Trinitarian Design of Gradient Artificial Interphase Enables Colossal Granular Li Deposits for Stable Li-Metal Batteries.

The cycling lifespan of Li-metal batteries is compromised by the unstable solid electrolyte interphase (SEI) and the continuous Li dendrites, restricting their practical implementations. Given these challenges, establishing an artificial SEI holds promise. Herein, a trinitarian gradient interphase is innovatively designed through composite coatings of magnesium fluoride (MgF2), N-hexadecyltrimethylammonium chloride (CTAC), and polyvinylidene fluoride-hexafluoropropylene copolymer (PVDF-HFP) on Li-metal anode (LMA). Specifically, the MgF2/CTAC/PVDF-HFP SEI spontaneously forms a lithium fluoride (LiF)-rich PVDF-HFP-based SEI, along with lithium-magnesium (Li-Mg) alloy substrate as lithiophilic electronic conductor and positively charged CTAC during plating. Noticeably, the Li-Mg alloy homogenizes the distribution of electric field and reduce the internal resistance, while the electronically insulated LiF/PVDF-HFP composite SEI offers fast ion-conducting and mechanical flexibility, accommodating the volumetric expansion and ensuring stable Li-ion flux. Additionally, CTAC at the dendritic tip is pivotal for mitigating dendrites through its electrostatic shield mechanism. Innovatively, this trinitarian synergistic mechanism, which facilitates colossal granular Li deposits, constructs a dendrite-free LMA, leading to stable cycling performances in practical Li||LFP, popular Li||NCM811, and promising Li||S full cells. This work demonstrates the design of multifunctional composite SEI for comprehensive Li protection, thereby inspiring further advancements in artificial SEI engineering for alkali-metal batteries.

Damage-Tolerant and Self-Repairing Web-Like Borate Type Binder Enable Stable Operation of Efficient Si-Based Anodes.

Novel binder designs are shown to be fruitful in improving the electrochemical performance of silicon (Si)-based anodes. However, issues with mechanical damage from dramatic volume change and poor lithium-ion (Li+) diffusion kinetics in Si-based materials still need to be addressed. Herein, an aqueous self-repairing borate-type binder (SBG) with a web-like architecture and high ionic conductivity is designed for Si and SiO electrodes. The 3D web-like architecture of the SBG binder enables uniform stress distribution, while its self-repairing ability promotes effective stress dissipation and mechanical damage repair, thereby enhancing the damage tolerance of the electrode. The tetracoordinate boron ions ( - BO 4 - $ - {\mathrm{BO}}_4^ - $ ) in the SBG binder boosts the Li transportation kinetics of Si-based electrodes. Based on dynamic covalent and ionic conductive boronic ester bonds, the diverse requirements of the binder, including uniform stress distribution, self-repairing ability, and high ionic conductivity, can be met by simple components. Consequently, the proposed straightforward multifunction design strategy for binders based on dynamic boron chemistry provides valuable insights into fabricating high-performance Si-based anodes.

Bi-Directional H-Bonding Modulated Soft/Hard Polyethylene Glycol-Polyaniline Coated Si-Anode for High-Performance Li-Ion Batteries.

Ultrahigh-capacity silicon (Si) anodes are essential for the escalating energy demands driven by the booming e-transportation and energy storage field. However, their practical applications are strictly hampered by their intrinsically low electroconductivity, sluggish Li-ion diffusion, and undesirably large volume change. Herein, a high-performance Si anode, comprised of a modulated soft/hard coating of polyethylene glycol (PEG) (as Li-ion conductor) and polyaniline (PANI) (as electron conductor) on the surface of Si nanoparticles (NPs) through H-bonding network, is introduced. In this design, the abundant ─OH groups of soft PEG allow it to uniformly cover Si NPs while the hard PANI binds to PEG through its ─N─H group, thus constructing a tight connectin between Si and PEG-PANI (PP). Consequently, the elastic PP allows Si@PP to accommodate the huge volume expansion while possessing fine electronic/ionic conductivity. Therefore, the Si@PP anode exhibits a high initial Coulombic efficiency of 90.5% and a stable capacity of 1871 mAh g-1 after 100 cycles at 1 A g-1 with a retention of 85.7%. Additionally, the Si@PP anode also demonstrates a high areal capacity of 3.01 mAh cm-2 after 100 cycles at 0.5 A g-1 . This work reveals a scalable interface design of multi-layer multifunctional coatings for high-performance electrode materials in next-generation Li-ion batteries.

