The development of lifetime estimation models for Lithium-ion battery cells, which are working under highly variable mission profiles characteristic for wind power plant applications, requires a lot of expenditures and time resources. Therefore, batteries have to be tested under accelerated lifetime aging conditions. This paper presents a three-stage methodology used for accelerated lifetime testing of Lithium-ion batteries. The results obtained at the end of the accelerated aging process were used for the parameterization of a performance-degradation lifetime model, which is able to predict both the capacity fade and the power capability decrease of the selected Lithium-ion battery cells. In the proposed methodology both calendar and cycling lifetime tests were considered since both components are influencing the lifetime of Lithium-ion batteries. Furthermore, the proposed methodology was validated by running a verification stage of the lifetime model, where Lithium-ion battery cells were tested at normal operating conditions using an application specific mission profile.

This paper introduces a versatile Y-source boost dc/dc converter intended for distributed power generation, where high gain is often demanded. The proposed converter uses a Y-source impedance network realized with a tightly coupled three-winding inductor for high voltage boosting that is presently unmatched by existing impedance networks. The proposed converter also has more variables for tuning the required gain and, hence, more degrees of freedom for meeting design constraints. These capabilities have been demonstrated by mathematical derivation and experimental testing. For the experiments, a 300-W prototype has been built in the laboratory using silicon carbide devices for better efficiency. The prototype has been tested with a regulated power supply, before operating it with a high-temperature proton-exchange-membrane fuel cell. Results obtained confirm the practicality and performance of the proposed converter.

Lithium ion (Li-ion) batteries have been extensively used in consumer electronics because of their characteristics, such as high efficiency, long life, and high gravimetric and volumetric energy. In addition, Li-ion batteries are becoming the most attractive candidate as electrochemical storage systems for stationary applications, as well as power source for sustainable automotive and back-up power supply applications. This paper gives an overview of the Li-ion battery chemistries that are available at present in the market, and describes the three out of four main applications (except the consumers' applications), grid support, automotive, and back-up power, for which the Li-ion batteries are suitable. Each of these applications has its own specifications and thus, the chemistry of the Li-ion battery should be chosen to fulfill the requirements of the corresponding application. Consequently, this paper discusses as well, the suitability of the presented Li-ion battery chemistries for different applications.

Lithium-ion batteries have developed into a popular energy storage choice for a wide range of applications because of their superior characteristics in comparison to other energy storage technologies. Besides modelling the performance behavior of Lithium-ion batteries, it has become of huge interest to accurately diagnose their state-of-health (SOH). At present, Lithium-ion batteries are diagnosed by performing capacity or resistance (current pulse) measurements; however, in the majority of the cases, these measurements are time consuming and result in changing the state of the battery as well. This paper investigates the use of the electrochemical impedance spectroscopy (EIS) technique for SOH diagnosis of Lithium-ion battery cells, instead of using the aforementioned techniques, since this new method allows for online and direct measurement of the battery cell response in any working point. For the investigation, a 2.5 Ah Lithium-ion battery cell based on lithium iron phosphate and graphite (LiFePO ₄ /C), as active material, was used. The obtained results at different battery SOH levels have been analyzed in detail and are suggesting that the EIS technique represents a promising tool for diagnosis the lithium-ion battery cells' SOH; meaningful results regarding the pulse power capability decrease of the tested Li-ion battery cells were obtained by applying the EIS technique.