Esta pesquisa foi financiada pelo Escritório de Pesquisa Naval dos Estados Unidos.

1. Um método baseado em emulsão para criar eletrodos de esponja Zn
<ol><li>Adicione 2,054 mL de água deionizada a um copo de vidro de 100 mL.</li>
	<li>Adicione 4.565 mL de decana ao béquer.</li>
	<li>Mexa 0,1000 ± 0,0003 g de sulfato de dodecyl de sódio (SDS) até dissolver.</li>
	<li>Mexa em 0,0050 ± 0,0003 g de celulose de carcelulose de viscose média solúvel em água (CMC) à mão por 5 min ou até que o CMC esteja totalmente dissolvido. NOTA: Use ferramentas de agitação revestidas de plástico ou plástico. Mexer com ferramentas com uma superfície metálica pode afetar negativamente as esponjas Zn resultantes.</li>
	<li>Mexa em 0,844 ± 0,002 g de resina de celulose de carboximetila pré-inchada insolúvel. NOTA: Este tipo de resina insolúvel em água é cara (US$ 420 kg–1)6.</li>
	<li>Mexa esta mistura a 1.000 rpm por 5 min usando um agitador de pás aéreo equipado com uma pá de plástico.</li>
	<li>Despeje 50 g de pó Zn (tamanho médio de partícula de 50 μm, contendo 307 ppm de bismuto e 307 ppm de índio para supressão de corrosão) no béquer enquanto o agitador aéreo continua a girar a 1.000 rpm.</li>
	<li>Continue mexendo a pasta Zn por mais 5 min na mesma taxa, 1.000 rpm.</li>
	<li>Pare o agitador, remova o béquer e exacar a mistura colocando o béquer e seu conteúdo sob vácuo por 5 minutos em um dessecador à temperatura ambiente.</li>
	<li>Poro a pasta Zn em moldes de polipropileno (~10 mm de diâmetro e ~5 mm de altura) e deixe-os secar ao ar livre durante a noite. A forma do molde dita a forma da pasta seca e as esponjas Zn resultantes. NOTA: O tamanho e a forma do molde podem variar. Experimentos passados5 usam com sucesso moldes cilíndricos com diâmetros próximos a 10 mm. Encha a pasta Zn até uma altura de 5 mm ou menos. Quanto menor a altura, menor o tempo de secagem necessário. Consulte Tabela de Materiais para moldes disponíveis comercialmente.</li>
	<li>Remova cuidadosamente as preformas da pasta Zn seca dos moldes e coloque-as em uma carcaça de malha que repousa sobre um suporte de alumina entalhado5,6. NOTA: Fabricar invólucro de malha, por exemplo, dobrando uma folha de latão perfurado em um cilindro com um diâmetro ligeiramente maior do que o diâmetro desejado do eletrodo zn-esponja. Pulverize a folha de metal perfurada com lubrificante de nitreto de boro após dobrar em uma forma desejada.</li>
	<li>Coloque o conjunto em um forno de tubo (67 mm de diâmetro) com portas para fluir gás dentro e fora do tubo. NOTA: Use uma porta (a porta de entrada) para canalizar gás no forno. Use o outro (a porta de saída) para liberar gás do forno do tubo em um capô de fumaça.</li>
	<li>Tubo N2 gás no forno por 30 min a uma taxa de 5,7 cm∙min–1 para limpar o forno de ar. NOTA: O passo 1.13 pode ser alcançado conectando um tanque de gás N2 com um medidor de fluxo controlado digitalmente a um tubo conectado a uma das portas de entrada. Os medidores de fluxo de gás podem ser controlados manualmente ou por um computador.</li>
	<li>Estrangule o gás N2 a uma taxa constante de 2,8 cm∙min–1 após o expurgo de 30 minutos.</li>
