Christina Lampe-Onnerud

Benchmark study on high performing carbon anode materials

Four state-of-the-art carbon graphite morphologies, beads, fibers, flakes and potatoes have been benchmarked with respect to materials properties and electrochemical performance. All four anode materials exhibit various degree of graphitization and performance. Fibers have a higher degree of turbostatic structure. Flakes consist of a binary phase mix. Potatoes and beads have reached an intermediate degree of crystallinity. Although graphite flakes still show the highest performance in early cycles, new materials challenge not only in-cell capacity, but also rate capability and cyclability.

Safety studies of Li-ion key components by ARC

Thermal behaviors of metal cathode material, graphite anode material and electrolyte have been studied using the accelerated rate calorimetry (ARC(R)) technique. The pristine cathode, anode and electrolyte materials are stable up to 200/spl deg/C. The fully lithiated graphite has the lowest thermal stability and highest self-heating rate. The exothermic reactions of Li-ion cells at different states-of-charge have also been studied.

Safety studies on lithium-ion batteries by accelerating rate calorimetry

Exothermic reactions of lithium-ion cell at various state of charge have been studied by the accelerating rate calorimetry (ARCO) technique. The thermal stability of a cell is highly dependent on its state of charge. The fully discharged cell (discharged to 2.7 V) has the highest thermal stability with the onset temperature of thermal runaway of 120/spl deg/C, and the overcharged cell (charged to 4.8 V) has the least thermal stability, starting the thermal runaway reaction at 40/spl deg/C.