Elsevier

Carbon

Volume 64, November 2013, Pages 170-177
Carbon

Carbon black cathodes for lithium oxygen batteries: Influence of porosity and heteroatom-doping

https://doi.org/10.1016/j.carbon.2013.07.049Get rights and content

Abstract

Carbon materials have been widely used as cathodes in lithium oxygen batteries but the detailed influence of the structure of these materials on their performance is not very clear yet. In this study, the same starting pristine commercial carbon black (N330) was treated under different atmospheres and the resultant carbons were employed as cathode materials for lithium oxygen batteries. It was demonstrated that the porosity and surface topology of these carbons tremendously changed as their treating time increased. The parameters that influenced the battery performance were identified. It was found that the main factor determining the battery performance is the specific surface area of the carbon mesopores, while nitrogen- or oxygen-bearing functionalities, introduced in these carbons during their heat-treatment or by contact with air after their pyrolysis, had little or no influence on the battery performance.

Introduction

Lithium oxygen battery is one of the most promising energy storage candidates for meeting the future demands of the electric vehicles (EVs) or hybrid electric vehicles (HEVs) [1], [2]. However, the challenges for this battery system, such as the rate capability, cycle life, power performance, etc. should be overcome before lithium oxygen batteries can be used in practical applications [3]. It was reported that during discharge process of the battery, the product, Li2O2, deposits on the surface of the electrodes and eventually blocks the path ways for electrolyte and oxygen transportation, terminating the discharge process. Therefore, the electrodes are directly determining the battery performance.

To date, carbon materials are still the most studied cathode materials for lithium oxygen batteries, and efforts have been made to increase the oxygen solubility and diffusion, to decrease the accumulation of reaction products, and to create effective three-phase electrochemical interface of these materials [4], [5], [6], [7], [8]. For example, one-dimensional carbon materials (CNTs, CNFs) have been reported to exhibit good performance because they could form an interconnected porous electrode with high void volume [9], [10]. Graphene nanosheets, a two-dimensional material showed significantly improvement for the battery performance due to its unique morphology and structures [11], [12], [13]. It was also reported that heteroatom-doping to carbon nanotubes and graphene nanosheets further increased the battery performance because of the active sites introduced into the pristine samples [14], [15], [16]. Due to abundance and low cost, carbon black has also been extensively studied as a cathode in lithium oxygen batteries. For example, several carbon black powders have been studied by Xiao et al. [4] and the results suggested that the pore volume and the pore size affect the battery performance. Hall et al. [8] also suggested that electrode made of carbon aerogel with appropriate pore volume and pore diameter delivered high discharge capacity. The findings indicated that the limited discharge capacity was associated to pore clogging as claimed by others [17]. However, recently Luntz et al. [18], [19] reported that the electrical passivation caused by the formation of discharge product layer on the electrode was the limiting factor by using the electrochemical experiments and modeling. They found that even a very thin layer (4–5 nm) of the insulated film of Li2O2 was sufficient to terminate the discharge reaction due to the increased electrical resistance at the electrode/electrolyte interface, then preventing further O2 reduction. This would imply that the specific capacity should be related to the effective carbon surface area, accessible to the electrolyte and oxygen. In the present paper, various carbons all derived from the same starting commercial pristine carbon black (N330) were obtained by threating this carbon black in different treating atmospheres and for different times. The resulting carbons have been used as cathode in lithium oxygen batteries, revealing that the discharge capacity is proportional to the specific surface area of mesopores in these carbon electrodes. For the first time, the influence of various parameters resulting from the heat-treatment of the same starting carbon black, such as the content of disorganized carbon and heteroatom-doping effects, is studied in detail as well on the performance of the lithium oxygen battery.

