Abstract
The heat generation of LiMn2O4, Li1.156Mn1.844O4, and Li1.06Mn1.89Al0.05O4 spinel cathode materials in a half-cell system was investigated by isothermal micro-calorimetry (IMC). The heat variations of the Li/LiMn2O4 cell during charging were attributed to the LiMn2O4 phase transition and order/disorder changes. This heat variation was largely suppressed when the stoichiometric spinel was doped with excess lithium or lithium and aluminum. The calculated entropy change (dE/dT) from the IMC confirmed that the order/disorder change of LiMn2O4, which occurs in the middle of the charge, was largely suppressed with lithium or lithium and aluminum doping. The dE/dT values obtained did not agree between the charge and the discharge at room temperature (25 °C), which was attributed to cell self-discharge. This discrepancy was not observed at low temperature (10 °C). Differential scanning calorimeter (DSC) results showed that the fully charged spinel with lithium doping has better thermal stability.
Original language | English |
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Pages (from-to) | 5837-5842 |
Number of pages | 6 |
Journal | Electrochimica Acta |
Volume | 52 |
Issue number | 19 |
DOIs | |
State | Published - May 25 2007 |
Externally published | Yes |
Funding
This work was performed under the auspices of the US Department of Energy, Energy Efficiency and Renewable Energy, Office of FreedomCAR and Vehicle Technologies, under Contract No. W-31-109-Eng-38. Also, the authors would like to acknowledge Dr. Z. Chen for material preparation.
Keywords
- Calorimetry
- Doping
- Entropy change
- Lithium ion batteries
- Manganese spinel
- Thermal safety