DETAILED ACTION
Notice of Pre-AIA or AIA Status
The present application, filed on or after March 16, 2013, is being examined under the first inventor to file provisions of the AIA .
Specification
The abstract of the disclosure is objected to because on line 2, "the flow field being..." should read "the flow field is...". A corrected abstract of the disclosure is required and must be presented on a separate sheet, apart from any other text. See MPEP § 608.01(b).
Claim Rejections - 35 USC § 103
The following is a quotation of 35 U.S.C. 103 which forms the basis for all obviousness rejections set forth in this Office action:
A patent for a claimed invention may not be obtained, notwithstanding that the claimed invention is not identically disclosed as set forth in section 102, if the differences between the claimed invention and the prior art are such that the claimed invention as a whole would have been obvious before the effective filing date of the claimed invention to a person having ordinary skill in the art to which the claimed invention pertains. Patentability shall not be negated by the manner in which the invention was made.
This application currently names joint inventors. In considering patentability of the claims the examiner presumes that the subject matter of the various claims was commonly owned as of the effective filing date of the claimed invention(s) absent any evidence to the contrary. Applicant is advised of the obligation under 37 CFR 1.56 to point out the inventor and effective filing dates of each claim that was not commonly owned as of the effective filing date of the later invention in order for the examiner to consider the applicability of 35 U.S.C. 102(b)(2)(C) for any potential 35 U.S.C. 102(a)(2) prior art against the later invention.
Claims 1-7 and 10 are rejected under 35 U.S.C. 103 as being unpatentable over Gaugler et al. (DE 102007048184 B3, as attached by applicant) in view of Molter (US 2001/0049044 A1).
Regarding claims 1-4 and 6, Gaugler teaches a bipolar plate (Fig. 1a, element 3; [0053]) for an electrolyzer ([0002]). The plate comprises an electrochemically active region ([0054], element 6) with a channel structure (8), identical to a flow field as claimed. The shape of the flow field as shown in Figs. 1a-b is substantially square-shaped, reading on the claim limitations of an equilateral n-sided polygon where n is an even natural number and wherein n is 4. Fig. 1a also shows at least four media apertures (elements 4 or 5) on four different sides of the flow field between the field and the outer edge of the bipolar plate. The media apertures are "arranged symmetrically with respect to an axis of symmetry that extends from a first anchor point, which is located between the first and the second side and is equidistant from the first and the second side, to a second anchor point, which is located between the third and the fourth side and is equidistant from the third and the fourth side:" Fig. 1b as annotated below. An equal number of media apertures are arranged on the four sides, as shown. These media apertures are arranged point-symmetrically about the center of the bipolar plate, annotated as M.
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Gaugler does not teach wherein the bipolar plate is made of a single layer, nor rectilinear channels in the bipolar plate. However, Molter teaches an electrochemical cell arrangement using a single-layered bipolar plate (Abstract). This single-layer bipolar plate comprises rectilinear channels ([0022]: as rectangular, linear flow channels). Molter also suggests bipolar plates shaped as “octagonal, hexagonal, or the like,” but typically square plates ([0017]).
It would have been obvious to one skilled in the art as of the effective filing date of the claimed invention to modify the bipolar plate of Gaugler to use a single layer with rectilinear channels. One would be motivated to do so because a two-layered plate is not necessary when coolant is not used in the electrochemical cell (Molter [0020]: "a single sheet is preferred..."), and a single-layered plate of rectilinear channels is expected to be simpler to construct and result in a thinner plate, allowing for additional plates in an electrolyzer stack of a limited size and therefore increased volumetric efficiency.
Regarding claim 5, modified Gaugler further teaches that the media apertures have sealing contours or envelopes in the same shape as the media apertures themselves (Gaugler [0038]: as circular full corrugations; Fig. 2a: circular media opening 5 is shown surrounded by said corrugations).
Regarding claims 7 and 10, modified Gaugler further teaches that it is known in the art to construct an electrolyzer out of stacked bipolar plates, such as those taught therein ([0002]-[0003]). Gaugler does not explicitly teach that these bipolar plates are identical or have identical features. However, it is obvious to one skilled in the art to try one of either a stack of identical bipolar plates or a stack of different bipolar plates, because there are only two apparent alternatives. When the number of alternatives to try is sufficiently small and well-established, a case of obviousness exists. See MPEP §2144.08. The limitation of claim 10 to “wherein most or all of the bipolar plates are structurally identical or at least have identical features” is therefore obvious.
Claim 8 is rejected under 35 U.S.C. 103 as being unpatentable over Gaugler et al. (DE 102007048184 B3) in view of Molter (US 2001/0049044 A1) as applied to claim 7 above, and further in view of Stahl et al. (US 2018/0102554 A1).
Regarding claim 8, Gaugler in view of Molter teaches all inherited limitations from claims 1 and 7 on which they depend, but does not teach “wherein bipolar plates which are next-adjacent in the stacking direction are arranged in a manner rotated through 180 degrees about the axis of symmetry.”
However, Stahl teaches that in an electrochemical stack comprising bipolar plates, successive bipolar plates may be substantially identical in form, but rotated 180° about an axis of rotation parallel to the stacking direction ([0038]). Although the disclosure of Stahl is primarily directed to fuel cells, the device may be an electrolyzer as these devices are disclosed as variants ([0003]).
