The Semicoherent Interface and Vacancy Engineering for Constructing Ni(Co)Se_2@Co(Ni)Se_2 Heterojunction as Ultrahigh-Rate Battery-Type Supercapacitor Cathode

摘要

Restricted rate capability is the key bottleneck for the large-scale energystorage of battery-type supercapacitor cathode due to its sluggish reactionkinetics. Herein, Ni(Co)Se_2@Co(Ni)Se_2 semicoherent heterojunctions withrich Se vacancies (Vr-Ni(Co)Se_2@Co(Ni)Se_2) as cathode are first constructed.Such a vacancy and heterointerface manipulation can not only essentially regulatethe electronic structure and enhance ions adsorption capability, but alsorationalize the chemical affinities of OH– ions in diffusion pathway revealedby systematic characterization analysis and first-principle calculations. Theas-prepared cathode delivers large specific capacity of 264.5 mAh g~(–1) at1 A g~(–1) and excellent cycle stability. Surprisingly, it presents ultrahigh rate withthe retention of 159.7 mAh g~(–1) even at 250 A g~(–1). Moreover, the single phasetransition mechanism of the cathode is elucidated systematically using seriesof ex situ techniques. In addition, contributed by the unique cathode and theself-synthesized N/S co-doped corncob-derived porous carbon (N/S-BPC,316.1 F g~(–1) at 1 A g~(–1)) anode, a high-performance hybrid supercapacitor (HSC)is developed, which shows the energy density of 68.1 Wh kg~(–1) at 0.75 kW kg~(–1)and a superior cycle performance. The findings highlight a coordinationstrategy for the rational design of ultrahigh-rate battery-type HSC cathode,greatly pushing their commercial application processes.