Section snippets

Sample preparation

Commercial N330 furnace carbon black (from Sid Richardson Carbon Corporation) was used as the starting material. It was heat-treated under NH3 or CO2 (with or without H2) atmospheres. The percentage of mass that was lost during the heat-treatment, W, was calculated as follows:W=initialmass-finalmassinitialmass×100

Results and discussion

The morphology and the distribution of particle sizes of some samples resulting from the heat-treatment of N330 in NH3 are shown in Fig. 1. The distribution of particle sizes of the carbon black was obtained from the analysis of SEM micrographs based on about 300 particles. It can be seen that the shape of the particles is kept almost the same, even after a loss of 75% of the pristine N330 carbon mass. However, the particle size is decreasing after the heat treatment. Several large particles

Conclusions

In summary, commercial carbon black (N330) was treated under various atmospheres (NH3, CO2 and CO2/H2). The mesopore surface areas increased as the treating time increased while the micropore surface area only increased until the mass loss reached 35% and then decreased. It is suggested that the surface area of mesopores plays an important role for the discharge capacity of lithium oxygen batteries due to the passivation effect of discharge product film on the carbon surface. Nitrogen and

Acknowledgements

This research was supported by Natural Sciences and Engineering Research Council of Canada, Canada Research Chair Program, Canada Foundation for Innovation, Ontario Early Researcher Award and the University of Western Ontario.

References (39)

  • G. Girishkumar et al.

    Lithium−air battery: promise and challenges

    J Phys Chem Lett

    (2010)
  • Y. Lu et al.

    The discharge rate capability of rechargeable Li–O2 batteries

    Energy Environ Sci

    (2011)
  • J. Xiao et al.

    Optimization of air electrode for Li/air batteries

    J Electrochem Soc

    (2010)
  • R. Mitchell et al.

    All-carbon-nanofiber electrodes for high-energy rechargeable Li–O2 batteries

    Energy Environ Sci

    (2011)
  • G. Zhang et al.

    Lithium–air batteries using SWNT/CNF buckypapers as air electrodes

    J Electrochem Soc

    (2010)
  • Y. Li et al.

    Superior energy capacity of graphene nanosheets for a nonaqueous lithium–oxygen battery

    Chem Comm

    (2011)
  • E. Yoo et al.

    Li–air rechargeable battery based on metal-free graphene nanosheet catalysts

    ACS Nano

    (2011)
  • J. Xiao et al.

    Hierarchically porous graphene as a lithium–air battery electrode

    Nano Lett

    (2011)
  • Y. Wang et al.

    To draw an air electrode of a Li–air battery by pencil

    Energy Environ Sci

    (2011)
  • Cited by (60)

    • Irreplaceable carbon boosts Li-O<inf>2</inf> batteries: From mechanism research to practical application

      2021, Nano Energy
      Citation Excerpt :

      Furthermore, recently, the nonmetal-based catalysts for Li-O2 batteries have also gained much attention due to their low-cost and light weight. Li et al. [35] reported a Si-CNT cathode for Li-O2 batteries by depositing nanosized Si onto the CNT surface (Fig. 4e). They revealed that the n-type Si nanodots could well modify surface defects of CNTs, which reduced the occurrence of side reactions between CNTs and electrolyte, leading to a significantly reduced overpotential from 1.2 V to 0.55 V.

    • Carbon-black-based self-standing porous electrode for 500 Wh/kg rechargeable lithium-oxygen batteries

      2021, Cell Reports Physical Science
      Citation Excerpt :

      The self-standing membrane exhibited a capacity of >7,000 mAh/gelectrode at a current density of 0.4 mA/cm2, which is the best performance among the carbon-black-based electrodes. Although previous studies already reported the high-capacity KB-based electrode for Li-O2 batteries in terms of capacity per weight of carbon (mAh /gcarbon),19–23 but the reports are very limited in terms of capacity per weight of carbon (mAh /gelectrode). Using the carbon electrode developed in this study, a Li-O2 cell with an energy density of 500 Wh/kg was fabricated and a repeated discharge-charge cycle was demonstrated at a 0.1 C-rate.

    • A convenient and efficient mass-production strategy to fabricate sustainable cathodes for lithium–oxygen batteries: Sucrose-derived active carbon coating technology

      2019, Electrochimica Acta
      Citation Excerpt :

      As for cathode, researchers commonly focus on the catalytic activity, microstructure and stability. Carbon-based materials with different morphologies, such as porous carbon [16], graphene nanosheet (GN) [17], carbon nanotubes (CNTs) [18], carbon nanofibers (CNFs) [19] and carbon powders (CP) [20], were investigated systematically. In order to further accelerate the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) of the cathodes, many kinds of catalyst were added into these carbon-based materials, including transition metal oxides (FeOx, CoOx, NiOx) [21–23], noble metal (Pt, Ru, Pd) [24–26] and other metal oxides (ZrO2, α-MnO2) [27,28].

    View all citing articles on Scopus
    View full text