	<li>Programe o forno para aumentar a temperatura linearmente de 20 para 369 °C ao longo de 68 min, mantenha a 369 °C por 5 h, suba linearmente de 369 para 584 °C ao longo de 105 min e, em seguida, desligue.</li>
	<li>Inicie o programa de forno enquanto o gás N2 continua a fluir.</li>
	<li>Pare manualmente o fluxo de gás N2após o porão de temperatura de 5h e o tubo no ar respiratório a 2,8 cm∙min–1. NOTA: O passo 1.17 pode ser alcançado conectando um tanque de ar respirando (não ar sintético) com um medidor de fluxo controlado digitalmente a um tubo conectado a uma porta de entrada adicional.</li>
	<li>Uma vez que o programa de aquecimento pare, deixe o forno esfriar até a temperatura ambiente sem resfriamento ativo, mas mantenha o ar de respiração fluindo.</li>
	<li>Remova as esponjas Zn resfriadas e as vi e/ou lixe-as para as dimensões desejadas. NOTA: Uma variedade de ferramentas de serragem pode ser usada, como serras rotativas portáteis ou serras de banda vertical. Lâminas abrasivas ou de diamante são apropriadas.</li>
</ol>2. Um método baseado em aquoso para criar eletrodos de esponja Zn
<ol><li>Adicione 10,5 mL de água deionizada a um copo de vidro de 100 mL.</li>
	<li>Mexa em 0,120 ± 0,001 g de goma de celulose solúvel de alta viscose, também conhecida como sal de sódio de celulose carboximetil (CMC). NOTA: Use ferramentas de agitação revestidas de plástico ou plástico. Mexer com ferramentas com uma superfície metálica pode afetar negativamente as esponjas Zn resultantes.</li>
	<li>Vórtice e mexa esta mistura à mão por 5 minutos ou até que o CMC seja dissolvido.</li>
	<li>Mexa 2.400 ± 0,001 g de amido de milho enquanto o vórtice por mais 2 minutos.</li>
	<li>Mexa em 120,00 ± 0,01 g de pó Zn (tamanho médio de partícula de 50 μm, contendo 307 ppm de bismute e 307 ppm de índio para supressão de corrosão) enquanto vórtice por mais 2 min.</li>
	<li>Pressione a pasta Zn resultante nas cavidades de molde desejadas. NOTA: O tamanho e a forma do molde podem variar. Experimentos passados6 usam com sucesso moldes cilíndricos com diâmetros próximos a 10 mm. Encha a pasta Zn até uma altura de 50 mm ou menos. A pasta Aquosa Zn é mais seca que a pasta Zn emulsion, de modo que a versão aquosa pode ser usada para fazer esponjas maiores que requerem menos tempo de secagem. Quanto menor a altura, menor o tempo de secagem necessário. O molde precisa ser capaz de dividir ao meio, pois a pasta aquosa Zn minimamente contrai após a secagem, ao contrário da pasta Zn emulsiona. A manteiga sem sal pode ser usada para lubrificar os moldes antes de pressionar na pasta aquosa Zn para ajudar na desmoldagem. A Figura 1A mostra os moldes personalizados embalados com pasta Zn seguindo o protocolo aquoso. A Figura 1B mostra o invólucro de malha feito à mão, o suporte de alumina entalhado e a esponja Zn resultante feita usando o método aquoso.</li>
	<li>Deixe os moldes cheios de pasta Zn secarem durante a noite a 70 °C ao ar livre em um forno.</li>
	<li>Siga as mesmas etapas de manuseio e tratamento térmico (1.11-1.19) descritas para o método baseado em emulsão.</li>
</ol>

