Shape control of hierarchical lithium cobalt oxide using biotemplates for connected nanoparticles

A new synthetic method using biotemplating for fabrication of LiCoO2 (LCO) for batteries of mobile products is developed. The LCO can be manufactured in various forms, and rapidly charged and discharged, even when using a thick electrode. Among three types of candidate biotemplates wood, cotton, and grass pollen, cotton was selected as the biotemplate considering its performance and potential for commercialization. Both the size of the primary particle and the shape of the secondary particle are controllable by using cotton. When using a thin electrode, the difference in capacitance between the LCO fabricated by the general method (solid-LCO) and the LCO made by using cotton (cotton-LCO) is within 3%, regardless of current density. On the other hand, the capacity difference in the case of a thick electrode between two samples is approximately 1.5 times higher than that observed for solid-LCO at very high current density (6C). The capacity retention values are 1.4% and 75.1% at 6C after the 100th cycle for solid-LCO and cotton-LCO, respectively. The superior performance at high current density for the cotton-LCO likely arises from decreasing the distance that the Li+ ion must diffuse in the solid-state by connected nanoparticles.