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 .
Drawings
The drawings were received on 4/18/24. These drawings are acceptable.
Claim Rejections - 35 USC § 102
In the event the determination of the status of the application as subject to AIA 35 U.S.C. 102 and 103 (or as subject to pre-AIA 35 U.S.C. 102 and 103) is incorrect, any correction of the statutory basis (i.e., changing from AIA to pre-AIA ) for the rejection will not be considered a new ground of rejection if the prior art relied upon, and the rationale supporting the rejection, would be the same under either status.
The following is a quotation of the appropriate paragraphs of 35 U.S.C. 102 that form the basis for the rejections under this section made in this Office action:
A person shall be entitled to a patent unless –
(a)(1) the claimed invention was patented, described in a printed publication, or in public use, on sale, or otherwise available to the public before the effective filing date of the claimed invention.
Claims 1, 8-9, and 14-16 are rejected under 35 U.S.C. 102(a)(1) as being anticipated by Zhang et al., “In situ formation of a 3D core-shell and triple-conducting oxygen reduction reaction electrode for proton-conducting SOFCs,” Journal of Power Sources, Vol. 385, pp. 76–83 (2018), available online March 22, 2018 (“Zhang”).
As to Claim 1:
Zhang discloses a conformal coating scaffold electrode, described as a three-dimensional core-shell, triple-conducting oxygen-reduction electrode in which the core is a bulk BaZr₀.₄Ce₀.₄Y₀.₂O₃₋δ (“BZCY”) scaffold and the shell includes cubic Ba(Zr₀.₄Ce₀.₄Y₀.₂)₁₋ₓCoₓO₃₋δ, Co₃O₄, and (Ce, Zr, Y)O₂ (Zhang, Pgs. 76–77 and 82);
a sintered perovskite mesh scaffold, wherein Zhang forms a porous BZCY scaffold by depositing BZCY powder on a dense electrolyte and sintering the deposited BZCY in air at 1200 °C for five hours, thereby producing a well-connected, three-dimensional scaffold having approximately 50% porosity; Zhang further reports that BZCY has the nominal composition BaZr₀.₄Ce₀.₄Y₀.₂O₃₋δ and a cubic structure having space group Pm-3m (Zhang, Pgs. 77–80); and
a conformal catalyst coating, wherein a cobalt-containing solution is infiltrated into the porous BZCY scaffold and reactively sintered to form a thin film of Ba(Zr₀.₄Ce₀.₄Y₀.₂)₁₋ₓCoₓO₃₋δ on the surface of the porous scaffold, together with Co₃O₄ and (Ce, Zr, Y)O₂ particles. Zhang characterizes this surface layer as the shell of the three-dimensional core-shell electrode, reports homogeneous distributions of Co, Ba, Zr, Ce, and Y throughout the electrode layer, and attributes the electrode’s enhanced oxygen-reduction activity primarily to the Ba(Zr₀.₄Ce₀.₄Y₀.₂)₁₋ₓCoₓO₃₋δ formed in the shell (Zhang, Pgs. 78 and 81–82).
Accordingly, Zhang discloses each limitation of claim 1 and anticipates the claimed conformal coating scaffold electrode.
As to Claim 8:
Zhang discloses the conformal coating scaffold electrode of claim 1, as set forth in the rejection of claim 1 above (Zhang, Pgs. 76–82); and
Zhang discloses a symmetrical cell comprising the conformal coating scaffold electrode. Specifically, Zhang describes fabricating a symmetrical cell having an electrode|BZCY|electrode configuration, in which porous BZCY scaffolds are formed symmetrically on both surfaces of a dense BZCY electrolyte. The porous BZCY scaffolds are infiltrated with a cobalt-containing solution and reactively sintered to form the disclosed three-dimensional core-shell electrodes on opposite sides of the electrolyte (Zhang, Pgs. 77–78). Zhang further expressly reports testing a “symmetrical cell” containing the three-dimensional core-shell electrode and provides polarization-resistance and stability results for that symmetrical cell (Zhang, Pgs. 76–77 and 80–82).
As to Claim 9:
Zhang discloses the symmetrical cell comprising the conformal coating scaffold electrode of claim 8, as set forth in the rejection of claim 8 above (Zhang, Pgs. 76–82); and
Zhang discloses that the symmetrical cell has a polarization resistance of less than about 0.2 Ω·cm². Specifically, Zhang reports polarization resistances of 0.094 Ω·cm² at 650 °C and 0.198 Ω·cm² at 600 °C in wet air containing 3 vol% H₂O for the symmetrical cell having the three-dimensional core-shell electrode. Each reported value is less than about 0.2 Ω·cm² (Zhang, Pgs. 76–77 and 81–82).
As to Claim 14:
Zhang discloses the conformal coating scaffold electrode of claim 1, as set forth in the rejection of claim 1 above (Zhang, Pgs. 76–82); and
Zhang discloses a single electrochemical cell comprising the conformal coating scaffold electrode. Specifically, Zhang fabricates an anode-supported fuel cell having a composite anode, an approximately 25 μm-thick BZCY electrolyte, and the infiltrated three-dimensional core-shell BZCY electrode as the cathode. Zhang states that preparation of the infiltrated cathode for the fuel cell was the same as preparation of the core-shell electrode used in the symmetrical cells (Zhang, Pg. 78). Zhang further reports operating the assembled fuel cell using H₂ as the fuel and ambient air as the oxidant, with the cell producing peak power densities of approximately 330 mW·cm⁻² at 650 °C and approximately 220 mW·cm⁻² at 600 °C (Zhang, Pgs. 78 and 82).
