Energy conversion and storage: hand-considered hypotheses, 201–300

Written one at a time, with the logical form declared. Each entry carries the form its argument takes — misattribution, hidden term, identity, bound, threshold, reversal, count, artefact, scale, inversion, selection, unit trap, derived quantity, and a few forms of my own — so that a reader can see the reasoning differs structurally and not merely in subject. The mechanism is physical or chemical in every case; no market, policy, or cost argument appears. None has been tested, and no literature is cited. Where a number appears it is an order-of-magnitude estimate, flagged as such, not a measurement. This is hypotheses 201–300 of a planned 1,000.

Intercalation and cell chemistry

Misattribution
H201. A 45° line on a Nyquist plot is treated as a signature of solid-state diffusion, and in thick electrodes it is often no such thing, because distributed ionic resistance in the pore network coupled to double-layer capacitance produces the same slope. Thickness is the discriminator: the diffusion tail keeps its angle while the transmission-line artefact steepens toward 90°.
Hidden term
H202. The separator is not inert; trace metal, binder, and conductive carbon in it add a residual current that is then charged to the material's coulombic efficiency. A separator-only symmetric cell in the same electrolyte should reproduce that residual, in which case the material's efficiency is a difference of two measurements.
Identity claim
H203. Loss of lithium inventory and loss of active material are counted as two aging modes, but in a cell with an oversized negative electrode they are one event observed at two terminals. A reference-electrode dQ/dV before and after aging will show the two electrode peaks moving in lockstep in the oversized cell and independently in a balanced one.
Bound
H204. Something has to cap rate at high loading, and it is not the material: the electrolyte's transference number and the electrode's tortuosity together set a ceiling that no particle coating can lift. The signature is a collapse of capacity per gram with loading whose slope is the same for chemically unrelated materials.
Threshold
H205. Above an areal capacity of roughly 3 mAh cm⁻² (estimate), a graphite anode plates at 2C however its particles are engineered, because the ionic potential drop through the electrode thickness exceeds the plating margin. Electrolyte conductivity and tortuosity should move the threshold, while a surface coating should not.
Reversal
H206. Conductivity and transference number do not peak at the same salt concentration, and the mismatch is why a more concentrated electrolyte can conduct less and still deliver more. A concentration series measuring both places the two optima apart, and the gap is a direct read on which transport number limits the electrode.
Count
H207. Four arcs are routinely fitted to a porous electrode's spectrum, yet only three processes exist: the interface, the solid, and the pore network's distributed ionic path. The fourth arc is contact resistance between electrode and current collector, and it betrays itself by moving when the fixture's torque changes while the other three hold still.
Artefact mimics effect
H208. Wetting takes time, so a fresh conversion electrode's first cycles include the separator and current collector gradually becoming accessible, which reads as activation. Hold an identical cell at open circuit for the same duration before cycling: if the impedance fall and the capacity ramp both appear, the activation was the assembly's.
Scale argument
H209. Below a secondary-particle diameter of roughly 2 µm (estimate) the interphase's growth law changes from parabolic to linear, because the particle surface can no longer accommodate the film's volume without tensile stress. A size series at fixed chemistry and fixed voltage window ought to show the transition at the same size at which the fade curve stops bending.