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J.F.P., D.R.R., e J.W.L. possuem patentes relacionadas a eletrodos de zinco: patentes dos EUA 9802254, 10008711, 10720635 e 10763500, patente da UE no 2926395 e patente da China no. 104813521.

Modificações e solução de problemas associadas a esses protocolos incluem o preenchimento da pasta Zn recém-misturada em uma cavidade de molde. Deve-se tomar cuidado para evitar bolsões de ar. Os vazios indesejados podem ser diminuídos tocando no molde após o preenchimento ou durante o preenchimento. Como a pasta Zn aquosa está seca, a pressão pode ser aplicada diretamente na pasta Zn para empurrar os bolsos de ar enquanto enche a cavidade do molde.
Uma limitação dos métodos é qu...

O objetivo dos métodos de fabricação relatados é criar eletrodos de esponja de zinco (Zn) que suprimem a formação de dendrite e a mudança de forma. Historicamente, esses problemas limitaram a vida útil do ciclo das baterias Zn. Os eletrodos de esponja de zinco resolveram esses problemas, permitindo baterias Zn com vida de ciclo mais longa1,2,3,4,5,6. A estrutura da esponja suprime a formação de dendrite e a mudança de forma porque (1) a estrutura zn fundida fios eletricamente todo o volume da esponja; (2) os poros seguram zincato perto da superfície zn-esponja; e (3) a esponja possui uma área de superfície elevada que diminui a densidade de corrente local abaixo dos valores identificados para brotar dendritos em eletrólitos alcalinos7. No entanto, se a área da superfície da esponja for muito alta, a corrosão substancial ocorre5. Se os poros de esponja forem muito grandes, a esponja terá uma baixa capacidade volumosa5. Além disso, se os poros de esponja forem muito pequenos, o eletrodo ZN terá eletrólito insuficiente para acessar Zn durante a descarga, resultando em baixa potência e capacidade5,6.
A lógica por trás dos métodos de fabricação relatados é criar esponjas Zn com porosidades de esponja apropriadas e diâmetros de poros. Experimentalmente, descobrimos que as esponjas Zn com porosidades de 50 a 70% e diâmetros de poros perto de 10 μm ciclo bem em baterias de células cheias e exibem baixas taxas de corrosão5. Notamos que os métodos existentes para a fabricação de espumas metálicas comerciais não conseguem alcançar morfologias semelhantes nestas escalas de comprimento8, de modo que os métodos de fabricação relatados são necessários.
As vantagens dos métodos aqui relatados sobre alternativas são caracterizadas pelo bom controle das características das esponjas e pela capacidade de fabricar esponjas Zn grandes e densas com valores de capacidade areal tecnologicamente relevantes5,6,9,10. Métodos alternativos para criar espumas Zn podem ser incapazes de criar poros comparáveis de 10 μm com porosidades de esponja perto de 50%. Tais alternativas podem, no entanto, exigir menos energia para fabricar, pois evitam etapas de processamento de alta temperatura. Os processos alternativos incluem as seguintes estratégias: partículas Zn de sinterização a frio11,depósito de Zn em estruturas hospedeiras tridimensionais12,13,14,15,16,17, corte de folha de Zn em espumas bidimensionais18, e criação de espumas Zn através de decomposição spinodal19 ou dissolução de percolação20.
O contexto dos métodos relatados no corpo mais amplo da literatura publicada é estabelecido principalmente pelo trabalho de Drillet et al.21. Eles adaptaram métodos de fabricação de cerâmicas porosas para criar uma das primeiras espumas tridimensionais relatadas, embora frágeis, zn para baterias. Esses autores, no entanto, não demonstraram a capacidade de recarga, provavelmente devido à baixa conectividade entre as partículas Zn. Antes dos eletrodos de esponja Zn recarregáveis, a melhor alternativa para um eletrodo de papel alumínio Zn era um eletrodo Zn-powder, no qual o pó Zn é misturado com um eletrólito de gel. Os eletrodos de zinco em pó são usados comercialmente em baterias alcalinas primárias (Zn-MnO2), mas têm baixa capacidade de recarga porque as partículas Zn são passivadas pelo óxido Zn (ZnO), o que pode aumentar a densidade de corrente local que estimula o crescimento dendrite3,22. Notamos que existem outras estratégias de supressão de dendrite que não envolvem espuma ou arquiteturasesponjas 23,24.
Os métodos de fabricação de esponjas Zn relatados requerem um forno de tubo, fontes de ar e gás nitrogênio (N2), e um capuz de fumaça. Todas as etapas podem ser realizadas em um laboratório sem controle ambiental, mas o escapamento do forno do tubo durante o tratamento térmico deve ser canalizado para um capô de fumaça. Os eletrodos resultantes são apropriados para os interessados em criar eletrodos ZN recarregáveis capazes de alta capacidade areal (> 10 mAh cmgeo–2)6.
O primeiro método de fabricação relatado é uma rota baseada em emulsão para criar eletrodos de esponja Zn. A segunda, é uma rota aquosa. Uma vantagem da rota de emulsão é sua capacidade de criar pasta Zn que, quando seca, é fácil de desmold de uma cavidade de molde. Uma desvantagem é sua dependência de materiais caros. Para a rota aquosa, as formas de esponja podem ser desafiadoras para serem desmold, mas este processo usa materiais baratos e abundantes.
Ambos os métodos envolvem a mistura de partículas Zn com um agente porógeno e de aumento da viscosidade. A mistura resultante é aquecida sob N2 e, em seguida, ar de respiração (não ar sintético). Durante o aquecimento sob n2,as partículas Zn anneal e o porogen se decompõem; sob o ar respiratório, as partículas Zn se fundem e o porogen queima. Esses processos produzem espumas metálicas ou esponjas. As propriedades mecânicas e eletroquímicas das esponjas Zn podem ser ajustadas pela variada relação de massa Zn-to-porogen, tempo de aquecimento sob N2 e ar, e tamanho e forma das partículas Zn e porogen.

