Cooperative Electronic Structure Modulator of Fe Single-Atom Electrocatalyst for High Energy and Long Cycle Li-S Pouch Cell.
ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2023;
35:e2208999. [PMID:
36527728 DOI:
10.1002/adma.202208999]
[Citation(s) in RCA: 11] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/29/2022] [Revised: 12/01/2022] [Indexed: 06/17/2023]
Abstract
High-energy and long cycle lithium-sulfur (Li-S) pouch cells are limited by the insufficient capacities and stabilities of their cathodes under practical electrolyte/sulfur (E/S), electrolyte/capacity (E/C), and negative/positive (N/P) ratios. Herein, an advanced cathode comprising highly active Fe single-atom catalysts (SACs) is reported to form 320.2 W h kg-1 multistacked Li-S pouch cells with total capacity of ≈1 A h level, satisfying low E/S (3.0), E/C (2.8), and N/P (2.3) ratios and high sulfur loadings (8.4 mg cm-2 ). The high-activity Fe SAC is designed by manipulating its local environments using electron-exchangeable binding (EEB) sites. Introducing EEB sites comprising two different types of S species, namely, thiophene-like-S (-S) and oxidized-S (-SO2 ), adjacent to Fe SACs promotes the kinetics of the Li2 S redox reaction by providing additional binding sites and modulating the Fe d-orbital levels via electron exchange with Fe. The -S donates the electrons to the Fe SACs, whereas -SO2 withdraws electrons from the Fe SACs. Thus, the Fe d-orbital energy level can be modulated by the different -SO2 /-S ratios of the EEB site, controlling the electron donating/withdrawing characteristics. This desirable electrocatalysis is maximized by the intimate contact of the Fe SACs with the S species, which are confined together in porous carbon.
Collapse