As to Claim 15:
Zhang discloses the single electrochemical cell comprising the conformal coating scaffold electrode of claim 14, as set forth in the rejection of claim 14 above (Zhang, Pgs. 76–78 and 82); and
Zhang discloses that the single electrochemical cell further comprises a fuel electrode support. Specifically, Zhang expressly describes its complete electrochemical cell as an “anode-supported fuel cell.” The supporting anode comprises a composite of BZCY, NiO, and starch and is prepared by dry pressing followed by high-temperature sintering. Zhang further discloses that, during operation of the cell, H₂ fuel is supplied to the anode side, thereby establishing that the anode support is the claimed fuel electrode support (Zhang, Pg. 78).
As to Claim 16:
Zhang discloses the single electrochemical cell comprising the fuel electrode support of claim 15, as set forth in the rejection of claim 15 above (Zhang, Pgs. 76–78 and 82); and
Zhang discloses that the fuel electrode support comprises NiO, one or more perovskite precursors, and a pore former. Specifically, Zhang discloses an anode-supported fuel cell having a composite supporting anode prepared from 60 wt% NiO, 40 wt% BaZr₀.₄Ce₀.₄Y₀.₂O₃₋δ (“BZCY”) powder, and 10 wt% starch, followed by dry pressing and high-temperature sintering. The NiO corresponds to the claimed NiO, the BZCY powder corresponds to the claimed perovskite precursor, and the starch corresponds to the claimed pore former (Zhang, Pgs. 77–78).
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.
The factual inquiries for establishing a background for determining obviousness under 35 U.S.C. 103 are summarized as follows:
1. Determining the scope and contents of the prior art.
2. Ascertaining the differences between the prior art and the claims at issue.
3. Resolving the level of ordinary skill in the pertinent art.
4. Considering objective evidence present in the application indicating obviousness or nonobviousness.
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 2-3, 6, 7, and 17 are rejected under 35 U.S.C. 103 as being unpatentable over Zhang et al., “In situ formation of a 3D core-shell and triple-conducting oxygen reduction reaction electrode for proton-conducting SOFCs,” Journal of Power Sources, Vol. 385, pp. 76–83 (2018), available online March 22, 2018 (“Zhang”), and further in view of WO 2019079231 A1 (WO’231).
As to Claim 2:
Zhang discloses the conformal coating scaffold electrode of claim 1, as set forth in the rejection of claim 1 above (Zhang, Pgs. 76–82);
Zhang further discloses that the sintered perovskite mesh scaffold comprises BaZr₀.₄Ce₀.₄Y₀.₂O₃₋δ (“BZCY”). Specifically, Zhang forms a porous BZCY scaffold and sinters the scaffold in air at 1200 °C for five hours to obtain a well-connected scaffold having approximately 50% porosity (Zhang, Pgs. 76–78).
However, Zhang does not expressly disclose a scaffold containing a nonzero amount of ytterbium.
WO’231 discloses proton-conducting barium zirconate-cerate compounds having the formula BaZr₀.₄Ce₀.₄Y₀.₂₋ₜYbₜO₃, wherein
0
≤
t
≤
0.2
, and specifically discloses BaZr₀.₄Ce₀.₄Y₀.₁Yb₀.₁O₃ (“BZCYYb4411”) (WO’231, Pgs. 2–6). Expressed according to the notation of claim 2, BZCYYb4411 corresponds to:
x
=
0.4
for Zr, which is within
0.1
≤
x
≤
0.8
;
y
=
0.4
for Ce, which is within
0
≤
y
≤
0.8
;
z
=
0.1
for Y, which is within
0
≤
z
≤
0.3
; and
1
-
x
-
y
-
z
=
0.1
for Yb.
WO’231 further discloses that these barium zirconate compounds can be sintered to provide high proton-conductivity polycrystalline materials and that BZCYYb4411 combines chemical stability and bulk proton conductivity with ease of sintering and grain growth (WO’231, Pgs. 5–6).
It would have been obvious to a person skilled in the art before the effective filing date of the instant application to modify Zhang’s sintered BZCY scaffold by partially replacing yttrium with ytterbium, as taught by WO’231, thereby providing a scaffold comprising BaZr₀.₄Ce₀.₄Y₀.₁Yb₀.₁O₃₋δ, in order to obtain the chemical stability, bulk proton conductivity, and ease of sintering and grain growth expressly attributed to BZCYYb4411 by WO’231.
As to Claim 3:
Zhang discloses the conformal coating scaffold electrode of claim 1, as set forth in the rejection of claim 1 above (Zhang, Pgs. 76–82);
Zhang further discloses that the sintered perovskite mesh scaffold comprises BaZr₀.₄Ce₀.₄Y₀.₂O₃₋δ (“BZCY”). Specifically, Zhang forms a porous BZCY scaffold and sinters the scaffold in air at 1200 °C for five hours to obtain a well-connected scaffold having approximately 50% porosity (Zhang, Pgs. 76–78).
However, Zhang does not disclose that its sintered BZCY scaffold comprises BaZr₀.₄Ce₀.₄Y₀.₁Yb₀.₁O₃₋δ (“BZCYYb4411”) or BaZr₀.₁Ce₀.₇Y₀.₁Yb₀.₁O₃₋δ (“BZCYYb1711”).
