Electrochemical cells with tabs

Abstract

The present invention provides electrochemical cells and batteries having one or more electrically conductive tabs and carbon sheet current collectors, where the tabs are connected to the carbon sheet current collectors; and methods of connecting the tabs to the carbon based current collectors. In one embodiment, the electrically conductive tabs are metallic tabs.

1 . An electrochemical cell, said electrochemical cell comprising:
 a positive electrode comprising a positive electrode material and a positive electrode current collector, wherein the positive electrode material is in electronically conductive contact with the positive electrode current collector;   a negative electrode comprising a negative electrode material and a negative electrode current collector, wherein the negative electrode material is in electronically conductive contact with the negative electrode current collector;   an electronically insulative and ion conductive medium in ionically conductive contact with said positive electrode and said negative electrode, wherein said ionic conductive medium comprises an ion conductive layer and an electrolyte solution;   at least one positive electrode tab having a first attachment end and a second attachment end, wherein the first attachment end of said at least one positive electrode tab is connected to said positive electrode current collector;   at least one negative electrode tab having a first attachment end and a second attachment end, wherein said first attachment end of said at least one negative electrode tab is connected to said negative electrode current collector;   wherein the positive electrode current collector comprises a conductive non-metal substrate.   
     
     
         2 . The cell of  claim 1 , wherein the positive electrode current collector is a conductive carbon sheet selected from the group consisting of a graphite sheet, a carbon fiber sheet, a carbon foam, a carbon nanotube film and a mixture thereof, each of which has an in-plane electronic conductivity of at least 1000 S/cm; and wherein each of the tabs is made of an electrically conductive material. 
     
     
         3 . The cell of  claim 1 , wherein the in-plane electronic conductivity of the conductive carbon sheet is at least 2000 S/cm. 
     
     
         4 . The cell of  claim 1 , wherein the in-plane electronic conductivity of the conductive carbon sheet is at least 3000 S/cm. 
     
     
         5 . The cell of  claim 1 , wherein the positive electrode and the positive electrode tab form an interface, wherein the resistance of the interface is less than about 25 mOhm-cm 2 . 
     
     
         6 . The cell of  claim 1 , wherein the resistance of the interface is less than about 2.5 mOhm-cm 2 . 
     
     
         7 . The cell of  claim 1 , wherein said at least one positive electrode tab is a plurality of metal tabs attached to the positive electrode current collector. 
     
     
         8 . The cell of  claim 2 , wherein the positive electrode current collector, the negative electrode current collector or both comprise a graphite sheet. 
     
     
         9 . The cell of  claim 2 , wherein the positive electrode current collector, the negative electrode current collector or both are treated with a resin. 
     
     
         10 . The cell of  claim 2 , wherein the electrically conductive material is a metal selected from the group consisting of copper, nickel, chromium, aluminum, copper, titanium, stainless steel, gold, tantalum, niobium, hafnium, zirconium, vanadium, indium, cobalt, tungsten, tin, beryllium, and molybdenum and alloys thereof. 
     
     
         11 . The cell of  claim 1 , wherein the positive electrode materials are transition metal oxides, phosphates and sulfates, or a lithium insertion transition metal oxide having a formula selected from the group consisting of Li x MO 2 , M′ 2-y O 4 , LiV 2 O 5 , LiV 6 O 13 , Li x″ M″XO 4  and Y x′″ M′″ 2 (XO 4 ) 3 ,
 wherein:   M is a transition metal selected from the group consisting of Mn, Fe, Co, Ni, Ti, V and a combination thereof and the subscript x is a real number between about 0.01 and about 1;   M′ is a transition metal selected from the group consisting of Mn, Co, Ni, Ti, V and a combination thereof, the subscript x′ is between about −0.11 and 0.33 and the subscript y is a real number between about 0 and 0.33;   M″ is a transition metal selected from the group consisting of Fe, Mn, Co, Ni, and a combination thereof, X is selected from the group consisting of P, V, S, Si and a combination thereof and the subscript x″ is a real number between about 0 and 2;   Y is Li, Na or a combination thereof, M′″ is a transition metal selected from the group consisting of Fe, V, Nb, Ti, Co, Ni and a combination thereof, X is selected from the group consisting of P, S, Si, and a combination thereof and the subscript x′″ is a real number between 0 and 3; and   wherein the positive electrode materials are optionally doped with a metallic cation selected from Fe 2+ , Ti 2+ , Zn 2+ , Ni 2+ , Co 2+ , Cu 2+ , Mg 2+ , Cr 3+ , Fe 3+ , Al 3+ , Ni 3+ , Co 3+  or Mn 3+ .   
     
