A high-performance primary nanosheet heterojunction cathode composed of Na0.44MnO2 tunnels and layered Na2Mn3O7 for Na-ion batteries.

A high-performance primary nanosheet heterojunction cathode composed of Na0.44MnO2 tunnels and layered Na2Mn3O7 for Na-ion batteries. ChemSusChem. 2020 Jan 28;: Authors: Zheng P, Su J, Wang Y, Zhou W, Song J, Su Q, Reeves-McLaren N, Guo S Abstract Due to its large capacity and high average potential, the structure and reversible O-redox compensation mechanism of Na2Mn3O7 have recently been analyzed. However, capacity fade and low coulombic efficiency following subsequent cycles have also been shown, which result from oxygen evolution at high charge voltages. Herein, a Na0.44MnO2•Na2Mn3O7 heterojunction of primary nanosheets was prepared by a sol-gel-assisted high temperature sintering method. In the nanodomain regions, the close contact of Na0.44MnO2 not only supplies multidimensional channels to improve the rate performance of the composite, but also plays the role of pillars for enhancing the cycling stability and Coulombic efficiency; this is accomplished by suppressing oxygen evolution, which is confirmed by HRTEM, cyclic voltammetry and charge-discharge curves. As the cathode of a Na-ion battery, at 200 mA g-1 after 100 cycles, the Na0.44MnO2 •Na2Mn3O7 heterojunction retains an 88 % capacity and the Coulombic efficiency approaches 100 % during the cycles. At 1000 mA g-1, the Na0.44MnO2 •Na2Mn3O7 heterojunction has a discharge capacity of 72 mAh g-1. In addition, the average potential is as high as 2.7 V between a range of ...
Source: ChemSusChem - Category: Chemistry Authors: Tags: ChemSusChem Source Type: research