Noninvasive In Situ NMR Study of "Dead Lithium" Formation and Lithium Corrosion in Full-Cell Lithium Metal Batteries.

Capacity retention in lithium metal batteries needs to be improved if they are to be commercially viable, the low cycling stability and Li corrosion during storage of lithium metal batteries being even more problematic when there is no excess lithium in the cell. Herein, we develop in situ NMR metrology to study "anode-free" lithium metal batteries where lithium is plated directly onto a bare copper current collector from a LiFePO4 cathode. The methodology allows inactive or "dead lithium" formation during plating and stripping of lithium in a full-cell lithium metal battery to be tracked: dead lithium and SEI formation can be quantified by NMR and their relative rates of formation are here compared in carbonate and ether-electrolytes. Little-to-no dead Li was observed when FEC is used as an additive. The bulk magnetic susceptibility effects arising from the paramagnetic lithium metal were used to distinguish between different surface coverages of lithium deposits. The amount of lithium metal was monitored during rest periods, and lithium metal dissolution (corrosion) was observed in all electrolytes, even during the periods when the battery is not in use, i.e., when no current is flowing, demonstrating that dissolution of lithium remains a critical issue for lithium metal batteries. The high rate of corrosion is attributed to SEI formation on both lithium metal and copper (and Cu+, Cu2+ reduction). Strategies to mitigate the corrosion are explored, the work demonstrating that both polymer coatings and the modification of the copper surface chemistry help to stabilize the lithium metal surface.A.B.G acknowledges the support from the Royal Society (RP/R1/180147) and EPSRC-EP/M009521/1. C.V.A acknowledges financial support from the TomKat Center Postdoctoral Fellowship in Sustainable Energy at Stanford, and a Visiting Fellowship from Corpus Christi College at the University of Cambridge. S.M thanks the Blavatnik Cambridge Fellowships. C.P.G thanks the EU/ERC for an Advanced Fellowship. A.B.G thanks the NanoDTC Cambridge for travel funding

Potentiometric MRI of a Superconcentrated Lithium Electrolyte: Testing the Irreversible Thermodynamics Approach.

Superconcentrated electrolytes, being highly thermodynamically nonideal, provide a stringent proving ground for continuum transport theories. Herein, we test an ostensibly complete model of LiPF6 in ethyl-methyl carbonate (EMC) based on the Onsager-Stefan-Maxwell theory from irreversible thermodynamics. We perform synchronous magnetic resonance imaging (MRI) and chronopotentiometry to examine how superconcentrated LiPF6:EMC responds to galvanostatic polarization and open-circuit relaxation. We simulate this experiment using an independently parametrized model with six composition-dependent electrolyte properties, quantified up to saturation. Spectroscopy reveals increasing ion association and solvent coordination with salt concentration. The potentiometric MRI data agree closely with the predicted ion distributions and overpotentials, providing a completely independent validation of the theory. Superconcentrated electrolytes exhibit strong cation-anion interactions and extreme solute-volume effects that mimic elevated lithium transference. Our simulations allow surface overpotentials to be extracted from cell-voltage data to track lithium interfaces. Potentiometric MRI is a powerful tool to illuminate electrolytic transport phenomena

Toward an Understanding of SEI Formation and Lithium Plating on Copper in Anode-Free Batteries.

Funder: Blavatnik Family Foundation"Anode-free" batteries present a significant advantage due to their substantially higher energy density and ease of assembly in a dry air atmosphere. However, issues involving lithium dendrite growth and low cycling Coulombic efficiencies during operation remain to be solved. Solid electrolyte interphase (SEI) formation on Cu and its effect on Li plating are studied here to understand the interplay between the Cu current collector surface chemistry and plated Li morphology. A native interphase layer (N-SEI) on the Cu current collector was observed with solid-state nuclear magnetic resonance spectroscopy (ssNMR) and electrochemical impedance spectroscopy (EIS). Cyclic voltammetry (CV) and time-of-flight secondary ion mass spectrometry (ToF-SIMS) studies showed that the nature of the N-SEI is affected by the copper interface composition. An X-ray photoelectron spectroscopy (XPS) study identified a relationship between the applied voltage and SEI composition. In addition to the typical SEI components, the SEI contains copper oxides (Cu x O) and their reduction reaction products. Parasitic electrochemical reactions were observed via in situ NMR measurements of Li plating efficiency. Scanning electron microscopy (SEM) studies revealed a correlation between the morphology of the plated Li and the SEI homogeneity, current density, and rest time in the electrolyte before plating. Via ToF-SIMS, we found that the preferential plating of Li on Cu is governed by the distribution of ionically conducting rather than electronic conducting compounds. The results together suggest strategies for mitigating dendrite formation by current collector pretreatment and controlled SEI formation during the first battery charge

Selective NMR observation of the SEI–metal interface by dynamic nuclear polarisation from lithium metal

