Array of nanosheets render ultrafast and high-capacity Na-ion storage by tunable pseudocapacitance

TLDR

Sodium‑ion batteries offer a low‑cost, safe alternative to lithium‑ion technology, but fast charging and high power density are limited by sluggish sodiation kinetics. The study aims to demonstrate a high‑capacity, high‑rate sodium‑ion anode using ultrathin layered tin(II) sulfide nanostructures that maximize extrinsic pseudocapacitance. The anode is fabricated from ultrathin layered tin(II) sulfide nanostructures, and its pseudocapacitance is maximized and confirmed through kinetic analysis. The graphene‑foam‑supported tin(II) sulfide nanoarray delivers a reversible capacity of ~1,100 mAh g⁻¹ at 30 mA g⁻¹ and ~420 mAh g⁻¹ at 30 A g⁻¹, surpassing lithium‑ion performance, and its surface‑dominated redox reaction suggests applicability to other layered materials.

Abstract

Sodium-ion batteries are a potentially low-cost and safe alternative to the prevailing lithium-ion battery technology. However, it is a great challenge to achieve fast charging and high power density for most sodium-ion electrodes because of the sluggish sodiation kinetics. Here we demonstrate a high-capacity and high-rate sodium-ion anode based on ultrathin layered tin(II) sulfide nanostructures, in which a maximized extrinsic pseudocapacitance contribution is identified and verified by kinetics analysis. The graphene foam supported tin(II) sulfide nanoarray anode delivers a high reversible capacity of ∼1,100 mAh g(-1) at 30 mA g(-1) and ∼420 mAh g(-1) at 30 A g(-1), which even outperforms its lithium-ion storage performance. The surface-dominated redox reaction rendered by our tailored ultrathin tin(II) sulfide nanostructures may also work in other layered materials for high-performance sodium-ion storage.