Sr-induced Fermi Engineering of ß-FeOOH for Multifunctional Catalysis.

Designing a multifunctional electrocatalyst to produce H2 from water, urea, urine, and wastewater, is highly desirable yet challenging because it demands precise Fermi-engineering to realize stronger π-donation from O 2p to electron(e- )-deficient metal (t2g ) d-orbitals. Here a Sr-induced phase transformed ß-FeOOH/α-Ni(OH)2 catalyst anchored on Ni-foam (designated as pt-NFS) is introduced, where Sr produces plenteous Fe4+ (Fe3+ → Fe4+ ) to modulate Fermi level and e- -transfer from e- -rich Ni3+ (t2g )-orbitals to e- -deficient Fe4+ (t2g )-orbitals, via strong π-donation from the π-symmetry lone-pair of O bridge. pt-NFS utilizes Fe-sites near the Sr-atom to break the H─O─H bonds and weakens the adsorption of *O while strengthening that of *OOH, toward hydrogen evolution reaction (HER) and oxygen evolution reaction (OER), respectively. Invaluably, Fe-sites of pt-NFS activate H2 -production from urea oxidation reaction (UOR) through a one-stage pathway which, unlike conventional two-stage pathways with two NH3 -molecules, involves only one NH3 -molecule. Owing to more suitable kinetic energetics, pt-NFS requires 133 mV (negative potential shift), 193 mV, ≈1.352 V, and ≈1.375 V versus RHE for HER, OER, UOR, and human urine oxidation, respectively, to reach the benchmark 10 mA cm-2 and also demonstrates remarkable durability of over 25 h. This work opens a new corridor to design multifunctional electrocatalysts with precise Fermi engineering through d-band modulation.

Electron-Sponge Nature of Polyoxometalates for Next-Generation Electrocatalytic Water Splitting and Nonvolatile Neuromorphic Devices.

Designing next-generation molecular devices typically necessitates plentiful oxygen-bearing sites to facilitate multiple-electron transfers. However, the theoretical limits of existing materials for energy conversion and information storage devices make it inevitable to hunt for new competitors. Polyoxometalates (POMs), a unique class of metal-oxide clusters, have been investigated exponentially due to their structural diversity and tunable redox properties. POMs behave as electron-sponges owing to their intrinsic ability of reversible uptake-release of multiple electrons. In this review, numerous POM-frameworks together with desired features of a contender material and inherited properties of POMs are systematically discussed to demonstrate how and why the electron-sponge-like nature of POMs is beneficial to design next-generation water oxidation/reduction electrocatalysts, and neuromorphic nonvolatile resistance-switching random-access memory devices. The aim is to converge the attention of scientists who are working separately on electrocatalysts and memory devices, on a point that, although the application types are different, they all hunt for a material that could exhibit electron-sponge-like feature to realize boosted performances and thus, encouraging the scientists of two completely different fields to explore POMs as imperious contenders to design next-generation nanodevices. Finally, challenges and promising prospects in this research field are also highlighted.

Advanced inorganic lithium metasilicate binder for high-performance silicon anode.

Silicon (Si) is considered a high-capacity anode material with potential for next-generation lithium-ion batteries. However, the commercial application of Si anode is seriously hindered by huge volume variation (>300%) and limited Li+ diffusion ability. Herein, lithium metasilicate (LS), a novel inorganic binder, was innovatively developed to accommodate these challenges. Favorable compatibility is observed between the LS binder and Si nanoparticles (SiNPs) due to the existence of Si element within the LS skeleton. The interaction of the LS binder and SiNPs leads to a strong adhesion effect, enhancing the cycling stability of Si anode. The Si electrode with the LS binder presented an average discharge capacity of 2123 mAh/g at 0.84 A/g after 100 cycles. Furthermore, the presence of the Li+ transport channel within the LS binder enhances Li+ diffusion ability within Si anode. As a result, the average discharge capacity reaches 663 mAh/g at 8.4 A/g. This work thus explored new inorganic binder design approaches for Si anode, contributing to the advancement of high-performance Si anode.

Recent Progress of Self-Supported Metal Oxide Nano-Porous Arrays in Energy Storage Applications.

