Direct synthesis of tin spheres/nitrogen-doped porous carbon composite by self-formed template method for enhanced lithium storage

Abstract

• Self-formed template method is developed to prepare Sn/N-doped porous C composite. • N-doped C introduces more defects and low lithium-ion diffusion energy barrier. • The Sn/NPC electrode achieves excellent lithium-ion storage properties. • A Sn/NPC||LiCoO 2 full cell is assembled to expound the real application. • The alloying/dealloying reaction mechanism is detailly investigated by in-situ XRD. To inhibit the agglomeration of tin-based nanomaterials and simplify the complicated synthesis process, a facile and eco-friendly self-formed template method is reported to synthesize tin submicron spheres dispersed in nitrogen-doped porous carbon (Sn/NPC) by pyrolysis of a mixture of disodium stannous citrate and urea. The vital point of this strategy is the formation of Na 2 CO 3 templates during pyrolysis. This self-formed Na 2 CO 3 acts as porous templates to support the formation of NPC. The obtained NPC provides good electronic conductivity, ample defects, and more active sites. Serving as anode for Li-ion batteries, the Sn/NPC electrode obtains a stable discharge capacity of 674.1 mAh/g after 150 cycles at 0.1 A/g. Especially, a high discharge capacity of 331.2 mAh/g can be achieved after 1100 cycles at 3 A/g. Additionally, a full cell coupled with LiCoO 2 as cathode yields a discharge capacity of 524.8 mAh/g after 150 cycles at 0.1 A/g. In-situ XRD is implemented to investigate the alloying/dealloying reaction mechanisms. Density functional theory calculation ulteriorly explicates that NPC heightens intrinsic electronic conductivity, and NPC especially pyrrolic-N and pyridinic-N doping facilitates the Li-adsorption ability. Climbing image nudged elastic band method reveals low Li + diffusion energy barrier in presence of N atoms, which accounts for the terrific electrochemical properties of Sn/NPC electrode.