Polymorphic Cobalt Sulfide-Embedded Graphene Foam with Ultralong Cycling and Ultrafast Rate Capability for Potassium-Ion Batteries

Abstract

Potassium-ion batteries (KIBs) attract growing attention due to their low price and abundant resources. However, the main drawback is the large-sized potassium ions, which results in a lack of superior capacity and desirable stable materials. We herein propose the Co 9 S 8 /GF nanocomposite synthesized by a solvothermal route followed by heat treatment under the reduction atmosphere with the CoS/GF nanocomposite as the control group. The as-synthesized Co 9 S 8 has a typical morphology of vertically arranged uniform nanosheet arrays. The Co 9 S 8 /GF nanocomposite electrode delivers a capacity of 345.65 mAh•g −1 after 600 cycles at 500 mA•g −1 and even 343.06 mAh•g −1 after 1360 cycles at 5000 mA•g −1 in KIBs. Besides, the discharge capacity can reach 461.05 mAh•g −1 after the current increases to 5000 mA•g −1 and a reversible capacity of 578.40 mAh•g −1 when the current density recovers to 250 mA•g −1 again. At last, the charge storage behaviors are mainly discussed, and the unique structure can suffer the volumetric change, especially at high current density, which opens up a novel and effective way to build the embedded porous structure for the next-generation KIB technology.

A bimetallic sulfide FeCoS4@rGO hybrid as a high-performance anode for potassium-ion batteries

“…The charge transfer process can be classified into two categories: faradaic reaction-controlled and diffusion-controlled processes, as described by the equation: i = av b . 33 In Fig. 3f, the b -values for the oxidation and reduction peaks fall between 0.5 and 1, indicating that both faradaic processes and surface diffusion contribute to the overall charge transfer kinetics.…”