RESPONSE TO AMENDMENT
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 .
Amendments to the specification and the claims, filed 18 June 2026, have been entered in the above-identified application.
Claims 1-5 and 8-12 remain pending in the application.
Claims 1-5 remain withdrawn in the application.
Claims 6-7 and 13 remain cancelled in the application.
Election/Restrictions
Applicant's election with traverse of claims 8-12 in the reply filed on 18 June 2026 is acknowledged. The traversal is on the grounds that the subject matter of the claims drawn to a method of controlling a flow battery system and claims drawn to a battery flow system is similar and there would not be a search burden to the examiner (Applicant’s remarks, page 9). This is not found persuasive because, as the application is a filed as a national stage application under 35 U.S.C. 371, the requirement for restriction is for a lack of unity of invention of the claimed inventions, and not for an undue search burden on the examiner (MPEP 1893.03(d)). The claimed invention I, claims 1-5, and invention II, claims 8-12, were shown to lack unity of invention due to their shared technical feature of the flow battery system of claim 1 not being a special technical feature as it does not make a contribution over the prior art in view of Mittal (WIPO Patent Application Publication no. 2020/144509), as described in detail in the previous office action mailed 08 April 2026.
The requirement is still deemed proper and is therefore made FINAL.
Withdrawn Objections/Rejections
The objection to the specification and drawings, made of record in the office action mailed on 08 April 2026, page 7, has been withdrawn due to Applicant’s amendment in the response 18 June 2026.
The 35 U.S.C. §112b rejections of claim 8 made of record in the office action mailed 08 April 2026, pages 7-8, have been withdrawn due to Applicant’s amendment in the response filed 18 June 2026.
The 35 U.S.C. §102 rejection of claims 8-9 as being anticipated by Hennessy (US Patent Application Publication No. 2013/0154364) have been withdrawn due to Applicant’s arguments in the response filed 18 June 2026.
The 35 U.S.C. §103 rejection of claims 10-11 as being obvious over Hennessy (US Patent Application Publication No. 2013/0154364) ) in view of Edmiston (US Patent Application Publication No. 2012/0088171) has been withdrawn due to Applicant’s arguments in the response filed 18 June 2026.
The 35 U.S.C. §103 rejection of claim 12 as being obvious over Hennessy (US Patent Application Publication No. 2013/0154364) in view of Song (US Patent Application Publication No. 2018/0316031) has been withdrawn due to Applicant’s arguments in the response filed 18 June 2026.
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 text of those sections of Title 35, U.S. Code not included in this action can be found in a prior Office action.
Claims 8 and 9 are rejected under 35 U.S.C. 102(a)(1) as being anticipated by Mittal (WIPO Patent Application Publication no. 2020/144509).
Regarding Claim 8, Mittal teaches a method for controlling a flow battery system (abstract), the flow battery system comprising a positive electrolyte tank containing a positive electrolyte ([82] and fig. 6 ref. #304) and a negative electrolyte tank containing a negative electrolyte ([82] and fig. 6 ref. #302). The battery system also contains a primary stack (cell, [82] and fig. 6 ref. #306-1) comprising a positive porous electrode and a negative porous electrode separated by a membrane ([45], and fig. 1 ref. #108, #110, and #112), the positive porous electrode of the primary stack and the negative porous electrode of the primary stack being coupled to a power bus (negative bipolar plate and positive bipolar plate, [47], and fig. 1 ref. #114 and #116).
The flow system also contains a primary stack positive electrolyte pump configured to pump said positive electrolyte from the positive electrolyte tank though the positive electrode of the primary stack (sperate pump, [48], and fig. 1 ref.# 118-2) and a primary stack negative electrolyte pump configured to pump said negative electrolyte from the negative electrolyte tank though the negative electrode of the primary stack (sperate pump, [48], and fig. 1 ref.# 118-1).
