Fibrin biopolymer hydrogel-templated 3D interconnected Si@C framework for lithium ion battery anodes

Silicon is considered a promising candidate for lithium-ion battery anodes because of its exceptionally high capacity. However, employing Si in real applications remains a challenge, owing to dramatic reduction in the capacity after a few cycles. Redesigning the advanced electrode structure, including the available free volume and continuous conductive scaffold, may potentially circumvent this problem. Here, we demonstrate a new method of creating binder- and conductive additive-free three-dimensional (3D) porous network Si@C electrodes via fibrin hydrogel templating followed by pyrolysis. Hydrogen bonds between hydroxyl groups on Si and amides of fibrin enable the hierarchical 3D structures. These comprise well-distributed Si nanoparticles (SiNPs) in carbon frameworks, with each particle conformally encapsulated by the carbon layer. We confirm that carbon is doped with nitrogen and that pyridinic N and pyrrolic N are the predominant configurations. The 3D Si@C electrode exhibits a good rate performance (capacity of 730 mAh g(-1) at 1000 mA g(-1) (0.5C, Si + C basis)) and also a stable cycling property (54% capacity retention after 500 cycles at 500 mA g(-1)). Compared to a conventional mixture (SiNPs/alginate/Super P), the 3D Si@C electrode exhibits significantly improved electrochemical properties.

Automated summary

The three-dimensional porous network Si@C electrode, created via fibrin hydrogel templating followed by pyrolysis, demonstrates good rate performance and stable cycling property. Doped with nitrogen, the electrode exhibits significantly improved electrochemical properties compared to conventional mixtures.