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Size effects in the Li(4+x)Ti(5)O(12) spinel.
W J H Borghols1, M Wagemaker, U Lafont
1Department of Radiation, Radionuclides and Reactors, Faculty of Applied Sciences, Delft University of Technology, Mekelweg 15, 2629 JB Delft, The Netherlands.
Journal of the American Chemical Society
|November 19, 2009
Summary
Investigating nanosized lithium titanate (Li(4+x)Ti(5)O(12)) reveals optimal particle size balances high capacity with stability. Near-surface effects influence lithium storage, but excessive storage causes irreversible capacity loss, impacting battery performance.
Area of Science:
- Materials Science
- Electrochemistry
- Solid-State Chemistry
Background:
- Nanosized electrode materials offer enhanced electrochemical performance due to increased surface area.
- Lithium titanate (Li(4+x)Ti(5)O(12)) is a promising anode material for lithium-ion batteries due to its zero-strain property.
- Surface effects in nanomaterials can significantly impact their electrochemical behavior and long-term stability.
Purpose of the Study:
- To investigate the electrochemical behavior and structural properties of nanosized Li(4+x)Ti(5)O(12) spinel.
- To understand the relationship between particle size, near-surface lithium storage, and capacity retention.
- To elucidate the origin of curved voltage profiles in nanosized Li(4+x)Ti(5)O(12) and its implications for nanoinsertion materials.
Main Methods:
- Electrochemical (dis)charging experiments to evaluate capacity and cycling stability.
- Neutron diffraction to analyze structural changes and lithium ion occupancy.
- Analysis of voltage profiles and capacity fade as a function of particle size.
Main Results:
- Nanosized Li(4+x)Ti(5)O(12) exhibits higher lithium ion occupancy and capacity in the near-surface region.
- Excessive near-surface lithium storage leads to irreversible capacity loss, likely due to surface reconstruction or mechanical failure.
- Curved voltage profiles in nanosized Li(4+x)Ti(5)O(12) are attributed to varied structural environments and redox potentials in the near-surface area, not strain.
Conclusions:
- An optimal particle size exists for nanosized Li(4+x)Ti(5)O(12) to maximize capacity while mitigating irreversible losses.
- The unique zero-strain characteristic of Li(4+x)Ti(5)O(12) necessitates a surface-environment-based explanation for its observed voltage profile anomalies.
- The findings offer insights into designing stable and high-performance nanoinsertion materials for advanced energy storage applications.
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