     
         12 . The cell of  claim 1 , wherein the positive electrode material is a positive electrode active material comprising phosphates, sulfates, a lithium insertion transition metal oxide selected from the group consisting of LiCoO 2 , spinel LiMn 2 O 4 , chromium-doped spinel lithium manganese oxide, xLi 2 MnO 3 (1−x)LiMO 2 , LiNi y Mn 1-y O 2 , LiMO 2 , LiNi x Co 1−x O 2  and vanadium oxide or LiMPO 4  or LiFeTi(SO 4 ) 3 ;
 wherein:   M is selected from Ni, Co or Mn;   M′ is selected from the group consisting of Fe, Ni, Mn and V; and   x and y are each independently a real number between 0 and 1.   
     
     
         13 . The cell  claim 2 , wherein the carbon sheet has a thickness of about 10 μm to about 1000 μm. 
     
     
         14 . The cell of  claim 2 , wherein the carbon sheet optionally comprises less than 5% of a conductive additive selected from the group consisting of carbon black, carbon fiber and carbon nanotubes. 
     
     
         15 . The cell of  claim 2 , wherein the carbon sheet has a purity of at least 95%. 
     
     
         16 . The cell of  claim 1 , wherein the negative electrode material is a negative electrode active material selected from the group consisting of graphite microbeads, natural graphites, carbon fibers, graphite flakes, carbon nanotubes, Li metal, Si, Sn, Sb and Al. 
     
     
         17 . The cell of  claims 16 , wherein the negative electrode current collector is selected from the group consisting of a metal foil and a carbon sheet selected from a graphite sheet, a carbon fiber sheet, a carbon foam, a carbon nanotube film or a mixture thereof. 
     
     
         18 . The cell of  claim 17 , wherein the metal foil is copper foil. 
     
     
         19 . The cell of  claim 17 , wherein the metal foil has a thickness between about 5 μm and 300 μm. 
     
     
         20 . The cell of  claim 17 , wherein the negative electrode current collector is a carbon sheet having the thickness between about 10 and 1000 μm. 
     
     
         21 . The cell of  claim 1 , wherein each of the second attachment ends is optionally coupled to an electrically conductive member for connecting to an external circuit. 
     
     
         22 . The cell of  claim 1 , wherein the ion conductive layer is an ion conductive membrane or a microporous layer. 
     
     
         23 . The cell of  claim 1 , wherein the electrolyte solution comprises a salt selected from the group consisting of LiPF 6 , LiBF 4 , LiClO 4  and a compound having the formula:
   (R a SO 2 )N − Li + (SO 2 R a ),   wherein each R a  is independently C 1-8 perfluoroalkyl or perfluoroaryl.   
     
     
         24 . The cell of  claim 23 , wherein the electrolyte solution comprises a salt selected from CF 3 SO 2 N − (Li + )SO 2 CF 3 , CF 3 CF 2 SO 2 N − (Li + )SO 2 CF 3 , CF 3 CF 2 SO 2 N − (Li + )SO 2 CF 2 CF 3 , CF 3 SO 2 N − (Li + )SO 2 CF 2 OCF 3 , CF 3 OCF 2 SO 2 N − (Li + )SO 2 CF 2 OCF 3 , C 6 F 5 SO 2 N − (Li + )SO 2 CF 3 , C 6 F 5 SO 2 N − (Li + )SO 2 C 6 F 5  or CF 3 SO 2 N − (Li + )SO 2 PhCF 3 . 
     
     
         25 . The cell of  claim 24 , wherein the electrolyte solution comprises CF 3 SO 2 N − (Li + )SO 2 CF 3 . 
     
     
         26 . The cell of  claim 1 , wherein the electrolyte solution comprises a solvent selected from the group consisting of a lactone, ethylene carbonate, propylene carbonate, dimethylcarbonate, diethylmethylcarbonate and mixtures thereof. 
     
