Among other things, the present disclosure provides a particle comprising a form of sulfur and/or lithium sulfide (Li2S) that is doped with a group VIA element, such as selenium (e.g. Se34), tellurium (e.g. Te52), or polonium (e.g. Po84). The present disclosure also provides a cell comprising a negative electrode, a separator, and a positive electrode comprising the particles of the present disclosure.