Key scientific challenges in current rechargeable non-aqueous Li–O2 batteries: experiment and theory

Abstract

Rechargeable Li-air (henceforth referred to as Li-O2) batteries provide theoretical capacities that are ten times higher than that of current Li-ion batteries, which could enable the driving range of an electric vehicle to be comparable to that of gasoline vehicles. These high energy densities in Li-O2 batteries result from the atypical battery architecture which consists of an air (O2) cathode and a pure lithium metal anode. However, hurdles to their widespread use abound with issues at the cathode (relating to electrocatalysis and cathode decomposition), lithium metal anode (high reactivity towards moisture) and due to electrolyte decomposition. This review focuses on the key scientific challenges in the development of rechargeable non-aqueous Li-O2 batteries from both experimental and theoretical findings. This dual approach allows insight into future research directions to be provided and highlights the importance of combining theoretical and experimental approaches in the optimization of Li-O2 battery systems.

Porous AgPd–Pd Composite Nanotubes as Highly Efficient Electrocatalysts for Lithium–Oxygen Batteries

“…In previously reported results, very large toroid-like Li 2 O 2 particles with size up to 1 µm can normally be observed during the ORR process. [ 46,50 ] What we have here is very different. The different morphology of Li 2 O 2 , which could be attributed to the different electrocatalyst and its morphology, could result in different electrochemical performance.…”

“…The different morphology of Li 2 O 2 , which could be attributed to the different electrocatalyst and its morphology, could result in different electrochemical performance. [ 16,46,[49][50][51] After full charging, the obvious NT structure appears again (Figure 4 d), indicating the high reversibility of Li 2 O 2 . The corresponding SAED pattern in the inset of Figure 4 d confi rms the cubic structure of the AgPd and Pd composite.…”

Examining the Role of Electrolyte and Binders in Determining Discharge Product Morphology and Cycling Performance of Carbon Cathodes in Li-O2Batteries

“…Li-O 2 batteries are an exciting class of energy storage devices with exceptional theoretical capacities which could facilitate longrange electrical vehicles if fully optimized systems are realized. [1][2][3][4][5] Energy storage in Li-O 2 batteries proceeds via different mechanisms to those associated with conventional Li-ion batteries, necessitating detailed studies into the fundamental processes associated with discharge and charge.6-8 It has been shown in a number of studies that the energy storage mechanism for Li-O 2 batteries involves the reversible formation/decomposition of Li 2 O 2 upon discharge and charge respectively.9-13 While the O 2 required to form Li 2 O 2 during discharge can theoretically be provided from ambient air, the majority of systems investigated to date have used pure O 2 to avoid unwanted side-reactions due to the ingress of atmospheric CO 2 and H 2 O.14,15 The formation of parasitic by-products in Li-O 2 batteries (which have been found to form extensively on charging due to cathode and electrolyte instabilities) is a major hurdle to their widespread implementation. 16,17 The nature of Li 2 O 2 (i.e morphology, crystallinity, size and location on the cathode) formed during discharge, and its impact on capacity, cycle life and charging behavior has attracted recent research interest.…”

“…Li-O 2 batteries are an exciting class of energy storage devices with exceptional theoretical capacities which could facilitate longrange electrical vehicles if fully optimized systems are realized. [1][2][3][4][5] Energy storage in Li-O 2 batteries proceeds via different mechanisms to those associated with conventional Li-ion batteries, necessitating detailed studies into the fundamental processes associated with discharge and charge.…”

“…[1][2][3][4][5] Energy storage in Li-O 2 batteries proceeds via different mechanisms to those associated with conventional Li-ion batteries, necessitating detailed studies into the fundamental processes associated with discharge and charge. [6][7][8] It has been shown in a number of studies that the energy storage mechanism for Li-O 2 batteries involves the reversible formation/decomposition of Li 2 O 2 upon discharge and charge respectively.…”