Disordered carbons obtained from cherry stones were tested as electrodes for lithium batteries and their properties were compared with those of short multiwalled carbon nanotubes (s-MWCNT), proposed as candidates for use in these electrochemical devices. Cells were cycled (up to 100 cycles) over a wide range of rates (C/10 to 5C). Previously, their structural, textural, and morphological properties were examined by X-ray diffraction patterns, <mml:math display="inline"><mml:mrow><mml:msub><mml:mi mathvariant="normal">N</mml:mi><mml:mrow><mml:mn>2</mml:mn></mml:mrow></mml:msub></mml:mrow></mml:math>N2 adsorption data, and electron microscopy images (scanning electron microscopy and transmission electron microscopy), respectively. All carbons exhibited irreversible capacity (IC) to an extent roughly governed by the H/O content among other variables. The best performing carbons were obtained at low calcination temperatures <mml:math display="inline"><mml:mrow><mml:mrow><mml:mo>(</mml:mo><mml:mrow><mml:mn>500</mml:mn><mml:mo>°</mml:mo><mml:mi mathvariant="normal">C</mml:mi></mml:mrow><mml:mo>)</mml:mo></mml:mrow></mml:mrow></mml:math>(500°C) . Although these conditions can increase IC, the effect can be offset by limiting the amount of Li inserted in the first charge. Moreover, this method improves capacity retention and rate capabilities. This approach allows one to obtain activated carbons with specific capacities of as high as <mml:math display="inline"><mml:mrow><mml:mn>200</mml:mn><mml:mspace width="0.5em"></mml:mspace><mml:mtext>mAh</mml:mtext><mml:mspace width="0.5em"></mml:mspace><mml:msup><mml:mi mathvariant="normal">g</mml:mi><mml:mrow><mml:mo>−</mml:mo><mml:mn>1</mml:mn></mml:mrow></mml:msup></mml:mrow></mml:math>200mAhg−1 at 5C; a high rate indeed. Their performance after as many as 100 cycles over a wide range of charge/discharge rates surpassed that of s-MWCNT and matched that of the best performing carbons reported so far.

The electrochemical behavior of an Au-coated <mml:math display="inline"><mml:mrow><mml:mi mathvariant="normal">Li</mml:mi><mml:msub><mml:mi mathvariant="normal">Ni</mml:mi><mml:mrow><mml:mn>0.5</mml:mn></mml:mrow></mml:msub><mml:msub><mml:mi mathvariant="normal">Mn</mml:mi><mml:mrow><mml:mn>1.5</mml:mn></mml:mrow></mml:msub><mml:msub><mml:mi mathvariant="normal">O</mml:mi><mml:mrow><mml:mn>4</mml:mn></mml:mrow></mml:msub></mml:mrow></mml:math>LiNi0.5Mn1.5O4 nanospinel in lithium cells was studied at two different temperatures (25 and <mml:math display="inline"><mml:mrow><mml:mn>50</mml:mn><mml:mo>°</mml:mo><mml:mi mathvariant="normal">C</mml:mi></mml:mrow></mml:math>50°C ) and at five charge/discharge rates (C/6, C/4, 2C, 4C, and 8C). Two different coating methods were tested and the resulting products characterized by X-ray diffraction, X-ray photoelectron spectroscopy, and transmission electron microscopy. One method, which involved treatment with <mml:math display="inline"><mml:mrow><mml:mi mathvariant="normal">H</mml:mi><mml:mi mathvariant="normal">Au</mml:mi><mml:msub><mml:mi mathvariant="normal">Cl</mml:mi><mml:mrow><mml:mn>4</mml:mn></mml:mrow></mml:msub></mml:mrow></mml:math>HAuCl4 in the presence of HCOH as reductant, resulted in poorer cell performance irrespective of the particular charge/discharge regime used, probably by effect of the attack on the material degrading its surface during the coating process. The other coating method involved evaporating Au on the spinel, the effect of coating on cell performance being dependent on both temperature and the charge/discharge rate. Thus, low rates (C/6, C/4) increased the capacity delivered by the cell at <mml:math display="inline"><mml:mrow><mml:mn>50</mml:mn><mml:mo>°</mml:mo><mml:mi mathvariant="normal">C</mml:mi></mml:mrow></mml:math>50°C by ca. 20% relative to the bare spinel. This beneficial effect can be ascribed to the coating layer altering the electrolyte decomposition and the spinel particles being protected from attack by the species formed in the electrolyte decomposition. At high rates (2C, 4C), however, electrolyte decomposition played a minor role and crossing of the gold layer by lithium ions raised an energy barrier to be overcome. Under these conditions, the capacity delivered by the cell was markedly degraded irrespective of the temperature used.

Six different carbons in variable particle size ranging from micrometric to nanometric and morphology (microbeads, flakes, nanofibers, and short and long multiwalled nanotubes) were tested as electrodes for Li-ion batteries. Their performance (particularly in regard to rate capability and cycling properties) was analyzed in terms of textural and structural properties as determined from <mml:math display="inline"><mml:mrow><mml:msub><mml:mi mathvariant="normal">N</mml:mi><mml:mrow><mml:mn>2</mml:mn></mml:mrow></mml:msub></mml:mrow></mml:math>N2 adsorption and X-ray diffraction data, respectively. All carbons exhibited irreversible capacity (IC) to an extent governed by a combination of textural [ <mml:math display="inline"><mml:mrow><mml:mrow><mml:mo>(</mml:mo><mml:mrow><mml:msub><mml:mi>S</mml:mi><mml:mrow><mml:mtext>BET</mml:mtext></mml:mrow></mml:msub></mml:mrow><mml:mo>)</mml:mo></mml:mrow></mml:mrow></mml:math>(SBET) and pore volume] and structural properties (average layer stacking height and orientation index). However, no direct correlation between IC and cell performance in terms of the rate capability and cycling properties was observed. These two properties are more markedly influenced by structural ordering in the graphite layers. At low rates, high particle sizes and crystallinity resulted in enhanced cell performance. Ensuring good performance at high rates, however, required both a highly layered ordering and a nanometric particle size in the carbon. Carbons with special morphologies such as nanotubes or nanofibers possess a high structural disorder which is detrimental for use as electrode materials in Li-ion batteries.