Electrochemical conversion of CO2 into chemicals and fuels offers a promising route towards a circular carbon economy. High-temperature CO2 electroreduction in solid oxide electrolysis cells (SOECs) delivers high selectivity and energy efficiency, but suffers from a tradeoff between mechanical robustness and electrochemical activity. Here we resolve this constraint using a hybrid ionic-conductor architecture that decouples electrocatalysis, ionic transport and mechanical support into function-specific layers. The resulting cell achieves one of the highest reported mechanical strengths (fracture load >7 N), while delivering 1.5-3.0fold higher CO2-to-CO activity than state-of-the-art SOECs over operating temperatures of 600-800 °C. Stable operation is maintained for over 1,000 hours at a current density of 1.0 A cm-2. Furthermore, we demonstrate scalability with a single-cell area of 100 cm 2 , achieving total currents up to 120 A and powers up to 200 W. This work establishes a general strategy for developing mechanically resilient, efficient, and scalable energy conversion devices.

Lattice-oxygen redox in layered oxides can enhance energy density, but its limited reversibility causes structural instability during deep cycling. Here we develop an iron-mediated strategy to regulate lattice-oxygen redox in layered oxide cathodes. In the Na2/3Mn7/12Mg1/4Fe1/6O2 cathode, Fe ions act as redox mediators, with Fe4+ capturing electrons from lattice oxygen during charging and Fe2+ donating electrons back to oxidized oxygen during discharging through chemical pathways. With the assistance of iron mediation, the reversibility of lattice-oxygen redox is dramatically improved from 75% to 99%. As a result, the lattice-oxygen-activated cathode enables a sodium-ion pouch cell to achieve an energy density of 206 Wh kg−1 and operate stably for 100 cycles at 50 mA g−1, with a capacity retention of 87.8%. Lattice-oxygen redox can raise the energy density of layered oxide cathodes, but poor reversibility causes structural degradation and capacity loss. Here the authors use iron as a bulk redox mediator to boost oxygen-redox reversibility and stabilize high-energy sodium-ion batteries.

Due to the increasing energy crisis and environmental pollution,it is urgent to develop new clean energy.However,due to its intermittent and regional characteristics,the efficient utilization of these energy sources through electrocatalytic conversion reactions has emerged as a key research focus.Currently,some commercially utilized alloy electrocatalysts often face challenges such as rapid degradation of catalytic activity,poor selectivity,and environmental unfriendliness.The adoption of a high-entropy strategy can effectively address these issues.As an emerging nanomaterial,high-entropy alloys(HEAs)primarily consist of no fewer than five metallic elements and show obvious advantages,including highly tunable compositions,abundant surface active sites,excellent chemical/electrochemical stability,etc.These properties enable effectively optimization of electronic structures and enhancement of atomic utilization,demonstrating broad application prospects.This paper starts with the synthesis strategies of HEAs,systematically elaborates on several common preparation methods,and introduces the latest advancements in electrocatalysis and secondary batteries.Finally,the current challenges for HEAs are summarized,and their future development is projected.

The application of medium-/high-entropy materials has revolutionized the design of solid-state electrolytes (SSEs) by stabilizing single-phase solutions from otherwise incompatible elements. However, navigating the vast compositional space of entropy-stabilized materials remains a significant challenge. To overcome this, we introduce a machine learning (ML)-accelerated approach to identify multi-cation NASICON oxide SSEs. By training a Gaussian Naive Bayes model on four key descriptors (ionic radius, electronegativity, valence state, and configurational entropy), we found four promising compositions incorporating Zr, Ti, Hf, Lu, Ga, and Sc. These compositions exhibit notable entropy-driven stabilization, demonstrated by the complete suppression of Na3PO4/ZrO2 impurity formation. Among them, the medium-entropy phase Na3.5Zr1.0Ti0.5Lu0.5Si2PO12 achieved remarkable performance, delivering an ionic conductivity of 1.3 mS cm-1 at room temperature, a critical current density of 1.9 mA cm-2, and over 10 000 hours of stable Na plating/stripping. When integrated into all-solid-state sodium batteries with a high-voltage Na3V2(PO4)2F3 cathode and a sodium anode, it further demonstrated exceptional battery performance indicators, including high-rate capability (110 mAh g-1 at 5C) and long-term cycling stability (80% capacity retention after 700 cycles at 2C). This work establishes entropy engineering, coupled with ML guidance, as a powerful paradigm for the rational design of next-generation SSEs.

