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The preparation of porous materials from renewable energy sources is attracting intensive attention due to in terms of the application/economic advantage, and pore structural design is core in the development of efficient supercapacitors or available porous media. In this work, we focused on the transformation of natural biomass, such as cotton, into more stable porous carbonaceous forms for energy storage in practical applications. Biomorphic cotton fibers are pretreated under the effect of NaOH/urea swelling on cellulose and are subsequently used as a biomass carbon source to mold the porous microtubule structure through a certain degree of calcining. As a merit of its favorable structural features, the hierarchical porous carbon fibers exhibit an enhanced electric double layer capacitance (221.7 F g at 0.3 A g) and excellent cycling stability (only 4.6% loss was observed after 6000 cycles at 2 A g). A detailed investigation displays that biomass-swelling behavior plays a significant role, not only in improving the surface chemical characteristics of biomorphic cotton fibers but also in facilitating the formation of a hierarchical porous carbon fiber structure. In contrast to traditional methods, nickel foams have been used as the collector for supercapacitor that requiring no additional polymeric binders or carbon black as support or conductive materials. Because of the absence of additive materials, we can further enhance capacitance. This remarkable capacitive performance can be due to sufficient void space within the porous microstructure. By effectively increasing the contact area between the carbon surface and the electrolyte, which can reduce the ion diffusion pathway or buffer the volume change during cycling. This approach opens a novel route to produce the abundantly different morphology of porous biomass-based carbon materials and proposes a green alternative method to meet sustainable development needs.

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Mg0.2Co0.2Ni0.2Cu0.2Zn0.2O high entropy oxide (HEO) with outstanding cycling stability and high capacity retention indicates it is a promising anode material for rechargeable lithium‐ion batteries. Rock salt HEO nanofiber has been prepared by electrospinning method. Polyacrylonitrile polymer facilitates the formation of nanowire morphology. The effect of calcination temperature on the phase composition and microstructure evolutions has been investigated. Pure rock salt phase can be obtained after firing at 850°C for 2 min. Calcination at higher temperature than 850°C will break the fiber into short segments and lead to the growth of grain. A reversible capacity of 365 mAh g−1 was achieved after 300 cycles at .2 A·g−1.

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