Covalent Attachment of Anderson-Type Polyoxometalates to Single-Walled Carbon Nanotubes Gives Enhanced Performance Electrodes for Lithium Ion Batteries

Single-walled carbon nanotubes (SWNTs) covalently functionalized with redox-active organo-modified polyoxometalate (POM) clusters have been synthesized and employed as electrode materials in lithium ion batteries. The Anderson cluster [MnMo6O24](9-) is functionalized with Tris (NH2C(CH2OH)(3)) moieties, giving the new organic-inorganic hybrid [N(nC(4)H(9))(4)](3)[MnMo6O18{(OCH2)(3)CNH2}(2)]. The compound is then covalently attached to carboxylic acid-functionalized SWNTs by amide bond formation and the stability of this nanocomposite is confirmed by various spectroscopic methods. Electrochemical analyses show that the nanocomposite displays improved performance as an anode material in lithium ion batteries compared with the individual components, that is, SWNTs and/or Anderson clusters. High discharge capacities of up to 932mAhg(-1) at a current density of 0.5mAcm(-2) can be observed, together with high long-term cycling stability and decreased electrochemical impedance. Chemisorption of the POM cluster on the SWNTs is shown to give better electrode performance than the purely physisorbed analogues.