Developing carbon scaffolds showing rational pore structures as cathode hosts is essential for achieving superior electrochemical performances of lithium-selenium (Li-Se) batteries. Hierarchically porous N-doped carbon polyhedrons anchored on crumpled graphene balls (NPC/CGBs) are synthesized by carbonizing a zeolitic imidazolate framework-8 (ZIF-8)/CGB composite precursor, producing an unprecedented effective host matrix for high-performance Li-Se batteries. Mesoporous CGBs obtained by one-pot spray pyrolysis are used as a highly conductive matrix for uniform polyhedral ZIF-8 growth. During carbonization, ZIF-8 polyhedrons on mesoporous CGBs are converted into N-doped carbon polyhedrons showing abundant micropores, forming a high-surface-area, high-pore-volume hierarchically porous NPC/CGB composite whose small unique pores effectively confine Se during melt diffusion, thereby providing conductive electron pathways. Thus, the integrated NPC/CGB-Se composite ensures high Se utilization originating from complete electrochemical reactions between Se and Li ions. The NPC/CGB-Se composite cathode exhibits high discharge capacities (998 and 462 mA h g-1 at the 1st and 1000th cycles, respectively, at a 0.5 C current density), good capacity retention (68%, calculated from the 3rd cycle), and excellent rate capability. A discharge capacity of 409 mA h g-1 is achieved even at an extremely high (15.0 C) current density.
Bibliographical noteFunding Information:
This research was supported by the Technology Development Program to Solve Climate Changes of the National Research Foundation (NRF) funded by the Ministry of Science, ICT & Future Planning (NRF-2017M1A2A2087577 and NRF-2017R1A4A1014806).
© 2018 American Chemical Society.
Copyright 2018 Elsevier B.V., All rights reserved.
- crumpled graphene balls
- hierarchically porous materials
- lithium-selenium batteries
- metal-organic frameworks
- spray pyrolysis
ASJC Scopus subject areas
- General Materials Science