Literature Survey of Fullerene Materials for Secondary Battery Applications

Will Cannon

Abstract

Ever-increasing energy consumption will continue to place a strain on our environment as traditional fuel sources, such as gasoline for internal combustion engines, continue to be the power source of choice for consumers and industry alike. In an effort to decrease our reliance on these sources, we must work to increase the efficiency, and thus economic viability, of alternative energy sources. One such example of an alternative energy source is that of a secondary battery, used in electric vehicles and consumer electronics. To increase the efficiency of secondary batteries, new materials are actively being researched. Fullerenes, namely C60, are a likely candidate for battery materials due to their reversible capability for redox chemistry via the intercalation/deintercalation of Li+ ions upon charging/discharging of battery. As our lab group moves into this field, a literature survey of fullerene materials has been conducted to determine where to begin our research. One such fullerene material has been selected to be synthesized using our novel electrochemical synthetic technique, and a research proposal for its synthesis has been drafted.

Introduction

Increasing global energy demands are currently backed by non-renewable fossil fuels, creating a significant environmental impact on our planet. [1] In order to reduce the use of fossil fuels, viable renewable alternative energy sources must improve their efficiency. One such renewable energy resource is that of secondary batteries, better known as rechargeable batteries. Currently, the best-known secondary battery is the lithium-ion battery (LIB), used for applications ranging from cars to computers. [2] Present lithium-ion batteries use graphite for an anode material (fig. 1), which has a theoretical capacity of 372 mAh/g. This theoretical capacity has been realized in current LIBs, which boast a practical capacity of ~350 mAh/g. [3] This has pushed researchers into finding new anode materials for lithium-ion batteries, including fullerenes.

Fig 1. A typical LIB, with added arrows indicating the direction of Li-ions during charge/discharge. Source: U.S. Department of Energy.

Fullerenes are a spherical allotrope of carbon that comes in a variety of sizes. The focus of this research was into a fullerene known as C60, a compound named for its 60 carbon atoms that are arranged into the shape of a soccer ball (Fig 2). C60 boasts a stable structure and the ability to reversibly accept 6 electrons, allowing it to intercalate more lithium-ions than graphite and making it a likely candidate for anode material. However, pure C60 makes a poor anode material, as its intercalation with lithium-ions results in C60 dissolving into the battery solution [5]. Thus, C60 must be modified in some way to ensure its stability during battery cycling. One possible modification is to incorporate the C60 into a framework. Thus, research into a variety of C60-frameworks was conducted, and one was selected to be synthesized in the future.

C60

Fig. 2: Structure of C60. Single bonds in black, double bonds in yellow. Reproduced from [6].

Results

A framework from Yuan et al featuring fullerene bonded to dimethoxy-methane (DMM) was selected for further study (Fig 3). This particular framework was selected due to its synthetic method (Fig 4) and porous construction. The synthetic method from the literature used a hydrothermal synthetic method [5], which was hypothesized to be replaceable by an electrochemical method, a process done previously by this lab group. Additionally, the porous construction of the framework gives space for the C60 to intercalate with more lithium-ions.

C60 Framework

Fig. 3: C60 Framework. O = red, C = black/blue. Reproduced from [6].

Synthesis of Framework

Fig. 4: Joining of Two C60 Molecules for Fullerene Framework. Reproduced from [6].

Future Work

Presently, research is being conducted into the electrochemistry of C60 and different functional groups with which to build a fullerene-framework. Once the research is able to resume on-campus, experimental trials for the electrochemical synthesis of the framework will be undertaken. If these trials succeed, more trials will be run using different functional groups.

References

  1. Bilgen, S. Structure and Environmental Impact of Global Energy Consumption. Renewable and Sustainable Energy Reviews 201438, 890–902.
  2. Armand, M.; Tarascon, J.-M. Building Better Batteries. Nature 2008451, 652–657.
  3. Xu, Q.; Lin, J.; Ye, C.; Jin, X.; Ye, D.; Lu, Y.; Zhou, G.; Qiu, Y.; Li, W. Air‐Stable and Dendrite‐Free Lithium Metal Anodes Enabled by a Hybrid Interphase of C 60 and Mg. Advanced Energy Materials 201910, 1903292.
  4. Harman, Sarah, and Charles Joyner. How Lithium-Ion Batteries Work. 24 Sept. 2017, www.energy.gov/eere/articles/how-does-lithium-ion-battery-work. Accessed 14 Aug. 2020.
  5. Jiang, Z.; Zhao, Y.; Lu, X.; Xie, J. Fullerenes for Rechargeable Battery Applications: Recent Developments and Future Perspectives. Journal of Energy Chemistry 2021, 55, 70–79
  6. Yuan, Y.; Cui, P.; Tian, Y.; Zou, X.; Zhou, Y.; Sun, F.; Zhu, G. Coupling Fullerene into Porous Aromatic Frameworks for Gas Selective Sorption. Chemical Science 2016, 7, 3751–3756