Rechargeable Lithium‐Ion Cells Using Graphitized Mesophase‐Pitch‐Based Carbon Fiber Anodes

Abstract

The electrochemistry of lithium intercalation into a graphitized mesophase-pitch-based carbon fiber with a radial-like texture used as the anode material in rechargeable lithium-ion cells was characterized. The radial-like texture in the cross section of the carbon fiber contributed to the rapid diffusion of lithium ions, resulting in the high rate capability. The anode performance of the graphitized carbon fiber was superior to that of the graphite. Experimental flat-plate C/LiCoO2 lithium-ion cells using the graphitized carbon fiber anode exhibited a high mid-discharge voltage of 3.7 V, a high rate capability, and a long cycle life of more than 400 cycles at 2 mA/cm 2 during charge-discharge cycling between 4.2 and 2.7 V. The long cycle life obtained for the cell was due to no significant change in resistance associated with the passivating films on the graphitized carbon fiber with extended cycles. It was also demonstrated that A size C/LiCoO2 cells using the graphitized carbon fiber anode have excellent rate performance at discharge currents between 0.25 and 3 A, a large discharge capacity of 0.95 Ah, and a high energy density of 310 Wh/dm 3 and 120 Wh/kg.

Defect-induced plating of lithium metal within porous graphene networks

“…1b). The reason why such a porous graphene anode delivers a capacity and energy density ( Table 1) that is almost threefold higher than conventional graphitic anodes 19 and stable over 1,000 charge/discharge cycles remains unclear. Some studies with graphene anodes have reported achieving a capacity higher than the theoretical capacity of graphite and have generally attributed it to the formation of Li 2 C 6 , corresponding to the intercalation of lithium ions on both sides of the graphene sheets 20,21 .…”

“…The PGN anode develops a maximum specific capacity of B915 mAh g À 1 (B2.5 times higher than the theoretical capacity of graphite), with coulombic efficiencies above 99%. For comparison, the practical capacity of graphitic anodes has also been included 19 . …”

Electrochemical Characterization of Gelatine Derived Ceramics

“…In both cases, the capacities' values were higher for the pyrolysed materials which were mixed with the preceramic polymer before pyrolysis. These values are higher than theoretical capacity of graphite which is known to be equal 372 mAg/h [2]. The all studied electrode materials were stable during galvanostatic polarization cycles.…”

“…They can be found in small portable electronic devices such as mobile phones, laptops, cameras. Graphite anodes of theoretical charge capacity equal to 372 mAh/g are known to be not stable during prolonged cycling and fast charging/discharging processes [2]. Thus, there is still a need to find material with longer cycle life time and better rate capability.…”

Carbonaceous Anode Materials

“…These anisotropies are directly related to the layered structure with strong intralayer interactions and very weak van der Waals interplanar interactions between adjacent graphene sheets. As a functional material, MPCFs with anisotropy-originating chemical and physical properties have also been utilized for anode materials for Li-ion batteries [25,26]. The anode performance of synthetic carbons and graphitic carbons in Li-ion batteries depends strongly on the precursor materials and the synthesis conditions.…”