Síntese e caracterização de espinélios de lítio e manganês obtidos via rota hidrotermal assistida por microondas
Ano de defesa: | 2014 |
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Autor(a) principal: | |
Orientador(a): | |
Banca de defesa: | |
Tipo de documento: | Tese |
Tipo de acesso: | Acesso aberto |
Idioma: | por |
Instituição de defesa: |
Universidade Federal de São Carlos
|
Programa de Pós-Graduação: |
Programa de Pós-Graduação em Química - PPGQ
|
Departamento: |
Não Informado pela instituição
|
País: |
BR
|
Palavras-chave em Português: | |
Área do conhecimento CNPq: | |
Link de acesso: | https://repositorio.ufscar.br/handle/ufscar/6328 |
Resumo: | Lithium and manganese oxide in spinel phase (LiMn2O4) was obtained by microwave-assisted hydrothermal route starting from completely soluble reagents. For this, a mixture of potassium permanganate and lithium hydroxide monohydrate (Li/Mn = 1.2) aqueous solutions and acetone (acetone/Mn = 1.1) was treated in a microwave reactor (850 W) at 140 °C for different times (10 s - 30 min) and under constant magnetic stirring. The obtained materials were characterized by X-ray diffraction, scanning and transmission electron microscopy, X-ray dispersive energy spectroscopy, electrons diffracton, inductively coupled plasma-atomic emission spectroscopy, cyclic voltammetry, thermogravimetry, structural refinement by Rietveld method and chronopotentiometry. The X-ray diffractogramm for the material synthesized in 5 min could be indexed to the JCPDS card number 35-0782 related to the LiMn2O4 in spinel phase, but the unwanted presence of K+ ions in its structure was verified. Thus, an ionic exchange step was included in the process, in which the newly-synthesized material was treated in an aqueous solution of lithium hydroxide in the same microwave reactor for different times (5 - 40 min) and under constant magnetic stirring. After 10 min, a material with low content of K+ ions and Li/Mn ratio = 0.52 was obtained, but it was electrochemically inactive. The material was submitted to a heat treatments in a conventional microwave oven for distinct times (1 - 5 min), having presented, after 4 min, the characteristic electrochemical profile of the spinel. The images obtained by scanning and transmission electron microscopy for this material showed the predominance of prismatic particles with nearly 10 - 25 nm. The results of charge and discharge tests showed that the specific capacity values are strongly dependent of the composite film thickness that composes the electrode. Thinner films presented a value of initial specific capacity of 100 ± 17 mA h g-1 with charge retention of 93% after 75 charge and discharge cycles at C/1 discharge rate. |
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Silva, Daiane Piva Barbosa daBocchi, Nerilsohttp://genos.cnpq.br:12010/dwlattes/owa/prc_imp_cv_int?f_cod=K4783990J3http://lattes.cnpq.br/11386113106178652016-06-02T20:34:59Z2014-12-172016-06-02T20:34:59Z2014-11-28SILVA, Daiane Piva Barbosa da. Synthesis and caracterization of lithium and manganese spinels obtained by microwave-assisted hydrothermal route. 2014. 135 f. Tese (Doutorado em Ciências Exatas e da Terra) - Universidade Federal de São Carlos, São Carlos, 2014.https://repositorio.ufscar.br/handle/ufscar/6328Lithium and manganese oxide in spinel phase (LiMn2O4) was obtained by microwave-assisted hydrothermal route starting from completely soluble reagents. For this, a mixture of potassium permanganate and lithium hydroxide monohydrate (Li/Mn = 1.2) aqueous solutions and acetone (acetone/Mn = 1.1) was treated in a microwave reactor (850 W) at 140 °C for different times (10 s - 30 min) and under constant magnetic stirring. The obtained materials were characterized by X-ray diffraction, scanning and transmission electron microscopy, X-ray dispersive energy spectroscopy, electrons diffracton, inductively coupled plasma-atomic emission spectroscopy, cyclic voltammetry, thermogravimetry, structural refinement by Rietveld method and chronopotentiometry. The X-ray diffractogramm for the material synthesized in 5 min could be indexed to the JCPDS card number 35-0782 related to the LiMn2O4 in spinel phase, but the unwanted presence of K+ ions in its structure was verified. Thus, an ionic exchange step was included in the process, in which the newly-synthesized material was treated in an aqueous solution of lithium hydroxide in the same microwave reactor for different times (5 - 40 min) and under constant magnetic stirring. After 10 min, a material with low content of K+ ions and Li/Mn ratio = 0.52 was obtained, but it was electrochemically inactive. The material was submitted to a heat treatments in a conventional microwave oven for distinct times (1 - 5 min), having presented, after 4 min, the characteristic electrochemical profile of the spinel. The images obtained by scanning and transmission electron microscopy for this