Funder: Oppenheimer Foundation, Cambridge. Blavatnik Cambridge Fellowships.Abstract: While lithium metal represents the ultimate high-energy-density battery anode material, its use is limited by dendrite formation and associated safety risks, motivating studies of the solid–electrolyte interphase layer that forms on the lithium, which is key in controlling lithium metal deposition. Dynamic nuclear polarisation enhanced NMR can provide important structural information; however, typical exogenous dynamic nuclear polarisation experiments, in which organic radicals are added to the sample, require cryogenic sample cooling and are not selective for the interface between the metal and the solid–electrolyte interphase. Here we instead exploit the conduction electrons of lithium metal to achieve an order of magnitude hyperpolarisation at room temperature. We enhance the 7Li, 1H and 19F NMR spectra of solid–electrolyte interphase species selectively, revealing their chemical nature and spatial distribution. These experiments pave the way for more ambitious room temperature in situ dynamic nuclear polarisation studies of batteries and the selective enhancement of metal–solid interfaces in a wider range of systems

Characterisation of CART-containing neurons and cells in the porcine pancreas, gastro-intestinal tract, adrenal and thyroid glands

<p>Abstract</p> <p>Background</p> <p>The peptide CART is widely expressed in central and peripheral neurons, as well as in endocrine cells. Known peripheral sites of expression include the gastrointestinal (GI) tract, the pancreas, and the adrenal glands. In rodent pancreas CART is expressed both in islet endocrine cells and in nerve fibers, some of which innervate the islets. Recent data show that CART is a regulator of islet hormone secretion, and that CART null mutant mice have islet dysfunction. CART also effects GI motility, mainly via central routes. In addition, CART participates in the regulation of the hypothalamus-pituitary-adrenal-axis. We investigated CART expression in porcine pancreas, GI-tract, adrenal glands, and thyroid gland using immunocytochemistry.</p> <p>Results</p> <p>CART immunoreactive (IR) nerve cell bodies and fibers were numerous in pancreatic and enteric ganglia. The majority of these were also VIP IR. The finding of intrinsic CART containing neurons indicates that pancreatic and GI CART IR nerve fibers have an intrinsic origin. No CART IR endocrine cells were detected in the pancreas or in the GI tract. The adrenal medulla harboured numerous CART IR endocrine cells, most of which were adrenaline producing. In addition CART IR fibers were frequently seen in the adrenal cortex and capsule. The capsule also contained CART IR nerve cell bodies. The majority of the adrenal CART IR neuronal elements were also VIP IR. CART IR was also seen in a substantial proportion of the C-cells in the thyroid gland. The majority of these cells were also somatostatin IR, and/or 5-HT IR, and/or VIP IR.</p> <p>Conclusion</p> <p>CART is a major neuropeptide in intrinsic neurons of the porcine GI-tract and pancreas, a major constituent of adrenaline producing adrenomedullary cells, and a novel peptide of the thyroid C-cells. CART is suggested to be a regulatory peptide in the porcine pancreas, GI-tract, adrenal gland and thyroid.</p

Viðbótarmeðferðir í hjúkrun fyrirbura og nýbura. Fræðileg samantekt

Vinsældir óhefðbundinna- og viðbótarmeðferða fara sífellt vaxandi meðal almennings og innan heilbrigðisstofnanna. Fjölmargar rannsóknir hafa skoðað áhrif ýmissa viðbótarmeð-ferða á fyrirbura og nýbura. Tilgangur þessarar fræðilegu úttektar er að skapa yfirlit yfir þekkingu á viðbótarmeðferðum sem hafa verið notaðar í hjúkrun á nýburum og fyrirburum. Í heimildarleitinni var haft í huga hvaða viðbótarmeðferðir væru mest notaðar hjá fyrirburum og nýburum og hvert notagildi þeirra væri miðað við rannsóknir. Þær viðbótar-meðferðir sem aðallega hafa verið rannsakaðar eru: nudd, kengúrumeðferð, lyktarmeðferð, tónlistarmeðferð og súkrósu notkun. Þar að auki voru rannsóknir á viðhorfum heilbrigðis-starfsfólks til notkunnar á óhefðbundnum meðferðum og viðbótarmeðferðum skoðaðar. Helstu niðurstöður sýndu að viðbótarmeðferðir hafa reynst vel hjá þessum hópi barna og sýna rannsóknir meðal annars að þær geta haft áhrif á að þyngdaraukning verði meiri, aukin tengslamyndun milli foreldra og barns, minni verkjahegðun, betri öndun, súrefnismettun og hjartsláttur betri og styttri spítaladvöl. Heilbrigðisstarfsfólk virtist einnig vera jákvætt gagnvart notkun á viðbótarmeðferðum hjá fyrirburum og nýburum. Mikilvægt er að hjúkrunarfræðingar kynni sér viðbótarmeðferðir, beiti þeim og miðli þekkingu sinni áfram þar sem þeir eru þeir aðilar sem eru oftast í mestum tengslum við börnin og aðstandendur þeirra. Vonast höfundar til þess að þessi úttekt sé hvatning til hjúkrunarfræðinga til aukinnar notkunnar og skilnings á viðbótameðferðum hjá nýburum og fyrirburum og geti þannig miðlað þekkingu sinni áfram til foreldra

Supporting data for "Selective NMR Observation of the SEI–Metal Interface by Dynamic Nuclear Polarisation from Lithium Metal"

1H, 7Li and 19F FIDs, Fourier transformed spectra, and metadata for the conventional and lithium metal DNP enhanced NMR of lithium metal microstructures and their SEI. The .zip file contains a folder system in the TopSpin format that has been organised by sample, as described in Supplementary Table 7 of the publication

Understanding Sorption of Aqueous Electrolytes in Porous Carbon by NMR Spectroscopy.