Achieving <15 min fast-charging technology for long-life sodium-ion batteries (SIBs) remains a formidable challenge, primarily due to parasitic reactions and unstable solid-electrolyte interphase (SEI) at the hard carbon (HC) interface. Here we develop a universal polymer-induced SEI strategy that enables an Ah-level SIB pouch cell to achieve <10 min fast-charging capability. We design a <4.0 nm functionalized polymer molecular layer, polyethylenesulfonyl fluoride (PESF), coated on the HC surface (PolyHC) to minimize electrolyte decomposition. The PESF with the -SO2F group attached has a powerful polar feature, which simultaneously induces an anion enriched at the PolyHC interface and tailors extra F atoms, contributing to the architecture of a ∼5.0 nm stable SEI that hybridizes polymer and NaF. This SEI with a resilient polymer skeleton permanently holds the generated inorganic component, enabling long-term structural stability during fast charging. The assembled 1.2 Ah pouch cell, paired with NaNi1/3Fe1/3Mn1/3O2 cathode and PolyHC anode, displays exceptional fast-charging capability and durability. This method is compatible with various HCs, offering a novel perspective for modulating the HC interface chemistry.

Sodium-ion batteries offer promise for large-scale energy storage, yet the environmental sensitivity of layered cathode materials significantly hinders commercialization. Current strategies often fail to simultaneously address water intercalation and cation exchange while maintaining electrochemical performance. Here, we demonstrate a nanoscale surface engineering approach through the formation of a precisely controlled ∼20 nm [BO3] gradient on layered oxide cathode surfaces. This gradient integration creates a protective interface by coordinating with [MnO6] polyhedra at the material surface, as confirmed by EELS analysis and DFT calculations. The surface-modified P2-Na0.67Mn0.88Al0.12B0.05O2 (NMABO) cathodes deliver 176 mAh g-1 initial capacity at 0.2C and 80.1% retention after 1000 cycles at 10C. Crucially, the engineered interface enables exceptional moisture resistance in NMABO with 80.3% capacity retention after 1300 cycles following 14-day air exposure and shows minimal capacity loss after 2-year storage under controlled conditions. Mechanistic investigations reveal that the [BO3] gradient simultaneously inhibits Jahn-Teller distortion and creates energetic barriers against H2O intercalation and Na+/H+ exchange. The strategy's universality is further validated on commercial O3-NaNi1/3Fe1/3Mn1/3O2 cathodes, which demonstrate robust stability in humid air and confirm superior acid and oxidation resistance. This work establishes a scalable approach for enhancing the environmental stability of sodium layered oxides through rational nanoscale interface design, addressing the fundamental degradation in ambient conditions.

The d orbital physics are closely related to the catalytic activity of transition-metal-based catalysts in Li-S batteries. However, challenges remain in understanding the optimal electronic configuration, causing a lack of guidance in the precise design of catalysts. Herein, by virtue of LaCoO3-based catalysts with different combinations of low-spin states and high-spin states of Co3+, a volcano relationship between dz2 filling number (from 0.95 to 1.29) and S/Li2S redox reaction kinetics is revealed. The best kinetics are provided at the dz2 filling number of 1.12. As a result, the assembled Li-S battery shows a low decay rate of 0.026% per cycle in a 1500-cycle test and a high energy density of 460.7 Wh kg-1 in a practical pouch cell. This work reveals the critical influences of dz2 electronic states on catalyzing the S/Li2S redox reaction and provides insights into finely regulating the electronic structures of high-performance catalysts for practical Li-S batteries.