Inversion of standard practice
H210. Maximizing electrode density is the standard route to volumetric energy, but for cells that must operate below about −20 °C it is the wrong objective, because tortuosity's penalty on ionic transport outweighs the density gain. A density series measured cold and warm will rank the electrodes oppositely.
Selection effect
H211. Single crystals that survive synthesis are the ones with the fewest boundaries, so the comparison that credits single-crystallinity for crack resistance sets survivors against a general population. Cracking statistics on polycrystals sorted by their as-synthesized boundary density, cycled identically, are what the claim actually requires.
Unit trap
H212. Energy density quoted per cell mass rather than per cell volume can invert the ranking of two chemistries when one uses a thinner, denser current collector, because the two numbers differ by the packing factor, which is a design choice. A comparison must fix the packing factor or report both, and then it is a comparison of designs, not of materials.
Derived quantity
H213. Tortuosity extracted from a symmetric-cell impedance is not geometric: it is the product of geometric tortuosity and a porosity exponent inherited from whichever Bruggeman relation the fit assumed. Only an independent tomographic measurement of the same electrode separates the geometry from the assumed exponent.
Conserved-quantity accounting
H214. Lithium inventory, electrolyte consumption, and gas generation must balance, so any claimed new degradation mode has to say where the lithium went. A sealed cell instrumented for pressure and sampled for gas closes the account, and a mode that cannot be closed is a mode that has been counted twice.
Limiting-case collapse
H215. At very low C-rate, layered-oxide compositions of different nickel fraction converge to nearly the same capacity because the surface's lithium-vacancy concentration equilibrates with the bulk. Composition comparisons made at C/20 are therefore comparisons of one equilibrium; the rate dependence, not the low-rate value, carries the compositional information.
Symmetry claim
H216. Charge and discharge overpotentials can differ for two distinct reasons, thermodynamic hysteresis and asymmetric kinetics, and a symmetric pulse at zero net current separates them. If the asymmetry vanishes as pulse amplitude approaches zero it is kinetic; if it persists it is hysteresis of the host lattice.
Two-regime crossover
H217. Interphase growth crosses from reaction-limited to transport-limited at a film thickness estimated at 5–10 nm, and the crossing should appear as a change in the Arrhenius slope of capacity fade. Plotting apparent activation energy against cumulative charge passed turns the crossover into a visible step rather than a fitted parameter.
Misattribution
H218. Voltage hysteresis in conversion electrodes is assigned to conversion overpotential, but a substantial share may be the mechanical work of the reaction front advancing against the surrounding matrix. Two matrices of different stiffness at identical chemistry and particle size isolate the mechanical term, which should scale with the matrix's elastic modulus.
Threshold
H219. Reconstruction should not be able to start on a small particle: elastic strain raises the oxygen-vacancy formation energy, and below a critical size that energy never falls far enough for a rocksalt layer to nucleate. A size series at fixed potential and temperature would show suppression at the small end, not merely a slower rate.
Artefact mimics effect
H220. Self-discharge reported for a charged cell at open circuit can be the electrometer's leakage acting on the cell's capacitance, which matters most below roughly 1 mAh (estimate). Two electrometers of different input impedance, or one guarded measurement, will give different self-discharge rates if the artefact is present.

