Catalysis

Composite number

Engineering

Materials science

Carbon fibers

Chemical engineering

Physical chemistry

Disproportionation

Organic chemistry

Hydrothermal circulation

Carbonization

Composite material

Chemistry

Scanning electron microscope

Electrode

Anode

Lignin

Hydrothermal carbonization

Advanced Functional Materials

The comprehensive utilization of biomass to obtain energy‐storage carbonaceous materials with special microstructures is of great significance. Herein, a universal method is proposed to fabricate oriented carbon microspheres (OCMSs) and 3D porous carbon (3DPC) block at the same time via high‐temperature hydrothermal “disproportionation” of biomass including but not limited to basswood, pinus sylvestris, red walnut, beech, bamboo, and sorghum straw. Through nuclear magnetic resonance, gas chromatography mass spectrometry, as well as various morphologic and structural characterizations, it is demonstrated that OCMS with (002) orientation originates from the carbonization of organic matters produced by the successive decomposition of hemicellulose, cellulose, and lignin during the high‐temperature hydrothermal process, while the 3DPC blocks exhibit abundant sp 3 defects and micropores with a surface area of 855.12 m 2 g −1 due to the constant loss of organic components from basswood blocks. As a result, the OCMS anode exhibits a high capacity of 201.1 mA h g −1 at 2000 mA g −1 after 2000 cycles, 3DPC cathode delivers a capacity of 95.7 mA h g −1 at 1.0 A g −1 after 5000 cycles. Remarkably, the as‐assembled OCMS//3DPC potassium ion hybrid capacitor exhibits an energy of 140.7 Wh kg −1 at 643.8 W kg −1 , with a long cycle life over 8500 cycles.

Hydrothermal “Disproportionation” of Biomass into Oriented Carbon Microsphere Anode and 3D Porous Carbon Cathode for Potassium Ion Hybrid Capacitor