     
         27 . The cell of  claim 1 , wherein at least one first attachment end of the tabs has a smooth surface. 
     
     
         28 . The cell of  claim 1 , wherein at least one first attachment end of the positive electrode tabs, the negative electrode tabs or both electrode tabs comprises an array of preformed micro indentations, wherein each indentation is about 1-100 μm in depth and about 1-500 μm in dimension. 
     
     
         29 . The cell of  claim 28 , wherein said array of indentations is evenly spaced. 
     
     
         30 . The cell of  claim 28 , wherein the first attachment end of each tab has a shape independently selected from the group consisting of a circle, an oval, a triangle, a square, a diamond, a rectangle, a trapezoidal, a U-shape, a V-shape, an L-shape and an irregular shape. 
     
     
         31 . The cell of  claim 28 , wherein the first attachment end of each tab has a dimension of at least 500 μm in width and 5 mm in length. 
     
     
         32 . The cell of  claim 1 , wherein at least one first attachment end of the positive electrode tabs, the negative electrode tabs or both electrode tabs is in direct contact with the positive electrode current collector. 
     
     
         33 . The cell of  claim 1 , wherein at least one first attachment end of the positive electrode tabs, the negative electrode tabs or both electrode tabs is in contact with the positive electrode current collector through a conductive layer. 
     
     
         34 . The cell of  claim 33 , wherein the conductive layer is in contact with the surface of said at least one positive electrode tab, negative electrode tab or both electrode tabs. 
     
     
         35 . The cell of  claim 33 , wherein the conductive layer has a thickness of about 1 nm to about 100 μm. 
     
     
         36 . The cell of  claim 33 , wherein the conductive layer comprises a conductive filler and a binder. 
     
     
         37 . The cell of  claim 36 , wherein the conductive filler is selected from the group consisting of carbon black, conducting polymers, carbon nanotubes and carbon composite materials. 
     
     
         38 . The cell of  claim 36 , wherein the binder is selected from the group consisting of a polymer, a copolymer and a combination thereof. 
     
     
         39 . The cell of  claim 1 , wherein each of the first attachment ends comprises an array of preformed micro openings having a plurality of protruding edges, wherein each said array of preformed micro openings has a dimension of about 1-1000 μm. 
     
     
         40 . The cell of  claim 39 , wherein said array of openings is evenly spaced. 
     
     
         41 . The cell of  claim 39 , wherein said array of openings has a shape selected from the group consisting of a circle, an oval, a triangle, a square, a diamond, a rectangle, a trapezoidal, a rhombus, a polygon and an irregular shape. 
     
     
         42 . The cell of  claim 1 , wherein the positive electrode tab, the negative electrode tabs or both electrode tabs are in contact with a protective coating selected from the group consisting of anodizing and oxide coatings, conductive carbon, epoxy and glues and paints or a layer of metal selected from copper, nickel, chromium, aluminum, titanium, stainless steel, gold, tantalum, niobium, hafnium, zirconium, vanadium, indium, cobalt, tungsten, tin, beryllium, molybdenum or chromium. 
     
     
         43 . The cell of  claim 1 , wherein the positive electrode tab, the negative electrode tabs or both electrode tabs are in contact with a layer of metal selected from nickel, silver, gold, palladium, platinum or rhodium. 
     
     
         44 . A method of connecting a tab to an electrode in an electrochemical cell, said method comprising:
 (a) providing an electrode comprising an electrode active material and a carbon current collector, wherein the electrode active material is in electronically conductive contact with the carbon current collector;   (b) providing a tab having a first attachment end for connecting to the electrode; and   (c) connecting the first attachment end of the tab to the carbon current collector through a process selected from the group consisting of riveting, staking, conductive adhesive lamination, hot press, ultrasonic press, mechanical press, crimping, pinching and a combination thereof.   
     
     
         45 . The method of  claim 44 , further comprising: depositing to said tab a protective coating selected from the group consisting of anodizing and oxide coatings, conductive carbon, epoxy and glues and paints or a layer of metal selected from copper, nickel, chromium, aluminum, titanium, stainless steel, gold, tantalum, niobium, hafnium, zirconium, vanadium, indium, cobalt, tungsten, tin, beryllium, molybdenum or chromium. 
     
