Xiaoyu Cao

Aqueous zinc‐ion batteries (AZIBs) have emerged as candidates for large‐scale and flexible energy storage owing to abundant zinc resources, low cost, high theoretical capacity, and intrinsic safety. Conventional liquid electrolytes remain limited by a narrow electrochemical stability window, hydrogen evolution, corrosion‐induced parasitic reactions, zinc dendrite growth, and electrolyte leakage, hindering practical deployment. Hydrogel electrolytes have evolved beyond quasi‐solid media into structurally programmable platforms that integrate polymer networks, bound water, and ionic species to regulate water activity, Zn ²⁺ solvation environments, ion transport, and interfacial reactions. This review presents a cross‐scale design framework for multifunctional hydrogel electrolytes in AZIBs, encompassing structural foundations, multiscale regulation strategies, and device‐level applications. The structural classification, electrochemical advantages, and fundamental design principles of hydrogel electrolytes are summarized. Nine representative regulation strategies are discussed, from molecular interactions to network architectures and interfacial engineering, including solvation regulation, hydrogen‐bond reconstruction, hierarchical crosslinking, ordered transport channels, spatially heterogeneous structures, and dynamic dual‐network designs. The emerging applications of hydrogel electrolytes in wearable electronics, multifunctional integrated devices, and physiological‐environment‐compatible bioelectronics are further highlighted. The mechanistic and engineering challenges are analyzed, and a cross‐scale synergistic design pathway is proposed to accelerate the transition of hydrogel electrolytes from empirical optimization toward predictable and engineering‐reliable systems.

Attracted by ∼100% element recovery rate, direct regeneration of spent NCM (SNCM) has been deemed as next‐generation recycling strategy. However, practical SNCM is always mixed with inactive impurities (PVDF and conductive carbon), which introduces undesirable heteroatoms and serious secondary damage, resulting in inferior performance. Herein, we propose a vacuum‐assisted impurities removing strategy to upcycle SNCM with tailored spin states of vital elements. Accompanied with triggered electronic configuration reconstruction of Ni/Mn species, the as‐formed strengthened Ni ²⁺ –O ²⁻ –Mn ⁴⁺ superexchange brings about built‐in electric field and robust lattice structures with minor distortions. Meanwhile, oxygen vacancy formation energy increases about 1.1 eV, and electron localization effect is greatly alleviated, leading to durable stability and rapid reaction kinetics. The as‐optimized samples exhibit high capacity retention of 93.5% at 1.0 C after cycling. Even at ultra‐high rates of 8.0 C and 10.0 C, they could retain 116.7 and 110.4 mAh g ⁻¹ . Assisted by kinetics analysis and in/ex situ measurements, enhanced Li‐diffusion and eliminated internal strains are revealed. Moreover, this strategy could be applied to upcycle spent NCM613, Ni65 and NCM811. This work is expected to illustrate the advantages of electronic configuration reconstruction and superexchange interaction creation during regeneration, meanwhile offer full‐process regeneration strategies toward upcycled NCM.

Attracted by ∼100% element recovery rate, direct regeneration of spent NCM (SNCM) has been deemed as next‐generation recycling strategy. However, practical SNCM is always mixed with inactive impurities (PVDF and conductive carbon), which introduces undesirable heteroatoms and serious secondary damage, resulting in inferior performance. Herein, we propose a vacuum‐assisted impurities removing strategy to upcycle SNCM with tailored spin states of vital elements. Accompanied with triggered electronic configuration reconstruction of Ni/Mn species, the as‐formed strengthened Ni ²⁺ –O ²⁻ –Mn ⁴⁺ superexchange brings about built‐in electric field and robust lattice structures with minor distortions. Meanwhile, oxygen vacancy formation energy increases about 1.1 eV, and electron localization effect is greatly alleviated, leading to durable stability and rapid reaction kinetics. The as‐optimized samples exhibit high capacity retention of 93.5% at 1.0 C after cycling. Even at ultra‐high rates of 8.0 C and 10.0 C, they could retain 116.7 and 110.4 mAh g ⁻¹ . Assisted by kinetics analysis and in/ex situ measurements, enhanced Li‐diffusion and eliminated internal strains are revealed. Moreover, this strategy could be applied to upcycle spent NCM613, Ni65 and NCM811. This work is expected to illustrate the advantages of electronic configuration reconstruction and superexchange interaction creation during regeneration, meanwhile offer full‐process regeneration strategies toward upcycled NCM.

DNA hydrogels are promising platforms for portable biosensing, but their combination with high-activity catalytic nanomaterials remains hindered by interfacial incompatibility and inconsistent device-level retention. Here, a tube-anchored hydrogel microreactor is developed, coupling Co–Ni dual-atom nanozymes (CoNi DANs), interfacial stabilization, and CRISPR-triggered release within a standard centrifuge tube. CoNi DANs are synthesized on a defect-rich nitrogen-doped carbon scaffold, achieving high metal loading and improved peroxidase-like activity relative to those of their single-atom counterparts. Carboxymethyl cellulose-mediated interfacial stabilization then suppresses CoNi DAN aggregation through electrostatic complementarity and polymeric steric shielding, enabling uniform dispersion of CoNi DANs within the DNA hydrogel. A polydopamine-based dual-anchoring strategy further combines covalent grafting with sequence-specific DNA hybridization, providing a chemically reinforced hydrogel–device interface. Upon target recognition, CRISPR/Cas12a trans-cleavage activity induces controlled hydrogel degradation and on-demand release of CoNi DANs for colorimetric and electrochemical dual-mode readout. Using atrazine as a proof-of-concept analyte, the platform achieves limits of detection of 6.1 and 2.1 pg mL–1 for colorimetric and electrochemical modes, respectively, with satisfactory recoveries in real samples. A smartphone-assisted digital readout module further improves the portability of the colorimetric mode. The dual-interface design, uniting material-level compatibilization with device-level dual-anchoring, provides a generalizable framework for embedding high-activity nanozymes into responsive DNA hydrogel microreactors for portable on-site biosensing.

Direct regeneration is regarded as a next‐generation recycling strategy for spent lithium‐ion batteries (LIBs) owing to high element recovery and low energy consumption. However, limited by pristine design from 5–8 years ago, the simple recovery for spent LiCoO ₂ (LCO) hardly induced the suitable electrochemical abilities for modern energy‐storage systems. Moreover, commercial LCO with conventional O3 phase inherently suffers from poor high‑voltage stability. Herein, using the fading traits of spent LCO as upcycling springboards, they are successfully regenerated toward fresh LCO with O2–O3 intergrown architecture through lattice reconstruction and ion‑exchange‑induced phase transformation. The O2‑phase content is precisely controlled by tailoring Li‑deficiency level of SLCO. Assisted by intertwined lattice dislocations, O2 and O3 phases are coherently interlocked, effectively alleviating lattice expansion and oxygen release. Meanwhile, the lowered energy band (1.359 eV) and diffusion energy barrier (0.375 eV) play important roles for energy‐storage abilities. The optimized material delivers a capacity of 223.3 mAh g ⁻¹ at 0.1 C and retains 90.6% after 100 cycles at 1.0 C, outperforming commercial LCO. With a modified electrolyte, a capacity retention of 73.6% is achieved after 500 cycles at 5C. This work highlights the advantages of O2–O3 intergrown LCO and provides a promising upcycling route toward high‑performance cathodes.