Embedding Metal Selenide Over Carbon Nanotubes For Economically Viable Sodium-Ion Batteries Anode

Abstract

Excessive use of fossil fuels is negatively impacting the global economy. Using fossil fuels as an energy source also results in the emission of greenhouse gases which significantly contribute to global warming. Therefore, it is important to replace fossil fuels with environmentally friendly and cost-effective energy sources. For instance, lithium-ion batteries are known to be suitable for powering automobiles and other electrical appliances and therefore considered as a potential candidate for such replacement. However, they are expensive, while the geographical availability of lithium is another challenge. Therefore, searching for a suitable alternative to lithium-ion batteries is very important. Owing to the comparable electrochemical properties of sodium metal (in sodium ion batteries), intensive research is being carried out to investigate its potential to replace lithium-ion batteries in future. Furthermore, remarkable electrochemical properties of multiple metal selenides (MMSs) have drawn the attention towards their application as anode materials for sodium ion batteries. However, their high intrinsic conductivities, limited cycle stability, low-rate capabilities and availability of more redox sites are still the problems to be addressed via extensive research. The cost of precursors for their fabrication can be tackled by selecting cheaper elemental combinations such as Copper and Zinc coupled with carbon matrix, which increases intrinsic conductivity, rate capability, and long-term cyclic stability. A facile methodology is prepared to improve intrinsic conductivity, a hierarchically porous metal selenide over carbon nanotubes. The porous structure with embedded nanoparticles in combination with carbon matrix, result in extraordinary electrochemical performance. In this research work, incorporated such structure (as anode materials) into sodium-ion batteries resulted in good rate capability of 298.5 and 295.8 mA h g-1 for CuZnSe, 210.7 and 207.1 mA h g-1 for CuZnSe@CNTs, 252.6 and 248.6 mA h g-1 for Cu3ZnSe@CNTs, 81.7 and 78.9 mA h g-1 for ZnSe@CNTs even at high current rates of 2 A g−1 and 4 A g−1 respectively, and sufficient cyclic stability with columbic efficiency between 98-99% (with few exemptions) This novel combination of Copper and Zinc Selenide over carbon nanotubes in sodium-ion batteries can be a good applicant for energy storage devices.