In this work, we synthesize a series of linear-comb block copolymers, polystyrene-b-poly(polyethylene glycol methyl ether acrylate) (PS-PPEGMEA), and study the microphase separation mechanism by LiTFSI-doping. The increasing salt concentration promotes the microphase separation of PS-PPEGMEA and also deflects the phase transition boundaries to the lower PPEGMEA volume fraction. We reveal that the effective interaction parameter exhibits a linear to nonlinear dependence on increasing salt concentration and is eventually weakened by the formation of ion clusters at high salt concentration. We further quantify the conformational asymmetry of PS-PPEGMEA by theoretical analysis and point out that the limit of the order-order transition boundaries is defined by strong segregation theory. Therefore, electrostatic interaction and conformational asymmetry jointly determine the microphase separation of PS-PPEGMEA block copolymer electrolytes. This study provides a fundamental understanding of the phase behaviors of salt-doped linear-comb block copolymers and suggests experimental strategies to modulate their nanostructures, which could be very useful for developing novel solid polymer electrolytes.