Titanium- and niobium-doped fluorophosphates as positive electrodes for sodium-ion batteries

Autor(es)

Morais, William G. ^[1] ; Leite, Marina M. ^[1] ; Torresi, Roberto M. ^[1]

Afiliação do(s) autor(es)

^[1] Univ Sao Paulo, Dept Quim Fundamental, Inst Quim, Av Prof Lineu Prestes 748, BR-05508000 Sao Paulo, SP - Brazil

• Tipo de documento: Artigo Científico
• Fonte: JOURNAL OF ELECTROANALYTICAL CHEMISTRY; v. 897, SEP 15 2021.
• Citações Web of Science: 0

Resumo

Sodium fluorophosphates are among the most promising materials for positive electrodes in sodium-ion batteries; however, their low electronic conductivity, kinetics limitations, and structural instability prevent them from reaching their full potential. We obtained sodium vanadium fluorophosphates (NVPF) doped with Ti4+ (NVTPF) and Nb5+ (NVNPF) via an original low-temperature synthesis. It was observed that Ti4+ doping facilitated access to electrode sites and provided higher capacities at high current densities while Nb5+ provided a 91.7% capacity retention from the 20th to 200th cycle, which was over the 80.1% capacity retention of NVPF. Moreover, both NVTPF and NVNPF provided diffusion coefficients in the range of similar to 10(-10) cm(2) s(-1), which was better than similar to 10(-12) cm(2) s(-1) of NVPF. Additionally, electrochemical impedance spectroscopy and ex situ X-ray diffraction measurements confirmed that Ti4+ enhanced the electrode kinetics and stabilized its structure through sodiation/desodiation reactions. The results presented in this paper might provide insights and new directions to enhance the electrochemical storage properties of fluorophosphates. (AU)

• Processo FAPESP: 15/26308-7 - Otimização das propriedades físico-químicas de materiais nano-estruturados e suas aplicações em reconhecimento molecular, catálise e conversão/armazenamento de energia
• Beneficiário: Roberto Manuel Torresi
• Modalidade de apoio: Auxílio à Pesquisa - Temático
• Processo FAPESP: 20/07768-5 - Materiais para eletrodos positivos de alta voltagem em baterias de íons Li+ e Na+
• Beneficiário: Marina Moraes Leite
• Modalidade de apoio: Bolsas no Brasil - Pós-Doutorado
• Processo FAPESP: 18/23072-0 - Estudo de novos materiais ativos para aplicação como eletrodos positivos e negativos em baterias de íon-sódio
• Beneficiário: William Gomes de Morais
• Modalidade de apoio: Bolsas no Brasil - Pós-Doutorado