Ultrathin surface coatings for improved electrochemical performance of lithium ion battery electrodes at elevated temperature

Document Type

Article

Publication Date

6-7-2012

Abstract

To enhance the cycling stability of LiMn 2O 4 especially at elevated temperature, we use the atomic layer deposition (ALD) method to deposit ultrathin and highly conformal ZnO coatings (as thin as 0.34-1.7 nm) onto LiMn 2O 4 cathodes with precise thickness-control at atomic scale. We prepare two types of ALD-modified electrodes: one is an electrode composed of ALD-coated LiMn 2O 4 particles and uncoated carbon/polyvinylidenefluoride (PVDF) network; the other is ALD-coated LiMn 2O 4 composite electrode. All ALD-modified LiMn 2O 4 electrodes demonstrate significantly enhanced cycling performances than bare electrodes at both 25 and 55 °C. In particular, the electrode coated with 6 ZnO ALD layers (1.02 nm thick) shows the best cycling performances among electrodes coated with ALD films of different thicknesses at both 25 and 55 °C, indicating cycling performances of coated electrodes can be easily optimized by accurately tuning coating thickness via varying ALD growth cycles. Furthermore, an electrode consisting of LiMn 2O 4 particles coated with 6 ZnO ALD layers and uncoated carbon/PVDF network shows even better electrochemical performances than an electrode coated with 6 ZnO ALD layers at both 25 and 55 °C. The enhanced electrochemical performances of ALD-coated cathodes are ascribed to the high-quality ALD coatings that are highly conformal, dense, complete, and thus effectively protect active material from Mn dissolution especially at elevated temperature. © 2012 American Chemical Society.

Publication Source (Journal or Book title)

Journal of Physical Chemistry C

First Page

11867

Last Page

11876

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