Mittal also teaches an auxiliary stack (cell, [82] and fig. 6 ref. #306-2) comprising a positive porous electrode and a negative porous electrode separated by a membrane ([45], and fig. 1 ref. #108, #110, and #112), the positive porous electrode of the auxiliary stack and the negative porous electrode of the auxiliary stack being coupled to the power bus (negative bipolar plate and positive bipolar plate, [47], and fig. 1 ref. #114 and #116). There is an auxiliary stack positive electrolyte pump configured to pump said positive electrolyte from the positive electrolyte tank though the positive electrode of the auxiliary stack ([86], fig. 6 ref. #604-2) and an auxiliary stack negative electrolyte pump configured to pump said negative electrolyte from the negative electrolyte tank though the negative electrode of the auxiliary stack ([86], fig. 6 ref. #602-2).
Mittal also teaches the method comprising monitoring a detected power load on the power bus, done using a current sensor ([21]), then activating the auxiliary stack positive electrolyte pump and the auxiliary stack negative electrolyte pump if the detected power load on the power bus is greater than a first threshold power load ([72], the output limit of the first stack). Next, intermittently deactivating the primary stack positive electrolyte pump and the primary stack negative electrolyte pump if the detected power load on the power bus is less than a second threshold power load which is lower than the first threshold power load ([61] and [86], when there is no load on the primary stack).
When the primary stack positive electrolyte pump and the primary stack negative electrolyte pump are deactivated, power is supplied to the power bus from the positive electrolyte within the positive porous electrode of the primary stack and the negative electrolyte within the negative porous electrode of the primary ([86], as the porous membranes will still contain the electrolyte and are not required to have been electrically isolated from the flow battery unit ([75], the stacks may be isolated either only electrically, only fluidically, or both electrically and fluidically).
Regarding Claim 9, Mittal teaches the positive porous electrode of the auxiliary stack and the negative porous electrode of the auxiliary stack are coupled to the power bus by relays (isolation switches, [84], ref. #502-2) and the method further comprises controlling switching of the relays based on the detected power load on the power bus ([85]).
Claim Rejections - 35 USC § 103
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 text of those sections of Title 35, U.S. Code not included in this action can be found in a prior Office action.
Claims 10-11 are rejected under 35 U.S.C. 103 as being unpatentable over Mittal (WIPO Patent Application Publication no. 2020/144509).
Regarding Claim 10, Mittal teaches the first threshold power load being anything greater than 100% of the power rating of the primary stack ([72]). While this value does not fall within the claimed range of 90% to 100%, it is close. A prima facie case of obviousness exists where the claimed ranges or amounts do not overlap with the prior art but are merely close (MPEP 2144.05.I).
Regarding Claim 11, Mittal teaches the second threshold is 0% of the power rating of the primary stack ([61] and [86], when there is no load on the primary stack). While this value does not fall within the claimed range of 2% to 10%, it is close. A prima facie case of obviousness exists where the claimed ranges or amounts do not overlap with the prior art but are merely close (MPEP 2144.05.I).
Claims 10 and 11 are rejected under 35 U.S.C. 103 as being unpatentable over Mittal (WIPO Patent Application Publication no. 2020/144509) in view of Edmiston (US Patent Application Publication No. 2012/0088171).
Mittal is relied upon as described above.
Regarding Claim 10, In the alternative if Mittal is silent to the first threshold power load is between 90% and 100% of the power rating of the primary stack.
Edmiston teaches a system and methods for independently controlling the operation of fuel cell stacks (title). The system includes a plurality of stacks (fuel cell stacks) that can be enabled and disabled dependent on the detected power load (electrical load) (abstract and [0006]). The first threshold power load (open circuit voltage level) is between 60% and 95% of the power rating of the primary stack ([0085]). This overlaps with the claimed range of 90% to 100% of the power rating of the primary stack. In the case where the claimed ranges "overlap or lie inside ranges disclosed by the prior art" a prima facie case of obviousness exists (MPEP 2144.05).
It would have been obvious to one of ordinary skill in the art, at the time of the effective filing date of the claimed invention, to use a first threshold of 60% to 95% of the power rating of the primary stack in the method of Mittal as taught by Edmiston. One of ordinary skill in the art would have been motivated to make this inclusion as it would prevent the flow battery system from being temporarily overloaded and being unable to provide sufficient power to the electrical load.
