Loofah-derived carbon as an anode material for potassium ion and lithium ion batteries

Abstract

In this work, we report a facile and inexpensive strategy to synthesize loofah-derived pseudo-graphite (LPG) through alkali treatment process followed by a one-step pyrolysis procedure. This mesoporous hard carbon material offers superb dual functionality for both lithium-ion battery (LIB) and potassium-ion battery (KIB) anodes. Tested against lithium and potassium, LPG delivers a specific capacity of 225 mAh·g−1 in LIBs and 150 mAh·g−1 in KIBs after 200 cycles at the current density of 100 mA g−1. The good performance of LPG for both LIBs and KIBs mainly originates from its dual storage mechanism. On one hand, wider layered pseudo-graphite units provide space for Li+/K+ intercalation at higher voltages (>0.17 V in LIBs, > 0.56 V in KIBs). On the other hand, highly accessible mesoporous structure and defect-activated units in the near-surface region make it possible for Li+/K+ deposition at low voltages. The different performance of LPG in LIBs and KIBs may originate from varied ion-storage mechanisms. Despite the similar diffusion coefficient (D+), lower capacity of LPG for potassium can be contributed to its limited intercalation kinetics in higher voltage (>0.56 V) and evidently higher resistance in the charge-transfer process (Rct).