The demand for high-performance and cost-effective energy storage solutions for mobile electronic devices and electric vehicles has been a driving force for technological advancements. Among the various options available, transitional metal oxides (TMOs) have emerged as a promising candidates due to their exceptional energy storage capabilities and affordability. In particular, TMO nanoporous arrays fabricated by electrochemical anodization technique demonstrate unrivaled advantages including large specific surface area, short ion transport paths, hollow structures that reduce bulk expansion of materials, and so on, which have garnered significant research attention in recent decades. However, there is a lack of comprehensive reviews that discuss the progress of anodized TMO nanoporous arrays and their applications in energy storage. Therefore, this review aims to provide a systematic detailed overview of recent advancements in understanding the ion storage mechanisms and behavior of self-organized anodic TMO nanoporous arrays in various energy storage devices, including alkali metal ion batteries, Mg/Al-ion batteries, Li/Na metal batteries, and supercapacitors. This review also explores modification strategies, redox mechanisms, and outlines future prospects for TMO nanoporous arrays in energy storage.

V-Integration Modulates t2g -Electrons of a Single Crystal Ir1- x (Ir0.8 V0.2 O2 )x -BHC for Boosted and Durable OER in Acidic Electrolyte.

Realizing efficacious π-donation from the O 2p orbital to electron-deficient metal (t2g ) d-orbitals along with separately tuned adsorption of *O and *OOH, is an imperious pre-requisite for an electrocatalyst design to demonstrate boosted oxygen evolution reaction (OER) performance. To regulate the π-donation and the adsorption ability for *O and *OOH, herein, a facile strategy to modulate the electron transfer from electron-rich t2g -orbitals to electron-deficient t2g -orbitals, via strong π-donation from the π-symmetry lone pairs of the bridging O2- , and the d-band center of a biomimetic honeycomb (BHC)-like nanoarchitecture (Ir1- x (Ir0.8 V0.2 O2 )x -BHC) is introduced. The suitable integration of V heteroatoms in the single crystal system of IrO2 decreases the electron density on the neighboring Ir sites, and causes an upshift in the d-band center of Ir1- x (Ir0.8 V0.2 O2 )x -BHC, weakening the adsorption of *O while strengthening that of *OOH, lowers the energy barrier for OER. Therefore, BHC design demonstrates excellent OER performance (shows a small overpotential of 238 mV at 10 mA cm-2 and a Tafel slope of 39.87 mV dec-1 ) with remarkable stability (130 h) in corrosive acidic electrolyte. This work opens a new corridor to design robust biomimetic nanoarchitectures of modulated π-symmetry (t2g ) d-orbitals and the band structure, to achieve excellent activity and durability in acidic environment.

Revealing Lithium Configuration in Aged Layered Oxides for Effective Regeneration.

Layered oxides LiNixCoyMnzO2 are widely used as the main cathode material for high-energy lithium-ion batteries. Over long-term cycling, irreversible phase transformations in layered oxides usually occur along with the loss of active lithium, which directly reflects in the sharp decrease of capacity. However, it is difficult to accurately and rapidly determine lithium content in aged materials, raising extreme impediments in the direct recycling of layered oxides. Herein, we propose a facile method for quick and accurate calculation of the residual lithium content through the developed relationship of shear strain and the states of charge. Based on this recognization, a discharge capacity close to the original capacity of the pristine material is achieved in the regenerated material by combining a hydrothermal method with annealing treatment. The recycled material demonstrates a dramatic improvement in electrochemical properties, especially the high rate performance. This method not only effectively realizes the quantitative regeneration of cathode materials but also provides a possible strategy for the future development of direct regeneration.

Partially Carbonized Polymer Binder with Polymer Dots for Silicon Anodes in Lithium-Ion Batteries.

Large-scale applications of conventional conductive binders for silicon (Si) anodes are challenging to accomplish due to their complex synthesis steps and high cost. Herein, a carbonized polymer dots-assisted polyvinyl alcohol-chitosan (PVA-CS-CPDs) binder is developed through a simple and low-cost hydrothermal method. Through rational design, the PVA-CS-CPDs binder retains rich polar groups while forming conjugated structures. The conjugated structure endows the PVA-CS-CPDs with high electronic conductivity, and the retained polar groups maintain strong binding strength. The proposed water-soluble binding system acts as both a binder and conductive additive, enabling stable cycling for high-Si-content (90 wt.%) anodes without any other conductive additives.

