抄録
Composites consisting of β-MnO2 nanocrystals and acetylene black were synthesized by a thermal decomposition of Mn(NO3)2 with acetylene black. The effects of heating temperature and the specific surface area (SBET) of starting acetylene black on the formation and properties of β-MnO2/acetylene black composite were investigated. The decomposition of Mn(NO3)2 mixed with acetylene black progresses at lower temperature than that of Mn(NO3)2 alone. The formation and the size of β-MnO2 nanocrystals depended strongly on the heating temperature (T) and SBET of starting acetylene black. The amount of lithium insertion and voltage feature in the 1st discharge process depends strongly on the size of β-MnO2 nanocrystals. The electrochemical lithium insertion progressed topotactically for β-MnO2 nanocrystals with 22 nm in size, remaining the framework of their rutile structure to give the large amount of lithium insertion (Li/Mn = 1.15 in the solid).
