The Synthesis And Electrochemical Behaviors Of Li[Li_0.1Ni_0.35Mn_0.55]O₂ As Cathode Material

Lithium-ion batteries a new type of secondary batteries developed during 1990's.Lithium manganese oxides have advantages as the positive active materials for lithium-ion batteries, such as nontoxicity, low cost etc. it also has disadvantages such as capacity fade, cycles problem etc . Li[Li_1/3Mn_2/3]O₂ is inactive ,not only layered structure but also chemical properties is stabilization. So many people doped Ni, Co, Cr etc transitional metals in it ,substituted a part of Li⁺ and Mn⁴⁺ by Ni²⁺, Co²⁺, Cr³⁺ in 3b position, synthesized a new type of materials which have improved in cycling and safety properties.In this paper, we have prepared Li[Li_0.1Ni_0.35Mn_0.55]O₂ by improving co-precipitation. The experiment result show: the appropriate temperature is 900°C.In 3.0⁴.4V potential window(vs.Li⁺/Li) the electrode of Li[Li_0.1Ni_0.35Mn_0.55]O₂ show electrochemical properties with a first discharged capacity of 159mAh/g and retaining 149.2mAh/g after 30 cycles at a current rate of 25 mA/g under room temperature.We prepared Li[Li_0.1Ni_0.35Mn_0.55]_0.95Co_0.05O₂ by the means as well as Li[Li_0.1Ni_0.35Mn_0.55]O₂. Studied the effect of doping a little Co on the electrochemical properties of Li[Li_0.1Ni_0.35Mn_0.55]O₂. In 3.0⁴.4V potential window(vs.Li⁺/Li)the electrode of Li[Li_0.1Ni_0.35Mn_0.55]_0.95Co_0.05O₂ showed electrochemical properties with a first discharged capacity of 186.8mAh/g and retaining 181.2mAh/g after 40 cycles at a current rate of 25 mA/g under room temperature.At last, we studied the insertion of magnesium and zinc ion in Li[Li_0.1Ni_0.35Mn_0.55]_0.95Co_0.05O₂. In electrolyte 1molMg (ClO₄) ₂+ LiClO₄/EC+DMC and the potential windows of (0.9 2.08V vs Zn²⁺/Zn ) the electrode of Li[Li_0.1Ni_0.35Mn_0.55]_0.95Co_0.05O₂ showed electrochemical properties with a first discharged capacity of 146mAh/g and retaining 117.7mAh/g after 30 cycles at a current rate of 25 mA/g under room temperature. In electrolyte 1mol Zn (ClO₄)₂+ LiClO₄/EC+DMC and the potential windows of (0.9 2.08V vs Zn²⁺/Zn ) the electrode of Li[Li_0.1Ni_0.35Mn_0.55]_0.95Co_0.05O₂ showed electrochemical properties with a first discharged capacity of 100mAh/g and retaining 61.3mAh/g after 30 cycles at acurrent rate of 25 mA/g under room temperature. In electrolyte lmol Zn (CIO4) 2/EC+DMC and the potential windows of (0.9—2.08V vs Zn2+/Zn ) the electrode of LifLio.1Nio.35Mno.5530.95Coo.05O2 showed electrochemical properties with a first discharged capacity of 69.7mAh/g and retaining49.7mAh/g after 15cycles at a current rate of 25 mA/g under room temperature.