The ongoing energy revolution and technological development of energy storage require high-energy-density lithium battery systems beyond 500 Wh kg-1. However, the commercialized lithium-ion batteries using graphite as the anode with a limited theoretical energy density of about 350 Wh kg-1 are far from this goal. Promisingly, the lithium metal batteries (LMBs) matched with a variety of cathode materials have great potential to achieve ultra-high-energy-densities in practice. Nevertheless, the energy density of LMBs depends greatly on the energy density of different types of cathodes. Therefore, research on how to improve the output energy density and durability of various cathode materials under practical working conditions is essential for realizing the ultra-high-energy-density LMBs. In this review, we systematically explore the pathway to achieving high-energy and durable LMBs from the perspective of key cathode materials to pouch cell configuration design. We discuss the fundamental characteristics and key challenges of five promising cathode materials, including a lithium cobalt oxide cathode, a high-nickel oxide cathode, a Li-rich oxide cathode, a sulfur cathode, and an oxygen cathode, and also summarize the feasible solutions and recent progress in addressing the key bottlenecks. Furthermore, using pouch cell configurations as a typical pattern, we precisely summarize the impact of each component in pouch cells on energy density and provide detailed routes for acquiring the maximum practical energy density by using different cathode materials in pouch cells. This review offers guidelines for promoting the practical applications of high-energy-density LMBs.

The exploitation of emerging anionic redox chemistry opens a promising pathway to boost the capacity of Li-rich layered cathodes. Lithium-rich layered sulfides are receiving unprecedented emphasis to achieve sustainable capacity based on sulfur redox chemistry. However, maintaining high capacities during cycling is still a challenge as Li+ intercalation/deintercalation is only partially reversible, especially for Li2TiS3 model materials. Here, a feasible strategy of electronic structure regulation is adopted to achieve sustainable reversible anionic redox in Li-rich layered sulfides based on the Mott-Hubbard U-Δ theory. The practicality of activating reversible sulfur redox process in Li-rich layered sulfides is verified in partial Ni substituted Li[Li1/3-2x/3NixTi2/3-x/3]S2 (0 ≤ x ≤ 0.3) system. The optimal compound (x = 0.2) delivers the largest sustained reversible capacity up to 237.3 mAh g−1 based on the cumulated cationic and anionic redox mechanism, which is about 3 times as high as the unsubstituted Li2TiS3. Furthermore, it also exhibits outstanding rate capability (76 % capacity retention at 20.0C) and excellent cycling stability (90 % capacity retention after 500 cycles), which is comparable to most of prevailing Li-rich layered oxides and sulfides. This work demonstrates the feasibility of sulfur redox chemistry and provides a fundamental understanding of regulating anionic redox activity for developing high-capacity Li-rich layered cathodes.

Pushing LiCoO 2 (LCO) to a higher upper cut‐off voltage for charging is an effective way to achieve higher energy density. However, this high‐voltage operation intensifies oxygen redox reactions and irreversible sliding of O–Co–O slabs, which result in structural collapse and chemical instability in LCO. Herein, a local oxygen coordination optimization strategy is proposed by introducing transition metal (TM)‐O‐TM configurations to achieve reversible O1 phase transition in 4.8 V LCO. These configurations are formed by doping Ni, Fe, and Al into the lattice, where the Ni/Fe serves as pillars within Li layers, stabilizing the deep de‐intercalation structure and thus facilitating a reversible H1‐3/O1 phase transition at 4.8 V. Additionally, local oxygen environment alternation leads to an increased proportion of high‐spin state Co 3+ , diminishing the hybridization between the Co 3+ 3d‐t 2g and O 2p orbitals, thereby mitigating anion redox reactions. Consequently, lattice oxygen loss and detrimental surface phase degradation are inhibited, thereby preventing an increase in battery polarization voltage and enhancing the reversible H1‐3/O1 phase transformation. Ultimately, this significantly mitigates the accumulation of internal stress and prevents bulk failure during repeated deep (de)lithiation processes, thereby significantly enhancing the capacity retention of the optimized LCO cathode at an ultrahigh voltage of 4.8 V.