<table>
	<tbody>
		<tr>
			<td>Corn starch</td>
			<td>Argo</td>
			<td>Not applicable</td>
			<td>This acts as a porogen and viscosity-enhancing agent.</td>
		</tr>
		<tr>
			<td>Decane</td>
			<td>MilliporeSigma</td>
			<td>D901</td>
			<td></td>
		</tr>
		<tr>
			<td>Medium viscosity water-soluble carboxymethyl cellulose (CMC) sodium salt</td>
			<td>MilliporeSigma</td>
			<td>C4888-500G</td>
			<td>This CMC acts primarily as a viscosity-enhancing agent.</td>
		</tr>
		<tr>
			<td>Overhead stirrer</td>
			<td>Caframo Lab Solutions</td>
			<td>BDC3030</td>
			<td></td>
		</tr>
		<tr>
			<td>Small cylindrical models for Zn sponges</td>
			<td>VWR</td>
			<td>66014-358</td>
			<td>The caps of the vials can be used as molds.</td>
		</tr>
		<tr>
			<td>Sodium dodecyl sulfate</td>
			<td>MilliporeSigma</td>
			<td>436143</td>
			<td></td>
		</tr>
		<tr>
			<td>Water-insoluble IonSep CMC 52 preswollen carboxymethyl cellulose resin</td>
			<td>BIOpHORETICS</td>
			<td>B45019.01</td>
			<td>This CMC acts as a porogen and viscosity-enhancing agent.</td>
		</tr>
		<tr>
			<td>Zn powder</td>
			<td>EverZinc</td>
			<td>Custom order</td>
			<td></td>
		</tr>
	</tbody>
</table>

zinc-sponge battery electrodes that suppress dendrites

Relatamos dois métodos para criar eletrodos de esponja de zinco que suprimem a formação de dendrite e a mudança de forma para baterias de zinco recarregáveis. Ambos os métodos são caracterizados pela criação de uma pasta feita de partículas de zinco, porogen orgânico e agente de aumento da viscosidade que é aquecido sob um gás inerte e, em seguida, ar. Durante o aquecimento sob o gás inerte, as partículas de zinco se juntam, e o porogen se decompõe; sob o ar, os fusíveis de zinco e os orgânicos residuais queimam, produzindo uma espuma de metal de célula aberta ou esponja. Nós ajustamos as propriedades mecânicas e eletroquímicas das esponjas de zinco por variadas proporções de massa zinco-porogen, tempo de aquecimento sob gás e ar inertes, e tamanho e forma das partículas de zinco e porógeno. Uma vantagem dos métodos relatados é sua capacidade de ajustar finamente a arquitetura zinco-esponja. O tamanho e a forma selecionados das partículas de zinco e porogen influenciam a morfologia da estrutura dos poros. Uma limitação é que as esponjas resultantes possuem estruturas de poros desordenadas que resultam em baixa resistência mecânica em frações de baixo volume de zinco (<30%). As aplicações para estes eletrodos de esponja de zinco incluem baterias para armazenamento em grade, eletrônicos pessoais, veículos elétricos e aviação elétrica. Os usuários podem esperar que os eletrodos de esponja de zinco pedalem até 40% de profundidade de descarga a taxas tecnologicamente relevantes e capacidades areais sem a formação de dendritos separadores-perfurantes.