material showed the predominance of prismatic particles with nearly 10 - 25 nm. The results of charge and discharge tests showed that the specific capacity values are strongly dependent of the composite film thickness that composes the electrode. Thinner films presented a value of initial specific capacity of 100 ± 17 mA h g-1 with charge retention of 93% after 75 charge and discharge cycles at C/1 discharge rate.O óxido de lítio e manganês na fase espinélio (LiMn2O4) foi obtido via rota hidrotermal assistida por micro-ondas a partir de reagentes completamente solúveis. Para tal, uma mistura das soluções aquosas de permanganato de potássio e hidróxido de lítio monoidratado (Li/Mn = 1,2) e acetona (acetona/Mn = 1,1) foi tratada em um reator de micro-ondas (850 W) a 140 oC por diferentes tempos (10 s 30 min) e sob constante agitação magnética. Os materiais obtidos foram caracterizados por difratometria de raios X, microscopia eletrônica de varredura e transmissão, energia dispersiva de raios X, difração de elétrons, espectroscopia de emissão atômica em plasma indutivamente acoplado, voltametria cíclica, termogravimetria, refinamento estrutural pelo método de Rietveld e cronopotenciometria. O difratograma de raios X do material sintetizado em 5 min pôde ser indexado à ficha cristalográfica JCPDS 35- 0782, referente ao LiMn2O4 na fase espinélio, porém verificou-se a presença indesejada de íons K+ em sua estrutura. Assim, inseriu-se no processo uma etapa de troca iônica, na qual o material recém-sintetizado foi tratado em solução aquosa de hidróxido de lítio no mesmo reator de micro-ondas a 140 oC por diferentes tempos (5 40 min) e sob constante agitação magnética. Após 10 min, foi obtido um material com baixo teor de íons K+ e com uma razão Li/Mn = 0,52, porém eletroquimicamente inativo. O material foi submetido a tratamentos térmicos em forno de micro-ondas convencional por distintos tempos (1 5 min), tendo apresentado, após 4 min, o perfil eletroquímico característico do espinélio. Nas imagens obtidas por microscopia eletrônica de varredura e transmissão para este material observa-se a predominância de partículas com morfologia prismática com cerca de 10 25 nm. Os resultados dos testes de carga e descarga demonstraram que os valores de capacidade específica são fortemente dependentes da espessura do filme compósito que compõe o eletrodo. Filmes menos espessos apresentaram um valor de capacidade específica inicial de 100 ± 17 mA h g-1 com retenção de carga de 93% após 75 ciclos de carga e descarga a uma taxa de descarga C/1.Universidade Federal de Sao Carlosapplication/pdfporUniversidade Federal de São CarlosPrograma de Pós-Graduação em Química - PPGQUFSCarBREletroquímicaBaterias de lítioNanomateriaisEletrodos de inserçãoCIENCIAS EXATAS E DA TERRA::QUIMICASíntese e caracterização de espinélios de lítio e manganês obtidos via rota hidrotermal assistida por microondasSynthesis and caracterization of lithium and manganese spinels obtained by microwave-assisted hydrothermal routeinfo:eu-repo/semantics/publishedVersioninfo:eu-repo/semantics/doctoralThesisinfo:eu-repo/semantics/openAccessreponame:Repositório Institucional da UFSCARinstname:Universidade Federal de São Carlos (UFSCAR)instacron:UFSCARORIGINAL6440.pdfapplication/pdf13562062https://{{ getenv "DSPACE_HOST" "repositorio.ufscar.br" }}/bitstream/ufscar/6328/1/6440.pdf63ddee486c9be2cd2baaae0f61496cedMD51TEXT6440.pdf.txt6440.pdf.txtExtracted texttext/plain0https://{{ getenv "DSPACE_HOST" "repositorio.ufscar.br" }}/bitstream/ufscar/6328/4/6440.pdf.txtd41d8cd98f00b204e9800998ecf8427eMD54THUMBNAIL6440.pdf.jpg6440.pdf.jpgIM Thumbnailimage/jpeg10662https://{{ getenv "DSPACE_HOST" "repositorio.ufscar.br" }}/bitstream/ufscar/6328/5/6440.pdf.jpgab20e67711e0d919e35c2cdfab1cc875MD55ufscar/63282020-03-23 19:47:25.036oai:repositorio.ufscar.br:ufscar/6328Repositório InstitucionalPUBhttps://repositorio.ufscar.br/oai/requestopendoar:43222023-05-25T12:51:08.561446Repositório Institucional da UFSCAR - Universidade Federal de São Carlos (UFSCAR)false |
dc.title.por.fl_str_mv |
Síntese e caracterização de espinélios de lítio e manganês obtidos via rota hidrotermal assistida por microondas |
dc.title.alternative.eng.fl_str_mv |
Synthesis and caracterization of lithium and manganese spinels obtained by microwave-assisted hydrothermal route |
title |
Síntese e caracterização de espinélios de lítio e manganês obtidos via rota hidrotermal assistida por microondas |
spellingShingle |
Síntese e caracterização de espinélios de lítio e manganês obtidos via rota hidrotermal assistida por microondas Silva, Daiane Piva Barbosa da Eletroquímica Baterias de lítio Nanomateriais Eletrodos de inserção CIENCIAS EXATAS E DA TERRA::QUIMICA |
title_short |
Síntese e caracterização de espinélios de lítio e manganês obtidos via rota hidrotermal assistida por microondas |
title_full |
Síntese e caracterização de espinélios de lítio e manganês obtidos via rota hidrotermal assistida por microondas |