Layered oxide cathodes with lattice oxygen activity in sodium‐ion batteries often face poor oxygen redox reversibility and significant voltage decay, attributed to irreversible metal interlayer migration and oxygen loss, resulting in structure and energy degradation during cycling. Herein, a steric‐effect strategy is presented to suppress Li migration and stabilize Na‐O‐Li configurations by incorporating Zn into the conventional Na 0.78 Li 0.26 Mn 0.74 O 2 (NLM) framework, resulting in enhanced reversible lattice oxygen redox and mitigated voltage decay during cycling. In the engineered Na 0.65 Li 0.17 Zn 0.07 Mn 0.76 O 2 (NLZM), Zn simultaneously occupies both Na and transition metal (TM) sites, with Na‐layer Zn preferentially positioning beneath Li within the TM layers, suppressing Li migration into Na layers. This unique Zn configuration stabilizes Na layers through strong Zn─O bonding (ICOHP = −1.34 eV), effectively suppressing TM‐slab glide and mitigating lattice oxygen evolution. X‐ray diffraction and electron diffraction confirm effective mitigation of phase variations and preservation of the LiMn6 superstructure during desodiation/sodiation. Additionally, the NLZM demonstrates highly reversible lattice oxygen redox behavior and stable oxygen coordination (with no oxygen release). Consequently, thanks to the steric effect, NLZM achieves 95.8% voltage retention after 100 cycles, marking a significant improvement over NLM (71.6%) and highlighting the critical role of steric hindrance in stabilizing oxygen‐active cathodes.

In Li-O 2 batteries (LOBs), the electron transfer between triplet O 2 and singlet Li 2 O 2 possesses a spin-dependent character but is still neglected, while the spin-conserved electron transfer without losing phase information should guarantee fast kinetics and reduced energy barriers. Here, we provide a paradigm of spin-selective catalysis for LOB that the ferromagnetic quantum spin exchange interactions between Pt and Fe atoms in fully-exposed PtFe clusters filter directional e-spins for spin-conserved electron transfer at Fe−Fe sites. The kinetics of O 2 /Li 2 O 2 redox reaction is markedly accelerated as predicted by theoretical calculations, showing dramatically decreased relaxation time of the rate determining step for more than one order of magnitude, compared with the Fe clusters without spin-selective behavior. In consequence, the assembled LOB provides ultrahigh energy conversion efficiency of 89.6 % at 100 mA g −1 under a discharge-charge overpotential of only 0.32 V. This work provides new insights into the spin-dependent mechanisms of O 2 /Li 2 O 2 redox reaction, and the strategy of constructing spin catalysts at atomic level.

The inner Helmholtz plane and thus derived solid-electrolyte interphase (SEI) are crucial interfacial structure to determine the electrochemical stability of Zn-ion battery (ZIB). In this work, we demonstrate that introducing β-cyclodextrins (CD) as anion-receptors into Zn(OTf)2 aqueous electrolyte could significantly optimize the Zn anode SEI structure for achieving stable ZIB. Specifically, β-CD with macrocyclic structure holds appropriate cavity size and charge distribution to encase OTf- anions at the Zn metal surface to form β-CD@OTf- dominated inner Helmholtz structure. Meanwhile, the electrochemically triggered β-CD@OTf- decomposition could in situ convert to the organic-inorganic hybrid SEI (ZnF2/ZnCO3/ZnS‒(C-O-C/*CF/*CF3)), which could efficiently hinder the Zn dendrite growth with maintain the proper SEI mechanical strength stability to guarantee the long-term stability. The thus-derived Zn | |Zn pouch cell (21 cm2 size) with β-CD-containing electrolyte exhibits a cumulative capacity of 6450 mAh−2 cm−2 at conditions of 10 mAh cm−2 high areal capacity. This work gives insights for reaching stable ZIB via electrolyte additive triggered SEI structure regulation. Here, the authors report that introducing βcyclodextrins (CD) as anion-receptors into Zn(OTf)2 aqueous electrolyte could significantly optimize the Zn anode SEI structure for achieving stable ZIB.

