Local structures in mixed LixFe1−yMyPO4 (M=Co, Ni) electrode materials

摘要: We employ {sup 57}Fe Mossbauer spectroscopy as a local tool to probe electrical environments of Fe{sup 2+} and 3+} at different lithiation (x) cation-substitution (y) levels in Li{sub x}Fe{sub 1−y}M{sub y}PO{sub 4}/C (M=Co, Ni) Li-ion battery electrode materials. Upon delithiation the environment remains unaffected for parent y=0 system due LiFePO{sub 4}/FePO{sub 4} phase separation, whereas y>0 changes are seen 3+}. When 2+}/Fe{sup redox couple is partially-delithiated, decreasing quadrupole splitting value observed with increasing y, implying more symmetric environment. The concentration Co{sup 2+}/Ni{sup substituent introduces amounts Li atoms 3+}-containing phase, these nearest-neighbor suspected cause - Graphical abstract: Local iron 1−y}(Co/Ni){sub studied by levels. Highlights: • Fe spectroscopy. Co/Ni-for-Fe substitution results environmentmore » Due presence 2+}, introduced into phase. These suggested change environment.« less