Method of fabricating an energy storage device

Information

  • Patent Grant
  • 10763551
  • Patent Number
    10,763,551
  • Date Filed
    Thursday, March 2, 2017
    7 years ago
  • Date Issued
    Tuesday, September 1, 2020
    3 years ago
Abstract
A method of fabricating an energy storage device (1) comprising forming a stack comprising at least a first electrode layer (6), a first current collecting layer (12) and an electrolyte layer 8 disposed between the first electrode layer (6) and the first current collecting layer (12). Forming a first groove (24) in the stack through the first electrode layer (6) and the electrolyte layer (8), thereby forming exposed edges of the first electrode layer 6 and the electrolyte layer (8). Filling at least part of the first groove (24) with an electrically insulating material thereby covering the exposed edges of the first electrode layer (6) and the electrolyte layer (8) with the insulating material. Cutting through the insulating material and the first current collecting layer (12) along at least part of the first groove (24) in order to form an exposed edge of the first current collecting layer (12).
Description
REFERENCE TO RELATED APPLICATIONS

This application is a national stage application under 35 USC 371 of International Application No. PCT/GB2017/050550, filed Mar. 2, 2017, which claims the priority of United Kingdom Application No. 1604351.5, filed Mar. 15, 2016, the entire contents of each of which are incorporated herein by reference.


FIELD OF THE INVENTION

This invention relates to a method of fabricating an energy storage device, and particularly, to an energy storage device comprising thin film cells having a solid electrolyte.


BACKGROUND OF THE INVENTION

Solid-state thin film cells comprising layers of electrodes, electrolyte and current collectors are typically produced by first forming a stack comprising a first current collecting layer formed on a substrate, an electrode layer, an electrolyte layer, a second electrode layer and a second current collecting layer. The stack is then cut into separate sections to form individual cells. Each cell can then be coated with a protective layer in order to prevent passivation of the layers and possible shorts.


In order to form an electrical connection with the cell, for example in order to electrically connect current collectors of multiple cells stacked one on top of another, part of the protective layer is removed, for example by etching. Alternatively, a mask can be applied prior to the coating process to ensure that a portion of each current collector is left exposed. In each instance, the additional step of masking or etching adds complexity and cost the production process.


SUMMARY OF THE INVENTION

According to some embodiments, provided is a method of fabricating an energy storage device comprising: forming a stack comprising at least a first electrode layer, a first current collecting layer and an electrolyte layer disposed between the first electrode layer and the first current collecting layer; forming a first groove in the stack through the first electrode layer and the electrolyte layer, thereby forming exposed edges of the first electrode layer and the electrolyte layer; filling at least part of the first groove with an electrically insulating material thereby covering the exposed edges of the first electrode layer and the electrolyte layer with the insulating material; and cutting through the insulating material and the first current collecting layer along at least part of the first groove in order to form an exposed edge of the first current collecting layer.


In some embodiments, provided is a simple, fast and low cast way of producing a solid-state cell having exposed current collectors which can then be readily connected electrically to other cells forming part of a cell stack.


The stack further may further comprise a second current collecting layer associated with the first electrode layer, wherein the first electrode layer and the electrolyte layer are disposed between the first and second current collecting layers. The first groove may be formed in the stack through the second current collecting layer, thereby forming an exposed edge of the second current collecting layer.


The electrically insulating material may cover the exposed edge of the second current collecting layer.


Methods may further comprise forming a second groove in the stack through the first current collecting layer, the electrolyte layer and the first electrode layer, thereby forming exposed edges of the first current collecting layer, the electrolyte layer and the first electrode layer, filling at least part of the second groove with an electrically insulating material thereby covering the exposed edges of the first current collecting layer, the electrolyte layer and the first electrode layer, and cutting through the insulating material and the second current collecting layer along at least part of the second groove in order to form an exposed edge of the second current collecting layer.


The first current collecting layer may form a second electrode layer. Alternatively or in addition, the stack may further comprise a second electrode layer disposed between the first current collecting layer and the electrolyte layer and the first groove is further formed through the second electrode layer.


The first and/or second groove may be formed by a laser cutting operation. A gaseous monomer may be provided in the region of the first and/or second grooves during the laser cutting operation such that the gaseous polymer is polymerised by the laser cutting operation within the grooves to form the electrically insulating material. The step of filling at least part of the first groove with an electrically insulating material may comprise the step of filling at least part of the groove with a liquid. The liquid may comprise an organic suspended liquid material. The liquid may be cured in the groove. The energy storage device may be an electrochemical cell or a capacitor.





