Realizing the synergy of Sn cluster incorporation and nitrogen doping for a carbonaceous hierarchical nanosheet-assembly enables superior universal alkali metal ion storage performance with multiple active sites

Abstract

Energy storage devices with the merits of low cost and high energy/power densities (e.g., sodium/potassium ion batteries and hybrid capacitors) have recently drawn increasing interest due to their unique advantages as promising candidates for grid-level applications. However, the relatively larger K⁺/Na⁺ radius generally causes sluggish ion diffusion kinetics and inferior cycling stability. Herein, we realize the synergy of Sn cluster incorporation and nitrogen doping into a carbonaceous hierarchical nanosheet-assembly (denoted as c-SnNC-HNA) through a scalable one-pot strategy based on a supramolecular formation process, which can act as a universal alkali metal ion storage host with remarkable specific capacity and outstanding cycling performance. Specifically, a high specific capacity (411.4/386.2/1065.4 mA h g⁻¹ at 100 mA g⁻¹ for K⁺/Na⁺/Li⁺, respectively) and ultra-stable cycling capability can be obtained (74.8% retention rate for K⁺ after 4000 cycles at 5 A g⁻¹; almost 100% retention rate for Na⁺ after 4000 cycles at 5 A g⁻¹). The underlying mechanism is investigated based on ex situ XPS, in situ Raman analysis and GITT measurements. Importantly, potassium ion hybrid capacitors based on the c-SnNC-HNA anode can deliver a decent energy/power density of 112.5 W h kg⁻¹/49.1 W kg⁻¹ and exhibit superior cycling stability up to 10 K cycles at 2000 mA g⁻¹.