Rational Design and Engineering of 1D Heterostructured Porous Sn/CoSn_x@C Nanotubes for Superior Lithium Storage

Abstract

Tin is a good anode material for lithium storage because of its high theoretical capacity and good conductivity, but large volume changes during the charging/discharging process lead to poor rate performance and cycling stability. In this work, by assembling ZIF-67 nanosheets on SnO2@PDA nanotubes and following a calcination process, heterostructured Sn/CoSn x (x = 1, 2) alloy anchored N-doped porous carbon nanotubes with high lithium storage performance were rationally designed and successfully prepared (Sn/CoSn x @C). The Co incorporated in CoSn x intermetallic can buffer the internal stress, and combined with the porous structure, the large volume expansion can be effectively alleviated. Besides, coating the ultrafine Sn/CoSn x crystals within one-dimensional N-doped carbon can inhibit particle agglomeration, thus enhancing cyclic stability. Moreover, benefiting from the porous tubular structure that can shorten the mass/charge transport distance, the generated abundant heterointerfaces can promote reaction kinetics, achieving improved rate capacity. Therefore, the tubular structured Sn/CoSn x @C anode shows a high reversible specific capacity of 1713.2 mAh g–1 at a current density of 100 mA g–1, a high rate performance of 1394.1 mAh g–1 at 1.0 A g–1 and 1051.3 mAh g–1 at 5.0 A g–1, and an excellent cycling stability of 444.3 mAh g–1 at 5 A g–1 over 5000 cycles. These results demonstrate an effective strategy for developing high-performance metal alloy-based electrodes in the energy storage system.