Metal anodes, plating, and interphases

Misattribution
H221. Filaments seen through an optical window are not necessarily filaments, because stack pressure indents the separator and the indentation refracts light into something dendrite-shaped. Two separators of different stiffness, at one current density, should give different apparent dendrite densities if indentation is the cause.
Hidden term
H222. Copper, nickel, and carbon give different nucleation overpotentials for one electrolyte, and the reason is the collector's own interfacial impedance rather than the electrolyte's. Varying only the metallurgy, at fixed lithium and fixed pressure, turns the hidden term into the vertical offset between otherwise parallel curves.
Identity claim
H223. Dead lithium and interphase-encapsulated lithium are one substance counted twice, and a titration for either necessarily finds both. The test is an inventory sum: if the two methods together account for more lithium than the cell held, the categories overlap.
Bound
H224. The critical current density of a lithium electrode is bounded by the Sand time at the separator's porosity rather than by the bulk electrolyte's transport number, so a better bulk electrolyte cannot raise it past the porous-layer limit. A separator-porosity series at fixed electrolyte decides which of the two is binding.
Reversal
H225. Pressure helps until it hurts; below a threshold it flattens the deposit, above it the metal creeps into the separator's pores faster than it can be flattened, so the sign of the effect flips. The reversal pressure should scale with pore-throat size and creep rate, which makes it a separator property.
Count
H226. Symmetry is a constraint rather than an assumption: because both electrodes of a lithium–lithium cell are the same object, their interfacial time constants must be degenerate, and only two independent constants are available to the fit. A third arc therefore certifies that the two sides are no longer identical, which pre-cycling exactly one of them can confirm.
Artefact mimics effect
H227. Coulombic efficiency from a standard plating protocol measures the fraction of plated charge recovered at the chosen stripping rate, so the number depends on the rate as much as on the lithium lost. Reporting efficiency against stripping rate and extrapolating to zero rate would separate the loss from the recovery.
Scale argument
H228. Below about 10 nm (estimate) the interphase's electronic transport is tunnelling-dominated, so the electronic conductivity fitted from a parabolic growth law is a barrier width in disguise. Films of controlled thickness spanning that scale should show a change from exponential to linear thickness dependence of leakage current.
Inversion of standard practice
H229. Fluorinated electrolytes are chosen to produce a lithium-fluoride-rich interphase, yet that compound's very low electronic conductivity can make the film ionically limiting, so a thinner and fluoride-poorer interphase can outperform. A series in which fluoride content is varied while total film thickness is held approximately constant is the test.
Selection effect
H230. Anode-free cells that survive a hundred cycles are selected on their first-cycle nucleation overpotential, and the cells that nucleate easily are those with the largest effective collector area, which is not the property the study claims to have improved. Reporting nucleation overpotential alongside lifetime exposes the selection.
Unit trap
H231. Critical current density is quoted per geometric electrode area, but the area that actually plates grows as the deposit roughens, so later measurements in a series benefit from an area the first did not have. Normalizing to the plated area measured post mortem removes an apparent improvement that is really an expanding denominator.
Derived quantity
H232. The lithium transference number from a polarization-and-impedance protocol is derived from the ratio of initial to steady current, and both currents pass through the interphase's resistance. Thickening the interphase at fixed bulk electrolyte should move the reported transference number even though the bulk still carries the same ions.
Conserved-quantity accounting
H233. A cell sold as anode-free still holds lithium in its interphase and in its electrolyte, so a claim of zero excess must account for both. Complete digestion of a dismantled cell, referenced to the cathode's known lithium content, decides whether the claim concerns design or inventory.
Threshold
H234. Lithium creeps into a separator's pores below a stack-pressure threshold set by pore-throat size rather than by the separator's bulk modulus, so a stiff separator with wide throats can fail before a soft one with narrow throats. Porosimetry paired with pressure-dependent impedance should expose the inversion.
Limiting-case collapse
H235. At current densities well above the Sand limit every electrolyte produces the same mossy morphology, because the interfacial ion concentration reaches zero regardless of bulk transport number. Comparisons of electrolyte quality made in that regime are comparisons of one failure mode.
Misattribution
H236. A soft short in a lithium-metal cell is frequently a pressure-induced contact through the separator's largest pore, not a filament crossing the bulk. Narrowing the pore-size distribution while holding mean pore size constant should reduce soft shorts, which is the discriminating test.

