[Display omitted] • The MoS 2 -MoSe 2 lateral heterostructure is semiconducting, whereas the MoS 2 -NbS 2 lateral heterostructure is metallic. • The 2D MoS 2 -MoSe 2 and MoS 2 -NbS 2 LHS can withstand massive volume change during the charging-discharging processes. • The MoS 2 -MoSe 2 and MoS 2 -NbS 2 lateral heterostructures give high Li/Na storage capacities of 518 mAh/g and 677 mAh/g, respectively. • MoS 2 -NbS 2 LHS is more advantageous over MoS 2 -MoSe 2 LHS for anodes of LIBs/SIBs. The requirement of an efficient energy storage device has become an exclusive requisite for technological and scientific innovations. In the present work, by using the 2D monolayer semiconductor-semiconductor and semiconductor-metal lateral interface structures as the model structure, we performed periodic DFT calculations to examine the possibility of 2D MoS 2 -MoSe 2 and MoS 2 -NbS 2 lateral heterostructures (LHS) as the electrodes of a battery. The MoS 2 -MoSe 2 lateral interface is a semiconductor, whereas the MoS 2 -NbS 2 lateral interface preserves metallic character. Besides, we found that Li/Na ion adsorption is more influential on the lateral heterostructure and is exothermic, with ultrafast diffusion, and is comparable to their monolayers. Meanwhile, the calculated open-circuit voltage is enormously low, like other widely investigated pristine 2D materials. The enhanced electrical conductivity, short diffusion distances, minutely low equilibrium voltage with good stability, large theoretical capacity and ultrahigh mechanical strength offered bare 2D TMDs lateral heterostructures as a potential candidate for LIBs/SIBs applications. This work broadens the possibility of applications based on 2D TMD-based semiconductor-semiconductor and semiconductor-metal lateral heterostructures. The lateral heterostructures can give an exciting new paradigm and offer exciting opportunities for potential applications in portable electronic devices. [ABSTRACT FROM AUTHOR]