Characterization of Carbonaceous Active Materials Used for the Negative Electrode of Li-Ion Batteries and Capacitors

Abstract

During the course of investigating carbonaceous materials for the active materials of Li-ion batteries (LIB) or supercapacitors (SPC) we have found interesting properties and behaviors of the carbon in contact with an electrolyte containing Li + . In this article the author would like to exhibit these attractive matters. Especially use of carbon fiber (CF) attracted our attention since we can use a single fiber as the working electrode, which enables us to measure not only the conductivity change but also the volume change during Li insertion/extraction. Determination of the lithium diffusion coefficient in carbon could be performed with ease. Surprisingly propylene carbonate showed no decomposition during cathodic polarization of graphite in propylene carbonate electrolyte when we use a single graphitzed fiber. On the other hand, by the use of rounded graphite particle we suggested presence of holes on the graphene layer. We proved that homogeneous distribution of conductivity over the surface of coated electrode is the key factor to keep long cycle life.

Optimization of Soft Carbon Negative Electrode in Sodium-Ion Batteries Using Surface-Modified Mesophase-Pitch Carbon Fibers

“…These observations imply that elements with smaller atomic radii than Ag, such as C and Fe, might be dissolved in Ag particles during surface modification. Further studies may show that surface treatment with other metals 32,33 or functionalities 21,34 can be highly effective for further improving the performance of soft carbons.…”

“…[13][14][15][16] In the recent pasts (³1990-2000), soft carbons were widely studied for energy storage. 13,[17][18][19][20][21] For one type of soft carbon, mesophasepitch carbon fibers (MCF), high reversible capacities for Li insertion/extraction have been observed (up to 500 mAh g ¹1 ). 22 MCF are derived from petroleum and can be prepared as felt electrodes without binder or conductive additives.…”

Electrospun nanofibers: A prospective electro-active material for constructing high performance Li-ion batteries

“…Present day LIBs predominantly comprise graphitic anodes with Li-containing transition metal oxide (LiCoO 2 , LiMn 2 O 4 , and LiFePO 4 ) as a cathode because of its lower insertion potential (o0.1 V vs. Li), appreciable theoretical capacity (B372 mA h g À1 ), low-cost and eco-friendliness. 1,2,[53][54][55] Unfortunately, electrolyte decomposition in the first discharge, which leads to the formation of solid electrolyte interface, and SEI, and Li-plating at high current operation are the main issues from an HEV and EV point of view. 2 Therefore, high performance insertion anodes are anticipated to fulfill these requirements.…”