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

Abstract

The nanoscale Li₂Mn_0.8Ni_0.2SiO₄/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 Li₂Mn_0.8Ni_0.2SiO₄ 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 Pmn2₁ 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 Li₂Mn_0.8Ni_0.2SiO₄ 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. Li₂Mn_0.8Ni_0.2SiO₄/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.