Mechanism

Each fill mode is defined by the temporal pattern of active-material introduction across the cell's operational lifetime. Passive mode introduces active material exactly once, at fabrication, with no provision for subsequent introduction or removal. Active mode introduces active material continuously or on a fixed schedule throughout the operational lifetime, with the cell admitting bidirectional fluid exchange through dedicated cavity ports. Hybrid mode introduces an initial fill at fabrication and admits subsequent introduction events on demand, triggered by state-of-health attestation rather than by elapsed time.

The three modes share a common underlying cavity geometry, a sealed structural cavity bounded by the cured cementitious matrix on its lateral surfaces and by closures at its access ports, but differ in the closure population. Passive cells receive permanent closures (cast-in plugs, fused membranes, mechanically swaged caps) that are not designed to be opened during operational life. Active cells receive serviceable port assemblies (compression-fit fluid couplings, threaded ports with elastomer seals, magnetically actuated valves) that admit repeated opening and closing without compromising cavity integrity. Hybrid cells receive infrequently serviceable closures (single-use frangible seals, scheduled-replacement gaskets) that are designed for a small finite number of refresh events across the cell's lifetime.

Each fill mode presents a distinct mass-balance topology. Passive mode is closed-system from fabrication onward: the active material inventory present at fill time is the inventory available across the entire operational lifetime, and degradation manifests as monotonic capacity fade against that fixed inventory. Active mode is open-system: active material flows through the cavity at a rate set by refresh cadence, and degraded material exits the cavity through the same ports through which fresh material enters. Hybrid mode is intermittently open: the cavity behaves as closed-system between refresh events and as open-system at refresh events, with the lineage chain accumulating discrete open-system entries that bracket continuous closed-system service intervals. The mass-balance topology is reflected in the credentialed admissibility profile and consumed by downstream LCA and carbon-stewardship accounting.

The selection between modes propagates to formwork. Passive cavities are formed against single-use formwork inserts that remain encapsulated in the cured matrix or that are extracted leaving sealable port stubs. Active cavities are formed against reusable formwork inserts that key into the cavity-port hardware geometry and that are extracted along precisely defined withdrawal paths to preserve port concentricity and sealing-surface integrity. Hybrid cavities are formed against semi-permanent inserts that prepare the cavity for a refresh-port population that may be installed at fabrication or later in life, admitting a deferred-activation capability without forcing the fabrication-time decision.

Operating Parameters

Passive-mode cells are designed for operational lifetimes typically below 20 years, with the upper bound set by the active material's intrinsic calendar life rather than by any opportunity for refresh. Capacity declines monotonically from beginning-of-life through end-of-life, following the active-material chemistry's degradation curve. Acceptable end-of-life capacity fractions are application-dependent: behind-the-meter storage applications typically tolerate 60 to 70 percent retained capacity at end-of-life; grid-services applications demand 70 to 80 percent; portable applications may tolerate 50 percent or lower.

Active-mode cells are designed for operational lifetimes of 30 to 80 years or longer, with the upper bound set by the structural element's design life rather than by the active material. Refresh intervals are governed by the active material's degradation rate: aqueous flow-cell chemistries may admit weekly to monthly refresh; solid-particle slurry chemistries may admit annual refresh; redox-shuttle chemistries may admit continuous low-rate refresh through a recirculation loop. Refresh fluid volumes per event range from a few percent of cavity volume (top-up refresh) to greater than 100 percent (full-displacement refresh).

Hybrid-mode cells admit refresh events on a frequency governed by observed degradation. Typical refresh cadences range from one event per 5 to 15 years, with the cadence shortening as the cell approaches its design end-of-life or lengthening if observed degradation underruns the design assumption. Each refresh event displaces a substantial fraction of cavity volume, typically 40 to 90 percent, and is logged as a discrete event in the credentialed lineage chain.

