Substantial research regarding all-solid-state thin-film lithium-ion batteries has been done in the last few decades. An increasing number of electrode materials as well as electrolytes have become available as a thin film. In this contribution new challenges in combining the well characterized materials in an all-solid-state battery are discussed. The battery has to be balanced carefully, to keep a high energy density. Also new solid-solid interfaces are created, which are behave differently than known from a liquid cell.
The presented all-solid-state battery consists of LiFePO4 as the cathode material, LiPON as the solid electrolyte and tin as the anode material. Characterization is carried out using cyclic voltammetry (CV), chrono-potentiometry (CP) and transmission electron microscopy (TEM). The observed behavior of the complete cell is compared to that of the single materials. In contrast to conventional battery cells, solid-state batteries can be operated at elevated temperatures. Experiments under variation of temperatures demonstrate that the capacity of the cell is significantly dependent on the operation temperature, pointing to a capacity loss due to kinetic restrains at room temperature as it can be seen in the figure below. The obtained capacity after 100 cycles is starting at 20% of the LFP capacity at RT and reaching 80% at 80°C. Kinetic parameters can be derived from electrochemical measurements (CV) at different scan rates and temperature. The comparison of the peak currents yield kinetic information, which is compared to the properties of the individual materials.
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|Präsentation||Capacity of all solid-state batteries||capacity of an LFP/LiPON/Sn all solid state battery in dependence on the cycle number and the temperature||363 KB||Download|