Surface modifications of li-ion battery electrodes with ultrathin amphoteric oxide coatings for enhanced elevated-temperature cycleability

Document Type

Conference Proceeding

Publication Date

1-1-2013

Abstract

To enhance cycleability of LiMn2O4at elevated-temperature we use atomic layer deposition (ALD) method to deposit a variety of ultrathin and highly conformal amphoteric oxide (ZnO, ZrO 2, AI2O3) coatings for surface modification of LiMn2O4 electrodes. High-resolution transmission electron microscopic (HRTEM) images of ZnO, ZrO2 and AI2O 3ALD coated LiMn2O4particles demonstrate the high qualities of ALD coatings with respect to remarkable conformity, homogeneity and uniformity. Two types of ALD-modified LiMn2O 4electrodes are fabricated: one is ALD-coated LiMn2O 4 composite electrode, the other is electrode composed of ALD-coated LiMn2O4particles and uncoated carbon/poly- vinylidenefluoride (PVDF) network. All LiMn2O4 electrodes modified with 6 oxide ALD layers (as thin as ~1 nm) reveal significantly enhanced electrochemical performances than bare electrodes at both 25°C and 55°C. After 100 electrochemical cycles at 1 Cat 55°C, the electrode consisting of LiMn2O4particles coated with 6 ZnO ALD layers remains the highest capacity of 56.1 mAh/g, higher than 51.1 mAh/g of ZrO2 coated LiMn2O4 particles, 45.8 mAh/g of AI2O3coated LiMn2O4 particles and 27.0 mAh/g of the bare composite electrode as well as 44.5 mAh/g of the composite electrode coated with 6 ZnO ALD layers. These results indicate that ZnO ALD coating is the most effective protective film for improved cycling stability, followed by ZrO2 and AI2O3. It is also found that amphoteric oxide coating on LiMn2O 4particles is more effective to enhance the cycleability of LiMn 2O4 than coating on composite electrode. Furthermore, for coating either on composite electrode or on LiMn2O 4particles, the effect of ALD coating on improving capacity retention and increasing specific capacity of LiMn2O4 is more phenomenal at elevated temperature than at room temperature. © 2013 Materials Research Society.

Publication Source (Journal or Book title)

Materials Research Society Symposium Proceedings

First Page

13

Last Page

18

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