Unravelling the electrochemical characteristics and sodium storage mechanism of pistachio shell derived hard carbon as high plateau capacity anodes by operando Raman spectroscopy and full cell demonstration

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Hard carbon has emerged as a highly promising material for negative electrode in sodium-ion batteries (SIBs). This study focuses on the synthesis of an anode material through the pyrolysis of Pistachio shells, a commonly available nut waste, at different temperatures ranging from 900° to 1400°C. The material pyrolyzed at 1400 °C exhibits a remarkable reversible discharge capacity of 302 mAhg−1 and plateau capacity of 223 mAhg−1 at a current rate of 10 mAg−1, displaying stable cyclic performance and an impressive 80% capacity retention after 500 cycles at 200 mAg−1. The morphological, structural, and surface chemical characteristics of the cycled hard carbon anode materials were examined through ex-situ FE-SEM, XRD, and XPS analyses. Furthermore, the sodiation and desodiation mechanisms of the synthesized hard carbon were investigated using operando Raman Spectroscopy. The diffusion kinetics parameters were determined by Electrochemical Impedance Spectroscopy (EIS) and CV analyses. This study underscores the potential of Pistachio shells as a promising precursor for the synthesis of carbonaceous anode for SIBs, employing a straightforward one-step pyrolysis process. The excellent electrochemical performance, along with the ease of material sourcing and synthesis, places this nutty waste as a promising, sustainable and clean energy resource option for advancing sodium-ion battery technology.