     
         46 . The method of  claim 44 , further comprising: depositing a layer of metal selected from nickel, silver, gold, palladium, platinum or rhodium for improving the conductivity of the tab. 
     
     
         47 . The method of  claim 44 , wherein step (c) comprises aligning the carbon current collector with the tab; and applying riveting, staking, conductive adhesive lamination, hot press, ultrasonic press, mechanical press, crimping, pinching or a combination thereof to the carbon current collector. 
     
     
         48 . The method of  claim 47 , wherein the tab has a shape selected from the group consisting of a circle, an oval, a triangle, a square, a diamond, a rectangle, a trapezoidal, a U-shape, a V-shape, an L-shape and an irregular shape. 
     
     
         49 . The method of  claim 48 , wherein the carbon current collector is aligned to a predetermined point of the tab. 
     
     
         50 . The method of  claim 44 , wherein the tab is directly connected to the current collector through staking. 
     
     
         51 . The method of  claim 44 , wherein step (b) comprises piercing said attachment end of the tab to generate an array of openings having a plurality of protruding edges along the openings for connecting to the current collectors. 
     
     
         52 . The method of  claim 44 , wherein the tab is connected to the carbon current collector through a conductive adhesive layer. 
     
     
         53 . The method of  claim 52 , wherein the conductive adhesive layer has a thickness of about 1 nm to about 100 μm. 
     
     
         54 . The method of  claim 52 , wherein the conductive layer comprises a conductive filler and a binder. 
     
     
         55 . The method of  claim 54 , wherein the conductive filler is selected from the group consisting of carbon black, conducting polymers, carbon nanotubes and carbon composite materials. 
     
     
         56 . The method of  claim 52 , wherein the binder is selected from the group consisting of a polymer, a copolymer and a combination thereof. 
     
     
         57 . The method of  claim 52 , wherein the conductive layer is a conductive adhesive layer. 
     
     
         58 . The method of  claim 44 , wherein the attachment end of the tab has an array of preformed micro indentations, wherein each indentation is about 1-100 μm in depth and about 1-500 μm in dimension. 
     
     
         59 . The method of  claim 44 , wherein the array of indentations is evenly spaced. 
     
     
         60 . The method of  claim 44 , wherein the tab is made from a metal selected from the group consisting of copper, nickel, aluminum and austenitic nickel-based superalloys (INCONEL™), tantalum, niobium, hafnium, zirconium, vanadium, indium, cobalt, tungsten, beryllium and molybdenum. 
     
     
         61 . The method of  claim 44 , wherein the tab is made from a metal selected from the group consisting of copper, nickel, chromium, gold, tantalum, niobium, hafnium, zirconium, vanadium, indium, cobalt, tungsten, beryllium and molybdenum and alloys thereof. 
     
     
         62 . The method of  claim 44 , wherein the attachment end has a dimension of at least 0.25 mm 2 . 
     
     
         63 . The method of  claim 44 , wherein the carbon sheet is selected from the group consisting of a graphite sheet, a carbon fiber sheet and a carbon nanotube sheet or a blend thereof. 
     
     
         64 . The method of  claim 63 , wherein the carbon sheet is graphite sheet. 
     
     
         65 . The method of  claim 63 , wherein the carbon sheet has a thickness from about 10 μm to about 300 μm. 
     
     
         66 . The method of  claim 44 , wherein the electrode is a positive electrode or a negative electrode. 
     
     
         67 . A battery comprising:
 a housing;   a positive connector;   a negative connector;   a electrochemical cell of  claim 1  disposed in said housing; and   wherein said positive connector and said negative connector are mounted on said housing.   
     
     
         68 . The battery of  claim 67 , wherein:
 the positive connector has an inner end disposed within said housing and an outer end protrudes outside said housing;   the negative connector has an inner end disposed within said housing and an outer end protrudes outside said housing; and   wherein said at least one positive electrode tab is welded to the inner end of the positive connector and said at least one negative electrode tab is welded to the inner end of the negative connector.   
     
     
         69 . The battery of  claim 67 , wherein the positive connector is said at least one positive electrode tab and the negative connector is said at least one negative electrode tab, wherein the second attachment end of said at least one positive electrode tab and the second attachment end of said at least one negative electrode tab protrude outside said housing.