BRIEF DESCRIPTION OF THE DRAWINGS

In order to better understand the present invention, and to show more clearly how the invention may be put into effect, the invention will now be described, by way of example, with reference to the following drawings:



FIG. 1 is a schematic representation of an energy storage device comprising a plurality of cells, according to some embodiments;



FIG. 2 is a schematic illustration of the energy storage device shown in FIG. 1 in which the cells are electrically connected, according to some embodiments;



FIGS. 3a to 3h illustrate a method of manufacturing the cells of the energy storage device shown in FIG. 1, according to some embodiments;



FIG. 4 is a schematic illustration of a variation of the method illustrated in FIGS. 3a to 3h, according to some embodiments; and



FIG. 5 shows the portion of FIG. 4 within the area surrounded by a broken line, according to some embodiments.





DETAILED DESCRIPTION OF THE INVENTION


FIG. 1 shows an energy storage device 1 comprising a first electrochemical cell 2 positioned on top of a second electrochemical cell 4. The first and second cells 2, 4 are identical. The first cell 2, however, is inverted. Each cell 2, 4 comprises a stack having a negative current collecting layer 6 which also forms a negative electrode layer (which becomes the anode during discharge of the cell 2, 4), an electrolyte layer 8, a positive electrode layer 10 (which becomes the cathode on discharge of the cell 2, 4), and a positive current collecting layer 12. Each cell 2, 4 is bounded along opposite sides by an insulating material 14, 16.


On the left hand side of each cell 2, 4 (as shown in FIG. 1), the insulating material 14 covers the edges of the electrolyte layer 8, the positive electrode layer 10 and the positive current collecting layer 12. The edge of the negative current collecting layer/negative electrode layer 6 on the left hand side of each cell 2, 4 is exposed.


On the right hand side of each cell (as shown in FIG. 1), the insulating material 16 covers edges of negative current collecting layer/negative electrode layer 6, the electrolyte layer 8 and the positive electrode layer 10. The edge of the positive current collecting layer 12 on the right hand side of each cell 2, 4 is exposed.


A benefit of the energy storage device 1 is that electrical connectors 18, 20 can be provide along opposite sides of the two cells 2, 4, as shown in FIG. 2, such that the electrical connector 18 on the left contacts the negative current collecting layer 6 of each cell 2, 4, but is prevented from contacting the other layers by the insulating material 14, and the electrical connector 20 on the right contacts the positive current collecting layer 12, but is prevented from contacting the other layers by the insulating material 16. The insulating material 14, 16 therefore prevents a short between the current collecting layers 6, 12 and the other layers in each cell 2, 4. The electrical connectors 18, 20 may, for example, be a metallic material that is applied to the edges of the stack by sputtering. The cells 2, 4 can therefore be joined in parallel simply and easily.


A method of manufacturing the cells shown in FIGS. 1 and 2 will now be described with reference to FIGS. 3a to 3h.



FIG. 3a shows a positive current collecting layer 12 comprising nickel foil, but it will be appreciated that any suitable metal could be used such as aluminium, copper or steel, or a metalised material including metalised plastics such as aluminium on polyethylene terephthalate (PET). A first positive electrode layer 10 is deposited on the current collecting layer 12 for example by flood deposition or by vapour deposition, as shown in FIG. 3b. The positive electrode layer 10 forms the cathode during discharge and may comprise a material which is suitable for storing Lithium ions by virtue of stable chemical reactions, such as Lithium Cobalt Oxide or Lithium Iron Phosphate or alkali metal polysulphide salts. An electrolyte layer 8 is deposited on top of the positive electrode layer 10, as shown in FIG. 3c. For an electrochemical cell the electrolyte layer may comprise any suitable material which is ionically conductive, but which is also an electrical insulator such as Lithium Phosporous OxyNitride (LiPON). A negative electrode layer 6 is deposited on top of the electrolyte layer 8, as shown in FIG. 3d which completes assembly of a stack. The negative electrode layer 6 also provides a negative current collector (which acts as an anode during discharge). In some embodiments, the negative current collector and the negative electrode layer may be separate layers. The negative electrode layer may comprise a Lithium metal, Graphite, Silicon or Indium Tin Oxides. In embodiments in which the negative current collector is a separate layer, the negative current collector may comprise nickel foil, but it will be appreciated that any suitable metal could be used such as aluminium, copper or steel, or a metalised material including metalised plastics such as aluminium on polyethylene terephthalate (PET). Each layer may be deposited by flood deposition, which provides a simple and effective way of producing a highly homogenous layer.


