Boosting lifespan of conversion-reaction anodes for full/half potassium-ion batteries via multi-dimensional carbon nano-architectures confinement effect

Abstract

Transition metal selenides are regarded as prospective conversion-reaction anodes for potassium-ion batteries (PIBs) because of their relatively high electrical conductivity, large theoretical specific capacity, abundant resources and low cost. The challenge of the metal selenides originates from a serious volume change during cycling, which induces serious structural collapse and fast capacity degradation. In the present work, the multi-dimensional carbon nano-architectures confined bimetallic selenides (ZnSe/CoSe2@N-CNTs/rGO) were constructed by a facile MOF-assisted strategy. In such special nano-architectures, N-doped CNTs protect the metal selenides centers from serious volume expansion/electrode pulverization, as well as improve the sluggish kinetics. ZnSe/CoSe2@N-CNTs/rGO electrode boosts the lifespan of half PIBs with a large discharge specific capacity of 200 mAh g−1 at 2 A g−1 after 3800 cycles. The full PIBs battery with ZnSe/CoSe2@N-CNTs/rGO electrode as anode and Prussian blue as cathode exhibits well electrochemical performance (151 mAh g−1 at 100 mA g−1 after 100 cycles). DFT calculation suggests that the CNTs could change the K+ adsorption energy and decrease K+ diffusion energy barrier, which dramatically enhances K+ storage kinetics. This work offers an effective material engineering approach for designing hierarchical “all-in-one” electrodes with high excellent cycling stability for PIBs.