Supercapacitors and interfacial storage

Misattribution
H237. Double-layer capacitance is the uninvited guest in every pseudocapacitance measurement on a high-area oxide, and the scan-rate power law usually invoked to separate them cannot distinguish a surface redox wave from a distributed double layer. Area-normalized and mass-normalized rankings disagree, and only the ranking that survives both belongs to the material.
Hidden term
H238. Constriction resistance where electrode meets current collector grows with electrode thickness, and it is invisible in the material's own resistivity. A thickness series at fixed material puts the constriction into the slope of resistance against thickness rather than the intercept.
Identity claim
H239. The two knees often resolved in a supercapacitor's impedance spectrum may be one pore-mouth restriction sampled at two depths of the electrode. Two thicknesses decide it: the knees move together if the arcs share an origin, and part company if they do not.
Bound
H240. Surface area is the wrong lever past a certain point: once pores are wide enough for ions to keep their solvent shells, added area stores charge at the bulk permittivity and the volumetric capacitance saturates. A pore-size series at fixed electrolyte will show the plateau, and its height should scale with the electrolyte's window rather than with the area.
Reversal
H241. Shrinking pores first helps and then hurts: near the desolvated ion size the ions pack more densely, and below it the double layer cannot form properly, so capacitance per area peaks and turns over at a diameter estimated near 0.7 nm. The turnover marks where the electrolyte stops acting as a dielectric continuum.
Reversal
H242. Thickness trades foil for active material, so energy per device rises while power falls and the product peaks somewhere between. Two thicknesses measured for both quantities bracket the peak, whose position should move with electrolyte conductivity.
Count
H243. Holding a supercapacitor at voltage before measuring self-discharge separates charge redistribution from leakage, and once that separation is made only two time constants remain to be explained. Any three-exponential fit to the same data is splitting one process, and the test is whether the extra constant survives a change in hold time.
Artefact mimics effect
H244. Dissolution and reprecipitation can grow a film that raises accessible area, and the result is capacitance that climbs for a few thousand cycles — an improvement that is really a redistribution. Mass change plus post-cycling imaging decides it; capacitance alone cannot.
Scale argument
H245. When a pore is narrower than about two solvated-ion diameters, the electrolyte's dielectric constant stops being applicable, because the solvent's orientational correlation is truncated by the walls. Effective permittivity then becomes a function of pore size, and any model that assumes a bulk permittivity must fail in a pore-size-dependent, not random, way.
Reversal
H246. A small addition of a redox-active species to a supercapacitor electrolyte raises capacitance and usually shortens life, but at very low concentration it can lengthen life by scavenging radicals faster than it shuttles charge. The beneficial window is bounded on both sides, and its width should scale with the radical generation rate.
Selection effect
H247. The highest gravimetric capacitances cluster at the lowest mass loadings, because thin electrodes wet and measure more easily, so the reported record is partly a record of loading. Reporting capacitance at a technical loading, of order 10 mg cm⁻² (estimate), beside the thin-electrode value makes the selection visible.
Unit trap
H248. Capacitance per gram and capacitance per cubic centimetre differ by the electrode's density, so a low-density material can look superior gravimetrically while being inferior in the device. A claim of improvement must state the packing density it assumes, or the two metrics will rank the same materials oppositely.
Derived quantity
H249. A single RC time constant for a supercapacitor is a summary of a broad distribution, and it changes with thickness because the distribution's weights change rather than because the material's kinetics do. Fitting the distribution and reporting its median and width separates the two causes.
Conserved-quantity accounting
H250. Charge on the two electrodes of an asymmetric supercapacitor must be equal, so an electrode capacitance from a three-electrode cell cannot be inserted into a device prediction without a mass-balance correction. Building the device at the calculated mass ratio and measuring the deviation tests whether the balance was right.

