Effective wrapping of graphene on individual Li4Ti5O12 grains for high-rate Li-ion batteries

Yuhong Oh; Seunghoon Nam; Sungun Wi; Joonhyeon Kang; Taehyun Hwang; Sangheon Lee; Helen Hejin Park; Jordi Cabana; Chunjoong Kim; Byungwoo Park

doi:10.1039/C3TA14347C

Effective wrapping of graphene on individual Li₄Ti₅O₁₂ grains for high-rate Li-ion batteries†

Yuhong Oh,‡^a Seunghoon Nam,‡^a Sungun Wi,^a Joonhyeon Kang,^a Taehyun Hwang,^a Sangheon Lee,^a Helen Hejin Park,^b Jordi Cabana,^cd Chunjoong Kim*^cd and Byungwoo Park*^a

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* Corresponding authors

^a WCU Hybrid Materials Program, Department of Materials Science and Engineering, Research Institute of Advanced Materials, Seoul National University, Seoul 151-744, Republic of Korea
E-mail: byungwoo@snu.ac.kr
Fax: +82-2-885-9671
Tel: +82-2-880-8319

^b Department of Chemistry and Chemical Biology, School of Engineering and Applied Sciences, Harvard University, Cambridge, MA 02138, USA

^c Environmental Energy Technologies Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720-8168, USA

^d Department of Chemistry, University of Illinois at Chicago, Chicago, IL 60607, USA
E-mail: ckim0218@uic.edu
Fax: +1-312-996-0431
Tel: +1-312-355-4309

Abstract

An effective way of synthesizing graphene-wrapped Li₄Ti₅O₁₂ particles was developed by solid-state reaction between graphene oxide-wrapped P25 (TiO₂) and Li₂CO₃. Compared to the previously reported graphene/Li₄Ti₅O₁₂ composites, prior wrapping of TiO₂ with subsequent chemical lithiation led to more effectively confined Li₄Ti₅O₁₂. The Li₄Ti₅O₁₂ tightly bound by graphene exhibited a remarkable specific capacity of 147 mA h g⁻¹ at a rate of 10 C (1 C = 175 mA g⁻¹) after 100 cycles. This rate capability is one of the highest values among reported Li₄Ti₅O₁₂ with 150 ± 50 nm grains. The improved rate capability was attributed to the enhanced electronic conductivity of each Li₄Ti₅O₁₂ grain via uniform graphene wrapping, with single-grain growth during annealing from the initial ∼25 nm TiO₂ nanoparticles enclosed by outer graphene sheets. Graphene-eliminated Li₄Ti₅O₁₂ by thermal decomposition was also directly compared to the graphene-coated sample, to clarify the role of graphene with nearly equivalent particle size/morphology distributions.

Journal of Materials Chemistry A

Effective wrapping of graphene on individual Li₄Ti₅O₁₂ grains for high-rate Li-ion batteries†

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Effective wrapping of graphene on individual Li₄Ti₅O₁₂ grains for high-rate Li-ion batteries

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Journal of Materials Chemistry A