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As the most promising anode material for ultra-high specific capacity lithium-ion batteries, Si has been hindered from widespread use by large volume effects and limited electrical conductivity during cycling. In this study, NiO nanoflowers were coated onto the exterior of Si NPs by hydrothermal method. Si@NiO was then mixed and annealed with natural biomass gel extracted from moldy wheat to produce Si@NiO@Biochar ternary composites, which were prepared. Si NPs are the source of high specific capacity of anode materials. The carbon layer minimizes the electrode bulk effect and enhances cycling stability, while the NiO flowers expand the lithium-ion transport channel and reduce Si NPs bulk effect. Furthermore, the N element from wheat protein in the carbon layer enhances the electrical conductivity of the material. After 100 cycles at 0.1 A g−1 and 1000 cycles at 1 A g−1, the capacity of the electrode rose to 952.12 mAh g−1 and 1098.05 mAh g−1, respectively. The Si@NiO@Biochar material showed remarkable electrochemical stability at various current densities and the thickness grew by just 27.97% after 500 cycles. It can also be utilized in lithium-sulfur batteries because of its microporous structure and capacity to transport sulfur. The reversible capacity was 388.21 mAh g−1 after 70 cycles at 1 C. Biomass carbon from biomass gels coated on Si@NiO reduces biomass energy waste. This research is a significant step for commercializing Si anode materials and providing an eco-friendly new method for storing energy. [Display omitted] • Nitrogen-doped biochar is made from the recycling of mouldy wheat. • The simple preparation process and excellent results. • The volume expansion of the silicon is well limited. • The composite has low internal resistance and high cycle life. • It can be used in two scenarios: lithium batteries and lithium- sulfur batteries. [ABSTRACT FROM AUTHOR]

Heteroatom-doped porous carbon derived from covalent organic frameworks (COFs) is of great interest due to their unique nanostructure and ability to host a large ionic radius of K+. Herein, we reported F and N co-doped porous carbon (FNC) anode for potassium ion batteries (PIBs) for the first time by carbonized rational design COFs. The synthesized FNC retains characteristics of COFs such as a nanosheet structure, rich hierarchical pores, and large interlayer spacing, which facilitate K+ diffusion. Besides, generated abundant defects provide active sites for K+ storage. The specific introduction of F and N by COFs molecules enables the formation of conjugation effect (Π 7 8 , Π 6 7), stable C-F bonds and -C-F...N- interactions in carbon layers, improving the electrical conductivity and structural stability of FNC. As a result, the FNC anode shows a high reversible specific capacity of 292 mAh g−1 at 50 mA g−1 as well as excellent cyclability of 118 mAh g−1 at 1000 mA g−1 over 200 cycles. This work will serve as a guide for the synthesis of heteroatom co-doped porous carbon materials for high-performance potassium-ion storage. • The F and N doping porous carbon was fabricated by a facile carbonization of designed COFs. • Uniform doping of F and N in porous carbon improves electrical conductivity through conjugation effect. • The C-F and -C-F...N- interactions improve the structural stability of the electrode and diffusion speed of K+. • The FNC anode shows a high reversible specific capacity and cycling stability. [ABSTRACT FROM AUTHOR]