A MXene Colloid Electrolyte With Spatiotemporally Continuous Ion Transport for Fast-Charging Lithium Metal Batteries

Dendrite growth and interfacial instability in lithium metal batteries are closely associated with imbalanced lithium-ion transport, particularly at high current densities. Such an imbalance reflects the loss of spatiotemporal continuity in Li⁺ supply during cycling, manifested by localized amplification of potential and insufficient Li⁺ replenishment. Herein, a sulfonated MXene (Ti₃C₂(SO₃H)_x) colloid electrolyte is developed to regulate Li⁺ transport through the concurrent modulation of solvation structure and electric potential distribution. The ─SO₃H surface terminations alter the Li⁺ coordination environment and lower the interfacial desolvation barrier, while conductive MXene sheets redistribute local potential and current density, jointly shaping Li⁺ transport behavior. This electrolyte mitigates spatial localization of ion flux and sustains interfacial Li⁺ replenishment under high current densities, leading to uniform Li metal deposition. As a result, the MXene colloid electrolyte achieves a high Li⁺ transference number of 0.89, facilitating efficient Li⁺ transport. Consequently, Li||NCM622 cells employing the MXene colloid electrolyte achieve outstanding fast-charging capability and cycling durability at 10 C, delivering twice the cycle life of cells with the baseline electrolyte under equivalent capacity retention. This study shows that the MXene colloid electrolyte design achieves spatiotemporally continuous Li⁺ transport, providing a guiding framework for designing fast-charging lithium metal battery electrolytes.