Off-Planar, Two-Dimensional Polymer Cathode for High-Rate, Durable Rechargeable Magnesium Batteries

Abstract

Rechargeable magnesium batteries are of considerable interest due to their high theoretical capacity, and they are projected as good alternates for stationary energy storage and electric vehicles. Sluggish Mg2+ kinetics and scarce availability of suitable cathode materials are major issues hindering the progress of rechargeable magnesium batteries. Herein, a conjugated, off-planar, two-dimensional (2D) polymer is explored for reversible magnesium storage. The polymer cathode reveals high capacity and high cycling stability with high rate capability. Replacing the Mg metal anode with the Mg alloy, AZ31 further enhances the ion storage performance. At a high current density of 2 A g–1, stable capacity is shown for almost 5000 cycles with 99% Coulombic efficiency. A composite of carbon nanotube with the polymer delivers capacity values higher (>1.5 times) than that of a pristine polymer at a current density of 2 A g–1 and shows cycling up to 5 A g–1. Electrokinetic studies reveal a contribution of pseudocapacitive nature, and the mechanism is investigated by ex situ X-ray photoelectron spectroscopy and infrared spectroscopy. The use of 2D polymer electrodes opens up opportunities for developing high-rate, high-capacity, and stable rechargeable magnesium ion batteries.

Advances in studying interfacial reactions in rechargeable batteries by photoelectron spectroscopy

“…Even though these issues are still major obstacles there has been progress made and XPS is an invaluable tool for characterising and developing these systems. [152][153][154] In magnesium-ion batteries, the blocking nature of the SEI formed on Mg metal anodes can be overcome by several strategies. One compelling example is by Matsui et al 155 that uses intermetallic compounds such as Mg 3 Bi 2 to facilitate the deposition of Mg 2+ .…”

“…Even though these issues are still major obstacles there has been progress made and XPS is an invaluable tool for characterising and developing these systems. 152–154…”

An air chargeable hydrogen battery by reversible electrochemical trapping of the protons

“…5,18,19 Though this hydrogen-based energy economy by utilizing renewable and abundant energy sources is a promising energy vector, the temporal and geographic variations of renewable energy resources intro-duce a mismatch between the peak of its availability and the peak of its demand. [5][6][7]15,19 Here, we demonstrate the possibility of charging of a hydrogen battery with air, whose supply in principle is constant and infinite. This hydrogen battery electrochemically traps the protons in a quinone-based molecule during the discharge chemistry.…”

“…1 Moreover, pollution, global warming, and climate change have outnumbered their advantages. [2][3][4][5][6][7] In 2019, the annual global carbon dioxide (CO 2 ) emissions reached 38 gigatons (Gt) due to extensive and unrestricted use of fossil fuels. 8,9 The current energy consumption, which is ∼585 exajoules (EJ) per year, is expected to increase by at least 50% in the coming 20 years.…”

“…4,7,[10][11][12][13] To overcome the growing energy demands, and the challenges associated with carbonbased energy economy and conventional energy storage technologies, a transition to a carbon-neutral energy economy is inevitable, which demands the development of environmentally friendly and affordable energy storage devices. [2][3][4][5][6][7][10][11][12][13][14][15][16][17] All of these mandate the focus on hydrogen economy, which refers to the use of dihydrogen as a fuel whose combustion in principle should be carbon neutral. 5,18,19 Though this hydrogen-based energy economy by utilizing renewable and abundant energy sources is a promising energy vector, the temporal and geographic variations of renewable energy resources intro-duce a mismatch between the peak of its availability and the peak of its demand.…”