Improved electrochemical performance of amorphous MnO2 modified by a novel supermolecular compound

A novel modification treatment to improve the electrochemical performance of amorphous, nano-sized MnO2 is proposed in this paper. An "in situ polymerization reaction" method was employed to obtain the MPz(dtn)(4) or PMPzS(8)-MnO2 composition material. TG, IR, XRD and TEM methods were adopted for material characterization. The experimental results reveal that the amorphous nature and small particle size (10-20 nm) of the parent MnO2 material can be preserved after MPz(dtn)(4) or PMPzS(8) modification treatment. Galvanostatic charge and discharge was carried out to test the electrochemical property of the resulting material. It indicates that all modified products show an improved electrochemical performance comparing with their parent MnO2 phase as being reflected by the higher capacity and enhanced cycle life. To investigate the mechanism for improved electrochemical performance, ac impedance technique was employed. Preliminary results suggest that the capacity and the cycleability of the composition material are improved in some degree which may be ascribed to the increasing of intercalation/deintercalation from inter-granular modified compounds. (C) 2004 Elsevier B.V. All rights reserved.