New Ion Substitution Method to Enhance Electrochemical Reversibility of Co-Rich Layered Materials for Li-Ion Batteries

The recent development of high-energy LiCoO₂ (LCO) and progress in the material recycling technology have brought Co-based materials under the limelight, although their capacity still suffers from structural instability at highly delithiated states. Thus, in this study, a secondary doping ion substitution method is proposed to improve the electrochemical reversibility of LCO materials for Li-ion batteries. To overcome the instability of LCO at highly delithiated states, Na ions are utilized as functional dopants to exert the pillar effect at the Li sites. In addition, Fe-ion substitution (secondary dopant) is performed to provide thermodynamically stable surroundings for the Na-ion doping. Density functional theory calculations reveal that the formation energy for the Na-doped LCO is significantly reduced in the presence of Fe ions. Na and Fe doping improve the capacity retention as well as the average voltage decay at a cutoff voltage of 4.5 V. Furthermore, structural analysis indicates that the improved cycling stability results from the suppressed irreversible phase transition in the Na- and Fe-doped LCO. This paper highlights the fabrication of high-energy Co-rich materials for high voltage operations, via a novel ion substitution method, indicating a new avenue for the manufacturing of layered cathode materials with a long cycle life.     

Automated counting of phytoplankton by pattern recognition: a comparison with a manual counting method

Computer-based image analysis and pattern recognition methodswere used to construct a system able automatically to identify,count and measure selected groups of phytoplankton. An imageanalysis algorithm was employed to isolate and measure objectsfrom digitized images of a phytoplankton sample. The measurementsobtained were used to identify selected groups of phytoplanktonby a combination of artificial neural networks and simple rule-basedprocedures. The system was trained and tested using samplesof lake water covering an annual growth cycle from Lough Neaghin Northern Ireland. Total volume estimates were obtained forthe four major phytoplankton species, using both the automatedsystem and a manual counting method. Estimates of total cellvolume obtained from the automated system were within 10% ofthose derived by manual analysis of the same cells. The automatedsystem produced total cell volume estimates close to those obtainedfrom manual analysis of different aliquots of the same watersample. Variation between successive counts of the same watersample was higher with the automated system than with the manualcounting method. Limitations and possible improvements to thetechnology are discussed.     

Palaeomagnetic results from sediments of the Perth Basin,Western Australia,and their bearing on the timing of regional lateritisation

In an attempt to extend palaeomagnetic investigation of Late Palaeozoic and Mesozoic rock formations in Australia, 222 oriented samples have been collected from sedimentary horizons in the Perth Basin and adjacent areas. The thermal stability of the remanent magnetism has been established, but its direction remained oriented close to the direction of the present local geomagnetic field, irrespective of the age of formation sampled. Further attempts to partially demagnetise some specimens using chemical techniques also failed to isolate the primary component of magnetisation. The results have been interpreted as indicating an episode of “blanket” remagnetisation which occurred during the period of regional lateritisation. The presence of normal and reversed polarities indicates that remagnetisation occurred over an extended period of time. By comparing the paleomagnetic pole positions with the apparent polar-wander curve recognised for the Cenozoic of Australia, quantitative support for a Late Oligocene to Early Miocene age for the period of lateritisation is given. Other palaeomagnetic evidence suggests this age may be correlated to laterites in Northern Territory.