Probing Electrochemical Behaviour of Lignocellulosic, Orange Peel Derived Hard Carbon as Anode for Sodium Ion Battery

Hard carbon (HC) has emerged as potential anode material for sodium-ion batteries (SIB). However, it is plagued with several issues like low capacity, poor cyclability, significant electrolyte degradation on interface. Realization of HC as anode requires fundamental understanding of the effect of its porous structure/composition on electrochemical performance. Herein, we report the use of lignocellulosic orange peel precursor for HC synthesis with tuneable surface area (SA), controlled porosity using phosphoric acid treatment. Physicochemical properties of HC were further tailored using N-doping. The electrochemical response of various HCs was tested with careful attention to the effect of HC SA and nitrogen content on the performances as anode. We show that optimized bio-waste based HC exhibits Na⁺ specific capacity of 125 mAhg^-1 at 70 mAg^-1 with significantly suppressed CO₂ evolution during cycling, indicating mitigated electrolyte degradation and superior performance. We believe that this study sheds light on design rules for bio-waste low-cost precursors for synthesizing HC with tailored physical and electrochemical properties. Using such design guidelines, is crucial for developing HC based anode materials for SIB's.