Regulating Electronic Structure of Single-Atom Catalysts toward Efficient Bifunctional Oxygen Electrocatalysis.

Electronic structure of single-atom catalysts (SACs) is critical for bifunctional oxygen electrocatalysis by adjusting the binding energy in oxygen-containing intermediates. However, the regulation of electronic structure has always been a challenge to improve catalytic reactivity. Herein, by introducing a heterogenous metal, the electronic structure through a direct bonding interaction to the active center atom is effectively adjusted. Partial charge transfer between the two atoms optimizes the binding energy of intermediates and reducing the energy barrier of the catalytic reaction. Theoretical calculations confirm these effects and the uniform distribution of 3d orbitals, leading to the improvement of bifunctional oxygen electrocatalytic reactivity. Benefiting from these attributes, the as-constructed bifunctional catalyst enables outstanding electrocatalytic performances in both oxygen reduction and hydrogen oxidation in various energy storage systems. The generality and expandability of this strategy is demonstrated by further successful development of other dual-metal catalysts systems with various active metals.

Controllably Electrodepositing ZIF-8 Protective Layer for Highly Reversible Zinc Anode with Ultralong Lifespan.

Aqueous zinc-ion batteries with high safety and cost effectiveness have received much attention for large-scale energy storage. However, the inevitable dendrite growth derived from uneven zinc stripping/plating severely impedes practical application. In this work, we use controllable electrodeposition to construct a continuous and compact ZIF-8 protective layer and investigate the relationship between the morphology of the deposition layer and the zinc plating behavior. A continuous and insulating protective layer with suitable thickness can induce bottom deposition, and a prolonged battery life of over 5000 cycles at 10 mA cm-2 for 1 mA h cm-2 is achieved.

Epoxy Cross-Linking Enhanced the Toughness of Polysaccharides as a Silicon Anode Binder for Lithium-Ion Batteries.

The large volume expansion of a silicon anode induces serious mechanical failure and limits its applications. Owing to the intrinsic weak van der Waals force and poor toughness, it is unable to solve this issue with the current commercial poly(vinylidene difluoride) (PVDF) binder. The development of a binder with strong binding strength with silicon (Si) is urgent. Herein, a hydroxyl-rich three-dimensional (3D) network binder is synthesized by chemical cross-linking reactions between epichlorohydrin (ECH) and sodium hyaluronate (SH), which exhibits dramatically enhanced toughness and cohesive properties. The Si anode with the novel SH-ECH as the binder delivers excellent electrochemical performance, especially cycling stability. The discharge capacity could maintain 800.4 mAh g-1 after 1000 cycles at a current of 0.2 C with the average capacity decay rate per cycle of 0.015%. Our results pave a new way for the tailoring of the chemical structures of natural polymers to realize lithium-ion batteries (LIBs) with superior electrochemical performance.

9,10-Anthraquinone/K2CuFe(CN)6: A Highly Compatible Aqueous Aluminum-Ion Full-Battery Configuration.

Temporally intermittent and spatially dispersed renewable energy sources strongly call for large-scale energy storage devices. Aqueous aluminum-ion batteries show great potential for application due to their safety and low cost. Thus far, however, the ideal full-battery configuration is beyond the scope due to shortcomings with regards to suitable anode and cathode materials. Herein, we report a pioneering aqueous aluminum-ion battery system consisting of a Prussian white cathode, 1 M Al2(SO4)3 aqueous electrolyte, and an organic 9,10-anthraquinone anode. The oxidation capability of the Prussian white cathode during the first charging allows for the fabrication of the full battery without pre-inserting aluminum ions, thus making the rocking-chair-type battery feasible. Importantly, the open-framework structure of the Prussian white and distinct enolization charge storage mechanism of 9,10-anthraquinone ensure fast reaction kinetics. The full battery exhibits cycling stability with a capacity retention of 89.1% over 100 cycles at 500 mA g-1, finishing a cycle in about 10 min. This work provides a pathway for developing rechargeable aqueous aluminum-ion batteries.

Adhesive Sulfide Solid Electrolyte Interface for Lithium Metal Batteries.