A laser cutting tool is used to cut parallel alternate grooves 22, 24 in the upper and lower portions of the stack, as shown in FIG. 3e. The grooves 22 in the lower portion of the stack are offset from the grooves 24 in the upper portion of the stack. The region of the stack between a lower groove 22 and an adjacent upper groove 24 corresponds to a single cell.


Each groove 22 in the lower portion of the stack is cut through the current collecting layer 12, the positive electrode layer 10 and the electrolyte layer 8 to the negative electrode layer 6.


Each groove 24 in the upper portion of the stack is cut through the negative electrode layer 6, electrolyte layer 8 and positive electrode layer 10 to the current collecting layer 12.


The cutting operation creates edges along each layer which are exposed within the respective grooves and exposes part of an upper surface of the current collecting layer 12 in the upper grooves 24 and part of the lower surface of the negative electrode layer 6 in the lower grooves 22. It will be appreciated that the depth of each groove must be extremely precise in order to cut through only the desired layers and to prevent, or at least minimise, any removal of the layer that is to remain intact. A dual-photon laser cutting technique is the preferred cutting process because it is expected to provide the required accuracy. However, other suitable cutting processes may be used for each step, for example any process that is suitable for removing material to form a groove and/or to separate cells. Different cutting techniques for each step of forming the groove and for separating the cells may be used, for example ultrasound cutting may be followed by gas jetting.


In the embodiment shown, the cutting operation is conducted in an environment comprising a gaseous monomer which, during the cutting operation, polymerises on the edges of the layers formed by the cutting process and on the revealed upper surface of the current collecting layer 12 and the revealed lower surface of the negative electrode layer 6 at the bottom of each groove. The polymer provides an electrically insulating plug 26, 28 that covers the revealed edges and exposed portions of the surfaces of the layers within the groove, as shown in FIG. 3f Any suitable polymer may be used, such as ethylene, vinyl chloride or tetra fluoroethylene. In some embodiments, electrically insulating plugs could be formed by filling the grooves with a liquid such as an organic suspended liquid material and then curing the liquid in the groove.


Once the polymer has set, the stack is cut along the grooves 22, 24, as shown by dashed lines in FIG. 3g, into separate cells as shown in FIG. 3h. The cutting operation may again be performed using a laser. Each cut is through the centre of an insulating plug 26, 28 such that the plug 26, 28 is split in two pieces, each piece forming a protective covering over the edges and surfaces to which it has attached of each respective cell 2, 4.


Cutting through the entire stack creates exposed edges of the positive current collecting layer 12 and the negative electrode layer 6 of the first and second cells 2, 4, as shown in FIG. 3h.


The second cell 4 is inverted and placed on top of the first cell 2 to produce the energy storage device 1 shown in FIG. 1. An electrical connector 18, 20, for example a metallic layer, is then formed by sputtering along each side of the energy storage device 1 in order to connect the positive current collecting layers 12 of each cell 2, 4 on one side of the energy storage device 1 and the negative electrode layer/negative current collecting layers 6 on the opposite side of the energy storage device 1, as described previously and as shown in FIG. 2.



FIGS. 4 and 5 illustrate a variation of the method described above in which a continuous stack is built on a sheet of positive current collecting layer 12 that may, be for example, be drawn from a roll, from which hundreds and potentially thousands of cells can be cut. Once formed, the stack is folded back on itself, as shown in FIG. 4, to create a z-fold arrangement having at least ten, preferably hundreds, and potentially thousands, of layers with each of the insulating plugs 26, 28 aligned, as shown in FIG. 5. A laser cutting process is then used to cut through all of the stacks (shown by the broken lines in FIG. 5) in a single cutting operation for each of the aligned sets of plugs.


The stack may be formed such that it is in a charged state prior to the cutting of the grooves in the stack and prior to cutting the stack into separate cells. The cutting of the grooves, which separate the energy storage components of the cells from each other and/or the subsequent cutting of the current collecting layers to separate the stack into individual cells can improve safety of the manufacturing and subsequent handling processes because a large stack storing a high amount of energy does not need to be handled.