WO’231 discloses BaZr₀.₄Ce₀.₄Y₀.₁Yb₀.₁O₃ (“BZCYYb4411”), which is one of the alternative compositions expressly recited in claim 3 (WO’231, Pgs. 3 and 6). WO’231 further discloses that BZCYYb4411 has a cubic crystal structure and combines chemical stability and bulk proton conductivity with ease of sintering and grain growth. WO’231 also reports that the conductivity of polycrystalline BZCYYb4411 is approximately three times greater than that of the compared yttrium-doped barium zirconate material prepared under similar conditions (WO’231, Pg. 6).
It would have been obvious to a person skilled in the art before the effective filing date of the instant application to replace Zhang’s BZCY scaffold material with WO’231’s BZCYYb4411 material to provide a sintered scaffold comprising BaZr₀.₄Ce₀.₄Y₀.₁Yb₀.₁O₃₋δ, in order to obtain the chemical stability, bulk proton conductivity, and ease of sintering and grain growth expressly attributed to BZCYYb4411 by WO’231.
As to Claim 6:
Zhang discloses the conformal coating scaffold electrode of claim 1, as set forth in the rejection of claim 1 above (Zhang, Pgs. 76–82);
Zhang further discloses that the catalyst coating is formed as a connective thin-film shell on the surface of the porous BZCY scaffold. Zhang reports homogeneous distributions of Co, Ba, Zr, Ce, and Y throughout the electrode layer and identifies a thin film of Ba(Zr₀.₄Ce₀.₄Y₀.₂)₁₋ₓCoₓO₃₋δ formed on the surface of the porous scaffold. Zhang explains that this thin-film layer forms part of the shell of the three-dimensional core-shell electrode and provides conducting pathways that facilitate the oxygen-reduction reaction (Zhang, Pgs. 77 and 81–82).
However, Zhang does not expressly characterize the catalyst thin film as both continuous and uniform over the scaffold.
WO’231 discloses forming an electrode coating as a thin, dense interlayer film directly over and in contact with an underlying ceramic surface. WO’231 teaches forming and sintering the dense interlayer before applying a porous overlayer and explains that the dense film has a lower porosity than the porous overlayer. WO’231 further discloses depositing the thin film by vapor deposition, including pulsed-laser deposition, and depicts the dense interlayer extending along the underlying electrolyte-cathode interface (WO’231, Pgs. 2–5). The thin, dense interlayer film extending over the underlying surface teaches the claimed continuous and uniform film. WO’231 also explains that depositing the thin dense layer provides good contact between the porous cathode and the underlying ceramic material, thereby enabling high peak power densities (WO’231, Pg. 5).
It would have been obvious to a person skilled in the art before the effective filing date of the instant application to form Zhang’s catalyst thin-film shell as a continuous, uniform film over the scaffold using the thin, dense film teachings of WO’231, in order to provide the good contact and improved fuel-cell performance expressly described by WO’231.
As to Claim 7:
Zhang discloses the conformal coating scaffold electrode wherein the catalyst coating forms a continuous, uniform film over the scaffold of claim 6, as set forth in the rejection of claim 6 above (Zhang, Pgs. 76–82);
Zhang further discloses that the catalyst coating is a connective thin-film shell formed on the surface of the porous BZCY scaffold. Zhang identifies this thin film as comprising Ba(Zr₀.₄Ce₀.₄Y₀.₂)₁₋ₓCoₓO₃₋δ and explains that the resulting shell facilitates the oxygen-reduction reaction (Zhang, Pgs. 77 and 81–82).
However, Zhang does not disclose that the film has a thickness from about 20 nm to about 200 nm.
WO’231 discloses thin, dense cathode interlayer films having a thickness no greater than 500 nm, including no greater than 100 nm (WO’231, Pg. 5). More particularly, WO’231 discloses applying an approximately 100 nm-thick PBSCF catalyst layer by pulsed-laser deposition, with the deposited layer forming a conformal coating on the underlying electrolyte. The disclosed thickness of approximately 100 nm falls within the claimed range of about 20 nm to about 200 nm (WO’231, Pg. 9). WO’231 further reports that application of the approximately 100 nm film markedly increased power output and decreased offset resistance by improving cathode-electrolyte contact (WO’231, Pgs. 9–10).
It would have been obvious to a person skilled in the art before the effective filing date of the instant application to form Zhang’s catalyst thin-film shell with a thickness of approximately 100 nm, as taught by WO’231, in order to improve electrode contact, decrease resistance, and increase power output as expressly demonstrated by WO’231.
As to Claim 17:
Zhang discloses the single electrochemical cell having the fuel electrode support of claim 16, as set forth in the rejection of claim 16 above (Zhang, Pgs. 76–78 and 82);
Zhang further discloses that the fuel electrode support is prepared from a composite containing NiO, BZCY powder, and starch. Zhang identifies the BZCY component as BaZr₀.₄Ce₀.₄Y₀.₂O₃₋δ, which comprises Ba, Zr, Ce, and Y, and discloses dry pressing and high-temperature sintering the composite to form the supporting anode (Zhang, Pgs. 77–78).
However, Zhang does not disclose that the one or more perovskite precursors in the fuel electrode support further comprise Yb and thus does not disclose a BZCYYb precursor containing Ba, Ce, Zr, Y, and Yb.
WO’231 discloses BaZr₀.₄Ce₀.₄Y₀.₁Yb₀.₁O₃ (“BZCYYb4411”), which comprises each of the claimed elements Ba, Ce, Zr, Y, and Yb (WO’231, Pgs. 2–6). WO’231 further expressly incorporates BZCYYb4411 into an anode-support precursor mixture containing NiO, BZCYYb4411, and starch. The mixture is milled, pressed into a disc, and lightly sintered to form the supporting anode of an anode-supported electrochemical cell (WO’231, Pg. 9). WO’231 also teaches that BZCYYb4411 combines chemical stability and bulk proton conductivity with ease of sintering and grain growth (WO’231, Pg. 6).