Resultantes, totalmente tratadas pelo calor, esponjas Zn baseadas em emulsão têm densidades de 2,8 g∙cm–3 enquanto esponjas baseadas em aquosos se aproximam de 3,3 g∙cm–3. Durante o aquecimento sob o ar, uma camada de ZnO se forma nas superfícies Zn, que deve ter uma espessura de 0,5-1,0 μm (observada usando microscopia eletrônica de varredura)5. O sólido nas esponjas resultantes deve ser de 72% Zn (versão emulsion) ou 78% Zn (versão aquosa) com o restante sen...

Watch this Scientific Journal Video about Zinc-Sponge Battery Electrodes that Suppress Dendrites at JoVE.com

Zinc-Sponge Battery Electrodes that Suppress Dendrites

O objetivo dos protocolos relatados é criar eletrodos recarregáveis de zinco-esponja que suprimem dendritos e mudam de forma em baterias de zinco, como níquel-zinco ou zinco-ar.

Eletrodos da bateria zinco-esponja que suprimem dendritos

We report two methods to create zinc-sponge electrodes that suppress dendrite formation and shape change for rechargeable zinc batteries. Both methods are ...

zinc-sponge-battery-electrodes-that-suppress-dendrites

Research

JoVE Journal

Chemistry

4.2K visualizações.  U.S. Naval Research Laboratory, Washington, DC, 20375, United States. O objetivo dos protocolos relatados é criar eletrodos recarregáveis de zinco-esponja que suprimem dendritos e mudam de forma em baterias de zinco, como níquel-zinco ou zinco-ar.

Vídeo: Zinc-Sponge Battery Electrodes that Suppress Dendrites

Reductive Electropolymerization of a Vinyl-containing Poly-pyridyl Complex on Glassy Carbon and Fluorine-doped Tin Oxide Electrodes

Controllable electrode surface modification is important in a number of fields, especially those with solar fuels applications. Electropolymerization is one surface modification technique that electrodeposits a polymeric film at the surface of an electrode by utilizing an applied potential to initiate the polymerization of substrates in the Helmholtz layer. This useful technique was first established by a Murray-Meyer collaboration at the University of North Carolina at Chapel Hill in the early 1980s and utilized to study numerous physical phenomena of films containing inorganic complexes as the monomeric substrate. Here, we highlight a procedure for coating electrodes with an inorganic complex by performing reductive electropolymerization of the vinyl-containing poly-pyridyl complex onto glassy carbon and fluorine doped tin oxide coated electrodes. Recommendations on electrochemical cell configurations and troubleshooting procedures are included. Although not explicitly described here, oxidative electropolymerization of pyrrole-containing compounds follows similar procedures to vinyl-based reductive electropolymerization but are far less sensitive to oxygen and water.

A procedure for performing reductive electropolymerization of vinyl-containing compounds onto glassy carbon and fluorine doped tin-oxide coated electrodes is presented. Recommendations on electrochemical cell configurations and troubleshooting procedures are included. Although not explicitly described here, oxidative electropolymerization of pyrrole-containing compounds follows similar procedures to vinyl-based reductive electropolymerization.

Electropolimerização redutiva de um complexo poli-piridil-vinil no Glassy contendo carbono e flúor-dopado com óxido de estanho Eléctrodos

Controllable electrode surface modification is important in a number of fields, especially those with solar fuels applications. Electropolymerization is ...

Química

A Colorimetric Assay that Specifically Measures Granzyme B Proteolytic Activity: Hydrolysis of Boc-Ala-Ala-Asp-S-Bzl

The serine protease Granzyme B (GzmB) mediates target cell apoptosis when released by cytotoxic T lymphocytes (CTL) or natural killer (NK) cells. GzmB is the most studied granzyme in humans and mice and therefore, researchers need specific and reliable tools to study its function and role in pathophysiology. This especially necessitates assays that do not recognize proteases such as caspases or other granzymes that are structurally or functionally related. Here, we apply GzmB&#8217;s preference for cleavage after aspartic acid residues in a colorimetric assay using the peptide thioester Boc-Ala-Ala-Asp-S-Bzl. GzmB is the only mammalian serine protease capable of cleaving this substrate. The substrate is cleaved with similar efficiency by human, mouse and rat GzmB, a property not shared by other commercially available peptide substrates, even some that are advertised as being suitable for this purpose. This protocol is demonstrated using unfractionated lysates from activated NK cells or CTL and is also suitable for recombinant proteases generated in a variety of prokaryotic and eukaryotic systems, provided the correct controls are used. This assay is a highly specific method to ascertain the potential pro-apoptotic activity of cytotoxic molecules in mammalian lymphocytes, and of their recombinant counterparts expressed by a variety of methodologies.