Claims
  • 1. A method of fabricating an energy storage device comprising: forming a stack comprising first electrode layer, a first current collecting layer, and an electrolyte layer disposed between the first electrode layer and the first current collecting layer;forming a first groove in the stack through the first electrode layer and the electrolyte layer to form exposed edges of the first electrode layer and the electrolyte layer;filling at least part of the first groove with an electrically insulating material to cover the exposed edges of the first electrode layer and the electrolyte layer with the electrically insulating material; andcutting through the electrically insulating material and the first current collecting layer along at least part of the first groove in order to form an exposed edge of the first current collecting layer.
  • 2. The method of claim 1, wherein the stack comprises a second current collecting layer associated with the first electrode layer, wherein the first electrode layer and the electrolyte layer are disposed between the first current collecting layer and the second current collecting layer, and wherein the first groove is formed in the stack through the second current collecting layer, thereby forming an exposed edge of the second current collecting layer.
  • 3. The method of claim 2, wherein the electrically insulating material covers the exposed edge of the second current collecting layer.
  • 4. The method of claim 2, the method further comprising: forming a second groove in the stack through the first current collecting layer, the electrolyte layer, and the first electrode layer, to form exposed edges of the first current collecting layer, the electrolyte layer, and the first electrode layer;filling at least part of the second groove with an electrically insulating material to cover the exposed edges of the first current collecting layer, the electrolyte layer and the first electrode layer; andcutting through the insulating material and the second current collecting layer along at least part of the second groove to form an exposed edge of the second current collecting layer.
  • 5. The method of claim 1, wherein the first current collecting layer forms a second electrode layer.
  • 6. The method of claim 1, wherein the stack comprises a second electrode layer disposed between the first current collecting layer and the electrolyte layer and the first groove is formed through the second electrode layer.
  • 7. The method of claim 1, wherein the first groove is formed by a laser cutting operation.
  • 8. The method of claim 7, wherein a gaseous monomer is provided in a region of the first groove during the laser cutting operation such that a polymer is polymerised by the laser cutting operation within the first groove to form the electrically insulating material.
  • 9. The method of claim 1, wherein filling at least part of the first groove with an electrically insulating material comprises filling at least part of the groove with a liquid.
  • 10. The method of claim 9, wherein the liquid comprises an organic suspended liquid material.
  • 11. The method of claim 9, wherein the liquid is cured in the groove.
  • 12. The method of claim 1, wherein the energy storage device is an electrochemical cell.
Priority Claims (1)
Number Date Country Kind
1604351.5 Mar 2016 GB national
PCT Information
Filing Document Filing Date Country Kind
PCT/GB2017/050550 3/2/2017 WO 00
Publishing Document Publishing Date Country Kind
WO2017/158319 9/21/2017 WO A
US Referenced Citations (40)
Number Name Date Kind
3761500 Thomas Sep 1973 A
3993508 Erlichman Nov 1976 A
4047289 Wolff Sep 1977 A
4288381 Dozzi et al. Sep 1981 A
5136046 Park et al. Aug 1992 A
5250784 Muller et al. Oct 1993 A
5411592 Ovshinsky et al. May 1995 A
5718989 Aoki et al. Feb 1998 A
6616714 Gauthier et al. Sep 2003 B1
9755272 Gaben Sep 2017 B2
9768450 Song et al. Sep 2017 B2
9893376 Yang et al. Feb 2018 B2
20020110733 Johnson Aug 2002 A1
20030162086 Longhi et al. Aug 2003 A1
20050014065 Jung et al. Jan 2005 A1
20070238019 Laurent et al. Oct 2007 A1
20080263855 Li et al. Oct 2008 A1
20080264478 Ahn et al. Oct 2008 A1
20090148764 Kwak Jun 2009 A1
20100108939 Breger et al. May 2010 A1
20110126402 Kwak et al. Jun 2011 A1
20110129594 Kwak et al. Jun 2011 A1
