Li2Mn0.8Ni0.2SiO4/MnO2 nanocomposite for high-performance supercapacitor applications

The nanoscale Li2Mn0.8Ni0.2SiO4/MnO2 composite was successfully prepared via a two-step method. Firstly, by the preparation of MnO2 nanoparticles through an oxidation-reduction reaction; secondly, by synthesizing Li2Mn0.8Ni0.2SiO4 using an EDTA-assisted sol-gel method; finally, the two nanoparticles mixed together by hand milling to form the nanocomposite. The synthesized nanoparticles were characterized using several techniques. The nanocomposite presents a well-developed orthorhombic crystal structure with a Pmn2(1) space group, although there are small impurities of MnO and Li2SiO3. The BET surface area measurements indicate that all the prepared materials are mesoporous. The effect of nanoscale MnO2 on the electrochemical properties of the Li2Mn0.8Ni0.2SiO4 nanomaterials was evaluated. The composite (denoted as (LMNS/M2) exhibited a specific capacity of 962.4 C g(-1) at the current density of 2 A g(-1). Furthermore, a hybrid device using this composite as a cathode and commercial activated carbon (AC) as an anode was fabricated to examine the practical aspects of the novel electrode, which conducted a specific energy of 38.1 W h kg(-1) at a specific power of 938.4 W kg(-1). It preserved a capacity of 84% after 2000 cycles. Li2Mn0.8Ni0.2SiO4/MnO2 is a promising candidate for high-efficiency energy storage electrode materials for supercapacitor applications because of its superior performance and ease of preparation. The obtained results confirm the excellent electrochemical performance of the electrode as a promising electrode for energy storage applications.