Lattice-oxygen redox in layered metal oxide cathodes offers a promising way to exploit high-energy density sodium-ion batteries. However, oxidation and reduction of lattice-oxygen are always asymmetric, showing poor reversibility upon charging and discharging due to the activated oxygen loss and subsequent structural rearrangement. Here, a layered Na0.7[Li0.2Mn0.7Co0.1]O2 (NLMCO) is developed by balancing lattice-oxygen activity and reversibility, which can deliver a record energy density of 729.7 Wh kg-1, further exceeding the state-of-the-art Na0.75[Li0.25Mn0.75]O2 (NLMO, 638.4 Wh kg-1). In light of electron paramagnetic resonance spectroscopy, in situ differential electrochemical mass spectroscopy, and electrochemical testing results, the highly activated lattice-oxygen is effectively stabilized in NLMCO without oxygen molecule release while obvious oxygen release is detected in the highly activated NLMO. Benefiting from the enhanced transition metal-oxygen covalency and reduced band energy gap, the NLMCO electrode demonstrates simultaneously high lattice-oxygen activity and reversibility, thus resulting in excellent rate and cycling performance, as well as ultra-high energy density. The findings highlight the critical association of energy density and lattice-oxygen redox reversibility, which will inspire more interest in anionic redox-based high-energy batteries. A record energy density of 729.7 Wh kg-1 is obtained in Na0.7[Li0.2Mn0.7Co0.1]O2 (NLMCO) for sodium-ion batteries by simultaneously balancing lattice-oxygen activity and reversibility. Benefiting from the electronic structure and crystal structure modulation, NLMCO shows both high lattice-oxygen activity and reversibility, ultimately leading to ultra-high energy density, as well as excellent rate and cycling performance.image

Anionic redox chemistry has attracted increasing attention for the improvement in the reversible capacity and energy density of cathode materials in Li/Na-ion batteries. However, adverse electrochemical behaviors, such as voltage hysteresis and sluggish kinetics resulting from weak metal-ligand interactions, commonly occur with anionic redox reactions. Currently, the mechanistic investigation driving these issues still remains foggy. Here, we chemically designed Na0.8Fe0.4Ti0.6S2 and Na0.8Fe0.4Ti0.6O2 as model cathodes to explore the covalency effects on metal-ligand interactions during anionic redox process. Na0.8Fe0.4Ti0.6S2 with strengthened covalent interaction of metal-ligand bonds exhibits smaller voltage hysteresis and faster kinetics than Na0.8Fe0.4Ti0.6O2 during (de)sodiation process. Theoretical calculations suggest that Fe is the dominant redox-active center in Na0.8Fe0.4Ti0.6S2, whereas the redox-active center moves from Fe to O with the removal of Na+ in Na0.8Fe0.4Ti0.6O2. We attribute the above different redox behaviors between Na0.8Fe0.4Ti0.6S2 and Na0.8Fe0.4Ti0.6O2 to the charge transfer kinetics from ligand to metal. Moreover, the structural stability of Na0.8Fe0.4Ti0.6S2 is enhanced by increasing the cation migration barriers through strong metal-ligand bonds during desodiation. These insights into the originality of metal-ligand interactions provide guidance for the design of high-capacity and structurally stable cathode materials for Li/Na-ion batteries.

Manganese-based layered oxides are currently of significant interest as cathode materials for sodium-ion batteries due to their low toxicity and high specific capacity. However, the practical applications are impeded by sluggish intrinsic Na + migration and poor structure stability as a result of Jahn–Teller distortion and complicated phase transition. In this study, a high-entropy strategy is proposed to enhance the high-voltage capacity and cycling stability. The designed P2-Na 0.67 Mn 0.6 Cu 0.08 Ni 0.09 Fe 0.18 Ti 0.05 O 2 achieves a deeply desodiation and delivers charging capacity of 158.1 mAh g −1 corresponding to 0.61 Na with a high initial Coulombic efficiency of 98.2 %. The charge compensation is attributed to the cationic and anionic redox reactions conjunctively. Moreover, the crystal structure is effectively stabilized, leading to a slight variation of lattice parameters. This research carries implications for the expedited development of low-cost, high-energy-density cathode materials for sodium-ion batteries.

