Doping‐Induced Electronic/Ionic Engineering to Optimize the Redox Kinetics for Potassium Storage: A Case Study of Ni‐Doped CoSe₂

Abstract

Heteroatom doping effectively tunes the electronic conductivity of transition metal selenides (TMSs) with rapid K+ accessibility in potassium ion batteries (PIBs). Although considerable efforts are dedicated to investigating the relationship between the doping strategy and the resulting electrochemistry, the doping mechanisms, especially in view of the ion and electronic diffusion kinetics upon cycling, are seldom elucidated systematically. Herein, the crystal structure stability, charge/ion state, and bandgap of the active materials are found to be precisely modulated by favorable heteroatom doping, resulting in intrinsically fast kinetics of the electrode materials. Based on the combined mechanisms of intercalation and conversion reactions, electron and K+ ion transfer in Ni‐doped CoSe2 embedded in carbon nanocomposites (Ni‐CoSe2@NC) can be significantly enhanced via electronic engineering. Benefiting from the synthetic controlled Ni grains, the heterointerface formed by the intermediate products of electrochemical reactions in Ni‐CoSe2@NC strengthens the conversion kinetics and interdiffusion process, developing a low‐barrier mesophase with optimized potassium storage. Overall, an electronic tuning strategy can offer deeper atomic insights into the conversion reaction of TMSs in PIBs.

Sodium-Ion Storage Properties of Thermally Stable Anatase

“…The potential difference gradually decreases with the sodiation and desodiation progressing, resulting in a gradual decrease in Na ion diffusion coefficient. The diffusion coefficients of Na + (D Na + ) are calculated using the following equation [47,48]:…”

Insight into the Structural Variation and Sodium Storage Behavior of Polyoxometalates Encapsulated within Single‐Walled Carbon Nanotubes

“…In the first cycle, a strong and wide reduction peak was observed at around 0.5 V, which was attributed to the formation of solid electrolyte interphase (SEI). [36,37] The reduction peak at about 0.01 V corresponded to the Na + reduction/insertion into the PMo 12 @SWNT electrode interface, and the corresponding oxidation peak located at 0.08 V was attributed to desodiation of the interface. The CV curves in the 2nd and 3 rd cycles almost overlapped, indicating that the materials were stable during repeated potential cycling.…”

Aliovalent doping engineering enables multiple modulations of FeS2anodes to achieve fast and durable sodium storage

“…24,25 Meanwhile, the introduction of non-equivalent heteroatoms is inclined to cause the distortion of the material lattice (expansion or shrinkage of the lattice spacing) to a certain extent. 26,27 Therefore, heteroatom doping can alter the electronic structure of materials and accelerate the transport of electrons/ions, achieving an attractive sodium storage capacity. For example, Ni et al 28 adopted sulfur as a dopant to enhance the electrochemical performance of TiO 2 nanotube arrays, where the sulfur-doped TiO 2 nanotube arrays delivered superior sodium storage performance.…”