Enhanced Cyclability of Li–O₂ Batteries Based on TiO₂ Supported Cathodes with No Carbon or Binder

Abstract

The decomposition of carbon materials and organic binders in Li−air batteries has been reported repeatedly in recent literature. The decomposition of carbon can harm the batteries' cyclability further by catalyzing electrolyte degrading. Therefore, there is a critical need to exploit a new catalyst support substituting carbon and develop a binder free cathode preparation strategy for Li−air batteries. Herein, TiO 2 nanotube arrays growing on Ti foam are used as the catalyst support to construct carbon and binder free oxygen diffusion electrodes. After being coated with Pt nanoparticles by a cool sputtering approach, the TiO 2 nanotube arrays are used as cathodes of Li−O 2 batteries. Benefiting from the stability of TiO 2 in the discharge/charge processes, the Li−O 2 batteries realize enhanced cyclability at high current densities (for instance, more than 140 cycles at 1 or 5 A g −1 ), within wide discharge/charge voltage windows (for instance, 1.5−4.5 V). X-ray photoelectron spectra and a scanning electron microscope image of the cathodes after cycling at 5 A g −1 150 times indicate that the TiO 2 nanotubes can remain stable in the long term cycle test. 1 H nuclear magnetic resonance analysis reveals that the tetraethylene glycol dimethyl ether electrolyte has no degradation, showing enhanced stability compared with that in the carbon containing batteries.

The Lithium/Air Battery: Still an Emerging System or a Practical Reality?

“…Despite the possible decomposition of ether-based electrolytes, they are, to date, still the most studied in non-aqueous lithium/air systems. [85][86][87][88] …”

“…In addition to these examples, there have been many other studies involving the use of metal catalysts in lithium/air batteries. [ 87,[184][185][186] Further studies are still needed to fi nd suitable ways to develop stable and selective catalysts for the desired reactions.…”

Ruthenium nanocrystal decorated vertical graphene nanosheets@Ni foam as highly efficient cathode catalysts for lithium-oxygen batteries

“…[1][2][3][4] However, the development of practical Li-O 2 batteries faces several serious challenges, including high overpotential between charge and discharge, poor cycling stability, low Coulombic efficiency and low rate capability. [5][6][7][8] The reaction mechanism in a Li-O 2 cell involves an oxygen reduction reaction (ORR) in the discharge process and an oxygen evolution reaction (OER) in the charge process, during which molecular O 2 reacts reversibly with Li + ions (Li + +O 2 +2e − ↔ Li 2 O 2 , with an equilibrium voltage of 2.96 V vs Li). 9,10 This mechanism is very different from the traditional intercalation reactions of Li-ion batteries.…”

“…So far, it has been identified that catalysts and appropriate non-aqueous electrolytes can effectively overcome these problems. 6,7,12 Various catalysts, such as metal oxides, metal nitrides and noble metals have been investigated as suitable cathode catalysts in Li-O 2 cells to reduce the charge overpotential. [13][14][15] The use of catalysts can decrease the charge potential to~3.8 V from~4.2 V. 9,16,17 Therefore, finding suitable cathode catalysts is an effective approach to solve the overpotential problem.…”

Antimony Doped Tin Oxide–Synthesis, Characterization and Application as Cathode Material in Li-O2Cells: Implications on the Prospect of Carbon-Free Cathodes for Rechargeable Lithium-Air Batteries

“…26,27 To circumvent these issues, electrically conductive metal oxides are promising materials due to their inherent stability against oxidation. Hence, the magnéli phase Ti 4 O 7 28 as well as Pt supported on TiO 2 nanofibers 29 have been proposed as eligible compounds for Li-O 2 cathodes.…”