In Situ Growing Prussian Blue Nanocrystals on Ti3c2 Lamellae as High-Performance Electrode for Potassium-Ion Storage

Abstract

Surface modification plays an important role in tailoring electrode surface chemistry to improve electrochemical performance. Here, an attempt is made by in situ growing Prussian blue (PB) nanocrystals on well-conductive Ti3C2 lamellae. When used as an electrode, Ti3C2 functions as an electron bridge to connect current collector with potassium reservoir (viz. PB). Besides, the open-up Ti3C2 framework can buffer volumetric variation of PB during potassiation/depotassiation and also accommodate K+ through electric double-layer capacitive effect. On the other hand, exposed PB nanocrystals are in full contact with electrolyte, so that it will improve the accessibility of K+ by shortening their diffusion path. More strikingly, PB and Ti3C2 components do not operate on their own; instead, they show great synergy that significantly enhances the overall performance of the battery. This composite electrode delivers high K-storage capacity of 355 mAh g-1 after 1000 cycles at 1 A g-1 and exhibits outstanding rate-capacity of 267 mAh g-1 at 10 A g-1.

Keywords: Potassium ion storage, Surface, Prussian blue, Ti3C2, In situ growth