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Mesoporous MnO2 nanoparticles (meso-MnO2) were synthesized by a simple and cost effective soft template method. TEM and N2 adsorption-desorption studies revealed that MnO2 comprises of mesoporous nanoparticles with grains of 4-5 nm size and pores in the same range. Specific capacitance of 297 F g−1 was obtained at a high loading level of 1.55 mg.cm−2. This improved capacitive storage was attributed to high specific surface area, well connected nano grains and uniform pores. High specific surface area and uniform pores help for easy access of electrolyte by the material while excellent intergrain connectivity provides electronic wiring for efficient charge collection. © 2012 The Electrochemical Society. [DOI: 10.1149/2.016204esl] All rights reserved.

We report here on the lithium storage performance of α- and γ-Fe 2 O 3 , undergoing conversion reaction at C/10 and 2C. Both α-and γ-Fe 2 O 3 transform to nanostructured Fe/Li 2 O composite during the first discharge, while the first charge results in the formation of nanosized γ-Fe 2 O 3 . Such a transition from α-Fe 2 O 3 to γ-Fe 2 O 3 is attributed to its thermodynamics at the nanosize. Better storage performance of γ-Fe 2 O 3 at 2C compared with α-Fe 2 O 3 is attributed to the formation of highly crystalline, nanosized γ-Fe 2 O 3 . Apart from the reported inherent electronic conductivity of α-Fe 2 O 3 , the thermodynamics at the nanosize is also found to be one of the rate-limiting factors.

A material of key relevance as a cathode in rechargeable lithium batteries is LiFePO 4 , whose major shortcoming lies in its sluggish mass and charge transport, the overcoming of which requires a precise knowledge of transport properties, as of yet unavoidable. The present work aims at filling this gap. We report here a clear experimental investigation of electronic and ionic conduction as well as chemical diffusion for Li (D δ Li ) in LiFePO 4 single crystals. We show that the electronic conductivity, ionic conductivity, and chemical diffusivity of Li are essentially two-dimensional (b-c plane) in our single crystals. The ionic conductivities along all three axes are found to be much smaller than the electronic conductivities. Present results on LiFePO 4 are crucial for systematic optimization of its performance in Li-batteries in terms of doping or microstructural design.