We describe a simple, quantitative colorimetric assay that specifically measures the proteolytic activity of human, mouse or rat Granzyme B (GzmB). This protocol can be easily adapted for determining protease activity of other granule serine proteases by the hydrolysis of other synthetic peptide substrates with an appropriate recognition sequence.

Um ensaio colorimétrico que mede Especificamente granzima B Actividade proteolítica: Hidrólise de Boc-Ala-Ala-Asp-S-Bzl

The serine protease Granzyme B (GzmB) mediates target cell apoptosis when released by cytotoxic T lymphocytes (CTL) or natural killer (NK) cells. GzmB is ...

Metal-silicate Partitioning at High Pressure and Temperature: Experimental Methods and a Protocol to Suppress Highly Siderophile Element Inclusions

Estimates of the primitive upper mantle (PUM) composition reveal a depletion in many of the siderophile (iron-loving) elements, thought to result from their extraction to the core during terrestrial accretion. Experiments to investigate the partitioning of these elements between metal and silicate melts suggest that the PUM composition is best matched if metal-silicate equilibrium occurred at high pressures and temperatures, in a deep magma ocean environment. The behavior of the most highly siderophile elements (HSEs) during this process however, has remained enigmatic. Silicate run-products from HSE solubility experiments are commonly contaminated by dispersed metal inclusions that hinder the measurement of element concentrations in the melt. The resulting uncertainty over the true solubility and metal-silicate partitioning of these elements has made it difficult to predict their expected depletion in PUM. Recently, several studies have employed changes to the experimental design used for high pressure and temperature solubility experiments in order to suppress the formation of metal inclusions. The addition of Au (Re, Os, Ir, Ru experiments) or elemental Si (Pt experiments) to the sample acts to alter either the geometry or rate of sample reduction respectively, in order to avoid transient metal oversaturation of the silicate melt. This contribution outlines procedures for using the piston-cylinder and multi-anvil apparatus to conduct solubility and metal-silicate partitioning experiments respectively. A protocol is also described for the synthesis of uncontaminated run-products from HSE solubility experiments in which the oxygen fugacity is similar to that during terrestrial core-formation. Time-resolved LA-ICP-MS spectra are presented as evidence for the absence of metal-inclusions in run-products from earlier studies, and also confirm that the technique may be extended to investigate Ru. Examples are also given of how these data may be applied.

We present a procedure to determine the metal-silicate partitioning of siderophile elements, emphasizing techniques that suppress the formation of metal inclusions in experiments for the noble metals. The results of these experiments are used to demonstrate the effect of core-formation on the highly siderophile element composition of the mantle.

Partitioning Metal-silicato em alta pressão e temperatura: Métodos experimentais e um protocolo para suprimir Altamente sidérophile Elemento Inclusões

Estimates of the primitive upper mantle (PUM) composition reveal a depletion in many of the siderophile (iron-loving) elements, thought to result from ...

A Protocol for Electrochemical Evaluations and State of Charge Diagnostics of a Symmetric Organic Redox Flow Battery

