Free-standing electrodes of CuO nanorods in carbon nanotubes (CNTs) are developed by synthesizing porous CuO nanorods throughout CNT webs. The electrochemical performance of the free-standing electrodes is evaluated for their use in flexible lithium ion batteries (LIBs). The electrodes comprising CuO@CNT nanocomposites (NCs) were characterized by charge-discharge testing, cyclic voltammetry, and impedance measurement. These structures are capable of accommodating a high number of lithium ions as well as increasing stability; thus, an increase of capacity in long-term cycling and a good rate capability is achieved. We demonstrate a simple process of fabricating free-standing electrodes of CuO@ CNT NCs that can be utilized in flexible LIBs with high performance in terms of capacity and cycling stability.

Abstract
 1. Introduction
 2. Experimental
  2.1. CNT synthesis and negatively charged CNTwebs
  2.2. Fabrication of CuO@CNT NCs
  2.3. Cell fabrication
  2.4. Characterization
 3. Results and Discussion
  3.1. Characterization of CNT webs and CuO@CNT NCs
  3.2. Electrochemical properties of CuO@CNTNCs electrodes
  3.3. Microstructural changes of CuO@CNT NCelectrodes
 4. Conclusions
 References

• Sehyun Lee(Department of Organic Materials and Fiber Engineering, Soongsil University)
• Hyeonjun Song(Department of Information Communication, Materials, and Chemistry Convergence Technology, Soongsil University)
• Jun Yeon Hwang(Carbon Convergence Materials Research Center, Institute of Advanced Composite Materials, Korea Institute of Science and Technology(KIST))
• Seung Min Kim(Carbon Convergence Materials Research Center, Institute of Advanced Composite Materials, Korea Institute of Science and Technology(KIST))
• Youngjin Jeong(Department of Organic Materials and Fiber Engineering, Soongsil University, Department of Information Communication, Materials, and Chemistry Convergence Technology, Soongsil University) Corresponding Author