Properties and Structure of Spinel Li-Mn-O-F Compounds for Cathode Materials of Secondary Lithium-ion Battery

The spinel Li-Mn-O-F compound cathode materials were synthesized by solid-state reaction from calculated amounts LiOH-H₂O, MnO₂(EMD) and LiF. The results of the electrochemical test demonstrated that these materials exhibited excellent electrochemical properties. It's initial capacity is - 115 mAh.g¹ and reversible efficiency is about 100%. After 60 cycles, its capacity is still around 110 mAh.g¹ with nearly 100% reversible efficiency. The spinel Li-Mn-O-F compound possibly has two structure models: interstitial model [Li]-[Mn³⁺_xMn⁴⁺_2-x]O₄F_δ, in which the fluorine is located on the interstice of crystal lattice, and substituted model [Li]-[Mn³⁺_xMn⁴⁺_2-x]O_4-δF_δ, which the fluorine atom substituted the oxygen atom. The electrochemical result supports the interstitial model [Li][Mn³⁺_xMn⁴⁺_2-x]O₄F_δ.