Small but mighty: Empowering sodium/potassium‐ion battery performance with S‐doped SnO₂ quantum dots embedded in N, S codoped carbon fiber network

Abstract

SnO2 has been extensively investigated as an anode material for sodium‐ion batteries (SIBs) and potassium‐ion batteries (PIBs) due to its high Na/K storage capacity, high abundance, and low toxicity. However, the sluggish reaction kinetics, low electronic conductivity, and large volume changes during charge and discharge hinder the practical applications of SnO2‐based electrodes for SIBs and PIBs. Engineering rational structures with fast charge/ion transfer and robust stability is important to overcoming these challenges. Herein, S‐doped SnO2 (S–SnO2) quantum dots (QDs) (≈3 nm) encapsulated in an N, S codoped carbon fiber networks (S–SnO2–CFN) are rationally fabricated using a sequential freeze‐drying, calcination, and S‐doping strategy. Experimental analysis and density functional theory calculations reveal that the integration of S–SnO2 QDs with N, S codoped carbon fiber network remarkably decreases the adsorption energies of Na/K atoms in the interlayer of SnO2–CFN, and the S doping can increase the conductivity of SnO2, thereby enhancing the ion transfer kinetics. The synergistic interaction between S–SnO2 QDs and N, S codoped carbon fiber network results in a composite with fast Na+/K+ storage and extraordinary long‐term cyclability. Specifically, the S–SnO2–CFN delivers high rate capacities of 141.0 mAh g−1 at 20 A g−1 in SIBs and 102.8 mAh g−1 at 10 A g−1 in PIBs. Impressively, it delivers ultra‐stable sodium storage up to 10,000 cycles at 5 A g−1 and potassium storage up to 5000 cycles at 2 A g−1. This study provides insights into constructing metal oxide‐based carbon fiber network structures for high‐performance electrochemical energy storage and conversion devices.

Recent advances in rational design for high-performance potassium-ion batteries

“…547–550 However, the application of metal oxide anode materials in PIBs still faces the following challenges: (1) the volume changes greatly when the conversion reaction occurs with K + , resulting in severe extrusion of the electrode and loss of collector contact; (2) the ion and electronic conductivity is poor, resulting in a low ion diffusion coefficient and high resistance; and (3) the SEI is unstable and ICE is low. 346,551 To overcome these shortcomings, commonly used tools include nanofabrication, carbon coating, and surface engineering. 336,389–392,552–554…”

Self-Propagating Fabrication of a 3D Graphite@rGO Film Anode for High-performance Potassium-Ion Batteries

“…The development of PIBs has captured significant attention in recent years, and extensive research has been conducted on electrode materials that are indispensable components for PIBs. Presently, various materials including carbonaceous materials, ,− alloys, − metal oxides/sulfides, − and organic compounds − have been reported as anodes for PIBs. Among all, carbonaceous materials are considered the most promising anode candidates because of their low cost, environmental friendliness, and controllable structure.…”