Improved electrochemical performances of layered lithium rich oxide 0.6Li[Li1/3Mn2/3]O2·0.4LiMn5/12Ni5/12Co1/6O2 by Zr doping

摘要

A series of layered lithium-rich oxides 0.6Li[Li _(1/3) Mn _(2/3(1? x )) Zr _(2/3 x ) ]O _(2) ·0.4LiMn _(5/12) Ni _(5/12) Co _(1/6) O _(2) (0 ≤ x ≤ 10%) have been prepared by a spray-dry method. The crystal structural and morphological properties of all the samples have been studied by XRD, XPS, SEM, HRTEM and SAED. XRD results reveal Zr ~(4+) ions are doped into the lattice. HRTEM results suggest Zr ~(4+) ions can stabilize the layered structural feature during cycles. The electrochemical properties are remarkably upgraded by Zr ~(4+) ion doping. The discharge capacity of Zr4% doped samples remains 218.9 mA h g ~(?1) after 100 cycles with a capacity retention of 84% at 20 mA g ~(?1) between 2.0 and 4.8 V, while the undoped samples drop to 168.6 mA h g ~(?1) with a capacity retention of 72%. Moreover, Zr4% doped samples show the lowest voltage decay, about 0.16 V lower than the undoped samples after 100 cycles. This study suggests suitable Zr ~(4+) doping can improve the electrochemical performances and suppress voltage decay for layered lithium-rich oxides.