It would have been obvious to a person skilled in the art before the effective filing date of the instant application to replace Zhang’s BZCY precursor with WO’231’s BZCYYb4411 precursor in Zhang’s fuel electrode support, thereby providing a precursor comprising Ba, Ce, Zr, Y, and Yb, in order to obtain the chemical stability, bulk proton conductivity, and ease of sintering and grain growth expressly attributed to BZCYYb4411 by WO’231.
Claims 4 and 5 are rejected under 35 U.S.C. 103 as being unpatentable over Zhang et al., “In situ formation of a 3D core-shell and triple-conducting oxygen reduction reaction electrode for proton-conducting SOFCs,” Journal of Power Sources, Vol. 385, pp. 76–83 (2018), available online March 22, 2018 (“Zhang”), and further in view of Li et al., “Enhancing the catalytic activity and stability of the Pr₂NiO₄₊δ Ruddlesden-Popper perovskite air electrode for high-temperature steam electrolysis with barium doping,” Journal of Alloys and Compounds, Vol. 932, Article 167646 (2023), available online October 18, 2022 (“Li”).
As to Claim 4:
Zhang discloses the conformal coating scaffold electrode of claim 1, as set forth in the rejection of claim 1 above (Zhang, Pgs. 76–82);
Zhang further discloses a catalyst coating formed as a thin-film shell on the surface of a sintered, porous BZCY scaffold. Zhang explains that the shell provides catalytic activity for the oxygen-reduction reaction and attributes the enhanced electrochemical performance primarily to the active material formed in the shell (Zhang, Pgs. 76–77 and 81–82).
However, Zhang does not disclose that the conformal catalyst coating comprises Pr₂₋ₓBaₓNiO₄₊δ, wherein
0
≤
x
≤
0.4
.
Li discloses Pr₂₋ₓBaₓNiO₄₊δ Ruddlesden-Popper perovskite air-electrode materials, designated PBNO-x, wherein
x
=
0
,
0.1
,
0.2
,
0.3
,
or
0.4
. Each disclosed value falls within the claimed range of
0
≤
x
≤
0.4
(Li, Pgs. 1–3). Li specifically identifies PBNO-0.2 as Pr₁.₈Ba₀.₂NiO₄₊δ and discloses that Ba doping improves the structural stability and electrochemical activity of the PNO air electrode (Li, Pgs. 1–2 and 5). Li reports that PBNO-0.2 has an electrode polarization resistance of 0.06 Ω·cm² at 800 °C, approximately 66% lower than undoped PNO, and exhibits stable operation for 126 hours at a current density of 1 A·cm⁻² (Li, Pgs. 1 and 6–8). Li attributes the high catalytic performance of PBNO-0.2 to its high oxygen-vacancy concentration and concludes that PBNO-0.2 has high catalytic activity and stability as an air electrode for solid oxide electrochemical cells (Li, Pgs. 1, 5–8).
Zhang and Li are analogous arts because both references concern solid oxide electrochemical cells and catalytic air or oxygen electrodes configured to facilitate oxygen electrode reactions while providing low polarization resistance and operational stability (Zhang, Pgs. 76–82; Li, Pgs. 1–2 and 6–8).
It would have been obvious to a person skilled in the art before the effective filing date of the instant application to employ Li’s Pr₂₋ₓBaₓNiO₄₊δ, particularly Pr₁.₈Ba₀.₂NiO₄₊δ, as a catalytic material in Zhang’s conformal catalyst coating in order to obtain the improved catalytic activity, reduced polarization resistance, and enhanced operational stability expressly attributed to the Ba-doped material by Li.
As to Claim 5:
Zhang discloses the conformal coating scaffold electrode of claim 1, as set forth in the rejection of claim 1 above (Zhang, Pgs. 76–82);
Zhang further discloses a catalyst coating formed as a thin-film shell on the surface of a porous BZCY scaffold. Zhang attributes the enhanced oxygen-reduction activity of the electrode primarily to the active catalyst material formed in the shell (Zhang, Pgs. 76–77 and 81–82).
However, Zhang does not disclose that the conformal catalyst coating comprises Pr₁.₈Ba₀.₂NiO₄.₁ (“PBNO”).
Li discloses Pr₂₋ₓBaₓNiO₄₊δ materials and specifically discloses the
x
=
0.2
composition, PBNO-0.2, corresponding to Pr₁.₈Ba₀.₂NiO₄₊δ (Li, Pgs. 1–3). Li identifies oxygen content as a investigated compositional property and reports that the
x
=
0.2
composition undergoes a reduction in over-stoichiometric oxygen content and possesses the highest oxygen-vacancy concentration among the tested PBNO compositions (Li, Pgs. 2 and 4–5). Li further reports that PBNO-0.2 provides the lowest polarization resistance, improved electrochemical performance, and stable operation for 126 hours, and attributes its high catalytic performance to its oxygen-defect concentration (Li, Pgs. 1 and 5–8). Accordingly, Li teaches the cation composition Pr₁.₈Ba₀.₂Ni and identifies oxygen nonstoichiometry, represented by
δ
, as a compositional variable affecting catalytic activity.