State-of-health (SOH) instrumentation is mode-specific. Passive cells require minimal in-situ instrumentation beyond terminal-voltage and coulomb-counting hardware, since the operator has no actionable response to degradation other than eventual decommissioning. Active cells require continuous flow-rate, fluid-composition, and pressure instrumentation at each cavity port, with measurement cadences ranging from seconds to minutes. Hybrid cells require periodic SOH-attestation instrumentation: impedance spectroscopy, capacity-fade measurement against a reference protocol, and (in some embodiments) sampling ports for offline electrolyte assay. The attestation produces a signed SOH record that, when capacity falls below the operational threshold, triggers a refresh event and the associated lineage-chain entries.

Pressure-management envelopes differ markedly across the three modes. Passive cavities operate under a near-constant internal pressure set at fabrication and bounded above by the closure's burst pressure and below by the matrix's resistance to ingress. Active cavities operate under a managed pressure profile with a steady-state set-point and excursion limits during refresh events, typically maintained by a circulation-loop accumulator. Hybrid cavities operate at a passive-equivalent pressure between refresh events and tolerate an excursion envelope during refresh, with pressure transducers at each port logging excursion magnitude as a credentialed event. Pressure excursion outside envelope is itself a credentialed fault that may trigger isolation under the per-block fault-isolation primitive disclosed in companion filings.

Thermal-management envelopes likewise distinguish the modes. Passive cells are thermally coupled only through the surrounding structural matrix and the electrode terminals; their internal temperature follows the matrix's thermal mass. Active cells admit forced thermal management through the refresh-fluid loop, which can be operated at a controlled inlet temperature to evacuate heat during high-rate dispatch or to deliver heat during cold-start operation. Hybrid cells default to the passive thermal regime but admit a forced-thermal interval during refresh events. The thermal envelope is signed at commissioning and re-attested at each re-commissioning interval.

Alternative Embodiments and Mode Transitions

The disclosed primitive admits several embodiment variants beyond the three canonical modes. A passive cell may be retrofitted to active operation by drilling and porting a fielded structural element, subject to the structural element's geometric tolerance for service penetrations. An active cell may be transitioned to passive operation by sealing its ports at any point in its lifetime, for example, when the active material chemistry is no longer commercially supported and the cell is operated to end-of-life on its current charge. A hybrid cell may transition between active and passive operation as a function of grid-service economics: during periods when active-material renewal economics favor refresh, the cell operates in active mode; during periods when they do not, the cell operates in passive mode against its current charge.

Mode selection may also vary by cavity within a single structural element. A multi-cavity structural element (a column with multiple parallel cavity bores, a wall panel with a cavity grid) may operate some cavities in passive mode and others in active or hybrid mode, distributing the capital cost of serviceable port hardware across only those cavities for which active operation is economically justified. This multi-mode embodiment admits incremental capability upgrades over the structural element's lifetime: cavities may be activated as refresh economics improve, without requiring the structural element to be over-provisioned at fabrication time.

A further alternative embodiment introduces a fourth pseudo-mode, staged passive, in which a single cavity is loaded with a structured stack of active-material slugs separated by frangible internal barriers. Beginning-of-life operation draws on the upper slug; on capacity exhaustion, an actuator ruptures the next barrier in sequence, exposing fresh active material to the cavity electrolyte. The staged passive embodiment delivers some of the longevity benefit of hybrid mode without requiring serviceable external porting, at the cost of higher initial active-material inventory and limited refresh count (typically two to five stages). Staged passive is a constrained specialization of the hybrid mode and is admitted by the disclosed primitive as a configuration choice rather than a separate architecture.

A fifth alternative embodiment admits remote refresh operation in which the cavity ports terminate not at the cell's surface but at a centralized refresh manifold serving multiple cavities through a shared distribution system. The remote-refresh embodiment amortizes the cost of refresh-fluid handling and lineage-chain instrumentation across many cells, at the cost of a longer fluid path and the associated leakage and contamination risks. The manifold itself becomes a credentialed object whose composition envelope captures fluid-routing topology, valve-actuation history, and per-cavity refresh allocation, with each refresh event resolved to the specific cavity served.

