Electrochimica Acta j o u r n a l h o m e p a g e : w w w . e l s e v i e r . c o m / l o c a t e / e l e c t a c t a Big as well as light weight portable, Mn 3 O 4 based symmetric supercapacitive devices: Fabrication, performance evaluation and demonstration a b s t r a c t To keep up with the appeal for energy-saving and environment protection, scientists have turned to nature for inspiration to develop relative green approaches for the fabrication of materials. With this in mind, we demonstrate herein a green and facile method for the synthesis of Mn 3 O 4 hierarchical mate-rials with nanoscaled to microscaled porous structures. Nanostructured Mn 3 O 4 thin films are prepared by green and facile successive ionic layer adsorption and reaction (SILAR) method. These films are fur-ther assembled in order to fabricate big as well as lightweight and portable Mn 3 O 4 –Mn 3 O 4 symmetric supercapacitor cells. Scaling up has been realized by assembling several electrodes in parallel to build a prismatic cell. Electrochemical performance of these cells is tested by cyclic voltammetry and galvanos-tatic charge discharge techniques in neutral 1 M Na 2 SO 4 aqueous electrolyte. A laboratory cell achieved a maximum specific capacitance of 72 F g −1 with stable performance >10,000 cycles and a cell voltage of 1 V. Long-life cycling was achieved by removing dissolved oxygen from the electrolyte, which limits the cor-rosion of current collectors. The effects of temperature on supercapacitive properties of Mn 3 O 4 –Mn 3 O 4 symmetric cells are investigated. Additionally, actual demonstration of the cells with toy fan is given to prove the commercialization of the device. These encouraging results show the interest of developing such devices, including non-toxic and greener components as compared to the current organic-based devices.