Fuel cells and electrolysers

Misattribution
H251. The series resistance read off a fuel cell's high-frequency intercept is charged to the membrane, but in thin membranes the catalyst layer's ionic resistance dominates it. A thickness series should extrapolate to a nonzero intercept at zero membrane thickness, and that residual is the layer.
Hidden term
H252. The electrolyte's anions adsorb on the catalyst and suppress oxygen reduction by an amount that depends on which anion is present, so activities from perchlorate and sulfate differ by more than the catalysts do. Running one electrode in both, and correcting for the double-layer change, isolates the adsorption term.
Identity claim
H253. Platinum dissolution and Ostwald ripening in a catalyst layer are one process seen at two length scales, since dissolution supplies the mobile species and ripening is where it ends up. Two identical starting size distributions at different loadings ought to give the same dissolved fraction and different final distributions.
Bound
H254. Bubble coverage, not catalysis, is what stops an alkaline electrolyser: when the gas fraction at the electrode approaches the percolation threshold for the electrolyte, the ionic path is cut regardless of catalyst quality. Raising pressure shrinks the bubbles and should raise the current at which the cut occurs, which is a test the catalyst cannot pass.
Threshold
H255. Bubbles stop being individual objects above a current density that depends on how well the electrolyte wets the electrode, because coalescence into a film cuts the ionic path. A contact-angle series at fixed current should move that threshold in a way no catalyst change can mimic.
Reversal
H256. Ionomer content cuts both ways: more of it conducts protons better and transports oxygen worse, so performance peaks and then declines as loading rises. The peak's current density is where the two resistances cross, and it should shift with ionomer equivalent weight.
Count
H257. A five-parameter fit will always beat a four-parameter fit on the same polarization data, so an extra parameter is never evidence of an extra process. Four physical parameters — exchange current, Tafel slope, ohmic resistance, one mass-transport coefficient — exhaust the curve, and a fifth must predict an independent measurement such as a pressure dependence, or it is fit freedom.
Artefact mimics effect
H258. Part of the degradation attributed to catalyst instability in an accelerated test is corrosion of the carbon support driven by the test's own potential waveform, not by the mechanism the test names. Running the same waveform on a support-free catalyst, or on a corrosion-resistant support, separates the two.
Scale argument
H259. Active area is a frequency-dependent quantity in thin catalyst layers, because at fast perturbation only the mouths of the pores respond, and below about a micrometre of thickness (estimate) the effect is large enough to change the reported area by a factor. Two sweep rates on the same layer expose it.
Inversion of standard practice
H260. Hydrophobicity is not a virtue in itself: at high current the layer must shed water, and at low current it must retain it for proton conduction, so the sign of the treatment's effect is set by the operating point. A single operating point cannot rank the treatments, and a two-point test can.
Selection effect
H261. The best electrolyser catalysts are usually measured on small electrodes where bubbles detach easily, and the ranking can change at technical scale where bubbles are confined. A parallel test at two electrode sizes, same catalyst and same loading, is the minimal check.
Unit trap
H262. Overpotential quoted at 10 mA cm⁻² of geometric area ranks catalysts by loading as much as by activity, since a thicker layer holds more sites per geometric area. Quoting per active area can reverse the ranking, which means the original order was an order of loadings.
Derived quantity
H263. Active area from hydrogen underpotential deposition is derived using an assumed site density, and that density differs between facets and between platinum and its alloys. Measuring the same sample by underpotential deposition and by carbon-monoxide stripping, across facets, exposes the assumption as the ratio between the two numbers.
Conserved-quantity accounting
H264. Water balance in a proton-exchange electrolyser closes only when back-diffusion from cathode to anode is counted, and claims of dry operation usually omit it. A cell with a thinner membrane, where back-diffusion is larger, should tolerate lower anode water stoichiometry if the balance is right.
Threshold
H265. Four water molecules per sulfonate group (estimate) is where an ionomer stops conducting well, and the reason is geometric: below that water content the clusters no longer percolate, so protons must hop between isolated pockets. Conductivity against water content should break at the same content for chemically different ionomers, which distinguishes percolation from a chemical effect.
Misattribution
H266. The mass-transport loss seen at high current in a fuel cell is often the ionomer's resistance rising as the layer dries, not oxygen diffusion limitation. Current-interrupt or high-frequency impedance measured simultaneously would reveal the ohmic term growing with current if drying is the cause.
Two-regime crossover
H267. The Tafel slope of oxygen reduction changes at a potential that corresponds to a change in oxide coverage, so two slopes are one mechanism at two coverages. Measuring coverage spectroscopically at the same potentials, and showing the slope changes when coverage changes, decides between mechanism and coverage.
Limiting-case collapse
H268. Open-circuit voltage is a crossover measurement rather than a thermodynamic one, because at zero current every model reduces to the same balance of crossover and mixed potential. A cell with a thicker membrane will show a higher open-circuit voltage purely from reduced crossover, which is the diagnostic.
Symmetry claim
H269. Electrolyser and fuel-cell kinetics on the same catalyst are reciprocal only when the surface oxide state is the same, and the difference in Tafel slopes between the two directions measures the oxide's hysteresis. Cycling between modes at fixed temperature, waiting for steady state in each, separates hysteresis from mechanism.
Artefact mimics effect
H270. Cable inductance and a potentiostat's control loop produce a low-frequency inductive loop that is routinely read as a slow electrochemical process. Shorten the cable or change instruments: a real process stays where it is, an instrument artefact moves.

