LiNi_0.5Co_0.5O₂ as a long-lived positive active material for lithium-ion batteries

LiNi_0.5Co_0.5O₂ layered material could be a possible cathode material for advanced lithium-ion batteries in applications such as medical devices. The material was prepared by the co-precipitation method, which leads to a highly stoichiometric and homogeneous powder with a desirable particle size. It has shown reasonable cycling stability at a C/2 rate up to 100cycles, and is expected to be much more stable at lower rates and capable of providing the needed capacity. We also showed that the use of lithium fluoroalkyl-phosphate Li[PF₃(C₂F₅)₃] salt-based electrolyte significantly improves the calendar life of the battery. Aging tests have been performed under severe conditions (storage at 50 °C and 4.1 V) clearly show a huge capacity loss for the conventional cathode LiNi_0.8Co_0.2O₂ while LiNi_0.5Co_0.5O₂ electrode exhibits a limited capacity fading. Finally, because it has less nickel content, differential scanning calorimetry (DSC) measurements confirm that LiNi_0.5Co_0.5O₂ is much safe than the LiNi_0.8Co_0.2O₂ cathode.