Electrode Materials with Highest Surface Area and Specific Capacitance Cannot Be the Only Deciding Factor for Applicability in Energy Storage Devices: Inference of Combined Life Cycle Assessment and Electrochemical Studies

Hierachical nanosheets of Co 3 O 4 can deliver specific capacitance of ∼402 F g –1, which is 50% higher than that obtained using simpler disc shaped (∼230 F g –1 ) or conventional solid structures (∼150 F g –1 ). A simple question is then asked: should the particles showing other morphologies be discarded? As the electrode material is to be used in green or renewable energy technologies, the carbon footprint of each particle morphology was determined using the life cycle assessment (LCA) studies. The results led to inferences, which were strikingly different from those generally expected. It was seen that simpler morphologies, prepared using easier synthesis protocols, had five-times lower CO 2 footprints than hierarchical morphology (nanosheets). The results become extremely critical for proposing their large scale industrial use. They clearly indicate that the choice of nanostructured metal oxides in energy storage devices will have to be relooked from the aspect of their own environmental impacts. Particles with lowest environmental impact but comparable specific capacitances will win over other counterparts.