Xiaobo Ji

Room-temperature sodium–sulfur (RT Na–S) batteries have emerged as viable options for large-scale energy storage due to the plentiful supply and inexpensive cost of Na and S. However, their application is limited by poor conductivity, severe polysulfide shuttling, and slow redox kinetics. While conventional RT Na–S batteries suffer from the dissolution and migration of soluble polysulfide intermediates, sulfur confinement within microporous carbon can restrict long-chain polysulfide dissolution and promote a more spatially confined sulfur conversion pathway, thereby improving cycling stability and efficiency. This study involved the synthesis of hierarchically porous carbon materials from Luffa cylindrica through temperature controlled carbonization, which are then utilized as sulfur host matrices. The modified S/LC-1000 composite exhibits a well-developed micro/mesoporous structure and strong sulfur–carbon interactions. The optimized microporous/mesoporous LC-1000 host likely suppresses the dissolution of long-chain sodium polysulfides and promotes a more confined sulfur redox pathway. This pathway modulation, driven by sulfur confinement within micropores, enables efficient polysulfide immobilization while simultaneously facilitating enhanced ion/electron transport and improving overall electrochemical reversibility, thereby leading to improved stability and performance. The S/LC-1000 exhibits an initial discharge capacity of 1730 mAh g–1 and sustains about 1360 mAh g–1 after 300 cycles at 0.5 C while sustaining about 677 mAh g–1 after 10,000 cycles at 5C, demonstrating enhanced rate capability and diminished charge-transfer resistance. This study presents a sustainable and efficient approach for developing biomass-derived carbon hosts to address critical constraints of RT Na–S batteries and enhance their application.

Na2CO3 is a promising sacrificial presodiation agent owing to its high capacity, excellent air stability, and low cost. However, its practical application is severely hampered by a high decomposition overpotential (>4.3 V vs Na/Na+), inducing detrimental electrolyte oxidation and cell degradation. To break this high-voltage limit, we propose an in situ interfacial dual-modification strategy, synergistically introducing interfacial oxygen vacancies and triggering electronic reconstruction, which thermodynamically lowers the reaction Gibbs free energy and kinetically diminishes the activation barriers, resulting in a dramatically reduced decomposition potential by 350 mV. Operando three-electrode diagnostics within a full sodium-ion capacitor reveal that this interface engineering not only facilitates efficient Na+ release (496.9 mAh g–1) at lower potential but also reduces the actual working potential of cathode, thereby fundamentally avoiding high-voltage parasitic reactions, according well with the DEMS and TOF-SIMS results. Consequently, the full cell achieves a considerable 117.4% enhancement in energy density. Most importantly, this strategy demonstrates compelling practicality in ampere-hour-level devices, delivering a substantial 22.4% boost in energy density with only 3 wt % additive in 1.5 Ah pouch cells. This work bridges microscopic interfacial chemistry and macroscopic device performance, providing a scalable and efficient blueprint for low-potential presodiation toward high-energy-density sodium-ion devices.

A data-driven workflow decouples electronic and geometric descriptors to enable ML-accelerated discovery of sacrificial additives for stable Li–metal battery interfaces.

Hard carbons (HCs) are highly promising anodes for sodium‐ion batteries (SIBs). However, the elusive relationship between pore‐wall defects and closed‐pore structures severely impedes their rational design. Herein, a pioneering bottom‐up strategy is demonstrated, employing carbon dots (CDs) as transitional building blocks to construct micropore‐rich HCs with tuned curvature. The diffusion constraints of peripheral aliphatic chains surrounding the CDs induce highly rigid ester cross‐linking, achieving a misaligned stacking design of the precursors to eventually yield a defect‐rich, turbostratic framework with abundant closed pores. Consequently, the optimized anode delivers an exceptional specific capacity of 365.0 mAh g ⁻¹ and an initial coulombic efficiency (ICE) of 85.06%. Crucially, a novel “pore‐wall defect‐mediated sodium cluster nucleation” mechanism is unveiled to resolve the asymmetric kinetics, demonstrating that vacancy‐associated sites facilitate local charge transfer while the pore‐walls suppress the formation of charge‐transfer‐impeding SEI, thereby inducing quasi‐metallic sodium clustering. This work bridges the spatiotemporal gaps between defects and closed pores, as well as adsorption and pore‐filling stages, promoting the development of next‐generation advanced HC anodes for SIBs.

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.