It would have been obvious to a person skilled in the art before the effective filing date of the instant application to employ Li’s Pr₁.₈Ba₀.₂NiO₄₊δ material in Zhang’s conformal catalyst coating and to select an oxygen nonstoichiometry of
δ
=
0.1
, thereby providing Pr₁.₈Ba₀.₂NiO₄.₁, as an optimization of Li’s expressly disclosed oxygen-nonstoichiometry variable for obtaining the oxygen-defect concentration associated with improved catalytic activity and stability.
Claims 10 and 11 are rejected under 35 U.S.C. 103 as being unpatentable over Zhang et al., “In situ formation of a 3D core-shell and triple-conducting oxygen reduction reaction electrode for proton-conducting SOFCs,” Journal of Power Sources, Vol. 385, pp. 76–83 (2018), available online March 22, 2018 (“Zhang”), and further in view of Ding et al., “Self-sustainable protonic ceramic electrochemical cells using a triple conducting electrode for hydrogen and power production,” Nature Communications, Vol. 11, Article 1907 (2020) (“Ding”).
As to Claim 10:
Zhang discloses the symmetrical cell comprising the conformal coating scaffold electrode of claim 8, as set forth in the rejection of claim 8 above (Zhang, Pgs. 76–82);
Zhang further discloses evaluating the symmetrical cell at 650 °C for 70 hours and reports that its polarization resistance remained relatively stable without obvious degradation. Zhang attributes this stability to the compatibility of the electrode and electrolyte and to the three-dimensional core-shell structure formed by infiltration and high-temperature sintering (Zhang, Pgs. 76 and 82).
However, Zhang does not disclose operating the symmetrical cell for 200 hours or expressly disclose that the final polarization resistance after 200 hours is no more than about 10% greater than its initial polarization resistance.
Ding discloses evaluating the long-term area-specific polarization resistance of PNC electrodes in symmetrical cells at 500 °C and 600 °C under different water concentrations. Ding’s Supplementary Figure 18 shows that, under 20% H₂O, the polarization resistance remains substantially unchanged or decreases during operation extending beyond 200 hours. At 500 °C, the resistance remains approximately 0.225 Ω·cm² through about 200 hours; at 600 °C, the resistance remains approximately 0.08 Ω·cm² or decreases slightly through more than 200 hours. Thus, the final polarization resistance after 200 hours is no greater than, and therefore no more than about 10% greater than, the initial polarization resistance (Ding, Pg. 5; Ding Supplementary Information, Pg. 20, Supplementary Fig. 18).
Ding further explains that the electrode polarization resistances were measured over several hundred hours and that the stable resistance under 20% H₂O indicates strong electrode-electrolyte interfacial bonding. Ding attributes the demonstrated performance stability to the chemical stability of the electrode and strong interfacial bonding between the electrode and electrolyte (Ding, Pg. 5; Ding Supplementary Information, Pgs. 32–33).
Zhang and Ding are analogous arts because both references concern symmetrical proton-conducting ceramic electrochemical cells, oxygen electrodes, polarization resistance, and long-term electrode-electrolyte stability (Zhang, Pgs. 76–82; Ding, Pgs. 1–6 and Supplementary Information, Pgs. 20 and 32–33).
It would have been obvious to a person skilled in the art before the effective filing date of the instant application to configure Zhang’s symmetrical cell using Ding’s chemically stable oxygen-electrode and strongly bonded electrode-electrolyte interface teachings to maintain stable polarization resistance for at least 200 hours, such that the final polarization resistance is no more than about 10% greater than the initial polarization resistance, in order to obtain the long-term operational stability demonstrated by Ding.
As to Claim 11:
Zhang discloses the symmetrical cell comprising the conformal coating scaffold electrode of claim 8, as set forth in the rejection of claim 8 above (Zhang, Pgs. 76–82);
Zhang further discloses measuring polarization resistance in air and in wet air containing 3 vol% H₂O. Zhang also discloses measuring the polarization resistance of the symmetrical cell during a 70-hour stability test (Zhang, Pgs. 76, 78 and 81–82).
However, Zhang does not disclose measuring the initial and final polarization resistances in an environment containing from about 30 vol% to about 60 vol% H₂O in air.
Ding discloses measuring the area-specific polarization resistance of PNC electrodes in symmetrical cells under air environments containing 10 vol%, 20 vol%, and 50 vol% H₂O at 500 °C and 600 °C. The disclosed 50 vol% H₂O environment falls within the claimed range of about 30 vol% to about 60 vol% H₂O. Ding’s Supplementary Figure 18 presents repeated polarization-resistance measurements at 50 vol% H₂O, including first and final measurements taken over the reported testing period (Ding, Pg. 5; Ding Supplementary Information, Pg. 20, Supplementary Fig. 18).
Ding further explains that electrode polarization resistances under 10 vol%, 20 vol%, and 50 vol% H₂O were measured over extended periods to evaluate electrode activity and stability at elevated water pressure. Ding identifies electrode and interface degradation under high-steam conditions as a concern for protonic ceramic electrochemical cells (Ding, Pgs. 1–2 and 5; Ding Supplementary Information, Pgs. 32–33).
It would have been obvious to a person skilled in the art before the effective filing date of the instant application to measure the initial and final polarization resistances of Zhang’s symmetrical cell in air containing 50 vol% H₂O, as taught by Ding, to evaluate electrode activity and stability under the elevated-steam conditions expressly identified by Ding as relevant to protonic ceramic electrochemical cells.
