Investigations of lithium manganese oxide materials for lithium-ion batteries

Abstract

As candidates for cathode materials in lithium-ion batteries, lithium manganese oxides are attractive and competitive. In this work, the feasibility of using a novel manganese oxide with a large-tunnel structure (i.e. todorokite, tunnel size: 3 × 3) as cathode material in lithiumion batteries has been explored. It is found that the initial capacity of todorokite material with Mg 2+ in the tunnel is 151 mAh g −1 at a discharge current density of 0.1 mA cm −2. It still has a capacity of 128 mAh g −1 after four charge-discharge cycles. The effects of different cations, such as Co 2+, Ni 2+, Li + etc., in the todorokite tunnel structure, on the electrochemical characteristics of the materials are also studied using slow-rate cyclic voltammetry and electrochemical impedance spectroscopy (EIS). Finally, the intercalation process of Li + in the spinel manganese oxide films has been investigated using the in situ electrochemical quartz crystal microbalance (EQCM) method. It is shown that the intercalation process of Li + in the films can be divided into at least two stages. The results also implied co-intercalation of solvent with Li + in the second stage.