Thermoelectrics and thermal storage

Misattribution
H271. Porosity is the confounder in nanostructured thermoelectrics: a pore scatters phonons more strongly than a grain boundary of the same spacing, so part of the lattice-conductivity reduction credited to nanostructure belongs to voids. An independent porosity measurement, plus one fully dense nanostructured sample, splits the credit.
Hidden term
H272. Contacts contribute their own thermoelectric voltage, so a thin-film Seebeck coefficient depends on the metallization used to measure it. Two contact metals, extrapolated to zero contact resistance, expose the offset.
Identity claim
H273. Bipolar conduction and the bipolar thermal conductivity peak are one effect observed as a voltage and as a heat flow, not two. In a narrow-gap sample, the temperature at which the Seebeck coefficient peaks should coincide with the temperature at which the apparent thermal conductivity gains its extra term.
Bound
H274. Bipolar conduction sets a ceiling on the figure of merit that doping cannot move, because once minority and majority carrier densities become comparable the Seebeck coefficient falls faster than conductivity rises. Approaching the ceiling from both doping directions in a small-gap material should converge on the same high-temperature limit.
Threshold
H275. There is a carrier concentration above which the temperature coefficient of the Seebeck coefficient changes sign, because transport crosses from non-degenerate to degenerate statistics. A doping series measured across a temperature range should locate the sign change at a concentration that shifts with the density-of-states effective mass.
Reversal
H276. Grain refinement lowers lattice conductivity and mobility together, so the figure of merit rises, peaks, and falls as grains shrink. The peak sits where the two mean free paths are comparable, and it should migrate with temperature as the phonon mean free path changes.
Count
H277. Three instruments measure a thermoelectric: a four-point probe for conductivity, a thermocouple pair for the Seebeck coefficient, a heat-flow meter for thermal conductivity. Every other number in the paper is algebraic in those three, so a reported fourth transport property should be predicted from the first three measured on the same sample.
Artefact mimics effect
H278. The low-temperature phonon-drag peak in the Seebeck coefficient can be mimicked by thermal lag between sample and thermometer. Scanning the measurement frequency and showing that the peak moves distinguishes a real drag peak from an instrument constant.
Scale argument
H279. Thermal conductivity measured on nanocrystalline samples is a property of the sample plus its boundaries, so two laboratories using different dimensions will report different values for the same powder. Reporting dimensions with the value, or measuring two thicknesses, turns the ambiguity into data.
Inversion of standard practice
H280. Adding fins to a phase-change store raises the charge rate and lowers stored energy per unit volume, and past a fin fraction the loss exceeds the gain. The optimum fraction is where the conduction improvement's derivative equals the volume penalty, and two fin fractions with a model locate it.
Selection effect
H281. Record figures of merit are selected at the temperature where the figure peaks, while a leg operates across a range, and averaging over that range reorders the ranking. Reporting the range-averaged value beside the peak makes the selection visible.
Unit trap
H282. Thermal conductivity of a composite quoted per mass rather than per volume differs by the density ratio, so a threefold improvement can be a change of units. Quoting both, with the composite's density stated, is the only way to compare against the neat material.
Derived quantity
H283. A record figure of merit can be manufactured by degrading the denominator, because the quantity is a ratio and only the ratio is reported. Publishing the power factor and the thermal conductivity separately, with uncertainties, is what makes the record interpretable.
Conserved-quantity accounting
H284. Latent heat from scanning calorimetry must be integrated over the entire peak, and the instrument's scan-rate lag shifts the peak's edges, so the integrated value depends on rate unless the lag is corrected. Three rates extrapolated to zero tests whether the correction is adequate.
Threshold
H285. Subcooling of a salt hydrate before nucleation has a threshold set by the nucleating agent's particle size relative to the critical nucleus, and below that size no undercooling will produce nucleation. A particle-size series of the agent, at fixed undercooling, will show an abrupt change from no nucleation to reliable nucleation.
Two-regime crossover
H286. The charge rate of a phase-change store crosses from conduction-limited to convection-limited at a Rayleigh number set by the melt's viscosity and the enclosure height. Two enclosure heights at the same heating rate should place the crossover at the same Rayleigh number if the mechanism is right.