Regarding Claim 11, in the alternative if Mittal is silent to the second threshold is between 2% and 10% of the power rating of the primary stack.
Edmiston further teaches a second threshold, lower than the first threshold, at which the primary stack (a fuel cell stack) can be disabled. This threshold ranges from 1% to 50% of the power rating of the primary stack (the power output of an Nth fuel cell stack, when N = 1) ([0073]). This overlaps with the claimed second threshold range of 2% to 10% of the power rating of the primary stack. In the case where the claimed ranges "overlap or lie inside ranges disclosed by the prior art" a prima facie case of obviousness exists (MPEP 2144.05).
It would have been obvious to one of ordinary skill in the art, at the time of the effective filing date of the claimed invention, to use a second threshold of 1% to 50% of the power rating of the primary stack as taught by Edmiston in the method of Hennessy. One of ordinary skill in the art would have been motivated to make this inclusion as disabling the electrolyte pumps of Mittal at this second threshold would reduce parasitic energy losses from unnecessary pump activation.
Claim 12 is rejected under 35 U.S.C. 103 as being unpatentable over Mittal (WIPO Patent Application Publication No. 2020/144509) in view of Song (US Patent Application Publication No. 2018/0316031).
Mittal is relied upon as described above.
Mittal is silent to the method including intermittently deactivating the primary stack positive electrolyte pump and the primary stack negative electrolyte pump if the detected power load on the power bus is less than a second threshold power load comprises, over an hour period, deactivating the primary stack positive electrolyte pump and the primary stack negative electrolyte pump for at least 50 minutes.
Song teaches a method for operating a redox flow battery system (abstract). The method includes a step of switching the flow battery system into an idle mode when the flow battery system is not in a charging or discharging mode (abstract). Next, when the flow battery system is in idle mode over an hour period, Song teaches deactivating the primary stack positive electrolyte pump and the primary stack negative electrolyte pump for at 50 minutes ([0064]).
It would have been obvious to one of ordinary skill in the art, at the time of the effective filing date of the claimed invention, to deactivate the electrolyte pumps when below the second threshold in the method of Mittal for 50 minutes of an hour period as taught by Song. One of ordinary skill in the art would have been motivated to include this step as it would allow for decreased start up time when the flow battery system is required to give a larger output of energy (Song, [0057]).
Response to Arguments
Applicant’s arguments in the response filed on 18 June 2026 regarding the objection to the specification/drawings of record have been considered but are moot since the objection has been withdrawn.
Applicant’s arguments in the response filed on 18 June 2026 regarding the 35 U.S.C. §112b rejections of record have been considered but are moot since the rejection has been withdrawn.
Applicant’s arguments in the response filed on 18 June 2026 regarding the 35 U.S.C. §102 rejection of claims 8-9 as being anticipated by Hennessy (US Patent Application Publication No. 2013/0154364) made of record in the office action mailed on 08 April 2026 have been found persuasive, as it does not appear that Hennessy explicitly teaches disconnecting the cell stack from the electrolyte fluidically while still connecting the cell stack electrically. Therefore, the 35 U.S.C. §102 rejection of claims 8-9 as being anticipated by Hennessy (US Patent Application Publication No. 2013/0154364) has been withdrawn, as well as the 35 U.S.C. §103 rejections of claims 10-12 over Hennessy (US Patent Application Publication No. 2013/0154364) in view of other references.
Applicant’s arguments in the response filed on 18 June 2026 regarding the 35 U.S.C. §102 of claims 8-9 as anticipated by Mittal (WIPO Patent Application Publication no. 2020/144509) of record have been considered but have not been found persuasive.
