Abstract
Na3V2(PO4)3 is regarded as one of the promising cathode materials for next-generation sodium ion batteries, but its undesirable electrochemical performances due to inherently low electrical conductivity have limited its direct use for applications. Motivated by the limit, this study employed a porous carbon network to obtain a porous carbon network–Na3V2(PO4)3 composite by using poly(vinylalcohol) assised sol-gel method. Compared with the typical carbon-coating approach, the formation of a porous carbon network ensured short ion diffusion distances, percolating electrolytes by distributing nanosized Na3V2(PO4)3 particles in the porous carbon network and suppressing the particle aggregation. As a result, the porous carbon network–Na3V2(PO4)3 composite exhibited improved electrochemical performances, i.e., a higher specific discharge capacity (~110 mAh g−1 at 0.1 C), outstanding kinetic properties (~68 mAh g−1 at 50 C), and stable cyclic stability (capacity retention of 99% over 100 cycles at 1 C).
Highlights
Rapid advancements in renewable energy generation, including solar, wind, and geothermal systems, have encouraged the improvements in large-scale energy storage systems (ESS) for their efficient utilization [1–4]
In the case of the Porous Na3 V2 (PO4 )3 (NVP)/C composites, it clearly showed the formation of a porous carbon network that looked like a flower shape as a result of adding PVA in the precursor solution (Figure 1c)
We have successfully fabricated a composite, in which NVP particles were homogeneously dispersed in a porous carbon matrix by adopting a PVA-assisted sol-gel fabrication method
Summary
Rapid advancements in renewable energy generation, including solar, wind, and geothermal systems, have encouraged the improvements in large-scale energy storage systems (ESS) for their efficient utilization [1–4]. Reported the improved electrochemical properties of NVP by forming a carbon-coating layer on the surface of the particles [27]. The double sidedness of the carbon-coating strategy for electronic conductivity and ion diffusivity must be considered in the formation of carbon–NVP composites to have maximized benefits and the corresponding electrochemical properties. NVP/C composite had potential electrochemical advantages: (i) the thin and homogeneous carbon coating layer on NVP particles enhanced the interfacial electrical conductivity and sodium ion transfer; (ii) the suppression of NVP particle aggregation facilitated the uniform response of the particles; and (iii) the porous carbon framework provided a larger surface area that increased the active redox surface of the composites. In order to study the improvement of electrochemical properties, the characteristics of the carbon layer such as the porosity, specific surface area, and the coating layer thickness were investigated with the conventional simple carbon-coating method
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