Driven by the demand of higher energy density batteries, systems based on sulfur and oxygen as cathode materials with lithium electrode regained increased interest as successful candidates for beyond lithium-ion systems [1,2]. Nevertheless, at the surface of the lithium electrode the existence of a native surface film and the formation of a solid electrolyte interphase (SEI) leads to a heterogeneous electrodeposition and thus inhomogeneous current densities during the discharge and charge process. Ultimately, this will result in the formation of high surface area lithium (HSAL, during electrodeposition) and hole/pit formation (during electrodissolution) [3]. Therefore, lithium electrodes are mainly characterized by poor cycling performance with low Coulombic efficiencies, continuously loss of active material that arises in safety concerns.

For practical applications, the electrode-electrolyte interface needs to be tuned in order to avoid these barriers and to reduce the product costs [4]. Previously we have shown that controlling the chemical composition and morphology of the lithium-electrode surface by thinning the surface native film, improved cycling performances with low overpotentials of the lithium electrodeposition was obtained [5]. Furthermore, we would like to further expand such method of mechanically pre-treated lithium electrodes, by creating an artificial-SEI through dry and solution based methods [6]. In this way, it is possible to homogenize the flux of Li⁺ during the electrodeposition process resulting in stabilized electrochemical performances. Furthermore, we would like to present that such surface modification avoids also the formation of the hole/pits thus reduces the formation of the HSAL. Finally, these surface modifications can be successfully transferred to thin lithium electrodes (<30 µm) as the nominal capacities used with the common laboratory grade lithium electrodes (>150 µm) are extremely oversized. These demonstrations will present the strength of the above mentioned approaches to further improve the electrochemical performances through the interface engineering of lithium electrodes.

[1] H. Kim et al., “Metallic anodes for next generation secondary batteries“, Chem. Soc. Rev. 2013, 42, 9011.

[2] Sheng S. Zhang, “Problem, Status, and Possible Solutions for Lithium Metal Anode of Rechargeable Batteries”, ACS Appl. Energy Mater. 2018, 1, 910.

[3] G. Bieker et al., “Electrochemical in situ investigations of SEI and dendrite formation on the lithium metal anode“, Phys. Chem. Chem. Phys. 2015, 17, 8670.

[4] P. Albertus et al., “Status and challenges in enabling the lithium metal electrode for high-energy and low cost rechargeable batteries”, Nature Energy 2018, 3, 16.

[5] J. Becking et al., “Lithium-Metal Foil Surface Modification: An Effective Method to Improve the Cycling Performance of Lithium-Metal Batteries”, Adv. Mater. Interfaces 2017, 4, 1700166.

[6] J. O. Besenhard et al., “Inorganic film-forming electrolyte additives improving the cycling behavior of metallic lithium electrodes and the self-discharge of carbon-lithium electrodes”, J. Power Sources 1997, 43-44, 413.