Claim 12 is rejected under 35 U.S.C. § 103 as being unpatentable over Zhang et al., “In situ formation of a 3D core-shell and triple-conducting oxygen reduction reaction electrode for proton-conducting SOFCs,” Journal of Power Sources, Vol. 385, pp. 76–83 (2018), available online March 22, 2018 (“Zhang”), and further in view of Zhang et al., “Thermal-expansion offset for high-performance fuel cell cathodes,” Nature 591, 246–250 (2021), doi:10.1038/s41586-021-03264-1 (“Yuan”).
As to Claim 12:
Zhang discloses the symmetrical cell of claim 8, as addressed in the rejection of claim 8. More particularly, Zhang discloses an electrode|BZCY|electrode symmetrical cell having porous BZCY scaffolds deposited symmetrically on both surfaces of a dense BZCY electrolyte and sintered to form well-connected scaffolds. The scaffolds are infiltrated with a cobalt-containing solution and reactively sintered to form three-dimensional core-shell oxygen-reduction electrodes comprising a bulk BZCY scaffold and a thin-film catalytic shell (Zhang, Pgs. 76–77, 81–82).
Zhang further discloses that thermal-expansion mismatch between the electrode and electrolyte can generate internal strain during heating and cooling, resulting in delamination and rapid performance degradation. Zhang measures the thermal-expansion coefficients of the dense BZCY electrolyte and infiltrated BZCY electrode and reports that their similar values demonstrate good thermo-mechanical compatibility and help ensure operational stability (Zhang, Pg. 82).
However, Zhang does not expressly disclose operating its symmetrical cell through repeated thermal cycles from a first temperature to a second temperature and back to the first temperature.
Yuan discloses symmetrical solid-oxide-fuel-cell test cells having c-SYNC electrodes disposed on both sides of an SDC electrolyte (Yuan, Pgs. 248–249). Yuan subjects these symmetrical cells to a “harsh thermal cycling procedure” comprising 40 thermal cycles between 600 °C and 300 °C. Figure 3a shows the cells repeatedly cooled from 600 °C to 300 °C and heated back to 600 °C, using a heating rate of 30 °C min⁻¹ and a cooling rate of approximately 7.5 °C min⁻¹ (Yuan, Pgs. 249–250). Yuan uses this procedure to evaluate electrode polarization resistance and thermo-mechanical durability, including cracking and delamination following repeated thermal cycling (Yuan, Pgs. 249–250).
Zhang and Yuan are analogous art because both concern symmetrical electrochemical cells containing oxygen-reduction electrodes for solid oxide fuel cells, and both specifically address electrode-electrolyte thermal-expansion compatibility, operational stability, and avoidance of electrode delamination during heating and cooling (Zhang, Pgs. 76–77, 82; Yuan, Pgs. 246, 248–250).
It would have been obvious to a person skilled in the art before the effective filing date of the instant application to operate Zhang’s symmetrical cell using Yuan’s repeated thermal-cycling procedure—cycling from 600 °C to 300 °C and back to 600 °C—to evaluate the thermo-mechanical compatibility and operational durability that Zhang identifies as important for avoiding strain, delamination, and performance degradation during heating and cooling.
Claim 13 is rejected under 35 U.S.C. § 103 as being unpatentable over Zhang et al., “In situ formation of a 3D core-shell and triple-conducting oxygen reduction reaction electrode for proton-conducting SOFCs,” Journal of Power Sources, Vol. 385, pp. 76–83 (2018), available online March 22, 2018 (“Zhang”), in view of Zhang et al., “Thermal-expansion offset for high-performance fuel cell cathodes,” Nature 591, 246–250 (2021), doi:10.1038/s41586-021-03264-1 (“Yuan”), and further in view of Lee et al., “Durable high-performance Sm0.5Sr0.5CoO3–Sm0.2Ce0.8O1.9 core-shell type composite cathodes for low temperature solid oxide fuel cells,” International Journal of Hydrogen Energy 36, 6875–6881 (2011), doi:10.1016/j.ijhydene.2011.02.093 (“Lee”).
As to Claim 13:
Zhang discloses the symmetrical cell of claim 8, as addressed in the rejection of claim 8. More particularly, Zhang discloses an electrode|BZCY|electrode symmetrical cell having porous BZCY scaffolds deposited symmetrically on both surfaces of a dense BZCY electrolyte and subsequently infiltrated and reactively sintered to form three-dimensional core-shell oxygen-reduction electrodes comprising a bulk BZCY scaffold and a thin-film catalytic shell (Zhang, Pgs. 76–77, 81–82).
Zhang further discloses that thermal-expansion mismatch between the electrode and electrolyte can generate internal strain during heating and cooling, resulting in delamination and rapid performance degradation. Zhang reports that the similar thermal-expansion coefficients of its dense BZCY electrolyte and infiltrated BZCY electrode demonstrate good thermo-mechanical compatibility and help ensure operational stability (Zhang, Pg. 82).
However, Zhang does not expressly disclose operating its symmetrical cell through repeated thermal cycles, much less cycles in which the first temperature is about 100 °C and the second temperature is from about 600 °C to about 750 °C.
Yuan discloses operating symmetrical solid-oxide-fuel-cell test cells through repeated thermal cycles. Specifically, Yuan subjects c-SYNC|SDC|c-SYNC symmetrical cells to 40 thermal cycles between 600 °C and 300 °C, with repeated heating and cooling performed over approximately 90 hours. Yuan evaluates changes in polarization resistance, cracking, and electrode-electrolyte delamination resulting from the repeated thermal cycling (Yuan, Pgs. 248–250). Thus, Yuan teaches the repeated-thermal-cycling limitation of claim 12. However, Yuan does not disclose a first-cycle temperature of about 100 °C.