Publication status: PublishedIon adsorption at solid-water interfaces is crucial for many electrochemical processes involving aqueous electrolytes including energy storage, electrochemical separations, and electrocatalysis. However, the impact of the hydronium (H3O+) and hydroxide (OH-) ions on the ion adsorption and surface charge distributions remains poorly understood. Many fundamental studies of supercapacitors focus on non-aqueous electrolytes to avoid addressing the role of functional groups and electrolyte pH in altering ion uptake. Achieving microscopic level characterization of interfacial mixed ion adsorption is particularly challenging due to the complex ion dynamics, disordered structures, and hierarchical porosity of the carbon electrodes. This work addresses these challenges starting with pH measurements to quantify the adsorbed H3O+ concentrations, which reveal the basic nature of the activated carbon YP-50F commonly used in supercapacitors. Solid-state NMR spectroscopy is used to study the uptake of lithium bis(trifluoromethanesulfonyl)-imide (LiTFSI) aqueous electrolyte in the YP-50F carbon across the full pH range. The NMR data analysis highlights the importance of including the fast ion-exchange processes for accurate quantification of the adsorbed ions. Under acidic conditions, more TFSI- ions are adsorbed in the carbon pores than Li+ ions, with charge compensation also occurring via H3O+ adsorption. Under neutral and basic conditions, when the carbon's surface charge is close to zero, the Li+ and TFSI- ions exhibit similar but lower affinities toward the carbon pores. Our experimental approach and evidence of H3O+ uptake in pores provide a methodology to relate the local structure to the function and performance in a wide range of materials for energy applications and beyond.D.L. acknowledges the Cambridge Trust Scholarship and the China Scholarship Council (CSC). D.L. thanks Richard Chen for the high field NMR measurements. K.M. was supported by the Faraday Institution Degradation Project (FIRG001and FIRG024). A. B. G. acknowledges funding from the Royal Society (RP/R1/180147) and EPSRC-EP/M009521/1. This work was also supported by a UKRI Future Leaders Fellowship to A. C. F. (MR/T043024/1). CPG acknowledges support from a Royal Society Research Professorship (grant no. RP/R1/180147)

Understanding Sorption of Aqueous Electrolytes in Porous Carbon by NMR Spectroscopy.

Ion adsorption at solid-water interfaces is crucial for many electrochemical processes involving aqueous electrolytes including energy storage, electrochemical separations, and electrocatalysis. However, the impact of the hydronium (H3O+) and hydroxide (OH-) ions on the ion adsorption and surface charge distributions remains poorly understood. Many fundamental studies of supercapacitors focus on non-aqueous electrolytes to avoid addressing the role of functional groups and electrolyte pH in altering ion uptake. Achieving microscopic level characterization of interfacial mixed ion adsorption is particularly challenging due to the complex ion dynamics, disordered structures, and hierarchical porosity of the carbon electrodes. This work addresses these challenges starting with pH measurements to quantify the adsorbed H3O+ concentrations, which reveal the basic nature of the activated carbon YP-50F commonly used in supercapacitors. Solid-state NMR spectroscopy is used to study the uptake of lithium bis(trifluoromethanesulfonyl)-imide (LiTFSI) aqueous electrolyte in the YP-50F carbon across the full pH range. The NMR data analysis highlights the importance of including the fast ion-exchange processes for accurate quantification of the adsorbed ions. Under acidic conditions, more TFSI- ions are adsorbed in the carbon pores than Li+ ions, with charge compensation also occurring via H3O+ adsorption. Under neutral and basic conditions, when the carbon's surface charge is close to zero, the Li+ and TFSI- ions exhibit similar but lower affinities toward the carbon pores. Our experimental approach and evidence of H3O+ uptake in pores provide a methodology to relate the local structure to the function and performance in a wide range of materials for energy applications and beyond.D.L. acknowledges the Cambridge Trust Scholarship and the China Scholarship Council (CSC). D.L. thanks Richard Chen for the high field NMR measurements. K.M. was supported by the Faraday Institution Degradation Project (FIRG001and FIRG024). A. B. G. acknowledges funding from the Royal Society (RP/R1/180147) and EPSRC-EP/M009521/1. This work was also supported by a UKRI Future Leaders Fellowship to A. C. F. (MR/T043024/1). CPG acknowledges support from a Royal Society Research Professorship (grant no. RP/R1/180147)