Sodium-ion capacitors (SICs), recognized for their low cost, safety, and high-power output capabilities, have emerged as a promising complement to sodium-ion batteries. However, their hybrid design, which integrates a sluggish battery-type negative electrode with a fast capacitive positive electrode, presents a significant challenge: kinetics mismatch. This mismatch often results in reduced energy delivery at high rates. Herein, we introduce a novel composite structure where metallic Bi nanoparticles are uniformly embedded within amorphous carbon microsheets (referred to as Bi–C). This innovative design effectively mitigates the Na⁺ diffusion limitations and the substantial volume changes of Bi during sodiation, facilitating rapid and durable alloying processes. This Bi–C composite anode can then operate efficiently at high rates exceeding 100.0 A·g⁻¹ and maintains stability over 10,000 cycles, effectively bridging the kinetic gap with a capacitive porous carbon cathode. A SIC based on this kinetically and mechanically optimized Bi–C composite anode achieves unprecedented levels of energy and power outputs, delivering a maximum energy density of 131 Wh·kg⁻¹, an exceptionally high specific power of 112.5 kW·kg⁻¹, and a long cycling life over 20,000 cycles. Moreover, this SIC demonstrates stable performance even at low temperatures down to −40 °C.

Metal-ion capacitors (including Li⁺, Na⁺, and K⁺) effectively combine a battery negative electrode capable of reversibly intercalating metal cations, together with an electrical double-layer positive electrode. However, such novel cell design has a birth defect, namely kinetics mismatch between sluggish negative electrode and fast positive electrode, thus limiting the energy-power performance. Herein, we design a MoS₂-carbon composite anode with the ordered macroporous architecture and interlayer-expanded feature, exhibiting the fast and reversible Na⁺ redox processes. This kinetically favored anode is coupled with a homemade activated carbon cathode that allows for the excellent electrochemical performance of sodium-ion capacitor with respect to large specific capacity, high-rate capability, and robust cycling. Through quantification of the potential swings of anode and cathode via a three-electrode Swagelok cell, we for the first time observe the abnormal variation law of potential swings and thus directly providing the evidence that the kinetics gap has been filled up by this kinetically favored anode. Our results represent a crucial step toward understanding the key issues of kinetics mismatch for hybrid cell, thus propelling the development of design of kinetically favored anode materials for high-performance metal-ion capacitors.