Lithium ion batteries are currently being considered for using in a wide range of aerospace applications[1]. Batteries for these aerospace applications, such as aircraft and UAV (unmanned aerial vehicle), are required to operate at high rates(up to 15C or higher) and low temperatures (-40°C or lower). To address these requirements, a series of experiments have been undertaken to empirically determine those factors that limit the performance. For example, a reference electrode is introduced in the battery. The reference electrode enables the diagnosis of individual electrodes.  The voltage profile of 50C high power pulse discharge is shown in Figure 1 left. The result indicates that the positive voltage drops from 4.500V to 2.638V, and that the negative voltage rises from 0.083V to 0.689V, which means that the positive electrode dominates the polarization. Hence, further experiments would be aimed at the positive side, such as the weight loading and diverse positive materials. The voltage profile of 5C pulse discharge at -40°C is described in Figure 1 right. The result indicates that the positive voltage drops from 4.500V to 3.595V, and that the negative voltage increases from 0.054V to 0.925V, which means that the majority of the polarization is ascribed to the positive side and negative side, no dominations could be seen from that result. In order to reveal the limiting factors, further experiments could be aimed at the electrolyte or the separator possibly.

Fig. 1 Voltage profile for 50C pulse discharge at 25°C and Voltage profile for 5C pulse discharge at -40°C

References

[1] Richard Van Noorden.Nature.507 (2014)26-28.