Redox flow batteries have been considered as one of the most promising stationary energy storage solutions for improving the reliability of the power grid and deployment of renewable energy technologies. Among the many flow battery chemistries, non-aqueous flow batteries have the potential to achieve high energy density because of the broad voltage windows of non-aqueous electrolytes. However, significant technical hurdles exist currently limiting non-aqueous flow batteries to demonstrate their full potential, such as low redox concentrations, low operating currents, under-explored battery status monitoring, etc. In an attempt to address these limitations, we recently reported a non-aqueous flow battery based on a highly soluble, redox-active organic nitronyl nitroxide radical compound, 2-phenyl-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide (PTIO). This redox material exhibits an ambipolar electrochemical property, and therefore can serve as both anolyte and catholyte redox materials to form a symmetric flow battery chemistry. Moreover, we demonstrated that Fourier transform infrared (FTIR) spectroscopy could measure the PTIO concentrations during the PTIO flow battery cycling and offer reasonably accurate detection of the battery state of charge (SOC), as cross-validated by electron spin resonance (ESR) measurements. Herein we present a video protocol for the electrochemical evaluation and SOC diagnosis of the PTIO symmetric flow battery. With a detailed description, we experimentally demonstrated the route to achieve such purposes. This protocol aims to spark more interests and insights on the safety and reliability in the field of non-aqueous redox flow batteries.

We present the protocols for electrochemically evaluating a symmetric non-aqueous organic redox flow battery and for diagnosing its state of charge using FTIR.

Um protocolo para eletroquímicos Avaliações e estado de carga Diagnostics de um fluxo Redox Battery Symmetric Organic

Redox flow batteries have been considered as one of the most promising stationary energy storage solutions for improving the reliability of the power grid ...

Simple Methods for the Preparation of Non-noble Metal Bulk-electrodes for Electrocatalytic Applications

The rock material pentlandite with the composition Fe4.5Ni4.5S8 was synthesized via high temperature synthesis from the elements. The structure and composition of the material was characterized via powder X-ray diffraction (PXRD), M&#246;ssbauer spectroscopy (MB), scanning electron microscopy (SEM), differential scanning calorimetry (DSC) and energy dispersive X-ray spectroscopy (EDX). Two preparation methods of pentlandite bulk electrodes are presented. In the first approach a piece of synthetic pentlandite rock is directly contacted via a wire ferrule. The second approach utilizes pentlandite pellets, pressed from finely ground powder, which is immobilized in a Teflon casing. Both electrodes, whilst being prepared by an additive-free method, reveal high durability during electrocatalytic conversions in comparison to common drop-coating methods. We herein showcase the striking performance of such electrodes to accomplish the hydrogen evolution reaction (HER) and present a standardized method to evaluate the electrocatalytic performance by electrochemical and gas chromatographic methods. Furthermore, we report stability tests via potentiostatic methods at an overpotential of 0.6 V to explore the material limitations of the electrodes during electrolysis under industrial relevant conditions.

A facile preparation method of electrodes using the bulk material Fe4.5Ni4.5S8 is presented. This method provides an alternative technique to conventional electrode fabrication and describes prerequisites for unconventional electrode materials including a straightforward electrocatalytic testing method.

Métodos simples para a preparação de eletrodos a granel de metal não nobre para aplicações eletrocatalíticas

The rock material pentlandite with the composition Fe4.5Ni4.5S8 was synthesized via high temperature synthesis from the elements. The structure and ...

Accelerating Rate Calorimetry and Complementary Techniques to Characterize Battery Safety Hazards

The hazards associated with lithium-based battery chemistries are well-documented due to their catastrophic nature. Risk is typically qualitatively assessed through an engineering risk matrix. Within the matrix, potentially hazardous events are categorized and ranked in terms of severity and probability to provide situational awareness to decision makers and stakeholders. The stochastic nature of battery failures, particularly the lithium-ion chemistry, makes the probability axis of a matrix difficult to properly assess. Fortunately, characterization tools exist, such as accelerated rate calorimetry (ARC), that characterize degrees of battery failure severity. ARC has been used extensively to characterize reactive chemicals but can provide a new application to induce battery failures under safe, controlled experimental conditions and quantify critical safety parameters. Due to the robust nature of the extended volume calorimeter, cells may be safely taken to failure due to a variety of abuses: thermal (simple heating of cell), electrochemical (overcharge), electrical (external short circuit), or physical (crush or nail penetration). This article describes the procedures to prepare and instrument a commercial lithium-ion battery cell for failure in an ARC to collect valuable safety data: onset of thermal runaway, endotherm associated with polymer separator melting, pressure release during thermal runaway, gaseous collection for analytical characterization, maximum temperature of complete reaction, and visual observation of decomposition processes using a high temperature borescope (venting and cell can breach). A thermal &#8220;heat-wait-seek&#8221; method is used to induce cell failure, in which the battery is heated incrementally to a set point, then the instrument identifies heat generation from the battery. As heat generates a temperature rise in the battery, the calorimeter temperature follows this temperature rise, maintaining an adiabatic condition. Therefore, the cell does not exchange heat with the external environment, so all heat generation from the battery under failure is captured.

