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[Display omitted] Self-supporting tree skeleton and densely stackable phenolic resin are cleverly coupled together by a "rebar-concrete" structure. The thick electrode as a master of space utilization has extremely high areal and volumetric energy density. This work confirms the effective coupling of the self-supporting skeleton and powder materials, providing novel ideas for the preparation of thick electrodes with high mass loading. • A "rebar-concrete" structure is proposed to facilitate the high space utilization of thick electrodes. • The areal capacitance of the thick electrode reaches an astonishing 11F cm−2. • The assembled SSC device delivers competitive areal energy density of 0.63 mWh cm−2. The thick electrode design with high packing density of active materials can increase the capacity in a limited space. However, the key challenge is still to develop a system with high space utilization and ensure electron/ion transport in thick electrode. This work proposes an interesting "rebar-concrete" structure, which successfully prepared wood/phenolic resin-derived thick electrode with high space utilization by in-situ polymerization of phenolic resin (concrete) in the wood (rebar) channel. The electrode exhibits an excellent three-dimensional interconnected hierarchical pore structure due to the uniform activation of in-situ anchored KOH particles. The mass loading (35 mg cm−2) and areal capacitance (11F cm−2) of the obtained composite electrode are increased to 446 % and 1257 % of the original balsa wood, respectively. The assembled symmetric supercapacitor (SSC) exhibits a high energy density of 0.63 mWh cm−2 (3.91 mWh cm−3) and an excellent cycle stability (95 % retention after 50 000 cycles), showing good practicability in lighting LEDs or driving a fan. This strategy achieves effective coupling of self-supporting skeleton and powder materials, providing more insights and possibilities for the preparation of high energy density thick electrodes. [ABSTRACT FROM AUTHOR]

• Anisotropic cellulose nanofibril/silver nanowire materials are constructed via a directional freeze-drying method. • The existence of AgNWs reinforces the solar-thermal energy conversion and storage capacity. • The ss-CPCMs exhibit improved thermal conductivity, thermal stability and recyclability. • This work provides insights into the thermal transmission mechanism in anisotropic supporting materials. Improving the thermal stability and energy storage density of phase change materials (PCMs) in thermal energy storage systems is a key task for their practical applications in industrial production. Whereas, limited by the inherently inferior heat transfer and unsatisfactory visible light response capability, PCMs exhibit extremely low thermal storage/release capability, inhibiting their developments. Herein, we constructed porous cellulose nanofibril (CNF)/silver nanowire (AgNW) hybrid supporting materials possessing the highly ordered structure and characteristically anisotropic thermal transmission capacity by directional freeze-drying, in order to encapsulate octadecanol (OCO) and octodecane (OCC) by vacuum impregnation method. Profited by the infrequently anisotropic structures and high thermal conductivity AgNWs, CNF/AgNW hybrid materials present dissimilar thermal transmission rates in the transverse and longitudinal directions. The close contact of AgNWs to CNFs allows the energy harvesting by solar-excited AgNWs to rapid transfer to CNFs, which increases the phonon propagation of the cellulosic material lattice and implements the improvement of the thermal transmission ability of the hybrid carriers. The obtained series of composite PCMs show an improved thermal conductivity (enhanced by 72.7%), and thermal enthalpy is comparatively approaching the theoretical value. Rejoicingly, the composites are thermally and durably stable. This novel-innovative targeted functional strategy provides insights into the thermal transmission mechanism in anisotropic supporting materials, and the resulting shape-stable composite PCMs (ss-CPCMs) can be employed as promising candidates for renewable thermal energy storage systems in virtue of their characteristic comprehensive performances. [ABSTRACT FROM AUTHOR]

[Display omitted] • High P-doped (9.24 at%) thick carbon electrodes (CW-P) by phytic acid treatment. • SSC exhibits high capacitance of 4.7F cm−2/206.5F g−1 at 1.0 mA cm−2. • Excellent capacitance retention of 90.5% after 20 000 cycles (@20 mA cm−2). • High energy density up to 0.94 mW h cm−2 (41.2 Wh kg−1). • High power density up to 0.6 mW cm−2 (26.3 W kg−1). Keeping outstanding electrochemical performance under high mass loading is critical to develop functional thick electrodes. Here, we report a high phosphorus-doped wood-derived carbon thick electrode for supercapacitor via phytic acid treatment, which can form hydrogen bonds with cellulose molecules in the wood. The content of phosphorus reaches up to 9.24 at% in carbonized wood with P-doping (CW-P-9.24), higher than most previously reported P-doped carbonaceous materials. CW-P-9.24 electrode (800 μm, 17.17 mg cm−2) exhibits greatly improved electrochemical performance, especially in energy density and cyclic stability. Significantly, the symmetrical supercapacitor device exhibits high areal and specific capacitance of 4.7 F cm−2 and 206.5 F g−1 at 1.0 mA cm−2 with prominent retention of 90.5% through the long-term cycling at 20 mA cm−2 for 20,000 cycles, and 0.94 mW h cm−2 (41.2 Wh kg−1) at power density of 0.6 mW cm−2 (26.3 W kg−1), and possesses excellent volumetric capacitance and energy density of 29.3 F cm−3 and 5.8 Wh cm−3, respectively. The outstanding performance can be attributed to the excellent hierarchical structure, low tortuosity, and high phosphorus doping with fast accessible channels at high current density. The extraordinary performance of CW-P has been elucidated by density functional theory calculations, which confirm the enhanced activity by P-doping. These results demonstrate that the CW-P electrode is promising for practical application in energy storage devices and encourage more investigations for thick electrode. [ABSTRACT FROM AUTHOR]