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In this work, we demonstrate that a new mechanical attrition process can be used to prepare nanosilicon powder from metallurgical grade silicon lumps. Composite Li-ion anode made from this nanometer-size powder was found to have a high reversible capacity of 2400 mAh g −1 and an improved cycling stability compared to micrometer-sized powder. It is proposed that improved battery cycling performance is ascribed to the nanoscale silicon particles which supresses the volume expansion owing to its superplasticity. [ABSTRACT FROM AUTHOR]

Abstract: Samples of Sn30TM30C40 and of Sn30Co15TM15C40, with TM=3d transition metals, were prepared by vertical-axis attritor milling. The structure and performance of these samples were studied by X-ray diffraction (XRD) and by electrochemical testing. The XRD patterns of Sn30TM30C40 show an amorphous-like diffraction pattern only for the sample with TM=Co. The other prepared samples show broadened Bragg peaks of their main starting material, along with an amorphous-like background, even after 32h of milling. Samples with TM=Co and TM=Ni show stable differential capacity versus potential plots and stable cycling for at least 100 cycles with reversible capacities of 425 and 250mAhg−1, respectively. All samples prepared with 15at.% Co show good capacity retention for at least 100 cycles ranging from 270mAhg−1 for samples with TM=Ni to 500mAhg−1 for samples with TM=Ti. The differential capacity versus potential plots for all the prepared Sn30Co15TM15C40 samples show similar structure to that of Sn30Co30C40 except when TM=Cu. This shows the possibility of preparing tin-based negative electrode materials using a combination of cobalt and TM, especially if one looks to reduce the cobalt content. [Copyright &y& Elsevier]

Abstract: Using a vertical-axis attritor, samples of (Sn x Co1−x )60C40 for 0≤ x ≤0.7 have been prepared in increments of Δx =0.1. The effect of Sn content on the structure and performance of the Sn–Co–C nanocomposites was examined by X-ray diffraction (XRD), 119Sn Mössbauer effect spectroscopy and electrochemical methods. XRD shows a diffraction pattern characteristic of a nanostructured material having amorphous CoSn grains in a carbon matrix for x =0.5. Broad Bragg peaks of Co3C, SnCo3C0.7 and CoSn2 were observed for samples with 0≤ x ≤0.1, 0.1≤ x ≤0.4 and 0.5< x ≤0.7, respectively. 119Sn Mössbauer effect spectroscopy shows the presence of an amorphous CoSn component in samples with 0.3≤ x ≤0.6. Samples with a large amount of the SnCo3C0.7 phase showed small capacity for lithium. Therefore, SnCo3C0.7 is best described as an inactive phase. The sample with x =0.7 shows the highest specific capacity (about 600mAh/g) of all samples prepared but exhibited poor capacity retention after cycle 45. Excellent charge–discharge capacity retention, reasonable specific capacity (>450mAh/g) along with stable differential capacities were observed for samples near x =0.5. [Copyright &y& Elsevier]

Abstract: High energy ball milling, vertical-axis attritor milling and co-sputtering were used to prepare Sn30Co30C40 or Sn36Co41C23 electrode materials. By varying the milling conditions, it was possible to obtain nanostructured materials by mechanical methods whose X-ray diffraction patterns mimicked the diffraction pattern of the co-sputtered material. Electrochemical testing showed that composite electrodes made from each of the prepared materials showed stable charge–discharge capacity for at least 100 charge–discharge cycles and stable differential capacity versus potential profiles. Although the materials appear to be similarly nanostructured, the sputtered material showed a reversible capacity near 610mAh/g, close to the theoretical capacity of 661mAh/g, while the best material prepared by mechanical methods attained a specific capacity near 470mAh/g. Further experiments are required to understand the differences in the nanostructure of these materials that leads to the differences in attained specific capacity. [Copyright &y& Elsevier]