Mechanism
The cell is a closed thermodynamic system with respect to mass: its boundary admits only electrons through the external circuit and heat through the cell wall. No working fluid, no fuel, and no oxidant cross the boundary during normal cycling. Energy enters or leaves only as electrical work plus incidental thermal flow. The cell's atomic inventory, protons, oxygen atoms, electrolyte solvent molecules, fixed framework atoms, is the same in every state of charge; only the binding configuration of those atoms changes between charged and discharged states.
Charging redistributes hydrogen and oxygen atoms from sorbed states within the membrane phase into bound states at the electrodes. Hydrogen becomes covalently bound at the first carbon electrode (forming C-H bonds in graphane-class composition, disclosed separately) while oxygen becomes bound at the second electrode in a complementary half-reaction. The atoms that populate these bound states originate from water molecules previously sorbed in the membrane; the membrane's sorbed-water mass decreases by exactly the mass added to the electrodes. Discharging reverses the redistribution: bound hydrogen and oxygen recombine to re-form water, which is re-sorbed by the membrane, returning the spatial mass distribution to its discharged-state configuration. Across the full cycle, total cell mass is unchanged because no atom has crossed the boundary; only their bound-versus-sorbed allocation has been rearranged.
Stored energy varies independently of mass because energy is held in the bond chemistry rather than in any added or removed substance. The free-energy difference between (water sorbed in membrane) and (hydrogen bound at first electrode plus oxygen bound at second electrode) is the cell's thermodynamic capacity. That difference is supplied by external electrical work during charging and recovered during discharging; the underlying atomic inventory is identical in both end states. Mass conservation and energy variability are therefore decoupled in the disclosed architecture, yielding the asymmetry that defines this primitive.
Operating Parameters
Total cell mass is constant to within the precision admitted by sealed-cell engineering, typical mass-balance closure better than 0.1% of cell mass across a charge-discharge cycle, with deviations attributable to incidental gas permeation through the cell wall or to small-magnitude side reactions rather than to the principal cycling chemistry. Stored energy varies from approximately zero in the fully-discharged state (water fully sorbed in the membrane, electrodes carrying minimal bound hydrogen or oxygen) to the cell's nameplate capacity in the fully-charged state (electrodes saturated with covalently bound H and O respectively, membrane water content at its minimum).
Mass closure can be verified empirically by gravimetric comparison of the assembled cell at known states of charge. A precision weigh of the cell at full discharge, followed by a controlled charge to nameplate capacity and a re-weigh, should reveal mass change at or below the closure precision noted above. Departures from closure indicate boundary leakage (electrolyte loss, gas permeation, or seal degradation) and serve as diagnostic indicators of cell health. The mass-balance check is itself a non-destructive test admitted by the closed-system architecture; conventional open-system cells cannot be qualified by this protocol because their mass changes monotonically by design.
Local density at the electrodes increases during charging by the amount of bound mass added per unit electrode volume: hydrogen at 1 to 8 weight percent of the first electrode's carbon framework, with corresponding density rise at the second electrode for bound oxygen. Membrane density decreases by the corresponding sorbed-water removal. The spatial redistribution is internal and bounded; it produces measurable density gradients between electrodes and membrane that scale with state of charge but does not change the cell's overall mass or external dimensions. State of charge can therefore be inferred from local density measurement (e.g., by tomographic or gravimetric-section techniques) without requiring mass exchange across the cell boundary.
Alternative Embodiments
The mass-conservation property holds across a family of sealed-cell embodiments distinguished by the choice of bound-state chemistry. The principal embodiment uses C-H bonding at the first electrode and an oxygen-bound state at the second electrode, with water sorbed in a polymer-electrolyte membrane as the reservoir species. Alternative embodiments substitute different reservoir species (alcohol-water mixtures, ionic-liquid electrolytes that retain water at low activity) provided the reservoir-to-electrode mass transfer remains fully internal. Alternative bound-state chemistries (for example, partial hydrogenation of doped carbon frameworks, or oxygen binding in transition-metal-oxide second-electrode lattices) likewise preserve mass conservation provided no gaseous species is vented during cycling.
Embodiments may further differ in the spatial scale across which the bound-versus-sorbed redistribution occurs. In a thin-film embodiment the reservoir membrane and the electrodes are separated by submillimeter distances and the redistribution is essentially local; in a flow-cell embodiment a circulating reservoir loops through external piping (still inside the cell boundary) and the redistribution traverses meters of plumbing. Both embodiments preserve mass at the cell-boundary level, which is the operative property of the disclosure; internal redistribution path length is an engineering parameter rather than a defining feature.
A pressure-vented variant that admits limited gas-phase exchange (for safety relief at fault conditions) remains within scope when normal cycling does not invoke the vent path. A variant in which the cell is hermetically sealed but admits temperature-dependent vapor partitioning between membrane and headspace also conserves mass at the cell-boundary level even though the internal vapor-versus-sorbed allocation varies.
Composition And State Variables
Cell composition in the discharged state comprises a carbon framework at the first electrode (substantially sp² hybridized, low residual hydrogen), an oxygen-host framework at the second electrode (low residual bound oxygen), and a membrane phase saturated with water plus dissolved ionic species. Cell composition in the charged state comprises the same frameworks now populated with bound hydrogen (at the first electrode) and bound oxygen (at the second electrode), with the membrane phase correspondingly depleted of sorbed water. The atomic inventory is invariant; only the binding allocation differs. State of charge is the natural progress variable; total cell mass is independent of state of charge to within the closure precision noted above.
Prior-Art Distinction
Mass conservation under cycling is not a property of conventional battery and fuel-cell architectures. Open-system fuel cells (proton-exchange-membrane fuel cells, solid-oxide fuel cells) consume hydrogen and oxygen drawn from external reservoirs and exhaust water; their mass is not conserved across operation, and energy delivery is constrained by the rate of mass throughput. Metal-air batteries consume metal anodes (zinc, lithium, aluminum) and draw oxygen from ambient air; their mass changes monotonically toward the discharged state and cannot be restored without replacement of the consumed anode. Conventional lithium-ion batteries are nominally sealed and conserve mass at the cell-boundary level, but their internal energy storage proceeds via lithium intercalation between electrodes, the principal cycling species (lithium ions) traverses a fixed inventory across the cell, similar in spirit to the disclosed architecture, but the bound-versus-sorbed redistribution is electrochemical-intercalation-based rather than covalent-bond-formation-based.
The disclosed architecture is distinguished from sealed lithium-ion cells by the chemistry of the bound states (covalent C-H and electrode-oxygen bonds rather than intercalated lithium), and by the explicit reservoir role of the membrane sorbed-water phase. The energy-mass asymmetry is therefore not unique to the disclosure as a category but the specific mechanism by which it is realized, covalent bond formation at electrodes drawing from membrane sorbed water, is the operative inventive feature.
Disclosure Scope
The disclosure encompasses any sealed electrochemical cell whose total mass is substantially conserved across charging and discharging operations and whose stored energy varies through internal redistribution of atomic inventory between bound electrode states and a sorbed reservoir state. Scope includes the principal embodiment (C-H bonding at the first electrode, oxygen binding at the second electrode, membrane sorbed water as reservoir) and alternative embodiments employing equivalent internal-redistribution chemistries. Scope explicitly excludes open-system architectures in which working fluid, fuel, or oxidant crosses the cell boundary during normal cycling, and excludes architectures in which a consumable electrode is monotonically consumed without internal regeneration. The energy-mass asymmetry described herein is recited in Provisional Application 64/052,368 as a structural property of the disclosed cell and is intended to support claims directed to closed-system mass conservation under variable state of charge.
