A sustainable route from kelp to a porous MnO/C network anode for high-capacity lithium-ion batteries

Green and environmentally friendly methods have attracted much attention in the recent research of electrode materials. Natural resources with specific structure and properties are expected to be utilized, and high-performance anodes can be prepared by effectively compounding them with the active components. By choosing kelp with high content of protein as the carbon precursor, a nitrogen-containing MnO/C hybrid with high electrical connectivity has been designed and synthesized. As a kind of seaweed, kelp has an outstanding swelling property in salt solution and its cell membrane is rich in alginate, which is in favor of incorporating and coordinating with Mn2+ to form nanosized MnO particles. Moreover, kelp can be used as a template to build the unique network structure, which is conductive to accommodate the volume expansion of MnO during the cycles. The synthesized MnO/C hybrid reveals a superior electrochemical performance when applied to lithium-ion batteries. A high reversible capacity of 978 mAh g−1 can be retained at a current density of 0.2 A g−1. This synthesis strategy based on biomass provides a possibility for large-scale preparation of high-capacity electrode materials.