20110294015 Pirk et al. Dec 2011 A1
20110311883 Oukassi et al. Dec 2011 A1
20120225199 Muthu et al. Sep 2012 A1
20120270114 Reynolds et al. Oct 2012 A1
20120312474 Kwak et al. Dec 2012 A1
20120321815 Song et al. Dec 2012 A1
20130160283 Wu Jun 2013 A1
20130298387 Kobier et al. Nov 2013 A1
20140007418 Song et al. Jan 2014 A1
20140120397 Kim et al. May 2014 A1
20140227609 Frey et al. Aug 2014 A1
20140255603 Xiao et al. Sep 2014 A1
20150010822 Nakahara et al. Jan 2015 A1
20150050522 Manthiram et al. Feb 2015 A1
20150102530 Wallace Apr 2015 A1
20150188186 Bedjaoui et al. Jul 2015 A1
20150280201 Bhardwaj Oct 2015 A1
20160372783 Min et al. Dec 2016 A1
Foreign Referenced Citations (39)
Number Date Country
101562245 Oct 2009 CN
101694876 Apr 2010 CN
102054986 May 2011 CN
102881873 Jan 2013 CN
103035900 Apr 2013 CN
103311513 Sep 2013 CN
103545519 Jan 2014 CN
105742607 Jul 2016 CN
105810934 Jul 2016 CN
106410186 Feb 2017 CN
42 27 720 Apr 1993 DE
1189296 Mar 2002 EP
2746288 Jun 2014 EP
1 402 544 Aug 1975 GB
2 128 604 May 1984 GB
57-96472 Jun 1982 JP
S64-21870 Jan 1989 JP
H4-269721 Sep 1992 JP
2000-149911 May 2000 JP
2002-343342 Nov 2002 JP
2003-226955 Aug 2003 JP
2009-182273 Aug 2009 JP
2009-246236 Oct 2009 JP
2009-544141 Dec 2009 JP
2010-251075 Nov 2010 JP
2011-108603 Jun 2011 JP
10-2016-0091172 Aug 2016 KR
10-2017-0008540 Jan 2017 KR
10-2017-0025874 Mar 2017 KR
2009055529 Apr 2009 WO
WO-2009055529 Apr 2009 WO
2010036723 Apr 2010 WO
2011052607 May 2011 WO
2012065767 May 2012 WO
2013035519 Mar 2013 WO
2015107194 Jul 2015 WO
2016001884 Jan 2016 WO
2016210419 Dec 2016 WO
2017087403 May 2017 WO
Non-Patent Literature Citations (15)
Entry
Mehrotra R. C. et al. (Jan. 1978). “Preparation and Characterization of Some Volatile Double Isopropoxides of Aluminium with Alkaline Earth Metals,” Inorganica Chemica Acta 29:131-136.
Yasushi, J. et al. (Nov. 16, 1984) “CAS No. [32843-22-4] Aluminate(1-), tetrakis(diphenylaminato)-, magnesium,” (2 pages).
Cucinella, S., et al. (1982). “Calcium Alkoxyalanates I. Synthesis and Physicochemical Characterization,” Journal of Organometallic Chemistry 224(1): 1-12.
Hudson, M. Sterlin Leo, et al. (2007). “Studies on Synthesis and Dehydrogenation Behavior of Magnesium Alanate and Magnesium-Sodium Alanate Mixture,” International Journal of Hydrogen Energy 32(18): 4933-4938.
Lu, Z., et al. (Apr. 2002). “Synthesis, Structure, and Electrochemical Behavior of Li[NixLi(1/3-2x/3)Mn(2/3-x/3)]O2,” Journal of the Electrochemical Society, 149(6): A778-A791.
Metz, Matthew V., et al. (2002). “Weakly Coordinating A1-, Nb-, Ta-, Y-, and La-Based Perfluoroaryloxymetalate Anions as Cocatalyst Components for Single-Site Olefin Polymerization,” Organometallics 21(18): 3691-3702.
Notice of Reasons for Rejection dated Aug. 26, 2019, directed to JP Application No. 2018-546903; 10 pages.
Park, K., et al. (May 2010). “Suppression of O2 evolution from oxide cathode for lithium-ion batteries: VOx-impregnated 0.5Li2MnO3-0.5LiNi0.4Co0.2Mn0.4O2 cathode,” Chemical Communications, 46(23): 4190-4192.
Park, Y. J., et al (Apr. 2004). “Structural investigation and electrochemical behaviour of Li[NixLi(1/3-2x/3)Mn(2/3-x/3)] O2 compounds by a simple combustion method,” Journal of Power Sources 129: 288-295.
Thackeray, M.M., et al. (Aug. 2006). “Comments on the structural complexity of lithium-rich Li1+xM1-xO2 electrodes (M=Mn, Ni, Co) for lithium batteries,” Electrochemistry Communications 8(9):1531-1538.
Turova, N. Ya., et al. (1977). “Hydrolysis and Alcoholysis of Alkali Metal Aluminium Hydrides,” Inorganica Chimica Acta, 21: 157-161.
Wu, Y., et al. (Mar. 2006). “High Capacity, Surface-Modified Layered Li[Li(1-x)/3Mn(2-x)/3Nix/3Cox/3]O2 Cathodes with Low Irreversible Capacity Loss,” Electrochemical and Solid-State Letters 9(5): A221-A224.
Birrozzi, A., et al. (2016). “Beneficial effect of propane sultone and tris(trimethylsilyl) borate as electrolyte additives on the cycling stability of the lithium rich nickel manganese cobalt (NMC) oxide,” 325:525-533.
International Search Report and Written Opinion dated May 12, 2017, directed to International Application No. PCT/GB2017/050550; 11 pages.
Search Report dated Oct. 6, 2016, directed to GB Application No. 1604351.5; 1 page.
Related Publications (1)
Number Date Country
20190115627 A1 Apr 2019 US