Wood‐Derived Hierarchically Porous Electrodes for High‐Performance All‐Solid‐State Supercapacitors

Abstract

The rapid development of many emerging technologies (e.g., electric vehicles and smart grids) requires advanced energy storage and conversion systems that have higher energy and power density, longer operational life, and better safety. A low‐cost, green, and sustainable process for fabrication of all‐solid‐state asymmetric supercapacitors (ASC) composed of a hierarchically porous carbonized wood (CW) anode, a cellulose paper separator, and a Co(OH)2@CW cathode is reported here. The hierarchically porous wood‐derived electrode exhibits a high areal capacitance of 3.723 F cm−2 (with an areal loading Co(OH)2 of 5.7 mg cm−2) at a current density 1.0 mA cm−2, and 1.568 F cm−2 at a current density of 30 mA cm−2. Moreover, the all‐solid‐state ASC exhibits outstanding energy density of 0.69 mWh cm−2 (10.87 Wh kg−1) at power density of 1.126 W cm−2 (17.75 W kg−1) while maintaining a capacitance retention of 85% after 10 000 continuous charge–discharge cycles. The high energy/power‐densities are attributed to the unique architecture of the electrodes derived from natural wood, which allow full exposure of active electrode materials, efficient current collection, and fast ion transport. Further, the materials are renewable, environmentally friendly, and biodegradable.

Wood‐Derived Lightweight and Elastic Carbon Aerogel for Pressure Sensing and Energy Storage

“…A Coulombic efficiency of 98.6% indicates good charge/discharge reversibility for the supercapacitor. The corresponding gravimetric and areal capacitances are 62.4 F g −1 at 0.5 A g −1 and 231 mF cm −2 at 0.5 mA cm −2 (based on the whole mass of the two carbon electrodes), respectively (Figure 6e), superior to those of many other carbon‐based all‐solid‐state SSC reported in literature (Table S6, Supporting Information) 56–58,61,63,65–67. The rate capacity of the assembled SSC (58.5%, from 0.5 to 4.0 A g −1 ) is also comparable to those of many other carbon‐derived SSC 57,67–71.…”

“…The corresponding gravimetric and areal capacitances are 62.4 F g −1 at 0.5 A g −1 and 231 mF cm −2 at 0.5 mA cm −2 (based on the whole mass of the two carbon electrodes), respectively (Figure 6e), superior to those of many other carbon‐based all‐solid‐state SSC reported in literature (Table S6, Supporting Information) 56–58,61,63,65–67. The rate capacity of the assembled SSC (58.5%, from 0.5 to 4.0 A g −1 ) is also comparable to those of many other carbon‐derived SSC 57,67–71. More impressively, the SSC reveals a high energy density of 8.6 Wh kg −1 at a power density of 250 W kg −1 , and maintains 5.0 Wh kg −1 at a power density of 2000 W kg −1 (Figure 6f), which are not only better than those of many other carbon‐derived SSC,56–58,61,63 but also comparable to those of some conducting polymer or metal oxides‐based supercapacitors66,67 (Table S6, Supporting Information).…”

“…The rate capacity of the assembled SSC (58.5%, from 0.5 to 4.0 A g −1 ) is also comparable to those of many other carbon‐derived SSC 57,67–71. More impressively, the SSC reveals a high energy density of 8.6 Wh kg −1 at a power density of 250 W kg −1 , and maintains 5.0 Wh kg −1 at a power density of 2000 W kg −1 (Figure 6f), which are not only better than those of many other carbon‐derived SSC,56–58,61,63 but also comparable to those of some conducting polymer or metal oxides‐based supercapacitors66,67 (Table S6, Supporting Information). As shown in Figure 6g, the SSC possesses a capacitance retention of ≈88.5% after 5000 cycles at a current density of 2 A g −1 , demonstrating its excellent cycling stability.…”

Thick Electrode Batteries: Principles, Opportunities, and Challenges

“…With respect to low‐tortuosity pore structure engineering, nature is generally regarded as the master in making hierarchically straight pores that normally function as water and nutrient transport pathways since these structures are found in various natural plants . Such mass‐transporting pore structures in natural plants (e.g., tree) inspired researchers to develop thick electrodes inheriting the nature‐made low‐tortuosity pores . Recently, inspired by the well‐oriented channels inherent in the structure of wood, Chen et al reported a wood‐derived carbon framework (CF) with superior electrical conductivity (13.75 S cm −1 ), high compressive strength (≈24 MPa), and low tortuosity as a 3D current collector for LBs .…”

Hybrid Materials from Ultrahigh‐Inorganic‐Content Mineral Plastic Hydrogels: Arbitrarily Shapeable, Strong, and Tough

“…Herein, by mimicking the biological route of biomineral formation via PILP penetration and solidification, we propose an artificial “mineral plastic hydrogel” route to fabricate arbitrarily shaping organic–inorganic hybrid structural materials, as shown in Figure . Delignified wood (DW) was selected as the porous scaffold owing to its high porosity [ 33 ] and wet shapeability, [ 34 ] and DW itself is also a good candidate for building structural materials with simple densification [ 35,36 ] or filling polymers. [ 37–39 ] Silica is an important type of structural biomineral widely found in the spicules of siliceous sponges [ 5 ] and diatom cell walls.…”