A polymer or a polymer electrolyte and cathode material for an alkali metal cell, in particular for a lithium-sulfur cell. To improve the performance and reliability of alkali metal cells, for example lithium-sulfur cells, a polymer based on the general chemical formula (I) is provided, where -[A]- stands for a unit which forms a polymer backbone, X stands for a spacer, x stands for the number of spacers X and is 1 or 0, Q stands for a positively charged group Q+ and a counterion Z−, or Q stands for a negatively charged group Q− and a counterion Z+, or Q stands for an uncharged group. Moreover, the invention relates to the use thereof, and a cathode, a separator, a protective layer, and a cell.