Algae-derived gel carbon framework encapsulating Si@NiO/Ni quantum dots to construct high-speed electron transport channels for lithium-ion battery anodes

Multilayered porous composites are promising anode materials with intricate porous structures, diverse material sources, and eco-friendly, non-polluting properties, which provide significant opportunities for the development of biochar materials aimed at sustainably improving the performance of lithium-ion batteries (LIBs). In this paper, a novel combination of porous biomass gel carbon and nano-transition metal oxides with silicon nanoparticles is introduced as an anode material for lithium-ion batteries, i.e., Si@NiO/Ni nanoflowers encapsulated in naturally nitrogen-doped algal gel carbon (Gelidium amansii: GAM). The biomass gel perfectly encapsulates the Si@NiO/Ni nanoflower and provides sufficient natural nitrogen for the porous carbon framework; the silicon nanoparticles (NPs) help to increase the specific capacity of the anode material; the carbon layer mitigates electrode volume expansion and enhances the cycling stability; while NiO expands the lithium-ion transport pathway and further reduces the volume effect of the silicon nanoparticles; and the alginate component of the carbon layer, N, works in conjunction with Ni to increase the material's electrical capacity. Ni in the carbon layer work together to increase the conductivity of the material. The Si@NiO/Ni nanoflower composite Si@NiO/Ni@GAM-5 encapsulated in algal biogel showed a reversible capacity of 1245.12 mAh g⁻¹ after 1000 cycles at a high current of 1 A g⁻¹.