Bamboo Leaves as Sustainable Sources for the Preparation of Amorphous Carbon/Iron Silicate Anode and Nickel–Cobalt Silicate Cathode Materials for Hybrid Supercapacitors

The design and discovery of sustainable electrode materials with outstanding capacitance for energy storage from environmentally friendly biomass as the raw material are a task filled with challenges and opportunities. In this work, we demonstrate that the hybrid supercapacitor (HSC) device is assembled by metal silicates for the first time. The amorphous carbon/iron silicate (C/Fe24Si4O43(OH)2, denoted as C/FeSi) anode and cobalt–nickel silicate (CoxNi2–xSiO4, denoted as CoNiSi) cathode materials are derived naturally from bamboo leaves (BLs) for the HSC device. The BLs-derived C/FeSi displays FeSi nanoparticles in situ growth on 3D hierarchical porous carbon, leading to high specific surface area, outstanding specific capacitance of 421 F·g–1 at 0.5 A·g–1, and prominent cycle performance of 86% retention after 10 000 cycles. The CoNiSi presents a 3D petal-like sheet structure and exhibits excellent electrochemical properties with 368 F·g–1 (184 C·g–1) at 0.5 A·g–1 and 89% retention after 10 000 cycles. The fabricated quasi-solid-state C/FeSi//CoNiSi HSC device delivers a remarkable areal specific capacitance of 492 mF·cm–2 (96 F·g–1) at 4 mA·cm–2 and a brilliant energy density of 3.35 Wh·m–2 (6.55 Wh·kg–1) at 3.5 W·m–2 (68.36 W·kg–1), which are preferable to most of state-of-the-art silicates-based SCs. The series-wound C/FeSi//CoNiSi HSC device can light up the red LED for over 2 min. These strengths prove that both C/FeSi and CoNiSi architectures derived from BLs can be regarded as hopeful and first-class electrode materials for SCs with excellent performance. This work not only supplies a potential thread for the construction of metal silicate architectures to recycle biomass rich in silicon to synthesize useful materials but also demonstrates that the high-performance HSC device can be achieved by using the biomass-derived silicates.