Yolk-shelled silicon/carbon materials (YS-Si/C) are the most promising anode candidates to further improve the energy density of commercial lithium-ion batteries. Yet, limited conductive promotion and low tap density resulting from hollow spaces, and complex fabrication processes caused by employing various templating methods, are still critical issues for practical applications of YS-Si/C. In this work, a suite of YS-Si/C anode materials with confined Si-yolks by the C-shell without and with carbon nanotubes (each confines a Co₃O₄ nanoparticle on its tip) on the outer, inner and both sides of the C-shell were facilely and controllably synthesised. The best YS-Si/C anode with carbon nanotubes on both sides of the C-shell can achieve an excellent reversible capacity of 220 mAh g^-1 under 40.0 A g^-1 with 100% reversible capacity retention after 1200 cycles. Importantly, an electrochemical transmission electron microscope measurement system was assembled and applied for the concurrent in operando quantification of the exerted mechanical force and real-time structural responses of YS-Si/C during lithiation/delithiation and Li dendrite formation/dissolution processes, which can be used to gain new insights into the phenomenological structural changes, providing valuable guidance for the rational structural design of high-performance electrode materials.

Sodium‐ion batteries (SIBs) and sodium‐ion capacitors (SICs) are promising candidates for cost‐effective and large‐scale energy storage devices. However, sluggish kinetics and low capacity of traditional anode materials inhibit their practical applications. Herein, a novel design featuring a layer‐expanded MoS₂ is presented that dual‐reinforced by hollow N, P‐codoped carbon as the inner supporter and surface groups abundant MXene as the outer supporter, resulting in a cross‐linked robust composite (NPC@MoS₂/MXene). The hollow N, P‐codoped carbon effectively prevents agglomeration of MoS₂ layers and facilitates shorter distances between the electrolyte and electrode. The conductive MXene outer surface envelops the NPC@MoS₂ units inside, creating interconnected channels that enable efficient charge transfer and diffusion, ensuring rapid kinetics and enhanced electrode utilization. It exhibits a high reversible capacity of 453 mAh g⁻¹, remarkable cycling stability, and exceptional rate capability with 54% capacity retention when the current density increases from 100 to 5000 mA g⁻¹ toward SIBs. The kinetic mechanism studies reveal that the NPC@MoS₂/MXene demonstrates a pseudocapacitance dominated hybrid sodiation/desodiation process. Coupled with active carbon (AC), the NPC@MoS₂/MXene//AC SICs achieve both high energy density of 136 Wh kg⁻¹ at 254 W kg⁻¹ and high‐power density of 5940 W kg⁻¹ at 27 Wh g⁻¹, maintaining excellent stability.