Bi3+/K+ synergistic pillar effect unleashes high initial coulombic efficiency and potassium-storage kinetics in titanium-based anodes

Bi 3+ /K + co-doping act as “dual pillars” to stabilize the layered structure. • Intercalated Bi 3+ increase the KTO interlayer spacing and stabilize the lattice. • Initial coulombic efficiency of Bi-KTO far exceeds that of other Ti-based materials. • K + /Bi 3+ synergy enhances potassium storage and cycling stability. Potassium-ion batteries (PIBs) are increasingly recognized as an important candidate for next-generation energy storage technology attributed to the advantages of sufficient potassium reserves, suitable redox potential, and environmental friendliness. The research of high-performance anode materials represents an essential factor in the development of PIBs. Among these, titanium (Ti)-based materials, known for their structural stability and environmental friendliness, face challenges including limited capacity and slow kinetics. To address these issues, in this work, we propose a synergistic “dual pillars” strategy that incorporates K + pre-intercalation and Bi 3+ doping into Ti-based materials, thereby enhancing their potassium storage performance. K + stabilizes the layered framework, while Bi 3+ further expands the interlayer spacing and optimizes the electronic structure, significantly improving both structural stability and ion diffusion kinetics. The Bi-KTO has a capacity reaching 106.2 mAh g −1 at 0.1 A g −1 and maintains 63 mAh g −1 after over 1500 cycles under 0.2 A g −1 . In particular, the initial coulombic efficiency of Bi-KTO is relatively high compared with other reported KTO-based anodes. At 0.2 A g −1 , the full cell retained 32.5 mAh g −1 after 500 cycles, surpassing most reported KTO-based anode for PIBs. These findings provide valuable insights for future in-depth investigations about KTO-based materials. Download: Download high-res image (340KB) Download: Download full-size image