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Desenvolvimento de formulações de ânodos para baterias de ião-sódio
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| 7.33 MB | Adobe PDF |
Authors
Abstract(s)
O trabalho realizado nesta dissertação teve como objetivo desenvolver e otimizar formulações
de ânodos para baterias de ião-sódio, utilizando hard carbon como material ativo. O trabalho
foi realizado no CeNTI em Vila Nova de Famalicão, de 26 de fevereiro a 1 de julho de 2025.
Foram preparadas cinco formulações de base aquosa com diferentes proporções de hard
carbon, carboxilmetilcelulose, carbon black e borracha de estireno-butadieno, aplicadas em
substratos de cobre e alumínio pela técnica de doctor blade, e uma parte destas posteriormente
calandradas. As formulações foram avaliadas do ponto de vista reológico através de ensaios,
onde se variam a taxa de corte, de adesão ao substrato através de ensaios realizados segundo
a norma ISO 2409:2020 (Paints and varnishes — Cross-cut test) e de condutividade elétrica pelo
método das quatro pontas. Os resultados permitiram apurar que o aumento do teor de carbon
black promove o aumento da viscosidade da formulação e o aumento da condutividade elétrica
e que o processo de calandragem melhora a adesão do ânodo ao substrato e diminui a
condutividade elétrica.
A formulação mais promissora foi a HC5 com uma composição sólidos de 86,2% de hard carbon,
8,0% de carbon black, 3,9 % de borracha de estireno-butadieno e 1,9 % de
carboxilmetilcelulose. Esta formulação, quando depositada com uma espessura de lâmina de
230 μm e velocidade de 5 mm/s, seca a 100 ⁰C e calandrada a 90⁰C com uma distância entre
rolos de 65 μm, formou um ânodo com uma espessura de 77 μm com elevada adesão ao
substrato e uma condutividade elétrica de 0,11 S/cm.
Posteriormente, fez-se um estudo preliminar do desempenho eletroquímico, recorrendo a
ensaios em half-cells (meias células) ao ânodo descrito e a uma versão do mesmo não
calandrada, através testes de carga e descarga e de espectroscopia de impedância
eletroquímica que revelaram capacidades específicas de descarga cerca de 100 mAh/g para
uma taxa de 1/10 C. Este resultado corresponde a cerca de 30% do valor reportada na literatura.
The work carried out in this dissertation aimed to develop and optimize anode slurries for sodium-ion batteries using hard carbon as the active material. The project was developed at CeNTI in Vila Nova de Famalicão, from February 26 to July 1, 2025. Five water-based slurries were prepared with different proportions of hard carbon, carboxymethyl cellulose, carbon black, and styrene-butadiene rubber. These were applied onto copper and aluminum substrates using the doctor blade technique, and some were subsequently calendered. The slurries were evaluated in terms of rheological behavior using shear rate controlled tests, adhesion to the substrate according to ISO 2409:2020 (Paints and varnishes — Cross-cut test), and electrical conductivity using the four-point probe method. The results showed that increasing the carbon black content led to higher viscosity and greater electrical conductivity, while the calendering process improved adhesion to the substrate but reduced electrical conductivity. The most promising slurry was HC5, with a solids composition of 86.2% hard carbon, 8.0% carbon black, 3.9% styrene-butadiene rubber, and 1.9% carboxymethyl cellulose. When deposited using a 230 μm blade-to-substrate gap at a speed of 5 mm/s, dried at 100°C, and calendered at 90°C with a roller gap of 65 μm, it formed an anode with a thickness of 77 μm, high substrate adhesion, and an electrical conductivity of 0.11 S/cm. A preliminary electrochemical performance study was conducted using half-cell tests on both calendered and non-calendered versions of the HC5 anode. Galvanostatic charge/discharge cycling and electrochemical impedance spectroscopy revealed specific discharge capacities of around 100 mAh/g at a 1/10 C rate. This result represents approximately 30% of the value reported in the literature
The work carried out in this dissertation aimed to develop and optimize anode slurries for sodium-ion batteries using hard carbon as the active material. The project was developed at CeNTI in Vila Nova de Famalicão, from February 26 to July 1, 2025. Five water-based slurries were prepared with different proportions of hard carbon, carboxymethyl cellulose, carbon black, and styrene-butadiene rubber. These were applied onto copper and aluminum substrates using the doctor blade technique, and some were subsequently calendered. The slurries were evaluated in terms of rheological behavior using shear rate controlled tests, adhesion to the substrate according to ISO 2409:2020 (Paints and varnishes — Cross-cut test), and electrical conductivity using the four-point probe method. The results showed that increasing the carbon black content led to higher viscosity and greater electrical conductivity, while the calendering process improved adhesion to the substrate but reduced electrical conductivity. The most promising slurry was HC5, with a solids composition of 86.2% hard carbon, 8.0% carbon black, 3.9% styrene-butadiene rubber, and 1.9% carboxymethyl cellulose. When deposited using a 230 μm blade-to-substrate gap at a speed of 5 mm/s, dried at 100°C, and calendered at 90°C with a roller gap of 65 μm, it formed an anode with a thickness of 77 μm, high substrate adhesion, and an electrical conductivity of 0.11 S/cm. A preliminary electrochemical performance study was conducted using half-cell tests on both calendered and non-calendered versions of the HC5 anode. Galvanostatic charge/discharge cycling and electrochemical impedance spectroscopy revealed specific discharge capacities of around 100 mAh/g at a 1/10 C rate. This result represents approximately 30% of the value reported in the literature
Description
Keywords
Sodium-ion batteries hard carbon anode formulations doctor blade adhesion electrical conductivity Baterias de ião-sódio Formulações de ânodos Adesão Condutividade elétrica