The utilization of anionic redox chemistry provides an opportunity to further improve the energy density of Li-ion batteries, particularly for Li-rich layered oxides. However, oxygen-based hosts still suffer from unfavorable structural rearrangement, including the oxygen release and transition metal (TM)-ion migration, in association with the tenuous framework rooted in the ionicity of the TM-O bonding. An intrinsic solution, by using a sulfur-based host with strong TM-S covalency, is proposed here to buffer the lattice distortion upon the highly activating sulfur redox process, and it achieves howling success in stabilizing the host frameworks. Experimental results demonstrate the prolonged preservation of the layered sulfur lattice, especially the honeycomb superlattice, during the Li+ extraction/insertion process in contrast to the large structural degeneration in Li-rich oxides. Moreover, the Li-rich sulfide cathodes exhibited a negligible overpotential of 0.08 V and a voltage drop of 0.13 mV/cycle, while maintaining a substantial reversible capacity upon cycling. These superior electrochemical performances can be unambiguously ascribed to the much shorter trajectories of sulfur in comparison to those of oxygen revealed by molecular dynamics simulations at a large scale (∼30 nm) and a long time scale (∼300 ps) via high-dimensional neural network potentials during the delithiation process. Our findings highlight the importance of stabilizing host frameworks and establish general guidance for designing Li-rich cathodes with durable anionic redox chemistry.

The moderate reversibility of Zn anodes, as a long-standing challenge in aqueous zinc-ion batteries, promotes the exploration of suitable electrolyte additives continuously. It is crucial to establish the absolute predominance of smooth deposition within multiple interfacial reactions for stable zinc anodes, including suppressing side parasitic reactions and facilitating Zn plating process. Trehalose catches our attention due to the reported mechanisms in sustaining biological stabilization. In this work, the inter-disciplinary application of trehalose is reported in the electrolyte modification for the first time. The pivotal roles of trehalose in suppressed hydrogen evolution and accelerated Zn deposition have been investigated based on the principles of thermodynamics as well as reaction kinetics. The electrodeposit changes from random accumulation of flakes to dense bulk with (002)-plane exposure due to the unlocked crystal-face oriented deposition with trehalose addition. As a result, the highly reversible Zn anode is obtained, exhibiting a high average CE of 99.8 % in the Zn/Cu cell and stable cycling over 1500 h under 9.0 % depth of discharge in the Zn symmetric cell. The designing principles and mechanism analysis in this study could serve as a source of inspiration in exploring novel additives for advanced Zn anodes.

Carbon materials have shown significant potential as catalysts for lithium-oxygen batteries (LOBs). However, the intrinsic carbon sites are typically inert, necessitating extensive modifications and resulting in a limited density of active sites. Here we present C 60 as a metal-free cathode catalyst for LOBs, using density functional theory calculations and experimental verifications. The lithiation reactions on the pristine carbon sites of C 60 are energetically favorable due to its curved π-conjugation over the pentagon–hexagon networks. The kinetic analysis specifically reveals low energy barriers for Li 2 O 2 decomposition and Li diffusion on C 60 . Consequently, C 60 exhibits significantly higher catalytic activity than typical carbon materials such as graphene and carbon nanotubes. Our electrochemical measurements validate the predictions, notably demonstrating that the intrinsic activity of C 60 is comparable to that of noble metals.

All-solid-state batteries (ASSBs) represent a promising battery strategy to achieve high energy density with great safety. However, inadequate kinetic property and poor interfacial compatibility remain great challenges, which impede their practical application. A prototype of dual-ion conductor of Li + synchronized with Cu + unlocks a four-electron redox reaction with high reversibility and fast kinetics. As a result, the constructed ASSB exhibited a high reversible capacity of 603.0 mA·hour g −1 and an excellent cycling retention of 93.2% over 1500 cycles. Moreover, because of the ion highway connecting active materials and catholytes constructed by dual-ion conductor, remarkable temperature tolerance (−60°C) and excellent rate performance (231.6 mA·hour g −1 at 20 mA cm −2 ) were achieved. The superior electrochemical performance can be ascribed to the migration pathway with small energy barrier and low tortuosity once the Cu + introduced into Li 6 PS 5 Cl. This work creates a unique perspective of ASSBs with dual-ion conducting strategy, thus inspiring a potential developing strategy of state-of-the-art ASSBs.