A novel Co(phen)2/C catalyst for the oxygen electrode in rechargeable lithium air batteries

Abstract

A novel Co(phen) 2 /C catalyst was prepared by coating cobalt(II) phenanthroline (phen) chelate on BP2000 carbon black and then heat treating in an inert atmosphere. The obtained Co(phen) 2 /C product with 1.0 wt% cobalt loading exhibits similar morphology and porosity characteristics to those of the bare BP2000. X-ray diffraction measurements demonstrate a face-centered cubic (fcc) α-Co phase embedded in the carbon support after pyrolysis. Charge/discharge tests of the lithium-oxygen cells using the prepared Co(phen) 2 /C catalyst show high discharge capacities of 4870 mAh g 1 (0.05 mA cm 2 ), 3353 mAh g 1 (0.1 mA cm 2 ) and 3220 mAh g 1 (0.15 mA cm 2 ), respectively. The Co(phen) 2 /C cathode exhibits reasonable reversibility with capacity retention of 1401 mAh g 1 ( 0.1 mA cm 2 ) after 10 cycles. The superior electrochemical performance of the prepared Co(phen) 2 /C catalyst and low cost of the phenanthroline chelating agent indicate that Co(phen) 2 /C is a promising cheap catalyst for lithium-air batteries. Recently, lithium-air batteries have attracted growing interest because they exhibit a huge theoretical specific energy of 11140 Wh kg 1 excluding O 2 , which provides a practical energy density of an order of magnitude that is larger than the current high-performance lithium ion batteries. Besides, oxygen as an active material from the environment is essentially unlimited. The first lithium-air battery with a structure of Li|organic electrolyte|air was reported in 1996 by Abraham and Jiang [1], and further developed by many scientists over the world [2][3][4][5][6][7][8][9][10][11][12][13][14][15]. However, the investigation and development on lithium-air batteries is still in its initial stage. Much fundamental research is required before it can be considered for further technological applications. There are impressive challenges on the development of electrolyte systems and air cathodes [16][17][18][19][20][21][22][23].As the specific capacity of rechargeable lithium air batteries is limited by the air cathode, the nature of the catalyst is important for fabricating higher capacity lithium air batteries [24][25][26][27][28][29][30]. Transition-metal macrocycles such as phthalocyanine, porphyrin, and their derivatives have emerged as some of the most promising non-noble oxygen reduction reaction catalysts (MN x -based catalysts) [31][32][33]. Cobalt phthalocyanine as a catalyst for O 2 electrodes displays a considerable performance in lithium air batteries, which has been reported by Abraham's group [1]. However, cobalt phthalocyanine is too expensive for large scale application. It is very important to develop active catalysts with low cost for lithium air batteries. In this work we report an inexpensive non-noble catalyst Co(phen) 2 /C prepared using a simple and cheap phenanthroline chelating ligand. Electrochemical performance of the prepared catalyst was investigated. Oxygen electrodes using the prepared Co(phen) 2 /C catalyst could deliver high capacities for rechargeable lithium air batt...

Lithium–oxygen batteries: bridging mechanistic understanding and battery performance

“…To avoid side reactions associated with solvent instability, creating all solid-state Li-O 2 batteries 42,[120][121][122][123][124][125][126] is one of the most promising future directions of reversible Li-O 2 batteries. Solidstate electrolytes are well suited to preventing electrolyte loss when exposed to air, and allow for complex air cathode structures to be synthesized that enable oxygen diffusion pathways deep within the air electrode.…”

Influence of Calcination Temperature on Performances of Co-N/C Electrocatalysts for Li/O₂ Cells

“…One of the most important issues is to develop inexpensive and effective oxygen reduction reaction/oxygen evolution reaction (ORR/OER) catalysts, which play key roles in Li/O2 batteries. [6][7][8][9][10] Until now, noble metals such as Pt, Au and their alloys as ORR/OER catalysts in Li/O2 battery have shown the best overall catalytic performance. [11][12][13] However, the high price and scarcity of precious metals severely limit their wide spread applications.…”

Polymeric Heterogeneous Catalysts of Transition‐Metal Oxides: Surface Characterization, Physicomechanical Properties, and Catalytic Activity

“…Polymeric metal phthalocyanines and cobalt phthalocyanine sulfonates coordinately bound to polymers have been observed to be more effective than conventional cobalt phthalocyanine sulfonate catalysts 4. 9 However, the synthesis of metal phthalocyanines is time consuming10–12 and cobalt phthalocyanine is too expensive for large‐scale applications 13…”