Commercial micron-scale low-cost MoS2 is subjected to an electrochemically derived 2H-to-1T phase transformation, which makes it capable of reversibly storing Mg(2+)/Li(+) and Mg(2+) in all-phenyl-complex (APC) electrolytes with and without Li(+), respectively. The MoS2/graphene composite shows a high capacity (225 mA h g(-1)) and great cyclic stability in the Li(+)-containing APC electrolyte.