Performance of Li-Ion Batteries: Contribution of Electronic Factors to the Battery Voltage

Abstract

The voltage is a key parameter for the performance of Li-ion cells. An increased average voltage results in a higher energy-and power density. Theoretically, the potential of Li-intercalation electrodes is related to the chemical potentials of both electrons and Li + -ions, and the voltage of a cell to their respective differences. As experimentally these quantities cannot be directly obtained, the exact contribution of electrons and Li + -ions to the voltage is still not known for the different materials. In this contribution, we investigate the correlation of the average cell voltage with the electronic ionization potential of different thin film cathode materials. Specifically, we relate the ionization potential obtained by photoelectron spectroscopy to the electron chemical potential at the onset of the charging plateau, and its difference to the ionization potential of lithium to the electronic contribution of the cell voltage. As experimental data both layered and olivine cathode materials are considered and we find a reasonable correlation between ionization potential and average voltage, as well as the electronic contribution as major factor for the battery voltage. The possible reasons for the deviation such as the ionic contribution and the presence of surface dipole potentials are discussed.

A semiconductor-electrochemistry model for design of high-rate Li ion battery

“…On the microscopic level, the interfaces in substrate/active materials and lithiation/delithiation materials can also be surveyed via this model [13] . Therefore, the electrochemical performance of a whole electrode would afford more accurate information by integral numbers of microscopic interfaces via this model, e.g., Gennady et al recently proposed a new view on mechanism of the battery voltage by using semiconductorelectrochemical theory [39] .…”

Deciphering the oxygen absorption pre-edge: a caveat on its application for probing oxygen redox reactions in batteries

“…4 indicates that for a wide variety of TMOs, the electronic part is the dominant contribution, which is supported by previous studies. [57][58][59] It is important to note, however, if the Li + changes its occupation 20 site, the ∆Li + may change significantly, leading to another factor on top of the typical TM redox potential. 60 Nonetheless, the map of the relative TM potentials in Fig.…”

Stoichiometry Dependence of Physical and Electrochemical Properties of the SnOx Film Anodes Deposited by Pulse DC Magnetron Sputtering

“…The Sn element rearrangement was likely a consequence of the high mobility [ 28 ] of the nanoscale Sn particles formed in the conversion reaction and the high mobility of Li + in the Li x Sn alloy (diffusion constants between 10 −7 and 10 −8 cm 2 /s [ 36 ]). Recently, researchers have introduced work function (WF) as a parameter to study the stability of electrodes [ 37 , 38 , 39 , 40 , 41 ]. The WF (Φ) is usually defined as the energy required to take away one electron from the Fermi level ( μ ), namely, Φ = φ − μ , where φ refers to the vacuum level.…”