Regulating the solid product growth is critical for achieving high capacities in rechargeable batteries based upon multi-phase and multi-electron dissolution-precipitation chemistries(e.g.lithium–sulfur chemistry).The intrinsic redox mediators,polysulfides,are insufficient for effective regulation due to the dynamically changed species and concentration.Herein cobaltocene(CoCp2)was introduced as a persistent extrinsic redox mediator to dictate an alternative growing pathway toward three-dimensional lithium sulfide growth,which enabled at most 8.1 times enhancement in discharge capacities at harsh conditions of high-rate(> 1 C)or electrolyte-lean operation(electrolyte/sulfur ratio of 4.7 μL mgS-1).The faster kinetics and higher diffusivity of CoCp2 play an essential role in regulating lithium sulfide growth and increasing discharge capacities.This work not only illustrates an effective strategy to increase the capacity of highrate or electrolyte-lean lithium–sulfur batteries but also paves a way toward the rational design of novel redox mediators for dissolution-precipitation energy chemistries.