Related Experiment Video
Updated: May 7, 2026
08:43
Molten-Salt Synthesis of Complex Metal Oxide Nanoparticles
Published on: October 27, 2018
Thermally driven metastable solid-solution Li(0.5)FePO4 in nanosized particles and its phase separation behaviors
1Department of Materials Science and Engineering, Pohang University of Science and Technology (POSTECH), Pohang 790-784, Republic of Korea.
Nanotechnology
|September 27, 2013
Summary
Phase separation in nanosized lithium iron phosphate (LiFePO4) particles is hindered by nanoparticle effects and requires significant over-potential. This suggests phase transitions during charging/discharging may proceed through a stable metastable phase.
Area of Science:
- Materials Science
- Electrochemistry
- Nanotechnology
Background:
- Nanosized LiFePO4 exhibits fast electrochemical response via non-equilibrium pathways.
- Understanding phase transition in LiFePO4 nanoparticles is crucial for battery performance.
Purpose of the Study:
- Investigate phase separation behavior in metastable LiFePO4.
- Identify critical factors influencing phase separation in nanosized LiFePO4 particles.
- Elucidate the role of over-potential and nanoparticle effects.
Main Methods:
- Preparation of metastable solid-solution Li0.5FePO4 via chemical delithiation and thermal treatment.
- Investigation of phase separation under varied kinetic conditions, including relaxed pellet/electrode experiments and applied over-potential.
- Analysis of structural changes under open circuit voltage (OCV) and external current.
Main Results:
- Depressed phase separation within nanosized particles due to large interfacial energy (nanoparticle effect).
- Phase separation occurs between particles rather than internally.
- Metastable phase stability in the absence of over-potential; phase separation requires significant over-potential, indicating depressed spinodal decomposition.
- Surface charge transfer is a potential rate-limiting activated process.
Conclusions:
- Nanosized LiFePO4 phase transitions likely proceed via the metastable phase due to suppressed spinodal decomposition and inter-particle separation.
- Over-potential is critical for inducing phase separation in nanosized LiFePO4.
- The nanoparticle effect significantly influences phase separation mechanisms.
Related Concept Videos
01:24Solid–Solid Solutions
The temperature-composition phase diagram of two solids, A and B, which are immiscible in the solid phase but form miscible liquids, shows that when the temperature is low, these two exist as separate, pure solids (A and B). As the temperature increases, they transition into a single-phase liquid solution where A and B coexist. Moving from point a1 to a2 in the phase diagram, the composition changes such that solid B begins to separate from the solution, enriching the remaining liquid with A.
02:33Phase Transitions: Sublimation and Deposition
Some solids can transition directly into the gaseous state, bypassing the liquid state, via a process known as sublimation. At room temperature and standard pressure, a piece of dry ice (solid CO2) sublimes, appearing to gradually disappear without ever forming any liquid. Snow and ice sublimate at temperatures below the melting point of water, a slow process that may be accelerated by winds and the reduced atmospheric pressures at high altitudes. When solid iodine is warmed, the solid sublimes...
02:39Phase Transitions: Melting and Freezing
Heating a crystalline solid increases the average energy of its atoms, molecules, or ions, and the solid gets hotter. At some point, the added energy becomes large enough to partially overcome the forces holding the molecules or ions of the solid in their fixed positions, and the solid begins the process of transitioning to the liquid state or melting. At this point, the temperature of the solid stops rising, despite the continual input of heat, and it remains constant until all of the solid is...
01:29The Colloidal State
The formation of a colloidal system is exemplified by an aqueous solution containing Cl− ions is introduced to another containing Ag+ ions, resulting in the precipitation of solid AgCl as extremely tiny crystals. Instead of settling out as a filterable precipitate, these crystals remain suspended in the liquid, showcasing a colloidal system.A colloidal system involves colloidal particles within the approximate range of 1 to 1000 nm in at least one dimension, dispersed in a medium called the...