Electrochemical Investigations of Li2Fe0.8-xMn0.2MxSiO4 (M = Mg2+, Zn2+) Cathodes for Lithium Ion Batteries

• Autor(a) principal: Li,Shu-Dan
• Data de Publicação: 2016
• Outros Autores: Zhao,Yun, Wang,Chen-Yi, Gao,Kun
• Tipo de documento: Artigo
• Idioma: eng
• Título da fonte: Journal of the Brazilian Chemical Society (Online)
• Texto Completo: http://old.scielo.br/scielo.php?script=sci_arttext&pid=S0103-50532016001102011
• topic: chemically modified electrode; lithium battery; applied electrochemistry; composite and nanocomposite materials

The Mn2+ and Mg2+ (or Zn2+) co-doped Li2Fe0.8-xMn0.2MxSiO4 (x = 0.05 and 0.1) are synthesized by a solid-state reaction route. Compared with the single doped Li2Fe0.8Mn0.2SiO4, the co-doped samples show improved cycling performance. The capacity retention can stay above 50% after 50 cycles, which is significantly higher than 30.4% for Li2Fe0.8Mn0.2SiO4. This phenomenon could be attributed to the increased structural stability caused by the incorporation of the electrochemically inactive M2+ ions. However, except for Li2Fe0.75Mn0.2Mg0.05SiO4, the other samples show decreased capacities, especially in the case of the Mn/Zn co-doping. Further tests indicate that the promotion of Li+ diffusivity may be a key reason for the improved rate and cycling performances. By contrast, the incorporation of Zn2+ impaired the cell performances such as increased internal polarization, hindered charge transfer, decreased Li+ diffusivity. In this work, the Mg2+ with smaller radius seems to be a better choice as the co-doping element at Fe sites than Zn2+.