Mode-transition events are themselves credentialed. A passive-to-active transition requires inspection of the cavity geometry to verify that field-installed porting will not compromise structural margins, attestation of the host-element credential against the modified geometry, and re-signature of the structural and storage envelopes. An active-to-passive transition records the final refresh event, seals the ports under a credentialed sealing protocol, and re-signs the storage envelope at the now-fixed inventory. Transitions are admitted only when the contemporaneous credential chain authorizes the new mode against the host-element's current structural state.

Composition

Each fill mode admits the full active-material composition envelope of the underlying cell architecture. Passive-mode cells favor compositions with high intrinsic calendar life and low self-discharge: lithium iron phosphate, sodium-ion, certain solid-state chemistries, and dry-sealed capacitive carbon systems. Active-mode cells favor compositions amenable to fluid handling: vanadium and iron-chromium flow-cell electrolytes, slurry-based zinc-air systems, redox-shuttle electrolytes for capacitive systems. Hybrid-mode cells favor compositions that retain electrochemical activity through partial displacement and recombination: carbon-bound systems with displaceable electrolyte, slurry systems with regenerable particles, and certain catalyst-mediated chemistries where the catalyst is fixed and the substrate is refreshed.

Closure-hardware composition varies by mode. Passive closures are typically cast-in cementitious plugs or fused polymer membranes, selected for chemical compatibility with the active material and for mechanical match to the surrounding matrix. Active closures incorporate stainless steel or fluoropolymer-lined fluid couplings, elastomer seals (EPDM, FKM, or chemistry-specific perfluoroelastomers), and quick-disconnect fittings. Hybrid closures use frangible seals (thin metal foils, scored polymer disks) that survive multiple refresh events but are designed for replacement rather than indefinite reuse.

Each closure population is paired with a credentialed sealing protocol that governs the operations performed at fabrication, refresh, and retirement. The protocol specifies torque or compression force for mechanical closures, cure schedule for fused closures, and inspection criteria for frangible closures. Protocol execution is logged as a credentialed event with operator identity, tool calibration record, and post-operation leak-test result, producing a per-closure provenance that propagates into the cell's lineage chain.

Prior Art

Sealed-for-life primary and secondary cells are well established in consumer electronics and automotive applications, but typically lack any provision for fluid exchange and are not designed for integration with structural elements. Flow batteries (Skyllas-Kazacos et al.) implement continuous active-material exchange through external tankage, but separate the cell stack from the active-material reservoir and do not co-locate active material with structural concrete. Fuel-cell architectures admit continuous fuel introduction but are not electrochemically reversible in the sense relevant to grid storage. Maintenance-refillable lead-acid cells (the now-rare flooded battery) admit periodic electrolyte top-up but not full active-material refresh.

The disclosed primitive is distinguished by the unification of three fill modes under a single cavity-bath architecture: the same structural element, formwork flow, and lineage instrumentation admit any of the three modes through differentiation only at the closure population. The inventor is unaware of prior art that articulates passive, active, and hybrid fill as a unified mode taxonomy with attestation-triggered transitions across a structural-storage cell's lifetime.

Disclosure Scope

Provisional 64/050,895 claims the cavity-bath architecture inclusive of all three fill modes and the mode-transition embodiments documented in this article. The disclosure scope extends to mode selection at fabrication time, mode transition during operational life, and multi-mode embodiments in which different cavities of a single structural element operate in different modes. The disclosure includes the integration of refresh events with credentialed lineage instrumentation: every refresh event is anticipated to be logged with refresh fluid identity, volume, source attestation, and resulting state-of-health observation, producing a tamper-evident operational record over the cell's lifetime. The disclosure does not claim any specific closure hardware, fluid coupling, or refresh-fluid composition as such; rather, it claims the architectural primitive of unifying three fill modes under one cavity geometry and one lineage-instrumentation framework. Subsequent continuations are anticipated to address attestation-protocol details, refresh-economics decision logic, and end-of-life recovery flows specific to each fill mode.