title_fullStr |
Síntese e caracterização de espinélios de lítio e manganês obtidos via rota hidrotermal assistida por microondas |
title_full_unstemmed |
Síntese e caracterização de espinélios de lítio e manganês obtidos via rota hidrotermal assistida por microondas |
title_sort |
Síntese e caracterização de espinélios de lítio e manganês obtidos via rota hidrotermal assistida por microondas |
author |
Silva, Daiane Piva Barbosa da |
author_facet |
Silva, Daiane Piva Barbosa da |
author_role |
author |
dc.contributor.authorlattes.por.fl_str_mv |
http://lattes.cnpq.br/1138611310617865 |
dc.contributor.author.fl_str_mv |
Silva, Daiane Piva Barbosa da |
dc.contributor.advisor1.fl_str_mv |
Bocchi, Nerilso |
dc.contributor.advisor1Lattes.fl_str_mv |
http://genos.cnpq.br:12010/dwlattes/owa/prc_imp_cv_int?f_cod=K4783990J3 |
contributor_str_mv |
Bocchi, Nerilso |
dc.subject.por.fl_str_mv |
Eletroquímica Baterias de lítio Nanomateriais Eletrodos de inserção |
topic |
Eletroquímica Baterias de lítio Nanomateriais Eletrodos de inserção CIENCIAS EXATAS E DA TERRA::QUIMICA |
dc.subject.cnpq.fl_str_mv |
CIENCIAS EXATAS E DA TERRA::QUIMICA |
description |
Lithium and manganese oxide in spinel phase (LiMn2O4) was obtained by microwave-assisted hydrothermal route starting from completely soluble reagents. For this, a mixture of potassium permanganate and lithium hydroxide monohydrate (Li/Mn = 1.2) aqueous solutions and acetone (acetone/Mn = 1.1) was treated in a microwave reactor (850 W) at 140 °C for different times (10 s - 30 min) and under constant magnetic stirring. The obtained materials were characterized by X-ray diffraction, scanning and transmission electron microscopy, X-ray dispersive energy spectroscopy, electrons diffracton, inductively coupled plasma-atomic emission spectroscopy, cyclic voltammetry, thermogravimetry, structural refinement by Rietveld method and chronopotentiometry. The X-ray diffractogramm for the material synthesized in 5 min could be indexed to the JCPDS card number 35-0782 related to the LiMn2O4 in spinel phase, but the unwanted presence of K+ ions in its structure was verified. Thus, an ionic exchange step was included in the process, in which the newly-synthesized material was treated in an aqueous solution of lithium hydroxide in the same microwave reactor for different times (5 - 40 min) and under constant magnetic stirring. After 10 min, a material with low content of K+ ions and Li/Mn ratio = 0.52 was obtained, but it was electrochemically inactive. The material was submitted to a heat treatments in a conventional microwave oven for distinct times (1 - 5 min), having presented, after 4 min, the characteristic electrochemical profile of the spinel. The images obtained by scanning and transmission electron microscopy for this material showed the predominance of prismatic particles with nearly 10 - 25 nm. The results of charge and discharge tests showed that the specific capacity values are strongly dependent of the composite film thickness that composes the electrode. Thinner films presented a value of initial specific capacity of 100 ± 17 mA h g-1 with charge retention of 93% after 75 charge and discharge cycles at C/1 discharge rate. |
publishDate |
2014 |
dc.date.available.fl_str_mv |
2014-12-17 2016-06-02T20:34:59Z |
dc.date.issued.fl_str_mv |
2014-11-28 |
dc.date.accessioned.fl_str_mv |
2016-06-02T20:34:59Z |
dc.type.status.fl_str_mv |
info:eu-repo/semantics/publishedVersion |
dc.type.driver.fl_str_mv |
info:eu-repo/semantics/doctoralThesis |
format |
doctoralThesis |
status_str |
publishedVersion |
dc.identifier.citation.fl_str_mv |
SILVA, Daiane Piva Barbosa da. Synthesis and caracterization of lithium and manganese spinels obtained by microwave-assisted hydrothermal route. 2014. 135 f. Tese (Doutorado em Ciências Exatas e da Terra) - Universidade Federal de São Carlos, São Carlos, 2014. |
dc.identifier.uri.fl_str_mv |
https://repositorio.ufscar.br/handle/ufscar/6328 |
identifier_str_mv |
SILVA, Daiane Piva Barbosa da. Synthesis and caracterization of lithium and manganese spinels obtained by microwave-assisted hydrothermal route. 2014. 135 f. Tese (Doutorado em Ciências Exatas e da Terra) - Universidade Federal de São Carlos, São Carlos, 2014. |
url |
https://repositorio.ufscar.br/handle/ufscar/6328 |
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por |
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openAccess |
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Universidade Federal de São Carlos |
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Programa de Pós-Graduação em Química - PPGQ |
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UFSCar |
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BR |
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Universidade Federal de São Carlos |
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