A parametric open circuit voltage model for lithium ion batteries

The financial support of EPSRC UK and Jaguar Land Rover Ltd is gratefully acknowledged.We present an open circuit voltage (OCV) model for lithium ion (Li-ion) cells, which can be parameterized by measurements of the OCV of positive and negative electrode half-cells and a full cell. No prior knowledge of physical parameters related to particular cell chemistries is required. The OCV of the full cell is calculated from two electrode sub-models, which are comprised of additive terms that represent the phase transitions of the active electrode materials. The model structure is flexible and can be applied to any Li-ion cell chemistry. The model can account for temperature dependence and voltage hysteresis of the OCV. Fitting the model to OCV data recorded from a Li-ion cell at 0°C, 10°C, 20°C, 30°C and 40°C yielded high accuracies with errors (RMS) of less than 5 mV. The model can be used to maintain the accuracy of dynamic Li-ion cell models in battery management systems by accounting for the effects of capacity fade on the OCV. Moreover, the model provides a means to separate the cell's OCV into its constituent electrode potentials, which allows the electrodes’ capacities to be tracked separately over time, providing an insight into prevalent degradation mechanisms acting on the individual electrodes.Publisher PDFPeer reviewe

Minimally invasive insertion of reference electrodes into commercial lithium-ion pouch cells

The authors gratefully acknowledge the financial support of EPSRC UK and Jaguar Land Rover Ltd for this work.Two procedures to introduce a lithium metal reference electrode into commercially manufactured lithium-ion pouch cells (Kokam SLPB 533459H4) are described and compared. By introducing a stable reference potential, the individual behavior of the positive and negative electrodes can be studied in operando under normal cycling. Unmodified cells and half-cells made from harvested electrode material were cycled under identical conditions to the modified cells to compare capacity degradation during cycling and thus validate each modification procedure for degradation testing. A configuration that did not affect the performance of the cell over 20 cycles was successfully developed.Publisher PDFPeer reviewe

Cultural security in Australian classrooms: entanglements with mainstream education as Aboriginal and Torres Strait Islander children transition to school

In Australia, Aboriginal and Torres Strait Islander children attend formal early education at rates lower than their non-Indigenous counterparts. Research on factors influencing attendance and engagement in early childhood education has focused primarily on Indigenous children, families or community. In comparison, there is a dearth of research on the preparedness of mainstream educational contexts to receive Indigenous children and families, and to ensure cultural security via appropriate curricula and connections with community. To address this gap, Coffin’s (2007) model of cultural security is used to position mainstream educational contexts as responsible for ensuring that cultural needs are met for Aboriginal and Torres Strait Islander children and families. In this chapter, the authors juxtapose Indigenous and non-Indigenous approaches to school transition and share extracts from a yarning session with an Aboriginal educator and researcher who facilitated an Indigenous-led school transition program. The program attended to the needs of children, families and community via culturally meaningful engagement, curriculum content and pedagogies. The yarning about the school transition program and Aboriginal and Torres Strait Islander children’s experiences of mainstream education highlights cultural entanglements between local traditions, protocols and curricula approaches, and mainstream schooling expectations