Lee discloses an electrolyte-supported symmetrical SSC–SDC|SDC|SSC–SDC cell having cathode layers deposited on both sides of an SDC electrolyte and expressly subjects the symmetrical cell to thermo-cycle testing (Lee, Pgs. 6875–6876). Lee performs 30 thermal cycles over a temperature range of 100 °C to 650 °C, using a ramping rate of 5 °C per minute and holding the cell at 650 °C for 30 minutes to measure polarization resistance during each cycle (Lee, Pgs. 6875–6876). Lee further states that the furnace temperature was “periodically varied between 100 and 650 °C” during the 30-cycle stability test (Lee, Pgs. 6879–6880). Accordingly, Lee teaches repeated operation from a first temperature of about 100 °C to a second temperature of 650 °C, which falls within the claimed range of about 600 °C to about 750 °C, and back to the first temperature.
Zhang, Yuan, and Lee are analogous art because each concerns solid oxide fuel-cell electrodes and symmetrical electrochemical cells, and each addresses electrode durability and thermo-mechanical stability during heating and cooling. Zhang identifies thermal-expansion mismatch during heating and cooling as a cause of strain, delamination, and degradation; Yuan evaluates symmetrical cells under repeated thermal cycling; and Lee uses repeated thermal cycling between 100 °C and 650 °C to evaluate cathode durability and microstructural changes under thermal stress (Zhang, Pg. 82; Yuan, Pgs. 248–250; Lee, Pgs. 6875–6876, 6879–6880).
It would have been obvious to a person skilled in the art before the effective filing date of the instant application to subject Zhang’s symmetrical cell to the repeated thermal-cycling procedure taught by Yuan and to employ Lee’s disclosed cycling range of about 100 °C to 650 °C and back to about 100 °C, in order to evaluate the cell’s operational durability and resistance to the thermal-stress-induced delamination and degradation identified by the references.
Claim 18 is rejected under 35 U.S.C. § 103 as being unpatentable over Zhang et al., “In situ formation of a 3D core-shell and triple-conducting oxygen reduction reaction electrode for proton-conducting SOFCs,” Journal of Power Sources, Vol. 385, pp. 76–83 (2018), available online March 22, 2018 (“Zhang”), in view of Zhang et al., “Thermal-expansion offset for high-performance fuel cell cathodes,” Nature 591, 246–250 (2021), doi:10.1038/s41586-021-03264-1 (“Yuan”), and further in view of Huang et al., “Performance of BaCe0.8Y0.2O3−δ Proton Electrolyte Materials for Solid Oxide Fuel Cells by Compositing the Transition Metal Oxide NiO,” Coatings 12, 1692 (2022), doi:10.3390/coatings12111692 (“Huang”).
As to Claim 18:
Zhang discloses the single electrochemical cell and fuel-electrode-support limitations of claims 14–16. Specifically, Zhang discloses an anode-supported fuel cell having an approximately 25-μm-thick BZCY electrolyte and a composite anode containing 40 wt% BZCY, 60 wt% NiO, and 10 wt% starch. Zhang prepares the anode-supported cell by dry pressing and high-temperature sintering and applies the infiltrated BZCY oxygen electrode to the resulting cell (Zhang, Pgs. 77, 81–82).
Zhang further identifies a Ni+BaZr0.1Ce0.7Y0.1Yb0.1O3−δ anode for solid oxide fuel cells, thereby identifying a Ni-containing fuel electrode employing the claimed BZCYYb1711 perovskite composition (Zhang, Pg. 83).
Yuan additionally discloses an anode-supported H2/air solid oxide fuel cell. Yuan prepares anode-supported half-cells having a NiO+YSZ fuel-electrode support, a YSZ electrolyte, and an SDC electrolyte layer, followed by deposition of the oxygen electrode (Yuan, Pg. 250).
However, Zhang does not disclose NiO, BZCYYb, and the pore former in a weight ratio of about 5:5:2. Zhang’s experimental composite anode instead contains 60 wt% NiO, 40 wt% BZCY, and 10 wt% starch (Zhang, Pg. 77). Yuan also does not disclose the claimed 5:5:2 ratio.
Huang discloses a single SOFC having a NiO–BCY hydrogen-electrode support. Huang initially discloses that the mass ratio of NiO to BCY in the hydrogen electrode is 5:5 (Huang, Pg. 2). Huang then expressly discloses that the hydrogen-electrode powder contains NiO, BCY, and starch in a mass ratio of 5:5:2 and that the hydrogen-electrode powder is co-pressed with the electrolyte powder and sintered to produce the single SOFC (Huang, Pgs. 2–3). Thus, Huang expressly teaches the claimed relative proportions of NiO, a proton-conducting barium-cerate perovskite, and starch.
Huang further teaches that NiO is commonly used as a component of SOFC anodes and that adding NiO is beneficial to sintering the proton-conducting perovskite material (Huang, Pgs. 1–2). Huang also expressly identifies prior work titled “Enhanced sinterability of BaZr0.1Ce0.7Y0.1Yb0.1O3−δ by addition of nickel oxide,” thereby identifying the claimed BZCYYb1711 composition as a proton-conducting perovskite compatible with NiO addition (Huang, Pg. 9).
Zhang, Yuan, and Huang are analogous art because each concerns solid oxide fuel cells having supported electrode structures. Zhang and Huang more particularly concern proton-conducting SOFCs having NiO/perovskite fuel electrodes, while Yuan confirms the use of a NiO-containing fuel-electrode support in an anode-supported SOFC architecture (Zhang, Pgs. 76–77; Yuan, Pg. 250; Huang, Pgs. 1–3).
