Electrode assembly, sealed secondary battery cell, battery pack and methods

Abstract

A battery pack having a population of secondary battery cells chargeable between a charged state and a discharged state, and a frame to hold secondary battery cells in the battery pack is provided, members of the population of secondary battery cells having an electrode assembly comprising a substantially polyhedral shape, and where the frame holds a cell array comprising a subset of the population of secondary batteries that are arranged adjacent to one another. A sealed secondary battery cell, electrode assembly, and methods of charging are also described.

What is claimed is: 
     
         1 . An electrode assembly for a secondary battery, wherein
 the electrode assembly has mutually perpendicular transverse, longitudinal and vertical axes corresponding to the x, y and z axes, respectively, of an imaginary three-dimensional Cartesian coordinate system, opposing longitudinal end surfaces that are separated from each other in the longitudinal direction, and a lateral surface surrounding an electrode assembly longitudinal axis A EA  and connecting the first and second longitudinal end surfaces, the lateral surface having opposing vertical surfaces that are separated from each other in the vertical direction on opposing vertical sides of the longitudinal axis, opposing transverse surfaces that are separated from each other in the transverse direction on opposing transverse sides of the longitudinal axis, wherein the opposing longitudinal surfaces have a combined surface area, L SA , the opposing transverse surfaces have a combined surface area, T SA , the opposing vertical surfaces have a combined surface area, V SA ,   the electrode assembly further comprises an electrode structure population, an electrically insulating separator population, and a counter-electrode structure population, wherein members of the electrode structure, electrically insulating separator and counter-electrode structure populations are arranged in an alternating sequence along the longitudinal direction,   members of the electrode structure population comprise an electrode current collector adjacent an electrode active material layer, the electrode active material layer comprising opposing transverse ends, and wherein members of the counter-electrode structure population comprise a counter-electrode current collector adjacent a counter-electrode active material layer, the counter-electrode active material layer comprising opposing transverse ends,   the electrode current collector has opposing electrode current collector surfaces separated from each other in the longitudinal direction, and is partially coated by the adjacent electrode active material layer, the electrode current collector having (i) an electrode current collector body region coated by the adjacent electrode active material layer and extending between the opposing first and second transverse ends of the adjacent electrode active material layer, and (ii) an electrode current collector end region on a first or second transverse end of the electrode current collector, the electrode current collector end region being bounded by and extending past the first or second transverse end of the adjacent electrode active material layer that is on a same transverse side as the electrode current collector end region.   a length of the electrode current collector end region in the transverse direction (L ER ) is as measured from the first or second transverse end of the adjacent electrode active material layer that is on a same transverse side as the electrode current collector end region, to a region where the electrode current collector end region connects with an electrode busbar, a height of the electrode current collector body region in the vertical direction (H BR ) is as measured between opposing vertical surfaces of the electrode current collector body region, and a height of the electrode current collector end region in the vertical direction (H ER ) is as measured between opposing vertical surfaces of the electrode current collector end region, wherein L ER <0.5×H BR  and H ER >0.5×H BR .   wherein the electrode assembly comprises a population of unit cells, each member of the unit cell population comprises, in a stacked series in the longitudinal direction, a unit cell portion of an electrode current collector, an electrode active material layer, an electrically insulating separator, a counter-electrode active material layer, and a unit cell portion of a counter-electrode current collector.   
     
     
         2 . The electrode assembly according to  claim 1 , wherein the counter-electrode current collectors have opposing counter-electrode current collector surfaces separated from each other in the longitudinal direction, and one of the opposing counter-electrode current collector surfaces comprises a coated region that is covered with the counter-electrode active material layer and an uncoated region that lacks the counter-electrode active material layer, the uncoated region being proximate one of the transverse ends of the counter-electrode current collector. 
     
     
         3 . The electrode assembly according to  claim 1 , wherein each member of the counter-electrode structure population comprises a counter-electrode current collector that is partially coated by the adjacent counter-electrode active material layer, the counter-electrode current collector having (i) a counter-electrode current collector body region coated by the adjacent counter-electrode active material layer and extending between the opposing first and second transverse ends of the adjacent counter-electrode active material layer, and (ii) a counter-electrode current collector end region on a first or second transverse end of the counter-electrode current collector, the counter-electrode current collector end region being bounded by and extending past the first or second transverse end of the adjacent counter-electrode active material layer that is on a same transverse side as the counter-electrode current collector end region. 
     
