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Model systems for electrochemical impedance spectroscopy (EIS) studies of solid-state electrolytes based on ceramic lithium ion conductor Li 7 La 3 Zr 2 O 12 (LLZO) and polymer electrolyte P(EO) 20 -LiClO 4 are investigated for the first time. The aim of the present study is to identify and quantify the lithium ion transition resistance of the ceramic/polymer interface. Symmetrical model systems consisting of LLZO pellets with sheets of P(EO) 20 -LiClO 4 are manufactured and investigated in detail. In such symmetric model systems we observed an additional ion-transfer process, which we attributed to the interface processes (i.e. distributed Li + transition across the interface). Based on the EIS measurement data obtained above the polymer electrolyte's melting temperature, at 70 • C the interface resistance of the lithium ion transition is estimated to be ∼9 k cm 2 and the capacitance of the process is in the order of 0.1 μF/cm 2 . According to our investigations, it is possible to predict interface resistivity of lithium ion transport for different polymer/ceramic composite electrolytes for solid state lithium battery applications.

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Layered double hydroxides (LDH) have shown to improve the zinc electrodeposition efficiency at the negative electrode of aqueous zinc‐ion batteries. In this work, a copper‐doped Zn−Al−CO3 layered double hydroxide (LDH) has been synthesized by co‐precipitation method under constant pH, and investigated as suitable solid‐state additive in zinc‐based negative electrodes. X‐ray diffraction patterns in combination with scanning electron microscope images show that the as‐synthesized LDHs are well crystalline and hexagonal platelet‐like. LDH was mixed with zinc powder in different ratios and the electrochemical performances of the mixtures were characterized by galvanostatic cycling with potential limitation (GCPL) at different current rates. The results show that an appropriate combination of zinc and LDH can be used to reach electrodeposition efficiency equal to 98 %. Thereafter, the performance of this electrode in a full cell is studied. In such configuration, the electrode shows that the electrodeposition efficiency remains high even at high current rates, which is an important characteristic for grid‐scale energy storage.

Quasi‐neutral aqueous zinc‐ion (Zn‐ion) batteries are nowadays among the most promising energy storage devices for smart‐grid applications. However, their practical use remains hindered by the low Zn electrodeposition efficiency at the negative electrode, which is especially reduced due to the parasitic evolution of gaseous hydrogen. Indium is a non‐toxic metal showing poor hydrogen evolution kinetics, but it is also very expensive. Therefore, an optimized mixture of bismuth and indium particles has been used as the substrate for the Zn electrodeposition and dissolution reaction to increase its reversibility and its efficiency in a quasi‐neutral ZnSO4 solution. This strategy not only allowed to prolong the cycle life of a full Zn‐ion cell of 10 times at 0.5 C due to the suppression of the hydrogen evolution reaction, as proved by the operando DEMS analysis, but also led to very homogeneous zinc deposits over prolonged cycling at realistic charge and current densities.