Carbonaceous materials have been demonstrated as the promising anode for potassium ion batteries (KIBs). However, up to now, limited number of strategies could improve the power density of carbonaceous anode without sacrificing the energy density, showing restricted stability and rate capability. In this manuscript, a defect-rich and interlayer spacing expanded graphene cushion (GC) is employed to build expressway network for K⁺ transport in soft carbon (SC) and buffer the volumetric variation. Meanwhile, SC is divided into nanodomains by GC, in which the diffusion distance is shortened and fracture energy is increased. During the electrochemical reaction process, K⁺ is preferentially transported along the wall of GC and then diffuses into/out of SC nanodomains. At 1.6 A g^-1, the voltage polarization decreases from 2.02 V of SC to 0.54 V of SCGC, and the discharge specific capacity increases from 4.9 to 197.6 mAh g^-1. Additionally, the unique cushion structure with high Young's modulus can increase the expansion tolerance and guarantee a long service life. The cycling stability test shows a capacity retention of 72.2% even after 1000 cycles at 1 A g^-1. Thus, this type of anode materials might be potentially suitable for high performance KIBs.

Synergistic effects between hard carbons and soft carbons are proven to be helpful for improving the electrochemical performance of carbonaceous anode for potassium-ion batteries (PIBs). However, the phase separation of precursors limits the synergistic effects and improvement of electrochemical performance. Here, inspired by the esterification reaction, the precursors of two sorts of carbon are connected at the molecular level, which boosts the synergistic effects in hybrid carbon, resulting in excellent electrochemical kinetics and low charge/discharge voltage. Consequently, the hybrid carbon anode exhibited a high specific capacity of 121 mAh·g⁻¹ at 3.2 A·g⁻¹, a high-rate capability, and stable cycling performance. After 500 cycles at 1 A·g⁻¹, the average capacity fading is only 0.078% per cycle.