Highly Improved Rate Capability for a Lithium-Ion Battery Nano-Li4Ti5O12 Negative Electrode via Carbon-Coated Mesoporous Uniform Pores with a Simple Self-Assembly Method
SCIE
SCOPUS
- Title
- Highly Improved Rate Capability for a Lithium-Ion Battery Nano-Li4Ti5O12 Negative Electrode via Carbon-Coated Mesoporous Uniform Pores with a Simple Self-Assembly Method
- Authors
- Kang, E; Jung, YS; Kim, GH; Chun, J; Wiesner, U; Dillon, AC; Kim, JK; Lee, J
- Date Issued
- 2011-11-22
- Publisher
- Wiley-VCH Verlag
- Abstract
- A mesostructured spinel Li4Ti5O12 (LTO)-carbon nanocomposite (denoted as Meso-LTO-C) with large (>15 nm) and uniform pores is simply synthesized via block copolymer self-assembly. Exceptionally high rate capability is then demonstrated for Li-ion battery (LIB) negative electrodes. Polyisoprene-block-poly(ethylene oxide) (PI-b-PEO) with a sp2-hybridized carbon-containing hydrophobic block is employed as a structure-directing agent. Then the assembled composite material is crystallized at 700 degrees C enabling conversion to the spinel LTO structure without loss of structural integrity. Part of the PI is converted to a conductive carbon that coats the pores of the Meso-LTO-C. The in situ pyrolyzed carbon not only maintains the porous mesostructure as the LTO is crystallized, but also improves the electronic conductivity. A Meso-LTO-C/Li cell then cycles stably at 10 C-rate, corresponding to only 6 min for complete charge and discharge, with a reversible capacity of 115 mA h g-1 with 90% capacity retention after 500 cycles. In sharp contrast, a Bulk-LTO/Li cell exhibits only 69 mA h g-1 at 10 C-rate. Electrochemical impedance spectroscopy (EIS) with symmetric LTO/LTO cells prepared from Bulk-LTO and Meso-LTO-C cycled in different potential ranges reveals the factors contributing to the vast difference between the rate-capabilities. The carbon-coated mesoporous structure enables highly improved electronic conductivity and significantly reduced charge transfer resistance, and a much smaller overall resistance is observed compared to Bulk-LTO. Also, the solid electrolyte interphase (SEI)-free surface due to the limited voltage window (>1 V versus Li/Li+) contributes to dramatically reduced resistance.
- Keywords
- TRANSITION-METAL OXIDES; MOLECULAR-SIEVES; ANODE MATERIAL; ELECTROCHEMICAL-BEHAVIOR; HIGH-POWER; LI4TI5O12; SPINEL; INSERTION; INTERCALATION; INTERPHASE
- URI
- https://oasis.postech.ac.kr/handle/2014.oak/16914
- DOI
- 10.1002/ADFM.201101123
- ISSN
- 1616-301X
- Article Type
- Article
- Citation
- ADVANCED FUNCTIONAL MATERIALS, vol. 21, no. 22, page. 4349 - 4357, 2011-11-22
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