It would have been obvious to one of ordinary skill in the art to construct the electrolyzer taught by Gaugler in view of Molter such that successive bipolar plates are rotated 180° along the axis of symmetry. The axis of rotation parallel to the stacking direction, from Stahl, is necessarily identical to the claimed axis of symmetry, because rotation along a different axis would cause the media openings of adjacent bipolar plates to misalign, resulting in a predictably inoperable product. One would have been motivated to use identical but rotated bipolar plates to simplify the process of manufacturing the electrolyzer stack taught by Gaugler in view of Molter, reducing costs ([0078]-[0079]) while still creating a long path for reactant fluid passage throughout the stack (Fig. 9, element 176: anodic fluid supplied to electrochemical device [0217]).
Claims 9 and 12 are rejected under 35 U.S.C. 103 as being unpatentable over Gaugler et al. (DE 102007048184 B3) in view of Molter (US 2001/0049044 A1) as applied to claim 7 above, and further in view of Frederiksen et al. (US 2007/0184328 A1).
Regarding claim 9, Gaugler in view of Molter teaches all inherited limitations from claims 1 and 7 upon which it depends, but does not teach that the “bipolar plates which are next-adjacent in the stacking direction are arranged in a manner rotated through 360/n degrees about an axis of rotation that extends perpendicular to the main extension plane of the bipolar plates.”
However, Frederiksen teaches that in a fuel cell stack, bipolar plates which are dimensionally similar may be rotated 90° to the preceding plate when stacked ([0023]: “separator plate” therein is referred to as bipolar separator plate throughout; see also claim 4), so that geometrically similar bipolar plates may be used throughout the stack ([0025]). The rotation is about “an axis of rotation that extends perpendicular to the main extension plane of the bipolar plates” ([0025]: “… after a rotation of 90° with respect to the first separator plate”). The art is analogous because a fuel cell is an obvious variant of an electrolyzer (Gaugler [0002]; Molter [0002]-[0003]). The teaching of 90° reads on the claim limitation of 360/n, because n=4 for a four-sided, i.e. square bipolar plate as taught by Gaugler in view of Molter.
In the alternative to n=4, i.e. when the bipolar plate of Gaugler and Molter is hexagonal, octagonal, etc. as suggested by Molter ([0017]), the angle of rotation is necessarily limited to 360/n degrees or an obvious-to-try multiple thereof because of the need to align the point-symmetrical media apertures on adjacent bipolar plates. A rotation which is not a multiple of 360/n degrees, between 360/n and 360 degrees, would predictably result in an inoperable electrolyzer stack as the media apertures of adjacent plates will not align. Because the number of predictably successful angles of rotations is sufficiently small, it is obvious to one skilled in the art to infer from the teachings of Frederiksen that other rotations of adjacent plates in the stack are possible when the bipolar plate is not square as is taught by Gaugler in view of Molter.
It would have been obvious to one of ordinary skill in the art to construct the electrolyzer of Gaugler in view of Molter with adjacent bipolar plates rotated 360/n degrees about an axis of rotation that extends perpendicular to the main extension plane of the bipolar plates as Frederiksen teaches. One would have been motivated to make this modification in order to use substantially similar plates throughout the stack ([0025]) and to reduce the number of bipolar plates needed. These modifications increase power density while simplifying the manufacture of the stack and reducing costs ([0029]).
Regarding claim 12, the bipolar plate taught by Frederiksen and applied to Gaugler and Molter further comprises an anode side (Frederiksen Fig. 1b, [0019]). The anode compartment taught by Frederiksen is formed by a sealing unit around the flow field (24a), disclosed as a flow field seal (Figs. 2-3, 50) which seals off media apertures on different sides (Fig. 1b; e.g. 30, 32). These sealed-off channels pass media through to the next layer of the stack ([0019], [0025]: passive manifolds 17, 30, 31, 32). Media apertures 25 and 21 as shown in Fig. 1b are fluidically coupled to the anode compartment within the sealed region ([0022]).
Allowable Subject Matter
Claim 11 is objected to as being dependent upon a rejected base claim, but would be allowable if rewritten in independent form including all of the limitations of the base claim and any intervening claims.
The following is a statement of reasons for the indication of allowable subject matter: The prior art does not teach the claim limitations of fluidically coupling media apertures on adjacent sides of the cathode compartment, nor a motivation for doing so. Frederiksen, the closest art of record, teaches fluidically coupling media apertures on non-adjacent or opposite sides of the cathode compartment, as shown in Fig. 1a.
Conclusion
The prior art made of record and not relied upon is considered pertinent to applicant's disclosure: US 2016/0002798 A1 to Rømer et al. teaches a bipolar plate for an electrolyzer which may have a square, hexagonal, or otherwise polygon-shaped flow field. US 2015/033342 A1 to Planque et al. teaches distribution of gases in a solid oxide electrolyzer cell, SOEC.
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/CBF/Examiner, Art Unit 1711
/MICHAEL E BARR/Supervisory Patent Examiner, Art Unit 1711
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