The electrodeposition of a polymer (polyacrylonitrile, PAN) is used to reduce the risk of thermal runaway in lithium-ion batteries, which is the most important cause of battery accidents and fires. PAN was electrodeposited on a graphite battery electrode, using cyclic voltammetry or chronoamperometry, in a solution with acrylonitrile as the solvent. The electrodeposited PAN film was characterised by Raman spectroscopy, microscopy, energy dispersive X-ray analysis, and thermogravimetric analysis, and it was found that the film thickness could be controlled by the amount of charge passed in the electrochemical experiments. The PAN-coated graphite battery electrode was then tested in lithium half-cells, obtaining capacities close to the uncoated graphite sample (ca. 360 mA h g−1) for thin (<10 µm) polymer coatings at 25 °C. Interestingly, for thicker polymer coatings (>20 µm) it was found that the capacity decreased drastically as the temperature increased beyond 80 °C. Such suppression in capacity has applications for thermal runaway protection since the electrochemical reactions of degradation of the electrolyte in contact with the electrode are the root cause of the thermal runaway process. Further work should look into alternative polymer and liquid electrolyte formulations to achieve the desired suppression of electrochemical capacity at high temperatures while retaining high capacities at the operational temperature range.

Polyacrylonitrile (PAN) is among the most common polymer materials in the world thanks to its versatility in a wide range of applications. Of importance to this work is its use in electrochemical cells. PAN has seen use as a separator material and as a binder material in lithium-ion cells. Expanding upon innovations made in recent decades for electrodepositing PAN onto conductive surfaces, this work details methods used to apply PAN as a thin coating to graphite composite electrodes; the resultant films may then be used for further electrochemical analysis in a lithium-ion cell. Graphite electrodes coated with electrodeposited PAN films were produced of a practical size for electrochemical testing in Swagelok cells; optical microscopy images of the resulting PAN coated graphite electrodes were also recorded to study the morphology of the coating.

Thermal runaway is one of the key safety concerns of lithium-ion batteries. The rapid increase in temperatures can result in catastrophic and often explosive failures of battery systems. Because lithium-ion cells have become the battery of choice in most portable gadgets, finding reliable and cheap methods to improve their safety is of economic importance. Application of materials within the battery is one of the most reliable ways to achieve this. Such methods are integrated into the battery itself, allowing for quicker responses as opposed to other monitoring systems. Polymers are among the materials highlighted to solve such safety concerns. Highly tuneable chemistries allow reliable employment of a positive temperature coefficient of resistivity (PTCR). This PTCR results in automatic battery shutdown when temperature increases beyond a certain threshold. However, this is often irreversible and further research improvements are required. This paper will highlight several known polymer materials and the methods in which they are employed to prevent thermal runaway within lithium-ion systems.

Approximately 420 VertiMills® (VTM) have been installed in mineral processing plants throughout the world, mainly in tertiary and regrind applications plus several in secondary grinding duties. Metso Minerals (Metso) and the Julius Kruttschnitt Mineral Research Centre (JKMRC) have commenced a collaborative research program in stirred milling technology focusing on mill performance evaluation, model development and scale-up methodology. Industrial VTMs are being assessed using a consistent circuit survey protocol to evaluate the performance of VTMs in comminution circuits. The survey protocol includes identification and modification of sampling points, appropriate sampling techniques, controlled circuit stability, and best sample analysis practice. To initiate this study four surveys were conducted in the tertiary grind circuit in the Ridgeway Concentrator at Cadia Valley Operations (CVO) that treats the full circuit throughput of over 800 tph. To deal with the high feed rate the site opted to lead the world in the application of stirred mills by installing the largest VTM, at 3000 hp (2240kW) in closed circuit with a hydrocyclone bank. On average the operating work index was 13.1 kWh/t, reducing the secondary grind product by 40 - 50 µm to the required 80 to 100 µm range. The applied specific energy is relatively low in these low-intensity stirred media mills at 2.7 kWh/t. The size specific energy was 24.2 kWh/t-75µm. Based on the survey and operating data the VTM circuit is performing well in this high-throughput tertiary grinding application, producing a sub-100µm product.