Experimental investigation of transition metal-based materials for electrochemical energy storage application

Abstract

To address environmental/ecological issues (global warming and carbon-capture), challenges associated with the energy economy, and their consequences on the quality of human life through sustainable development, has become the need of the hour. The unending global demand for energy generation and storage is regarded as one of the biggest challenges in the world, causing energy depletion. The tremendous risk of climate change, conjoined with the excessive use of fossil fuel, makes the continuous supply of energy increasingly difficult. This results in the emission of carbon dioxide, thereby, raising the earth’s temperature. The global economy is likely to consume more and more energy with the rise in energy demand of developing countries. According to a report by Bloomberg New Energy Finance (BNEF), the global energy storage market will be tripled by 2030, from the current energy demand of 125 gigawatts to 305 gigawatt-hours [1]. Therefore, efficient and large-scale energy storage systems are required to overcome the energy crisis. Energy storage converts energy from the forms which are difficult to store to a more conveniently or economically storable form [1]. There are a number of energy storage technologies such as; mechanical storage, thermal storage, electrochemical storage, and other chemical storage (hydrogen, biofuels, petroleum, natural gases, and coal, etc.) [2, 3]. The thesis limits its discussion to electrochemical energystorage technology, which is one of the cleanest, considered to be the most feasible, environmentally friendly and sustainable [4]. The electrochemical energy storage device includes rechargeable-batteries, flow-batteries, supercapacitors (SCs), etc. Conventional energy storage systems, like Li-ion batteries (energy density up to 500 Wh/kg) are not suitable for future hybrid electric vehicles, portable electronics, and high-end wearable systems due to their bulkiness, heavyweight and low performance. Batteries run out of energy; they die, overheat, take a long time to charge, and are environmentally disastrous, thus limiting the future use in high-end applications. SCs play a crucial role in bridging the gap between batteries and capacitors by providing higher power density (W/cm2) than those of batteries and higher energy density (range of mWh/cm2) than those of capacitors. SCs offer many advantages regarding superior charge-discharge rate, ultrahigh power densities (>10 kW/kg), exceptional long cycle life (>106 cycles) and efficiency, a wide range of operating temperatures, improved safety, high flexibility, no thermal breakdown, and are environmentally friendly. Due to the numerous advantages offered by SCs, they have attracted considerable attention in portable electronic devices, automotive/hybrid electric vehicles, digital telecommunication systems, uninterrupted power supply for computers and pulsed laser techniques, etc.