In the next step, we come to the characterization of the electrochemical properties of KSC and its performance as an active material in a CIB. To evaluate the electrochemical performance, Swagelok cells were assembled in which KSC electrodes were coupled with metallic Li, employing 0.5 M PP14Cl (1-Butyl-1-methylpiperidinium chloride) in PC (propylene carbonate) as electrolyte. The cells were first investigated by cyclic voltammetry (CV) (Figure ). During the first cathodic scan of the CV, a reduction peak at approximately 0.56 V was observed, indicating a possible reduction of K2SnCl6 and the release of chloride ions. Subsequent cycles revealed a pair of enhanced rectangular signals at around 0.8 -0.9 V vs. Li/Li + and similarly, during the anodic scan, oxidation peaks were observed at 0.2 -0.3 V vs. Li/Li + possibly corresponding to the reversible insertion/extraction of chloride ions into/from the electrode. Further, the KSC cells were also subjected to galvanostatic cycling tests. A vast capacity loss was observed in the first cycle (Figure ) at a current rate of 10 mA g -1 , with specific capacities of approximately 350 mA h g -1 in the initial discharge and only 90 mA h g -1 in the following charge. This result indicates the irreversible conversion of K2SnCl6 to tin chloridebased products, during which chloride ions are released to the lithium side. The resulting conversion products act as active material in the rest of the cycling. Figure shows the electrochemical charge-discharge profiles in the following cycles (at 10 mA g -1 ). While the discharge capacity showed a further decay from 120 mA h g -1 in the second cycle to 90 mAh g - 1 in the sixth cycle, a relatively stable charge capacity of 75 mA h g -1 was observed. Next, the rate capability performance of the electrode was investigated at current densities ranging from 10 to 100 mA g -1 , the results are shown in Figure . With increasing current rates, the KSC electrode delivered significantly decreasing capacities. Finally, cycle life results of the KSC electrode are displayed in Figure . A strong capacity decay was observed in the first 25 cycles (at 25 mA g -1 ). However, after 25 cycles, the Coulombic efficiency (CE) became stable and reached ~100 %, indicating that chloride ions shuttling became more or less reversible at this point. The electrode showed a stable reversible capacity of around 51 mA h g -1 after 50 cycles and about 85 % of the capacity remained from the 50 th to the 200 th cycle. The electrochemical impedance spectroscopy (EIS) Nyquist plots (Figure ) reveal a 45° sloping line in lowfrequency Warburg region, which is characteristic of a diffusion-limited charge storage process. In the medium-high frequency range, semicircles are found representing the charge transfer resistance, which is approximately 280 Ω, suggesting a strong interface connection between the electrode and the electrolyte. Nevertheless, an observed increase in charge transfer resistance after 25 cycles could be attributed to the electrode degradation on the surface due to stress induced by cycling. The XRD patterns of the KSC electrodes (Figure ) show a strong loss of crystallinity from the pristine electrode to the first discharge, suggesting that the K2SnCl6 phase transforms into an amorphous phase with smaller contributions from crystalline K-Sn alloy(s), metallic Sn and KCl. In agreement with the predictions from DFT calculations, this transformation is likely associated with a conversion-type mechanism of electrode reaction, in which the Sn 4+ ions are reduced to metallic Sn or K-Sn alloy(s), while chloride ions are released. The observed amorphization of the active material is not an uncommon finding for conversion electrodes. For example, amorphization was also reported from Mössbauer spectroscopy studies for the lithiation process in Fe0.5TiOPO4 and SnO2 electrodes. Furthermore, chloride-ion cathodes such as BiOCl , WOCl4 and FeOCl have witnessed similar behavior. To get further information on the discharged products, complementary characterization techniques are necessary. The diffraction pattern of the charged electrode sample showed a similar amorphous pattern, but only KCl peaks were visible. This suggests that the chloride ions released during discharge were incorporated into the KCl phase and that this phase also persists upon charge. Figure of the supporting information shows the XRD pattern of the lithium metal anode after 150 cycles (discharged state). The diffraction pattern shows the formation of LiCl, which confirms that the chloride ions have shuttled from the KSC electrode to the Li side during cycling. The FESEM images in Figure depict the structural changes observed in both the KSC and Li metal electrodes after 150 cycles.