Influence of Aviation Conditions on Lithium-Ion Batteries

Abstract

Stopping climate change and global temperature rise needs a determined course of action in several technology fields and the development of ZERO-CO2 aircrafts and low emission battery-ICE aircrafts, as well. Batteries in hybrid-electric or fully-electric aircrafts are an option to decrease emissions. The battery requirements for the aviation sector regarding specific energy, energy density and safety are high. Lithium-ion batteries are today the only commercially available technology to meet these requirements, but adequate technology readiness is only proven for the automobile sector while TRL levels 8 and 9 for implementation readiness of batteries in the aviation sector is still ongoing. A crucial aspect for aviation applications is the operation behavior in high altitude including low temperature, wide humidity ranges and especially low pressure. There is little published information available on the effects of low pressure on battery performance. Therefore, different commercially available lithium-ion batteries were tested from atmospheric pressure down to 250 hPa, which corresponds to a flight altitude up to 10,000 m, according to the International Standard Atmosphere (ISA). Since NMC and NCA cathode materials are promising for aviation due to their high specific energy, and LFP cells are promising because of their high safety, the following batteries were selected: 20 Ah HP602030 LFP cylindrical cell (EAS Batteries GmbH, GER). 10 Ah HE 341440 NCA cylindrical cell (EAS Batteries GmbH, GER). 12 Ah SLPB065070180 NMC pouch cell (Kokam Co. Ltd., KOR) To examine the influence of pressure on the battery behavior, constant current discharge tests at 1C 0.5C and 2C rates as well as impedance measurements in 10% SOC steps were performed in a climate controlled low-pressure chamber. The batteries were operated under different temperatures and in controlled low pressure. The pressure was first set to atmospheric pressure as a reference and then lowered to 750 hPa, 500 hPa and 250 hPa. To further examine altitude influences, current cycles and impedance spectroscopy were performed at different temperature and humidity values.The behavior of the cylindrical cells showed hardly any pressure dependency, while the examined pouch cell’s behavior did show a pressure dependency.All batteries showed strong temperature dependency but hardly any humidity dependency.In this presentation the influence of pressure, temperature and humidity on voltage, capacity, resistance and impedance of the afore mentioned batteries will be discussed. The batteries are compared regarding their aviation applicability with special respect to low pressure. The parameters for each environmental condition can then be used to parameterize a battery model suitable for aviation applications.