Theoretical insights into cathode designing and working mechanism in aluminium batteries

Abstract

The increasing energy demands of the world is resulting in exploration of renewable and clean alternative fuels capable of replacing the current energy sources efficiently. In this context, rechargeable batteries have been recognized as one of the capable clean energy sources due to their several advantages like concise size, high efficiency, and simple maintenance and are potentially consist of reversible cell reactions. Especially, Aluminium (Al) metal-based batteries with highly abundant Al metal, and higher volumetric capacity (∼8040 mAh/cm3) are emerging as the next alternate provider of energy. The marketing of Al battery technology is also anticipated to be much safer, because of the small expected size, low cost, and more environmental inertness of Al batteries compared to thermal runway and explosion sensitive Li-ion batteries. However, the field of Al batteries being in its initial phase of development require lots of understanding and efforts to make it a reliable choice. One of the very famous Al based batteries are Al-dual-ion batteries involving active participation of ionic liquid electrolytes during the charge/discharge reactions and overall output results. In Al-dual-ion batteries, which show huge advantages in terms of higher average voltage, fast charge/discharge rates, and efficient cycle stability with constant energy density, the choice of the cathode plays a quite important role in determining the overall battery efficiency. Therefore, choosing a suitable cathode which can deliver higher voltage and efficient storage capacity as well as maintaining the structural stability with a fast charge/discharge rate is the primary aim of Al batteries. Along with this, the rechargeable aluminium-sulfur (Al-S) battery, which has been proposed very recently (year 2016), stand out as the promising alternative of commercial batteries as they have the benefit of low cost, and eco-friendly sulfur cathode offering a maximum theoretical capacity (1675 mAh/g), which is the highest of all known solid cathode materials. Overall, Al-S batteries can deliver high energy density of 1300 Wh/Kg with the theoretical voltage of 1.27 V. For the better development of this promising field of Al-S batteries, it is very necessary to understand the complex electrochemical reactions occurring during charge/discharge process, as well as designing new cathode support which can not only serves to facilitate the electrochemical reaction, but also to improve the reversibility of S during charge/discharge. Therefore, the joint ventures of both experimental and theoretical effort are very necessary to understand the working mechanism of Al-dual-ion batteries as well as Al-S batteries which further help us to develop more efficient cathode systems furnishing higher voltage and storage capacity.