Electrochemical setup: All electrochemical measurements were carried out in an MBRAUN LABStar glove box with a N 2 (5.0, MTI Indus-trieGase AG) atmosphere (O 2 and H 2 O content ≤ 0.5 ppm). A home-built electrochemical cell made from Kel-F and designed for small amounts of electrolyte was used. The cell was sealed with an O-ring on the electrode, whose inner diameter of 1.1 cm 2 defined the available electrochemical active surface area. A Zn wire (5N, MaTecK) being in contact with a saturated solution of Zn[TFSI] 2 (99.5%, Solvionic) in [MPPip][TFSI] (99%, IoLiTec) served as a homemade reference electrode. A detailed description of the preparation of such electrodes and their long-time stability can be found in Ref. The reference electrode has an electrode potential of -0.65 V vs. the Fc/Fc + redoxcouple and the shift in the potential is lower than 23 mV h -1 . A Pt wire (99.99%, MaTecK ) was used as counter electrode. The potentials of the electrodes were controlled with a Zahner IM6 potentiostat operated with the Thales Z software.