Applicant argues that Mittal’s entire premise is for turning off the pumps to completely isolate the stack, both fluidically and electrically, to eliminate losses and self-discharge (Applicant’s remarks, page 11-13). To this the Examiner respectfully disagrees. While Mittal does explicitly state that disconnecting the stack, both fluidically and electrically, is beneficial, Mittal also teaches that the stack may be disconnected and the stacks may be isolated either only electrically, only fluidically, or both electrically and fluidically ([75]). In the instance in which the stack is only disconnected fluidically, this would constitute a “silent mode” in which there is still an electrical connection without a fluidic connection. This would result in the same latent properties in Mittal as in the claimed invention. Mere recognition of latent properties in the prior art does not render nonobvious an otherwise known invention (MPEP 2145.II).
Applicant further argues that Mittal explicitly uses DC contactors to sever the electrical connection to the load/source, referencing para. [49] and [68]-[70]. This is, however, a specific embodiment of the invention of Mittal that disconnects the stack both electrically and fluidically, and not an embodiment in which the stack is only disconnected fluidically, therefore it is not commensurate to the scope of the claims.
Applicant’s arguments in the response filed on 18 June 2026 regarding the 35 U.S.C. §103 of claims 10-11 over Mittal (WIPO Patent Application Publication no. 2020/144509) in view of Edmiston (US Patent Application Publication No. 2012/0088171) of record has been considered but have not been found persuasive as the Examiner disagrees that Mittal fails to teach supplying power to the power bus from the static electrolyte in the porous electrodes while the pumps are deactivated (see the response to arguments above for claims 8-9 for both Mittal).
Applicant further argues that Edmiston is not applicable art, as it pertains to a fuel cell and not a flow battery (Applicant’s remarks, page 16). To this, the Examiner respectfully disagrees. Edmiston teaches an analogous system with a plurality of stacks that can be operated independently (abstract and [0006]), which operates in an analogous mode to the flow batteries of Mittal and Hennessy (with the fuel flowing through the fuel cell in a similar manner to the electrolyte in the flow battery).
Applicant’s arguments in the response filed on 18 June 2026 regarding the 35 U.S.C. §103 of claim 12 over Mittal (WIPO Patent Application Publication No. 2020/144509) in view of Song (US Patent Application Publication No. 2018/0316031) of record have been considered but have not been found persuasive.
Applicant argues that Song teaches away from the claimed invention, as song teaches an idle mode in which the power electronics are deactivated. To this argument the Examiner respectfully disagrees. While Song does teach an idle mode in which the power electronics are deactivated, Song is used to modify Mittal with the teaching of deactivating the pumps for at least 50 minutes over an hour period. As Mittal already teaches disabling the pumps without electrical disconnection ([61] and [86], when there is no load on the primary stack), the teaching of disabling the pumps is used for the modification for Mittal, not the teaching of disabling all electronics. The combination of this teaching of Song with the invention of Mittal allows for decreased start up time when the flow battery system is required to give a larger output of energy (Song, [0057]). One of ordinary skill in the art is also a person of ordinary creativity, not an automaton (MPEP 2141.03.I), therefore one of ordinary skill in the art would have been able to see the advantage of disabling the pumps for 50 minutes of every hour independently of the other teachings of Song.
Conclusion
THIS ACTION IS MADE FINAL. Applicant is reminded of the extension of time policy as set forth in 37 CFR 1.136(a).
A shortened statutory period for reply to this final action is set to expire THREE MONTHS from the mailing date of this action. In the event a first reply is filed within TWO MONTHS of the mailing date of this final action and the advisory action is not mailed until after the end of the THREE-MONTH shortened statutory period, then the shortened statutory period will expire on the date the advisory action is mailed, and any nonprovisional extension fee (37 CFR 1.17(a)) pursuant to 37 CFR 1.136(a) will be calculated from the mailing date of the advisory action. In no event, however, will the statutory period for reply expire later than SIX MONTHS from the mailing date of this final action.
Any inquiry concerning this communication or earlier communications from the examiner should be directed to Myles Alan Lovasz whose telephone number is (571)272-0214. The examiner can normally be reached Monday-Friday 7:30 am - 5:00 pm.
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/MAL/
Myles Alan LovaszExaminer, Art Unit 1788 08/24/2026
/ALEXANDRE F FERRE/Primary Examiner, Art Unit 1788
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