Kang X, Jin Z, Peng H, Cheng Z, Liu L, Li X, Xie L, Zhang J, Dong Y. The role of selenium vacancies functionalized mediator of bimetal (Co, Fe) selenide for high-energy-density lithium-sulfur batteries.
J Colloid Interface Sci 2023;
637:161-172. [PMID:
36701862 DOI:
10.1016/j.jcis.2023.01.090]
[Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2022] [Revised: 01/08/2023] [Accepted: 01/19/2023] [Indexed: 01/22/2023]
Abstract
Lithium-sulfur (Li-S) batteries are currently only in the basic research stage and have not been commercialized, which is mainly affected by the poor conductivity of sulfur/lithium sulfide (S/Li2S), volume expansion effect of sulfur and the shuttle effect of lithium polysulfides (LiPSs). Herein, a three dimensional (3D) carbon nanotubes (CNTs) decorated cubic Co9Se8-x/FeSe2-y (0 < x < 8, 0 < y < 2) composite (Co9Se8-x/FeSe2-y@CNTs) is developed, and used as the functionalized mediator on polypropylene (PP) in Li-S batteries. Benefiting from the good electrical conductivity, large number of Se vacancies and the triple block/adsorption/catalytic effects of Co9Se8-x/FeSe2-y@CNTs, the cell with Co9Se8-x/FeSe2-y@CNTs//PP modified separator delivers a high reversible capacity (1103.5 mA h g-1) at 1C after three cycles activation at 0.5C and remains 446 mA g h-1 after 750 cycles with a 0.08% capacity decay rate each cycle. Moreover, at 0.2C, a high areal capacity of 3.63 mA h cm-2 after 100 cycles with a high sulfur loading of 4.1 mg cm-2 is obtained. The in-situ XRD tests revealing the transition path of α-S8 → Li2S → β-S8 during the first charge-discharge process, then β-S8 → Li2S → β-S8 conversion reaction in the next cycles, and firstly determine the sulfur-selenide active intermediates (Se1.1S6.9) during cycles. The work provides a new insight into the development of bimetallic selenide composites by defect engineering with highly adsorptive and catalytic properties for Li-S batteries.
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