A bi-objective optimization model for coordinated EV charging and battery swapping infrastructure planning in heterogeneous urban districts

The rapid growth of electric vehicles strains urban energy replenishment infrastructure. In land-constrained megacities, traditional greenfield construction faces severe challenges due to land scarcity and regional heterogeneity. To address these constraints, this study develops a bi-objective collaborative optimization model integrating a hybrid “new-build and upgrade” strategy. Formulated as a mixed-integer linear program, the model minimizes total annualized system cost and maximizes weighted spatial service coverage and is solved via the ϵ -constraint method to derive a complete cost-coverage Pareto front. A key feature of this framework is the introduction of a cross-regional service coordination mechanism, which leverages spatially heterogeneous resources to improve system-wide efficiency. Numerical experiments using three representative districts in Shenzhen, including Futian, Luohu, and Longhua, demonstrate that the model consistently prioritizes the technical upgrading of existing facilities across all regions. Specifically, the results indicate that the hybrid strategy can yield construction cost savings of up to 63.81 million CNY in a single region. Furthermore, regional heterogeneity is shown to fundamentally reshape network topographies: high-demand, high-cost districts such as Futian strictly limit new construction in favor of cross-regional sharing, whereas peripheral regions like Longhua evolve into energy hubs that absorb global spillover demand. The analysis identifies a nonlinear, convex relationship between total system costs and cross-regional service capacity. Establishing the cross-regional synergy threshold within a 30% to 40% interval is found to maximize the marginal benefits of resource complementarity and achieve near-global economic efficiency, thereby mitigating the negative effects of traffic congestion penalties associated with excessive cross-regional coordination.