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Amorphization Of Pseudocapacitive T−Nb2O5 Accelerates Lithium Diffusivity As Revealed Using Tunable Isomorphic Architectures, Wessel Van Den Bergh, Sean Wechsler, Hasala Nadeesini Lokupitiya, Lauren Jarocha, Kwangnam Kim, James Chapman, Kyoung E. Kweon, Brandon C. Wood, Steve Heald, Morgan Stefik Phd
Amorphization Of Pseudocapacitive T−Nb2O5 Accelerates Lithium Diffusivity As Revealed Using Tunable Isomorphic Architectures, Wessel Van Den Bergh, Sean Wechsler, Hasala Nadeesini Lokupitiya, Lauren Jarocha, Kwangnam Kim, James Chapman, Kyoung E. Kweon, Brandon C. Wood, Steve Heald, Morgan Stefik Phd
Faculty Publications
Intercalationpseudocapacitancecan combinecapacitor-likepower densitieswith battery-likeenergy densities.Such surface-limitedbehaviorrequiresrapid diffusionwhere amorphizationcan increasesolid-statediffusivity.Here intercalationpseudoca-pacitivematerialswith tailoredextentsof amorphizationin T-Nb2O5are first reported.Amorphizationwas characterizedwithWAXS, XPS, XAFS, and EPR which suggesteda peroxide-rich(O22) surface that was consistentwith DFT predictions.A seriesof tunableisomorphicarchitecturesenabledcomparisonswhileindependentlyvaryingtransportparameters.Throughprocessof elimination,solid-statelithium diffusionwas identifiedas thedominantdiffusive-constraintdictatingthe maximumvoltagesweep rate for surface-limitedkinetics(vSLT), termed the Surface-LimitedThreshold(SLT). ThevSLTincreasedwith amorphizationhoweverstable cycling requiredcrystallineT-Nb2O5. A current-responsemodel using series-impedanceswell-matchedtheseobservations.This perspectiverevealedthat amorphizationof T-Nb2O5enhancedsolid-statediffusionby 12.2% and increasedsurface-limitationsby 17.0% (stablesamples).This approachenabledretaining95% lithiationcapacityat ~800mVs1(1,600C-rate equivalent).