Battery having a low output voltage

1. An electrochemical battery cell comprising an anode having a primary anode active material, a cathode having a primary cathode active material, and an ion-conducting electrolyte in ionic contact with said anode and said cathode, wherein the electrochemical battery cell has an initial output voltage, Vi, measured at 10% depth of discharge, from a lower limit of 0.3 volts to an upper limit of 0.8 volts, and a final output voltage Vf measured at a depth of discharge no greater than 90%, wherein a voltage variation, (Vi−Vf)/Vi, is no greater than ±10% and a specific capacity between Vi and Vf is no less than 100 mAh/g or 200 mAh/cm 3 based on the primary cathode active material weight or volume, and wherein said primary anode active material is selected from potassium (K), aluminum (Al), zinc (Zn), titanium (Ti), manganese (Mn), iron (Fe), vanadium (V), cobalt (Co), nickel (Ni), or a combination thereof, and wherein said primary cathode active material is selected from a metal oxide, metal phosphate, metal sulfide, or a metal or semi-metal different than said primary anode active material, and said metal or semi-metal in said cathode is selected from tin (Sn), bismuth (Bi), antimony (Sb), indium (In), tellurium (Te), phosphor (P), magnesium (Mg), aluminum (Al), zinc (Zn), titanium (Ti), manganese (Mn), iron (Fe), vanadium (V), cobalt (Co), nickel (Ni), selenium (Se), or a combination thereof.

2. The electrochemical battery cell of claim 1 , wherein said anode further contains graphene as a protective material.

3. The electrochemical battery cell of claim 2 , wherein said primary anode active material is embraced by graphene sheets or embedded in a graphene film, graphene paper, graphene mat, or graphene foam.

4. The electrochemical battery cell of claim 2 , wherein said graphene contains a pristine graphene material having less than 0.01% by weight of non-carbon elements or a non-pristine graphene material having 0.01% to 50% by weight of non-carbon elements, wherein said non-pristine graphene is selected from graphene oxide, reduced graphene oxide, graphene fluoride, graphene chloride, graphene bromide, graphene iodide, hydrogenated graphene, nitrogenated graphene, boron-doped graphene, nitrogen-doped graphene, chemically functionalized graphene, or a combination thereof.

5. The electrochemical battery cell of claim 1 , wherein said primary cathode active material is embraced by graphene sheets or embedded in a graphene film, graphene paper, graphene mat, or graphene foam.

6. The electrochemical battery cell of claim 3 , wherein said primary cathode active material is embraced by graphene sheets or embedded in a graphene film, graphene paper, graphene mat, or graphene foam.

7. The electrochemical battery cell of claim 3 , wherein said graphene film, graphene paper, graphene mat, or graphene foam in said anode, having said primary anode active material embedded therein, is connected to a first battery terminal tab to function as an anode current collector and there is no separate or additional anode current collector to support said graphene film, graphene paper, graphene mat, or graphene foam.

8. The electrochemical battery cell of claim 5 , wherein said graphene film, graphene paper, graphene mat, or graphene foam in said cathode, having said primary cathode active material embedded therein, is connected to a battery terminal tab to function as a cathode current collector and there is no separate or additional cathode current collector to support said graphene film, graphene paper, graphene mat, or graphene foam.

9. The electrochemical battery cell of claim 7 , wherein said graphene film, graphene paper, graphene mat, or graphene foam, in said cathode, having said primary cathode active material embedded therein is connected to a second battery terminal tab and there is no separate or additional cathode current collector to support said graphene film, graphene paper, graphene mat, or graphene foam in said cathode.

10. The electrochemical battery cell of claim 1 , further comprising an anode current collector supporting said anode or a cathode current collector supporting said cathode.

11. The electrochemical battery cell of claim 1 , wherein the specific capacity between Vi and Vf is no less than 200 mAh/g or 400 mAh/cm 3 based on the cathode active material weight or volume.

