Iron vacancies and surface modulation of iron disulfide nanoflowers as a high power/energy density cathode for ultralong-life stable Li storage†
*b
Haitao
Liu
*c
and
Abstract
Iron disulfide-based cathodes have been regarded as promising for use in high-energy-density lithium batteries owing to their low cost. However, low utilization, sluggish lithium ion insertion kinetics and rapid capacity fading prevent their practical application. Herein, defect-rich iron disulfide nanoflowers are synthesized by self-assembly on a hierarchical porous catalytic heteroatom-doped carbon matrix. Both electrochemical experiments and density functional theory simulations reveal that the iron defects in the cathode help to decrease the diffusion barrier so that lithium ions can freely and easily insert into the crystal and improve the transport kinetics. Meanwhile, the hierarchical porous structure also accommodates volumetric changes and facilitates electrolyte immersion. As a consequence, the as-prepared cathode delivers an initial specific capacity of 841 mA h g−1 at 0.1C and retains an energy density of ∼500 W h kg−1 at a high power density of 26.7 kW kg−1 (20C). Even working for 3000 cycles at 4C, the cell can still preserve an energy efficiency of above 95% and display a high energy density of 220 W h kg−1 with an average capacity fading as low as 0.020% per cycle, showing its superior electrochemical stability and lifetime.
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