2.1.2. Enhanced Structural Stability
Since structural transition to thermodynamically undesirable
structures can only occur if the particle radius rp is larger
than the critical nucleation radius rc for that phase, it is possible
to eliminate such transitions by using nanoparticles with rp>rc.
Thus, small particles would more easily accommodate the
structural changes occurring during the cycling process where
Li is inserted and extracted. For example, layered LiMnO2
suffers from structural instability during cycling and as a result,
exhibits significant capacity fade. As a way to overcome such
difficulties, nanocrystalline structures have attracted increasing
attention, since the lattice stress caused by Jahn–Teller
distortion can be accommodated more easily, and hence they
exhibit much higher Li-intercalation capacity than their
conventional crystalline counterparts.[4]
In nanoparticles the charge accommodation occurs largely
at or very near the surface and the smaller the particles are, the
larger the portion of these constituent atoms at the surface.
This fact reduces the need for diffusion of Liþ in the solid
phase, greatly increasing the charge and discharge rate of the
cathode as well as reducing the volumetric changes and lattice
stresses caused by repeated Li insertion and expulsion.
2.1.2. Enhanced Structural Stability
Since structural transition to thermodynamically undesirable
structures can only occur if the particle radius rp is larger
than the critical nucleation radius rc for that phase, it is possible
to eliminate such transitions by using nanoparticles with rp>rc.
Thus, small particles would more easily accommodate the
structural changes occurring during the cycling process where
Li is inserted and extracted. For example, layered LiMnO2
suffers from structural instability during cycling and as a result,
exhibits significant capacity fade. As a way to overcome such
difficulties, nanocrystalline structures have attracted increasing
attention, since the lattice stress caused by Jahn–Teller
distortion can be accommodated more easily, and hence they
exhibit much higher Li-intercalation capacity than their
conventional crystalline counterparts.[4]
In nanoparticles the charge accommodation occurs largely
at or very near the surface and the smaller the particles are, the
larger the portion of these constituent atoms at the surface.
This fact reduces the need for diffusion of Liþ in the solid
phase, greatly increasing the charge and discharge rate of the
cathode as well as reducing the volumetric changes and lattice
stresses caused by repeated Li insertion and expulsion.
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