The release of Li + from stoichiometric LiCoO 2 (LCO) -a typical battery electrode material -is investigated by means of thermionic emission. Analysis of the data leads to an ionic work function of w Li+ (LCO) = 4.1 eV. Combination of this value with the electronic work function w e− (LCO) = 5.1 eV, also measured in this work by photoelectron spectroscopy, and with information available from the literature allows the set up, for the first time, of a complete thermodynamic cycle for a Li//LiCoO 2 battery. An open circuit cell voltage of 2.4 eV is derived in line with available literature information. The proofof-principle study presented here provides experimental data on the binding energy values, i.e., chemical potentials, of Li + -ions and electrons and thus of Li-atoms in LiCoO 2 as a battery cathode and is expected to open access to a better understanding and thus to a better design of battery materials.

The thermionic emission of Li+ from synthetic spodumene (LiAlSi2O6) has been investigated as a function of temperature and electric field. The data presented cover the entire range from the space charge limited Child-Langmuir regime, to the Richardson-Dushman regime, and finally the field assisted Schottky regime. From a self-consistent analysis of all data measured, the work function for Li+ emission from synthetic spodumene is determined as (2.47 ± 0.015) eV. The thermionic currents exhibit a voltage offset of (1.7 ± 0.1) eV, which can be traced to a combination of the ionic work function of the emitter, the recombination energy Li+ + electron, the electronic work function of the detector, and the contact potential between the detector and filament.

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In article number https://doi.org/10.1002/aenm.201703411, Karl‐Michael Weitzel and co‐workers describe a complete thermodynamic cycle for a LiCoO2//Li battery. The approach takes into account not only electronic but also ionic contributions to the open circuit cell voltage. The experimental data originate from work function measurements, w(e−) for electrons and w(Li+) for ions from LiCoO2.