Michael Thompson Pettes

Publications (2)26.4 Total impact

• Article: Thermal transport in three-dimensional foam architectures of few-layer graphene and ultrathin graphite.

  Michael Thompson Pettes, Hengxing Ji, Rodney S Ruoff, Li Shi
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  ABSTRACT: At a very low solid concentration of 0.45 ± 0.09 vol %, the room-temperature thermal conductivity (κ(GF)) of freestanding graphene-based foams (GF), comprised of few-layer graphene (FLG) and ultrathin graphite (UG) synthesized through the use of methane chemical vapor deposition on reticulated nickel foams, was increased from 0.26 to 1.7 W m(-1) K(-1) after the etchant for the sacrificial nickel support was changed from an aggressive hydrochloric acid solution to a slow ammonium persulfate etchant. In addition, κ(GF) showed a quadratic dependence on temperature between 11 and 75 K and peaked at about 150 K, where the solid thermal conductivity (κ(G)) of the FLG and UG constituents reached about 1600 W m(-1) K(-1), revealing the benefit of eliminating internal contact thermal resistance in the continuous GF structure.
  Nano Letters 05/2012; 12(6):2959-64. · 13.20 Impact Factor
• Article: Ultrathin graphite foam: a three-dimensional conductive network for battery electrodes.

  Hengxing Ji, Lili Zhang, Michael T Pettes, Huifeng Li, Shanshan Chen, Li Shi, Richard Piner, Rodney S Ruoff
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  ABSTRACT: We report the use of free-standing, lightweight, and highly conductive ultrathin graphite foam (UGF), loaded with lithium iron phosphate (LFP), as a cathode in a lithium ion battery. At a high charge/discharge current density of 1280 mA g(-1), the specific capacity of the LFP loaded on UGF was 70 mAh g(-1), while LFP loaded on Al foil failed. Accounting for the total mass of the electrode, the maximum specific capacity of the UGF/LFP cathode was 23% higher than that of the Al/LFP cathode and 170% higher than that of the Ni-foam/LFP cathode. Using UGF, both a higher rate capability and specific capacity can be achieved simultaneously, owing to its conductive (∼1.3 × 10(5) S m(-1) at room temperature) and three-dimensional lightweight (∼9.5 mg cm(-3)) graphitic structure. Meanwhile, UGF presents excellent electrochemical stability comparing to that of Al and Ni foils, which are generally used as conductive substrates in lithium ion batteries. Moreover, preparation of the UGF electrode was facile, cost-effective, and compatible with various electrochemically active materials.
  Nano Letters 04/2012; 12(5):2446-51. · 13.20 Impact Factor