     
         4 . The electrode assembly according to  claim 1 , wherein a length of the counter-electrode current collector end region in the transverse direction (L CER ) is as measured from the first or second transverse end of the adjacent counter-electrode active material layer that is on a same transverse side as the counter-electrode current collector end region, to a region where the counter-electrode current collector end region connects with a counter-electrode busbar, a height of the counter-electrode current collector body region in the vertical direction (H CBR ) is as measured between opposing vertical surfaces of the counter-electrode current collector body region, and a height of the counter-electrode current collector end region in the vertical direction (H CER ) is as measured between opposing vertical surfaces of the counter-electrode current collector end region,
 and wherein L CER <0.5×H CBR  and H CER >0.5×H CBR .   
     
     
         5 . The electrode assembly according to  claim 1 , wherein members of the electrode structure population comprise electrode current collector end regions having opposing surfaces separated from each other in the longitudinal direction, and wherein at least one of the opposing surfaces of electrode current collector end regions comprise a layer of thermally conductive material disposed thereon. 
     
     
         6 . The electrode assembly according to  claim 5 , wherein electrode current collector end regions electrically connect to the electrode busbar via at least one of the opposing surfaces, and wherein the layer of thermally conductive material is disposed on the other of the opposing surfaces. 
     
     
         7 . The electrode assembly according to  claim 1 , wherein members of the counter-electrode structure population comprise counter-electrode current collector end regions having opposing surfaces separated from each other in the longitudinal direction, and wherein at least one of the opposing surfaces of counter-electrode current collector end regions comprise a layer of thermally conductive material disposed thereon. 
     
     
         8 . The electrode assembly according to  claim 7 , wherein counter-electrode current collector end regions electrically connect to a counter-electrode busbar via at least one of the opposing surfaces, and wherein the layer of thermally conductive material is disposed on the other of the opposing surfaces. 
     
     
         9 . The electrode assembly according to  claim 5 , wherein the thermally conductive material comprises a thermally conductive ceramic material. 
     
     
         10 . The electrode assembly according to  claim 1 , wherein the electrode assembly has a substantially polyhedral shape, with opposing longitudinal end surfaces that are substantially flat, opposing vertical surfaces that are substantially flat, and opposing transverse surfaces that are substantially flat. 
     
     
         11 . The electrode assembly according to  claim 1 , wherein the ratio of V SA  to each of L SA  and T SA  is at least 5:1. 
     
     
         12 . A battery pack comprising a population of secondary battery cells chargeable between a charged state and a discharged state, and a frame to hold secondary battery cells in the battery pack, wherein
 (a) members of the secondary battery cell population have a rated capacity and comprise a hermetically sealed enclosure and an electrode assembly within the hermetically sealed enclosure,   (b) the electrode assembly has substantially polyhedral shape mutually perpendicular transverse, longitudinal and vertical axes corresponding to the x, y and z axes, respectively, of an imaginary three-dimensional Cartesian coordinate system,   (c) the electrode assembly comprises opposing longitudinal surfaces that are substantially flat and are separated from each other in the longitudinal direction, and a lateral surface surrounding an electrode assembly longitudinal axis A EA  and connecting the opposing longitudinal end surfaces, the lateral surface having opposing vertical surfaces that are substantially flat and are separated from each other in the vertical direction on opposing vertical sides of the longitudinal axis, and opposing transverse surfaces that are substantially flat and are separated from each other in the transverse direction on opposing transverse sides of the longitudinal axis, wherein the opposing longitudinal surfaces have a combined surface area, L SA , the opposing transverse surfaces have a combined surface area, T SA , the opposing vertical surfaces have a combined surface area, V SA , and the ratio of V SA  to each of L SA  and T SA  is at least 5:1,   (d) the electrode assembly further comprises an electrode structure population, an electrically insulating separator population, and a counter-electrode structure population, wherein members of the electrode structure, electrically insulating separator and counter-electrode structure populations are arranged in an alternating sequence in the longitudinal direction within the electrode assembly,   (e) wherein the frame holds a cell array comprising a subset of the population of secondary battery cells that are arranged adjacent to one another, with the members being arranged in the cell array such that opposing vertical surfaces of adjacent members in the cell array face each other to form an adjacent facing pair of vertical surfaces, each adjacent facing pair of vertical surfaces in the cell array comprising adjacent facing regions thereof, and   (f) wherein the adjacent facing regions of each adjacent facing pair of vertical surfaces in the cell array are separated by less than 1 mm from each other in the vertical direction, and are in thermal contact with one another via a thermally conductive pathway having thermally conductive material that has a thermal conductivity of at least 1 W/mK.   
     
