Abstract：Ultrafine spherical MnO₂particles were prepared via the liquid deposition method in a clustered countercurrent flow micro-channel reactor (C-CFMCR) , in which two streams of Mn SO₄and KMnO₄aqueous solutions reacted with each other.Scanning electron microscopy (SEM) , X-ray diffraction (XRD) , thermogravimetric and differential thermal analysis (TGA-DTA) and electrochemical workstation were used to characterize the samples.The influence of preparation conditions on particle morphologies and electrochemical properties were investigated.The results indicate that MnO₂with fine morphology and propertiesisobtainedunderoptimized operating conditions in C-CFMCR.With aging time of 2 h and calcination for 2 h at 220℃, MnO₂particles with a specific capacitance (SC) of about 175 F/g are synthesized.After 500 cycles of galvanostatic charge and discharge, the capacitance loss is about 10%.

Keywords：microreactor; liquid deposition; manganese dioxide; specific capacitance