混合离子导体能够同时传导多种离子，为探究单一相中混合离子传输对离子电导调控机制提供了重要支持。然而，多种可迁移离子在固态电解质中的可控引入及其在晶体骨架内的迁移机理仍面临挑战。本文采用一种骨架保持的Li⁺↔Na⁺阳离子交换策略，在NASICON型Li_3-xNa_xZr₂Si₂PO₁₂ (0 < x < 3)的骨架中同时引入Li⁺和Na⁺。研究表明，NaO₆和NaO₈配位多面体的相互贯通对混合离子导体的离子电导率具有显著影响。计算分析显示，Na⁺更倾向于从八面体配位的NaO₆位点迁移至八配位的NaO₈位点，同时伴随Li⁺从NaO₈位点向原NaO₆位点处的四面体LiO₄环境迁移，从而促进Li⁺/Na⁺位点分离。随着Na⁺在NaO₈位点占据比例的增加，瓶颈效应限制了Na⁺的迁移，同时阻碍了连续Li⁺迁移网络的形成，导致离子电导率由1.78 mS·cm^-1降低至0.50 mS·cm^-1。经再次离子交换后，NaO₈环境中的Na⁺被Li⁺所取代，形成五配位的LiO₅，从而重建Li⁺的渗透传输通道，实现体电导的可逆恢复。该研究揭示了基于Li⁺与Na⁺在可用位点间分散占据的快速双离子传导机制，为进一步发展固态混合离子导体开辟了新途径。

Hybrid ion conductors that transport multiple ionic conductive species provide a useful platform for understanding how mixed-ion transport governs ionic conductivity within a single phase. However, the controlled introduction of multiple mobile ions into solid-state electrolytes and a mechanistic understanding of their migration within the framework remain challenging. Herein, a skeleton-retained Li⁺↔Na⁺ cationic exchange was used to simultaneously induce Li⁺ and Na⁺ cations into the NASICON-type framework of Li_3-xNa_xZr₂Si₂PO₁₂ (0 < x < 3). We show the interpenetration of NaO₆ and NaO₈ coordination polyhedra significantly influences the ionic conductivity of hybrid ion conductors. Computational analysis indicates that Na⁺ transfer from octahedral NaO₆ sites to octa-coordinated NaO₈ sites is thermodynamically favorable, accompanied by  Li⁺  relocation from NaO₈ to tetrahedral LiO₄ environments at former NaO₆ sites, thereby promoting Li⁺/Na⁺ site segregation. The increased occupation of Na⁺ at NaO₈ sites not only suppresses Na⁺ mobility due to bottleneck limitations but also hinders the formation of a continuous Li⁺ migration network, thereby reducing the room-temperature ionic conductivity from 1.78 to 0.50 mS·cm^-1. Upon re-exchange,  Na⁺  in the NaO₈ sites is replaced by Li⁺ in penta-coordinated LiO₅, which re-establish percolating ion-transport pathways for Li⁺ and enable reversible recovery of the overall conductivity. These results reveal a fast dual-ion conduction mechanism enabled by the interpenetrating occupation of Li⁺ and Na⁺ across the available sites. This work opens a new avenue for the development of hybrid ion conductors.