Grid hardware and power conversion

Misattribution
H287. Aging of an inverter's DC-link capacitor credited to ripple current may be dominated by the ambient temperature's diurnal cycle, with which the ripple current merely correlates. A chamber test at fixed ripple and two ambient profiles separates them, since the ripple is unchanged while the thermal history is not.
Hidden term
H288. Part-load efficiency is the sum of two losses with opposite temperature coefficients, no-load loss falling with temperature and load loss rising, so the curve is a temperature-dependent object rather than a fixed characteristic. Two ambient temperatures should shift the curve's maximum without changing the data.
Identity claim
H289. One oscillation, two observers: the subsynchronous mode reported at two locations on a feeder can be a single mode filtered by two transfer functions. Synchronized recordings at both locations, with the phase relationship checked, decide whether the two are one.
Bound
H290. Ask a battery store for fast frequency response and the answer is set by the inverter, not the cells, because current limit and measurement latency bound the ramp before any electrochemical process does. A step test at two current limits, same cells and same state of charge, should show the ramp changing with the limit and not with the cell.
Threshold
H291. Below a state of charge estimated near 10% (estimate) for many lithium cells, internal resistance rises steeply because electrolyte is depleted in the electrode's pores. An impedance series across state of charge will show the rise as a change in slope, and the threshold should shift with electrolyte volume.
Reversal
H292. Heat per unit charge is not monotonic in rate: at low rates the entropic term can dominate and make faster charging cooler per charge, while at high rates the irreversible term takes over. The minimum between the two regimes is where the terms cross, and three calorimetry rates bracket it.
Identity claim
H293. Virtual impedance, virtual inertia, and the voltage-loop gain of a grid-forming inverter are not three independent knobs but one two-dimensional object reparameterized, which is why tuning one disturbs another. A transfer-function measurement at three settings that lie on a line in parameter space confirms the degeneracy; settings that scatter off it would refute it.
Artefact mimics effect
H294. Harmonic distortion measured at a point of common coupling can originate in the voltage sensor's own nonlinearity when the sensor is a resistive divider exposed to the same field. Two sensors of different types, measuring simultaneously, should disagree only if the artefact sits in the instrument.
Scale argument
H295. On a feeder shorter than a few kilometres (estimate), line resistance exceeds reactance, so the usual decoupling of active power to frequency and reactive power to voltage fails and the control must be reformulated. Comparing the measured power-flow Jacobian at two feeder lengths tests the failure.
Inversion of standard practice
H296. Adding parallel battery racks lowers resistance and can raise circulating current when the racks' open-circuit voltages differ, so adding capacity can reduce usable capacity. Deliberately mismatching two racks' states of charge, then measuring the circulating current, tests the inversion directly.
Selection effect
H297. Cells that fail formation are removed before the life test, and they are precisely the ones carrying the defect distribution of interest, so the reported life distribution is conditional on survival. Publishing the formation-failure rate beside the life distribution removes the truncation.
Unit trap
H298. Round-trip efficiency measured at the meter and at the cell terminals differs by the auxiliary loads, chiefly thermal management, which is a design choice rather than a property of the chemistry. Quoting both, with the auxiliary load at the measurement's ambient, makes the numbers comparable.
Derived quantity
H299. Capacity alone cannot describe a used cell: two cells at the same capacity can differ twofold in resistance (estimate), and the difference decides whether the pack derates. Reporting capacity and resistance as a pair, with their rates of change, restores the missing dimension.
Threshold
H300. Thermal runaway begins when heat generation outruns the separator's shutdown, and that race has a state-of-charge threshold: above a critical charge the exotherm arrives before the pores close. A charge series at fixed heating rate will show the onset temperature dropping discontinuously at the critical charge, not smoothly.

Status and form distribution

100 of 1,000. Each entry was written on its own and given the form its argument actually takes; the labels are printed so that structural repetition would be visible rather than hidden.

Distribution across the hundred: misattribution 9, threshold 9, reversal 8, artefact-mimics-effect 8, identity 7, bound 6, hidden term 6, scale argument 6, selection effect 6, unit trap 6, derived quantity 6, count 5, inversion of standard practice 5, conserved-quantity accounting 5, limiting-case collapse 3, two-regime crossover 3, symmetry/reciprocity 2. Some forms appear three times or fewer because the subject did not invite them more often, and forcing them would have produced the template this document is meant to avoid.

No claim here has been tested, and no number should be read as measured: the figures are stated as order-of-magnitude estimates for the purpose of making a prediction falsifiable. The value of a list is the ideas; the value of a test is separate.

If one of these is worth an experiment, it is H207 — that the fourth arc in a porous electrode's impedance is contact resistance, and that it moves with fixture torque while the other three hold still. It needs a torque wrench and an impedance analyser, and it would quietly reorder a literature.

Incoprea Research · hand-considered hypotheses 201–300 · energy conversion and storage · 3 November 2026 · ~/Desktop/Nov3/