Micro electrochemical energy storage cells

Abstract

Thin-film micro-electrochemical energy storage cells (MEESC) such as microbatteries and double-layer capacitors (DLC) are provided. The MEESC comprises two thin layer electrodes, an intermediate thin layer of a solid electrolyte and optionally, a fourth thin current collector layer; said layers being deposited in sequence on a surface of a substrate. The MEESC is characterized in that the substrate is provided with a plurality of through cavities of arbitrary shape, with high aspect ratio. By using the substrate volume, an increase in the total electrode area per volume is accomplished.

1. A thin-film micro-electrochemical energy storage cell (MEESC) in the form of a microbattery, said microbattery comprising:
 a substrate having two surfaces,    a thin layer anode consisting of alkali metal (M), alkali metal alloy or in the charged state consisting of lithiated carbon or graphite,    a thin layer cathode consisting of LiCoO 2 , LiNiO 2 , LiMn 2 O 4 , TiS 2 , V 2 O 5 , V 3 O 8  or lithiated forms of the vanadium oxides,    a solid electrolyte intermediate to said anode and cathode layers, consisting of a tin layer of an ionically conducting or electronically non-conducting material selected from glass, poly(ethylene oxide) based polymer electrolyte or polycrystalline material, and    optionally, a fourth current collector layer;    said anode or cathode layer being deposited in sequence on both surfaces of said substrate, said microbattery being characterized in that the substrate is provided with a plurality of through cavities of arbitrary shape, with an aspect ratio greater than 1, the diameter of said cavities being from about 15μ to about 150μ; said anode, cathode, solid electrolyte layers and optional current collector layer being also deposited throughout the inner surface of said cavities.    
     
     
       2. The microbattery of  claim 1 , wherein the substrate is made of a single crystal or amorphous material. 
     
     
       3. The microbattery of  claim 2 , wherein the substrate material is selected from the group consisting of glass, alumina, semiconductor materials for use in microelectronics and ceramic materials. 
     
     
       4. The microbattery of  claim 3 , wherein the substrate material is made of silicon. 
     
     
       5. The microbattery of  claim 1 , wherein the alkali metal (M) which forms the anode is lithium. 
     
     
       6. A lithium ion type microbattery according to  claim 1 , being fabricated in the discharge state where the cathode is fully lithiated and the alloy, carbon or graphite anode is not charged with lithium. 
     
     
       7. The microbattery of  claim 1 , wherein the through cavities of the substrate are formed by Inductive Coupled Plasma etching. 
     
     
       8. The microbattery of  claim 1 , wherein the through cavities of the substrate have an aspect ratio of between about 2 to about 50. 
     
     
       9. The microbattery of  claim 1 , wherein said cavities have a cylindrical geometry. 
     
     
       10. The microbattery of  claim 1 , wherein the solid electrolyte is a polymer electrolyte based on poly(ethylene oxide) and CF 3 SO 3 Li, (CF 3 SO 2 ) 2 NLi, or mixtures thereof. 
     
     
       11. The microbattery of  claim 1 , wherein the solid electrolyte is selected from Li x PO y N z  where 2<x<3, 2y=3z and 0.18<z<0.43, or LiS-SiS 2  glasses doped with up to 5% LiSO 4  or 30% LiI. 
     
     
       12. The microbattery of  claim 1 , wherein the solid electrolyte is a polymer electrolyte and it comprises between about 2 to about 15% (V/V) high surface area of inorganic, nanosize particles of ceramic powder which consists of Al 2 O 3 , SiO 2 , MgO, TiO 2  or mixtures thereof. 
     
     
       13. The microbattery of  claim 1 , wherein the solid electrolyte comprises Li 2 CO 3  doped with up to about 10% (% atomic weight relative to Li) of Ca, Mg, Ba, Sr, Al or B. 
     
     
       14. A self-powered semiconductor component comprising a microbattery according to  claim 2 . 
     
     
       15. A method for fabrication of an energy storage cell, comprising:
   providing a substrate having two surfaces and including a plurality of through cavities extending between said two surfaces; and        depositing thin film layers over said two surfaces and throughout an inner surface of said cavities, said thin film layers comprising an anode layer, a cathode layer, and an electrolyte intermediate to said anode and cathode layers.     
     
     
       16. The method according to  claim 15  and wherein said substrate comprises a single crystal substrate. 
     
     
       17. The method according to  claim 16  and wherein said single crystal substrate comprises a silicon substrate. 
     
     
       18. The method according to  claim 15  and wherein said substrate comprises an amorphous material. 
     
     
       19. The method according to  claim 15  and wherein said substrate comprises a material selected from the group consisting of glass, alumina, semiconductors and ceramic materials. 
     
     
       20. The method according to  claim 15  and wherein said anode layer comprises at least one material selected from the group consisting of an alkali metal, an alkali metal alloy, carbon and graphite. 
     
     
       21. The method according to  claim 20  and wherein said alkali metal comprises lithium. 
     
     
       22. The method according to  claim 15  wherein depositing said thin film layers comprises fabricating said thin film layers in a discharge state wherein said cathode layer is fully lithiated. 
     
     
       23. The method according to  claim 22  and wherein said metal alloy is not charged with lithium. 
     
     
       24. The method according to  claim 22  and wherein said carbon and said graphite are not charged with lithium. 
     
     
       25. The method according to  claim 15  and wherein said electrolyte comprises a polymer electrolyte. 
     
     
       26. The method according to  claim 15  and wherein said electrolyte comprises at least one material selected from the group consisting of glass, a polyethylene oxide based polymer, a polycrystalline material, ethylene carbonate ( EC ) , diethylcarbonate  ( DEC ) , dimethylcarbonate  ( DMC ) , ethyl methyl carbonate  ( EMC ) , butyl carbonate, propylene carbonate, vinyl carbonate, dialkylsulfites, LiPF   6   , LiBF   4   , LiAsF   6   , LiCF   3   , LiN ( CF   3   SO   2 ) 2   , LiI and LiBr.   
     
     
       27. The method according to  claim 15  and wherein said electrolyte is selected from Li x   PO   y   N   z    wherein  2 <x< 3 ,  2 y= 3 z and  0 . 18 <z< 0 . 43 , or LiS   2 - SiS   2    glasses doped with up to  5   %  LiSO   4    or  30   %  LiI.   
     
     
       28. The method according to  claim 15  and wherein said anode layer comprises a lithium metal foil. 
     
     
       29. The method according to  claim 15  and wherein said cathode layer comprises at least one material selected from the group consisting of LiCoO 2   , LiNiO   2   , LiMn   2   O   4   , TiS   2   , V   2   O   5   , V   3   O   13   , the lithiated form of V   2   O   5    and the lithiated form of V   3   O   13 . 
     
     
       30. The method according to  claim 15  and wherein depositing said thin film layers comprises depositing at least one PVDF- graphite layer on said cathode layer.   
     
     
       31. The method according to  claim 15  and wherein said anode layer and said cathode layer comprise carbon. 
     
     
       32. The method according to  claim 31  and wherein said electrolyte comprises a polymer electrolyte. 
     
     
       33. The method according to  claim 15  wherein depositing said thin film layers further comprises depositing a current collector layer. 
     
     
       34. The method according to  claim 33  and wherein said current collector layer is deposited over said anode layer, said electrolyte, and said cathode layer.