12. The electrochemical battery cell of claim 1 , wherein the specific capacity between Vi and Vf is no less than 400 mAh/g or 800 mAh/cm 3 based on the cathode active material weight or volume.

13. The electrochemical battery cell of claim 1 , wherein the specific capacity between Vi and Vf is no less than 1,000 mAh/g or 2,000 mAh/cm 3 based on the cathode active material weight or volume.

14. The electrochemical battery cell of claim 1 , wherein said primary anode active material is Al and the primary cathode active material is sulfur (S), a mixture of S and Se, or sulfur bonded to graphene surfaces and said electrolyte is selected from aqueous, organic, polymeric, or solid state electrolyte.

15. The electrochemical battery cell of claim 1 , wherein said metal oxide, metal phosphate, or metal sulfide is selected from a tin oxide, cobalt oxide, nickel oxide, manganese oxide, vanadium oxide, iron phosphate, manganese phosphate, vanadium phosphate, transition metal sulfide, or a combination thereof.

16. An electrochemical battery cell comprising an anode having a primary anode active material, a cathode having a primary cathode active material, and an ion-conducting electrolyte in ionic contact with said anode and said cathode, wherein the electrochemical battery cell has an initial output voltage, measured at 10% depth of discharge, from a lower limit of 0.3 volts to an upper limit of 0.8 volts, and a final output voltage Vf measured at a depth of discharge no greater than 90%, wherein a voltage variation, (Vi−Vf)/Vi, is no greater than ±10% and a specific capacity between Vi and Vf is no less than 100 mAh/g or 200 mAh/cm 3 based on the primary cathode active material weight or volume, and wherein said primary anode active material is selected from aluminum (Al), and wherein said primary cathode active material is selected from a metal oxide, metal phosphate, metal sulfide, an inorganic material, or a metal or semi-metal different than said primary anode active material and said metal or semi-metal in said cathode is selected from tin (Sn), bismuth (Bi), antimony (Sb), indium (In), tellurium (Te), phosphor (P), magnesium (Mg), aluminum (Al), zinc (Zn), titanium (Ti), manganese (Mn), iron (Fe), vanadium (V), cobalt (Co), nickel (Ni), sulfur (S), selenium (Se), or a combination thereof, and further wherein said electrolyte is selected from aqueous, organic, polymeric, or solid state electrolyte, not including ionic electrolyte.

17. The electrochemical battery cell of claim 16 , wherein said inorganic material is selected from carbon sulfur, sulfur compound, lithium polysulfide, transition metal dichalcogenide, a transition metal trichalcogenide, or a combination thereof.

18. The electrochemical battery cell of claim 1 , wherein said cathode further contains graphene as an electrochemical property modifier to said primary cathode active material wherein said graphene increases a cell specific capacity or increases or decreases a cell output voltage.

19. The electrochemical battery cell of claim 16 , wherein said cathode further contains graphene as an electrochemical property modifier to said primary cathode active material wherein said graphene increases a cell specific capacity or increases or decreases a cell output voltage.

20. The electrochemical battery cell of claim 18 , wherein said primary cathode active material is bonded to or physically supported by a surface of said graphene.

21. The electrochemical battery cell of claim 18 , wherein said graphene contain a pristine graphene material having less than 0.01% by weight of non-carbon elements or a non-pristine graphene material having 0.01% to 50% by weight of non-carbon elements, wherein said non-pristine graphene is selected from graphene oxide, reduced graphene oxide, graphene fluoride, graphene chloride, graphene bromide, graphene iodide, hydrogenated graphene, nitrogenated graphene, boron-doped graphene, nitrogen-doped graphene, chemically functionalized graphene, or a combination thereof.

22. The electrochemical battery cell of claim 1 , wherein the voltage variation, (Vi−Vf)/Vi, is no greater than ±5%.

23. An electronic device containing the electrochemical battery cell of claim 1 as a power source.

24. The electronic device of claim 23 , which contains a sensor, an actuator, a wireless device, a wearable device, or a medical device electronically connected to said electrochemical battery cell.