Steric-hindrance effect and self-sacrificing template behavior induced PDA@SnO2-QDs/N-doped carbon hollow nanospheres: Enhanced structural stability and reaction kinetics for long-cyclic Li-ion half/full batteries

Tin-based anode materials with high theoretical specific capacity are subject to huge volume expansion and poor reaction reversibility, leading to degradation of battery performance. Herein, the steric-hindrance effect and self-sacrificing template behavior of polydopamine were firstly developed to induce the formation of hollow nanospheres assembled by ultrafine SnO2 quantum dots (SnO2-QDs) and nitrogen-doped carbon (NC), containing residual polydopamine (PDA) cores. The PDA@SnO2-QDs/NC hol-low nanospheres could effectively accommodate the volume expansion and maintain structural stability. More importantly, the PDA core could capture oxygen free radicals produced by the charge/discharge process and be involved in the evolution of the SEI layer, achieving enhanced electrochemical reaction kinetics. The optimized PDA@SnO2-QDs/NC anode shows a specific capacity of 898 mAh g-1 after 300 cycles at 0.3 A g-1, and scarcely capacity attenuation after 1500 cycles at 1 A g-1. The long-cyclic life is up to 3000 cycles at 3 A g-1. Even after 200 cycles, the anode in the PDA@SnO2-QDs/NC||LFP full battery gives a reversible capacity of 489 mAh g-1 at 0.3 A g-1, with a capacity retention of 77 %. This work casts new light on tin-based anode materials and interface optimization.(c) 2022 Elsevier Inc. All rights reserved.

Automated summary

Hollow nanospheres composed of ultrafine SnO2 quantum dots (SnO2-QDs) and nitrogen-doped carbon (NC) with residual polydopamine (PDA) cores were successfully prepared using the steric-hindrance effect and self-sacrificing template behavior of polydopamine. The hollow structure effectively accommodated volume expansion and maintained structural stability. The PDA core captured oxygen free radicals and participated in the evolution of the solid electrolyte interface (SEI) layer, achieving enhanced electrochemical reaction kinetics. The optimized PDA@SnO2-QDs/NC anode exhibited high specific capacity and long-cyclic life, demonstrating the potential of tin-based anode materials and interface optimization.