Understanding the Predominant Potassium-Ion Intercalation Mechanism of Single-Phased Bimetal Oxides by in Situ Magnetometry

Abstract

The electrochemical performance of electrode materials is largely dependent on the structural and chemical evolutions during the charge−discharge processes. Hence, revealing ion storage chemistry could enlighten mechanistic understanding and offer guidance for rational design for energy storage materials. Here, we investigate the mechanisms of potassium (K)-ion storage in the promising bimetal oxide materials by in situ magnetometry. We focus on a single-phased hollow FeTiO 3 (SPH-FTO) hexagonal prism synthesized through a complexing-reagent assisted approach and find that the K-ion storage in this compound occurs predominantly with an intercalation mechanism and fractionally a conversion mechanism. We also demonstrate a K-ion hybrid capacitor assembled with the prepared SPH-FTO hexagonal prism anode and activated carbon cathode, delivering a high energy density and high power density as well as extraordinary cycling stability. This new understanding is used to showcase the inherently high K-ion storage properties from the earth-abundant FeTiO 3 .

Electrochemical interfacial catalysis in Co-based battery electrodes involving spin-polarized electron transfer

“…Subsequently, the increasing of Ms becomes sluggish until the potential reaches V3 (0.6 V), indicating that some additional reactions may present and weaken the magnetic change resulting from the conversion reaction. This unique magnetic response could be explained by a spin-polarized surface capacitance proposed in our previous work ( 24 – 27 ). Once the metallic Co nanoparticles are generated during the discharge process, the spin-polarized surface capacitance appears, where numerous spin-polarized electrons can be injected into the Co nanoparticles within a Thomas–Fermi estimate and form a space charge region, while the Li + ions as a charge compensator are stored outside the grain boundaries and surfaces.…”

“…In this work, using advanced operando magnetometry ( 24 – 27 ), we successfully achieved monitoring the real-time evolution of the electronic structure and chemical/physical environment of a transition metal compound involving interfacial catalytic processes. Specifically, a Co(OH) 2 /Li battery was selected because its continuous and reversible conversion process takes place under an applied voltage.…”

Scalable SPAN Membrane Cathode with High Conductivity and Hierarchically Porous Framework for Enhanced Ion Transfer and Cycling Stability in Li–S Batteries

“…The ever-growing application of high-energy storage devices have prompted researchers to develop promising batteries beyond current Li-ion technology. − Lithium sulfur (Li–S) batteries, because of their outstanding gravimetric energy density of 2600 Wh kg –1 , have attracted considerable interest as advanced energy storage devices . However, numerous inherent challenges of conventional Li–S batteries have blocked their practical application.…”

Advancements in cathode materials for potassium-ion batteries: current landscape, obstacles, and prospects

“…405 Additionally, the mechanism behind SEI layer formation and charge transfer kinetics in KIBs remains enigmatic, necessitating extensive investigations in the forthcoming studies. Given the high reactivity of potassium, the integration of advanced characterisation techniques, such as in situ transmission electron microscopy (TEM), cryo-electron microscopy, and in situ magnetometry, 406 in conjunction with computation, can offer valuable insights into the charge transfer kinetics, microstructures, and reaction mechanism of SEI. 407 Moreover, the advent of cutting-edge technologies like machine interaction, artificial intelligence, and big data analysis holds the potential to drive further advancements in electrolyte chemistry and the elucidation of SEI phenomena, as well as the development of compatible electrode materials for KIBs.…”