     
         13 . The battery pack according to  claim 12 , wherein the substantially flat opposing longitudinal, vertical, and transverse surfaces make up a combined surface area of greater than 66% of the electrode assembly. 
     
     
         14 . The battery pack according to  claim 12 , wherein the battery pack comprises a cell array with a number of secondary battery cells in the cell array that is at least 2. 
     
     
         15 . The battery pack according to  claim 12 , wherein subset of secondary battery cells in the cell array are in thermal contact with each other. 
     
     
         16 . The battery pack according to  claim 12 , wherein the battery pack comprises a plurality of cell arrays. 
     
     
         17 . The battery pack according to  claim 12 , further comprising a cooling tube to cool the cell array. 
     
     
         18 . The battery pack according to  claim 17 , wherein the cell array comprises opposing cell array end surfaces separated from each other in the vertical direction, and wherein the cooling tube extends in direction orthogonal to the vertical direction and along at least one of the opposing cell array end surfaces of the cell array to cool the at least one opposing cell array end surface. 
     
     
         19 . The battery pack according to  claim 17 , wherein the cell array comprises at least two secondary battery cells arranged adjacent to one another, such that the opposing vertical surfaces of the at least two secondary battery cells comprise a pair of external surfaces separated from each other in the vertical direction and located towards the opposing cell array end surfaces, and wherein the cooling tube extends in the orthogonal direction along at least one vertical cell array end surface that is adjacent to one of the pair of external surfaces to cool the external surface of the at least two adjacent secondary battery cells. 
     
     
         20 . The battery pack according to  claim 17 , comprising thermally conductive material between the cooling tube and the external surface of the secondary battery cell adjacent to the cooling tube. 
     
     
         21 . The battery pack according to  claim 20 , wherein the thermally conductive material comprises a thermally conductive adhesive. 
     
     
         22 . The battery pack according to  claim 20 , wherein the thermally conductive material comprises a compressible thermal interface material. 
     
     
         23 . The battery pack according to  claim 17 , comprising a first cell array arranged on a first vertical side of the cooling tube, and a second cell array arranged on a second vertical side of the cooling tube, wherein the cooling tube cools the external surfaces of the first and second cell arrays that are adjacent to the cooling tube on each of the first and second vertical sides. 
     
     
         24 . The battery pack according to  claim 17 , wherein the cooling tube comprises a first cooling tube, and wherein battery pack further comprises a second cooling tube extending in the same or different direction than the first cooling tube, that is orthogonal to the vertical direction, along the other of the cell array end surfaces that is adjacent to the other of the pair of external surfaces, such that both of the pair of external surfaces of the cell array are cooled. 
     
     
         25 . The battery pack according to  claim 12 , wherein the battery pack comprises a cooling tube that has a cooling fluid inlet side into which cooling fluid is introduced, and a cooling fluid outlet side that is downstream of the cooling fluid inlet side, wherein
 the cooling tube is arranged such that the cooling fluid inlet side of the cooling tube passes along a first cell array end surface in a direction orthogonal to the vertical direction, and the cooling fluid outlet side of the cooling tube passes by an opposing second cell array end surface in a direction orthogonal to the vertical direction.   
     
     
         26 . The battery pack according to  claim 17 , wherein the cooling tube(s) are configured to carry a liquid or gas coolant. 
     
     
         27 . The battery pack according to  claim 12 , wherein the thermally conductive pathway extends across at least 20% of the surface areas of the respective adjacent vertical surfaces of the cell array. 
     
     
         28 . The battery pack according to  claim 12 , wherein the thermally conductive material between each adjacent facing pair of vertical surface forms a contact patch between the adjacent facing pair that extends across at least 20% of the surface areas of the respective adjacent vertical surfaces of the cell array. 
     
     
         29 . The battery pack according to  claim 12 , wherein the thermally conductive material comprises a compressible thermal interface material comprising any selected from the group consisting of a compressible foam and an elastomeric material. 
     
     
         30 . The battery pack according to  claim 12 , wherein the thermally conductive material comprises a thermally conductive adhesive comprising any selected from the group consisting of an epoxy adhesive, a thermoplastic adhesive, silicone adhesive, and polyurethane adhesive.