Sodium modified molybdenum sulfide via molten salt electrolysis as an anode material for high performance sodium-ion batteries

Abstract

The paper reports a facile and cost effective method for fabricating sodium molybdenum sulfide nanoparticles through using MoS₂ sheets as the precursor by sodium-modification. The electrochemical performances of sodium molybdenum sulfide nanoparticles are studied as anode materials for sodium-ion batteries. The galvanostatic charge–discharge measurements have been performed in a voltage range of 0.01–2.6 V vs. Na⁺/Na under different current densities, using the as-prepared sodium molybdenum sulfide nanoparticles as a working electrode. Typically, the initial discharge and charge capacities of sodium molybdenum sulfide nanoparticles are 475 and 380 mA h g⁻¹, respectively, at a current density of 20 mA g⁻¹. The sodium molybdenum sulfide nanoparticles exhibit high capacity with a reversible discharge capacity of about 190 mA h g⁻¹ after 100 cycles. It should be emphasized that the discharge reaction consists of two steps which correspond to voltage plateaus of 0.93 V and 0.85 V vs. Na⁺/Na in the first discharge curve of the Na/MoS₂ battery, respectively. But there is only one apparent voltage plateau in the Na/Na–Mo–S battery, and it reduces to below 0.5 V vs. Na⁺/Na, which can enhance the power density. All of the findings demonstrate that sodium molybdenum sulfide nanoparticles have steady cycling performance and environmental and cost friendliness as next generation secondary batteries.