanometallate particles with a binder and electronic conductor powder in a low boiling point solvent. Some examples of low boiling point solvents include amyl acetate, acetone, diethyl carbonate, dimethyl carbonate, and n-methyl-2-pyrrolidone (NMP). The binder may be PTFE or PVDF, for example. Typically, the electronic conductor powder is carbon black, carbon nanotubes, carbon nanowire, or grapheme, having a particle size in the range of 5 nm to 10 microns.

(54) Step 606 dries the mixture, forming a A.sub.nM1.sub.xM2.sub.y(CN).sub.6 paste. In one aspect, the paste is 60 to 95 weight (wt) % A.sub.nM1.sub.xM2.sub.y(CN).sub.6, 0 to 30 wt % electronic conductor powder, and 1 to 15 wt % binder.

(55) Step 608 coats a metal current collector with the paste, forming a cathode. Step 610 dries the paste. Step 612 soaks the cathode in an organic first electrolyte including a salt with either alkali or alkaline-earth cations. Step 614 accepts a first electric field in the first electrolyte between the cathode and a first counter electrode. In response to the first electric field, Step 616 simultaneously removes A cations, impurities, and water molecules from interstitial spaces in the Prussian Blue hexacyanometallate crystal structure. Step 618 forms hexacyanometallate particles having a chemical formula of A.sub.nM1.sub.xM2.sub.y(CN).sub.6, where n<n, overlying the cathode.

(56) In one aspect, subsequent to forming A.sub.nM1.sub.xM2.sub.y(CN).sub.6 in Step 618, Step 620 soaks the cathode in an organic second electrolyte including a salt with A cations, where A is either an alkali or alkaline-earth cation. Typically, the A cations are Na.sup.+, K.sup.+, Mg.sup.2+, or Ca.sup.2+. The A cations may be the same material as the A cations or a different material than the A cations.

(57) Step 622 accepts a second electric field in the second electrolyte between the cathode and a second counter electrode including A elements. In response to the second electric field, Step 624 adds A cations into the interstitial spaces of the A.sub.nM1.sub.xM2.sub.y(CN).sub.6 crystal structure. Step 626 forms a cathode with hexacyanometallate particles having the chemical formula A.sub.nA.sub.mM1xM2y(CN).sub.6, where m is in a range of 0.5 to 2. In one aspect, Step 626 forms hexacyanometallate particles with the chemical formula of A.sub.mM1.sub.xM2.sub.y(CN).sub.6, where n=0.

(58) FIG. 7 is a flowchart illustrating a method for forming a non-metal battery anode. The method begins at Step 700. Step 702 provides a dried non-metal electrode powder. Step 704 mixes the dried non-metal electrode powder with a binder and an electronic conductor powder in a low boiling point solvent. Step 706 forms a paste. Step 708 coats a metal current collector with the paste, forming an anode. In Step 710 the paste dries. Step 712 soaks the anode in a first organic electrolyte including a salt with metal ions. Step 714 accepts a first electric field in the electrolyte between the anode and a metal first counter electrode. In response to the first electric field, Step 716 forms a metal solid electrolyte interphase (SEI) layer overlying the anode. In one aspect, the metal SEI layer additionally includes carbon, oxygen, hydrogen, and combinations of the above-mentioned elements.

(59) Subsequent to forming the SEI layer, Step 718 accepts a second electric field, opposite in polarity to the first electric field between the anode and the first counter electrode. Step 720 removes metal ions from the anode while maintaining the SEI layers intact.

(60) In one aspect, soaking the anode in the first organic electrolyte in Step 712 includes soaking in a first organic electrolyte with A cations such as Na, K, Mg, or Ca. Likewise, Step 714 uses a metal first counter electrode that additional includes the A cations used in Step 712. Then, Step 716 forms the anode from a composite that includes the A cations used in Steps 712 and 714.

(61) A battery with a hexacyanometallate cathode and non-metal anode has been provided with an associated cathode fabrication process. Examples of particular materials and process steps have been presented to illustrate the invention. However, the invention is not limited to merely these examples. Other variations and embodiments of the invention will occur to those skilled in the art.