It would have been obvious to a person skilled in the art before the effective filing date of the instant application to prepare Zhang’s fuel-electrode support using NiO, BZCYYb, and starch in Huang’s expressly disclosed 5:5:2 weight ratio because Huang teaches that this ratio is suitable for a NiO/proton-conducting-perovskite hydrogen-electrode support and further identifies NiO addition as beneficial to the sintering of BZCYYb1711.
Claims 19-20 are rejected under 35 U.S.C. § 103 as being unpatentable over Zhang et al., “In situ formation of a 3D core-shell and triple-conducting oxygen reduction reaction electrode for proton-conducting SOFCs,” Journal of Power Sources, Vol. 385, pp. 76–83 (2018), available online March 22, 2018 (“Zhang”), and further in view of US 20070065701 A1 (US’701).
As to Claim 19:
Zhang discloses the conformal coating scaffold electrode of claim 1, as set forth in the rejection of claim 1 above;
Zhang further discloses a symmetrical cell having an electrode|BZCY electrolyte|electrode configuration. Porous BZCY perovskite scaffolds are symmetrically deposited on both surfaces of a dense BZCY electrolyte and sintered to produce well-connected scaffolds having approximately 50% porosity. Co-containing solutions are subsequently infiltrated into the scaffolds and reactively sintered to form three-dimensional core-shell electrodes comprising a bulk BZCY scaffold and a conformal thin-film catalyst shell (Zhang, Pgs. 76–78 and 80–82).
However, Zhang does not expressly disclose incorporating its symmetrical cell into a broader device, such as a fuel-cell stack containing one or more individual electrochemical cells.
US’701 discloses a symmetrical, bi-electrode-supported solid oxide fuel cell comprising first and second porous electrode scaffolds and an intervening electrolyte layer (US’701, [0013], [0037]). US’701 further discloses that the conductive coatings on the cell function as interconnects to other cells in a stack (US’701, [0037]). Specifically, US’701 teaches using each symmetrical cell as an individual repeat unit within a plurality of like fuel-cell repeat units that, after sintering and electrode activation, form a complete monolithic solid-oxide fuel-cell stack (US’701, [0070]). US’701 explains that the individual fuel cells may be electrically connected in parallel or series to provide electric power at respectively lower or higher voltage (US’701, [0033]). Thus, US’701 teaches a device comprising at least one symmetrical electrochemical cell.
Zhang and US’701 are analogous arts because both references concern symmetrical solid-oxide electrochemical cells comprising porous ceramic electrode scaffolds disposed on opposing sides of a solid electrolyte, and both employ post-sintering infiltration or solution treatment to impart catalytic activity to the porous scaffolds (Zhang, Pgs. 76–78 and 80–82; US’701, [0013], [0037], [0068]–[0070]).
It would have been obvious to a person skilled in the art before the effective filing date of the instant application to incorporate Zhang’s symmetrical cell as an individual repeat unit in a fuel-cell-stack device, as taught by US’701, to provide a plurality of electrically interconnected cells capable of supplying the voltage and electric power expressly described by US’701.
As to Claim 20:
Zhang in view of US’701 discloses the device comprising the symmetrical cell of claim 19, as set forth in the rejection of claim 19 above;
Zhang further discloses assembling its conformal core-shell electrode with an anode-supported, thin-film BZCY electrolyte to form a complete fuel cell. The fuel cell includes a composite BZCY/NiO anode, an approximately 25-μm-thick BZCY electrolyte, and the infiltrated BZCY core-shell electrode as the cathode (Zhang, Pgs. 78 and 82). Zhang operates the fuel cell using hydrogen as the fuel and ambient air as the oxidant and reports peak power densities of approximately 330 mW·cm⁻² at 650 °C and approximately 220 mW·cm⁻² at 600 °C (Zhang, Pgs. 78 and 82).
However, although Zhang separately discloses a symmetrical test cell and a complete anode-supported fuel cell, Zhang does not expressly disclose incorporating its symmetrical cell into a broader operational device comprising a fuel cell or fuel-cell stack.
US’701 discloses a symmetrical, bi-electrode-supported solid oxide fuel cell comprising first and second porous electrode scaffolds and an intervening electrolyte layer (US’701, [0013], [0037]). US’701 expressly defines a fuel cell as a device comprising an electrolyte disposed between two electrodes, one reacting with fuel and the other reacting with an oxidizer (US’701, [0032]). US’701 further discloses using each symmetrical cell as a repeat unit within a plurality of like fuel-cell repeat units that, following sintering and treatment of the electrode scaffolds to provide respective anodic and cathodic catalytic properties, form a complete monolithic solid-oxide fuel-cell stack (US’701, [0068]–[0070]). Accordingly, US’701 teaches a device comprising a fuel cell, thereby satisfying one of the alternatives recited in claim 20.
It would have been obvious to a person skilled in the art before the effective filing date of the instant application to incorporate Zhang’s symmetrical cell and conformal core-shell electrode into the fuel-cell device or fuel-cell-stack architecture taught by US’701 to provide an operational device capable of generating electrical power.
Conclusion
The prior art made of record and not relied upon is considered pertinent to applicant's disclosure.
US 2015/0325860 A1 discloses a composition of matter is disclosed which is a perovskite having a composition A.sub.2-xA′.sub.xB.sub.2-yB′.sub.yO.sub.6-δ.
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/JIMMY VO/
Primary Examiner
Art Unit 1723
/JIMMY VO/ Primary Examiner, Art Unit 1723
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