A method to characterize the potential failure hazards of lithium batteries is achieved with accelerating rate calorimetry. Heat and pressure release, visual observation of the failure event, and the capture of evolved gases are collected in this experiment to identify the worst credible threats of batteries taken to failure.

The hazards associated with lithium-based battery chemistries are well-documented due to their catastrophic nature. Risk is typically qualitatively ...

Fabrication of Thin Film Silver/Silver Chloride Electrodes with Finely Controlled Single Layer Silver Chloride

This paper aims to present a protocol to form smooth and well-controlled films of silver/silver chloride (Ag/AgCl) with designated coverage on top of thin film silver electrodes. Thin film silver electrodes sized 80 &#181;m x 80 &#181;m and 160 &#181;m x 160 &#181;m were sputtered on quartz wafers with a chromium/gold (Cr/Au) layer for adhesion. After passivation, polishing and cathodic cleaning processes, the electrodes underwent galvanostatic oxidation with consideration of Faraday&#39;s Law of Electrolysis to form smooth layers of AgCl with a designated degree of coverage on top of the silver electrode. This protocol is validated by inspection of scanning electron microscope (SEM) images of the surface of the fabricated Ag/AgCl thin film electrodes, which highlights the functionality and performance of the protocol. Sub-optimally fabricated electrodes are fabricated as well for comparison. This protocol can be widely used to fabricate Ag/AgCl electrodes with specific impedance requirements (e.g., probing electrodes for impedance sensing applications like impedance flow cytometry and interdigitated electrode arrays).

This paper aims to present a method to form smooth and well-controlled films of silver chloride (AgCl) with designated coverage on top of thin film silver electrodes.

Fabricação de eletrodos de cloreto de prata/prata de filme fino com cloreto de prata de camada única finamente controlado

This paper aims to present a protocol to form smooth and well-controlled films of silver/silver chloride (Ag/AgCl) with designated coverage on top of thin ...

Screening of Coatings for an All-Solid-State Battery Using In Situ Transmission Electron Microscopy

With the ever-increasing use of Li-ion batteries, especially due to their adoption in electric vehicles, their safety is in prime focus. Thus, the all-solid-state batteries (ASSBs) that use solid electrolytes instead of liquid electrolytes, which reduce the risk of flammability, have been the center stage of battery research for the last few years. However, in the ASSB, the ion transportation through the solid-solid electrolyte-electrode interface poses a challenge due to contact and chemical/electrochemical stability issues. Applying a suitable coating around the electrode and/or electrolyte particles offers a convenient solution, leading to better performance. For this, researchers are screening potential electronic/ionic conductive and nonconductive coatings to find the best coatings with suitable thickness for long-term chemical, electrochemical, and mechanical stability. Operando transmission electron microscopy (TEM) couples high spatial resolution with high temporal resolution to allow visualization of dynamic processes, and thus is an ideal tool to evaluate electrode/electrolyte coatings via studying (de)lithiation at a single particle level in real-time. However, the accumulated electron dose during a typical high-resolution in situ work may affect the electrochemical pathways, evaluation of which can be time-consuming. The current protocol presents an alternative procedure in which the potential coatings are applied on Si nanoparticles and are subjected to (de)lithiation during operando TEM experiments. The high volume changes of Si nanoparticles during (de)lithiation allow monitoring of the coating behavior at a relatively low magnification. Thus, the whole process is very electron-dose efficient and offers quick screening of potential coatings.

Screening of Coatings for an All-Solid-State Battery Using In Situ Transmission Electron Microscopy

Utilizing the volume change of Si nanoparticles during (de)lithiation, the present protocol describes a screening method of potential coatings for all-solid-state batteries using in situ transmission electron microscopy.