Ultrathin core–shell V3S4@C nanosheets assembled into hierarchical nanotubes (V3S4@C NS‐HNTs) are synthesized by a self‐template strategy and evaluated as general anodes for alkali‐ion batteries. Structural/physicochemical characterizations and DFT calculations bring insights into the intrinsic relationship between crystal structures and electrochemical mechanisms of the V3S4@C NS‐HNTs electrode. The V3S4@C NS‐HNTs are endowed with strong structural rigidness owing to the layered VS2 subunits and interlayer occupied V atoms, and efficient alkali‐ion adsorption/diffusion thanks to the electroactive V3S4‐C interfaces. The resulting V3S4@C NS‐HNTs anode exhibit distinct alkali‐ion‐dependent charge storage mechanisms and exceptional long‐durability cyclic performance in storage of K+, benefiting from synergistic contributions of pseudocapacitive and reversible intercalation/de‐intercalation behaviors superior to those of the conversion‐reaction‐based Li+‐/Na+‐storage counterparts.

Metallic bismuth has drawn attention as apromising alloying anode for advanced potassium ion batteries (PIBs). However,s erious volume expansion/electrode pulverization and sluggish kinetics always lead to its inferior cycling and rate properties for practical applications.T herefore,a dvanced Bibased anodes via structural/compositional optimization and sur-/interface design are needed. Herein, we develop abottomup avenue to fabricate nanoscale Bi encapsulated in a3 DNdoped carbon nanocages (Bi@N-CNCs) framework with av oid space by using an ovel Bi-based metal-organic framework as the precursor.W ith elaborate regulation in annealing temperatures,t he optimizedB i@N-CNCs electrode exhibits large reversible capacities and long-duration cyclic stability at high rates when evaluated as competitive anodes for PIBs. Insights into the intrinsic K +-storage processes of the Bi@N-CNCs anode are put forward from comprehensive in situ characterizations.

This review elaborately summarizes the latest progresses in flexible non-lithium rechargeable batteries including flexible electrode construction, separators, solid electrolyte synthesis, full battery design, packaging and optimization.

Ultrathin core–shell V3S4@C nanosheets assembled into hierarchical nanotubes (V3S4@C NS‐HNTs) are synthesized by a self‐template strategy and evaluated as general anodes for alkali‐ion batteries. Structural/physicochemical characterizations and DFT calculations bring insights into the intrinsic relationship between crystal structures and electrochemical mechanisms of the V3S4@C NS‐HNTs electrode. The V3S4@C NS‐HNTs are endowed with strong structural rigidness owing to the layered VS2 subunits and interlayer occupied V atoms, and efficient alkali‐ion adsorption/diffusion thanks to the electroactive V3S4‐C interfaces. The resulting V3S4@C NS‐HNTs anode exhibit distinct alkali‐ion‐dependent charge storage mechanisms and exceptional long‐durability cyclic performance in storage of K+, benefiting from synergistic contributions of pseudocapacitive and reversible intercalation/de‐intercalation behaviors superior to those of the conversion‐reaction‐based Li+‐/Na+‐storage counterparts.

Multi-dimensional MnS@CNWs/rGO hybrid paper is smartly constructed and it exhibits ultra-stable and high-rate gravimetric/volumetric capacities towards Na-ion batteries as a flexible self-standing anode.

Metallic bismuth has drawn attention as a promising alloying anode for advanced potassium ion batteries (PIBs). However, serious volume expansion/electrode pulverization and sluggish kinetics always lead to its inferior cycling and rate properties for practical applications. Therefore, advanced Bi‐based anodes via structural/compositional optimization and sur‐/interface design are needed. Herein, we develop a bottom‐up avenue to fabricate nanoscale Bi encapsulated in a 3D N‐doped carbon nanocages (Bi@N‐CNCs) framework with a void space by using a novel Bi‐based metal‐organic framework as the precursor. With elaborate regulation in annealing temperatures, the optimized Bi@N‐CNCs electrode exhibits large reversible capacities and long‐duration cyclic stability at high rates when evaluated as competitive anodes for PIBs. Insights into the intrinsic K+‐storage processes of the Bi@N‐CNCs anode are put forward from comprehensive in situ characterizations.

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The specific chemical and physical evolutions of electrode materials under operating conditions should be understood to optimize their electrochemical performances. The in-situ/operando techniques including Raman spectrum, transmission electron microscope, X-ray diffraction, X-ray absorption spectrum, and magnetization are powerful tools, which can provide the real-time surficial/interfacial changes of electrodes, the transformation of crystal lattice structures, the adjustment of electronic states and even the influence of magnetic properties under operating conditions. In this Review, the advantages and limitations of these in-situ/operando techniques in investigating the inner energy storage mechanisms of various type electrode materials are analyzed. The representative research results such as the ion dependent storage mechanism, step-alloying processes and space charge storage theory are highlighted. In addition, the challenges and opportunities of in-situ/operando characterizations are proposed as well.