Developing advanced sodium-storage electrodes is of great importance for the advancement of sodium-ion batteries; herein, s-indacene-1,3,5,7(2H,6H)-tetraone (ICTO) is employed for the first time as an anode material for sodium-ion batteries (SIBs). By converting anhydride groups into conjugated carbonyl groups, the structural stability during sodium storage is largely enhanced. The ICTO half-cell delivers a high specific capacity of 379 mAh g–1 at 0.05 A g–1, with an adsorption-dominated sloping region contributing 350 mAh g–1. When assembled into a full cell with a sodium iron pyrophosphate phosphate (NFPP) cathode, the ICTO||NFPP system achieves an ultrahigh energy density of 190.04 Wh kg–1 and an exceptional initial Coulombic efficiency (ICE) of 99.99%. This work provides a new strategy for enhancing sodium storage performance in conjugated carbonyl organic small molecules.

Li-rich cation-disordered rocksalts (DRXs) are promising active materials for designing high-capacity positive electrodes for non-aqueous lithium-based batteries. However, the use of DRX-based positive electrodes results in pronounced cell potential hysteresis and low energy efficiency. The reasons for these detrimental behaviours remain unclear owing to the complex structural evolution of DRXs during battery operation. Here, via extensive physicochemical and electrochemical characterizations, we show that multiscale stereochemistry, particularly structure distortion at the atomic scale and short-range ordering in nanoscale domains, can thermodynamically and kinetically affect the potential hysteresis of Li||DRX cells. By using DRX models, we show that redox-inactive d⁰ transition metals (d⁰ TMs) influence the regulation of localized nanostructures. In particular, the out-of-centre distortion of d⁰ TMO₆ octahedra, driven by the pseudo Jahn–Teller effect, decreases cation short-range order, thereby facilitating a high-rate Li⁺ percolation pathway. Moreover, the pseudo Jahn–Teller effect of d⁰ TMs is found to weaken the ligand-to-metal charge transfer process of Ni–O and thermodynamically enhance the reversibility of the lattice oxygen redox. As a result, the kinetic and thermodynamic factors contributing to the potential hysteresis of Li metal cells with Nb-containing DRX at the positive electrode are effectively mitigated.

Layered oxide cathodes for sodium‐ion batteries are among the most promising candidate materials for large‐scale energy storage systems. However, they are sensitive to humid air during electrode processing and suffer from spontaneous surface degradation primarily manifested as residual alkali species such as NaOH, Na ₂ CO ₃ , and NaHCO ₃ , causing electrochemical performance degradation and delay of industrialization. Although similar surface alkali issues exist in lithium‐ion layered oxide cathodes, it brings distinct and more complex challenges in sodium‐ion batteries due to the unique presence of NaHCO ₃ , the severe Na ⁺ /H ⁺ exchange tendency, and the narrower processing windows, which, however, have received very limited attention in the last few years. This review discusses the residual alkali issue in layered oxide cathodes of sodium‐ion batteries from the formation mechanisms to characterization techniques as well as modification strategies. Particular emphasis is put on the aforementioned sodium‐specific chemistry (e.g., NaHCO ₃ ) and derived differences from the well‐established lithium‐ion systems, as well as related research perspectives in the future, aiming to stimulate the development of air‐stable, high‐performance sodium‐ion layered oxide cathodes toward practical applications.

Elevating the operating voltage of sodium metal capacitors (SMCs) to 4.5 V is crucial for achieving higher energy density, however, conventional carbonate‐based electrolytes suffer from cathode interfacial decomposition, disordering of the electric double‐layer (EDL) structure, and poor anode compatibility under high voltage. This study proposes an anion‐centered solvation reconstruction strategy. By introducing a low‐solvation molecular modulator that selectively coordinates with PF ₆ ⁻ anions, an anion‐dominated ordered EDL architecture is constructed on the cathode surface. This structure effectively suppresses EDL disordering and solvent oxidation under high voltage. Molecular energy‐level alignment enables sequential interfacial engineering: an ultra‐thin, high‐voltage‐adapted CEI‐EDL coupled interface on the cathode, and an F/B‐rich solid electrolyte interphase (SEI) on the anode for homogeneous sodium plating/stripping. With this designed all‐fluorinated electrolyte, the resulting SMCs achieve remarkably boosted performance within 2–4.5 V, delivering a high energy density of 185 at 300 W kg ⁻¹ , and an outstanding power density of 112.8 at 15 000 W kg ⁻¹ . This work not only demonstrates a viable high‐voltage SMCs system but, more importantly, establishes a distinctive anion‐centric solvation engineering paradigm, providing a novel approach for developing advanced storage devices with high‐energy/power density.