The activation of commercial Li2S remains to be one of the key challenges against its commercialization as a starting cathode material for a sulfur-based Li-ion battery system. In this work we take advantage of the lower oxidation potential of commercial Na2S (1-3 wt%) to serve as an in situ and local polysulfide injector for the activation of commercial Li2S (70 wt%). In contrast to applying pre-solvated redox mediators, this technique allows for the activation of commercial Li2S at lower voltages with an electrolyte content as low as 3 mu L mg(Li2S)(-1) at 3 mgmg(Li2S) cm(-2) and 4 mu L mg(Li2S)(-1) at 6.5 mg(Li2S) cm(-2) without any other material modification.