Simple synthesis of bimetal oxide@graphitized carbon nanocomposites via in-situ thermal decomposition of coordination polymers and their enhanced electrochemical performance for electrochemical energy storage

A simple and effective method is developed to synthesize bimetal oxide@graphitized carbon nanocomposites composed of graphitized carbons, Ni-Co oxides, and a small amount of Ni and Co metals (denoted as NCxO@G, where x represents Ni/Co mole ratio), by in-situ thermal decomposition of their corresponding coordination polymers. The resultant NCxO@G nanocomposites exhibit excellent electrochemical performance such as high specific capacity and good cycling stability. Experimental results demonstrate that the Ni/Co mole ratio plays an important role in determining the electrochemical behaviors, and a small amount of Ni and Co metals can boost the performance. A maximum specific capacity of ca. 673.5C g(-1) at current density of 1.2 A g(-1), a superior capacity retention (similar to 105% after 10,000 cycles at 10 mV s(-1)), and a remarkable energy density of 46 Wh kg(-1) with a high power density of 300 W kg(-1) can be achieved when the Ni/Co ratio equals to ca. 1.0, signifying that this kind of nanocomposites are potential candidates for electrochemical energy storage. (C) 2016 Elsevier Ltd. All rights reserved.