All solid-state Li metal batteries have drawn extensive attention because of the limited side reaction and consequent safety character. The applications of Li metal anodes are indispensable for realizing high energy density but still face many obstacles. One of the critical issues is the contact failure of the solid/solid interface. The rigid interface between a sulfide electrolyte and Li anode cannot afford the volume variation during cycling. Herein, we design an adhesive solid-state electrolyte film, which is supported by hot melt adhesive porous membranes for anode protection. The Li symmetric cells and all solid-state batteries based on adhesive electrolyte layers all exhibit enhanced long cyclic stability and suppressed voltage polarization. The peel strength tests confirm that the electrolyte layers decorated with adhesive components can offer intimate Li metal/electrolyte physical contact and withstand the volume variation of the Li anode. The adhesion force from porous membranes is believed to play a vital role in maintaining solid-solid interfacial contact stability. This work gives a new insight for interface engineering in all solid-state Li metal batteries.

Platinum Atomic Clusters Embedded in Defects of Anatase/Graphene for Efficient Electro- and Photocatalytic Hydrogen Evolution.

Electro- and photocatalytic hydrogen evolution reaction (e-HER and p-HER) are two promising strategies to produce green hydrogen fuel from water. High intrinsic activity, sufficient active sites, fast charge-transfer capacity, and good optoelectronic properties must be taken into consideration simultaneously in pursuit of an ideal bifunctional catalyst. Here, platinum atomic clusters embedded in defects of TiO2 nanocrystals/graphene nanosheets (Pt-T/G) are reported as a bifunctional catalyst for electro- and photocatalytic hydrogen evolution reaction (e-HER and p-HER). High activity is delivered due to the charge transfer from the other part of the catalyst to the active center (Pt2-O4-Tix), decreasing the activation energy of the rate-limiting step, which is revealed by synchrotron X-ray absorption spectroscopy, photoelectrochemical measurements, and simulated calculations. In regard to e-HER, it outperforms the commercial 20 wt % Pt/C catalyst by a factor of 17.5 on Pt mass basis, allowing for a 93% reduction in Pt loadings. In regard to p-HER, it achieves photocatalytic efficiency (686.8 µmol h-1) without any attenuation in 9 h.

Selective Adsorption and Electrocatalysis of Polysulfides through Hexatomic Nickel Clusters Embedded in N-Doped Graphene toward High-Performance Li-S Batteries.

The shuttle effect hinders the practical application of lithium-sulfur (Li-S) batteries due to the poor affinity between a substrate and Li polysulfides (LiPSs) and the sluggish transition of soluble LiPSs to insoluble Li2S or elemental S. Here, we report that Ni hexatomic clusters embedded in a nitrogen-doped three-dimensional (3D) graphene framework (Ni-N/G) possess stronger interaction with soluble polysulfides than that with insoluble polysulfides. The synthetic electrocatalyst deployed in the sulfur cathode plays a multifunctional role: (i) selectively adsorbing the polysulfides dissolved in the electrolyte, (ii) expediting the sluggish liquid-solid phase transformations at the active sites as electrocatalysts, and (iii) accelerating the kinetics of the electrochemical reaction of multielectron sulfur, thereby inhibiting the dissolution of LiPSs. The constructed S@Ni-N/G cathode delivers an areal capacity of 9.43 mAh cm-2 at 0.1 C at S loading of 6.8 mg cm-2, and it exhibits a gravimetric capacity of 1104 mAh g-1 with a capacity fading rate of 0.045% per cycle over 50 cycles at 0.2 C at S loading of 2.0 mg cm-2. This work opens a rational approach to achieve the selective adsorption and expediting of polysulfide transition for the performance enhancement of Li-S batteries.

Stable Lithium Metal Anode Enabled by a Lithiophilic and Electron/Ion Conductive Framework.

Li metal anode has been considered as the ideal anode for next-generation batteries due to its ultrahigh capacity and lowest electrochemical potential. However, its practical application is still impeded by low Coulombic efficiency, huge volume change, and safety hazards arising from Li dendrite growth. In this work, a three-dimensional (3D) structured highly stable Li metal anode is designed and easily preapred. Benefiting from the in situ reaction between Li metal and AlN, highly Li+ conductive Li3N and lithiophilic LiAl alloy have been simultaneously formed and homogeneously distributed in the framework, in which Li metal is finely dispersed and embedded. The outstanding electron/ion mixed conductivity of Li3N/LiAl and 3D composite structure with enhanced interfacial area significantly improve the electrode kinetics and suppress the volume change on cycling, while a lithiophilic effect of LiAl alloy and uniform distribution of Li ion flux inside the electrode avoid dendritic Li deposition. As a result, the proposed Li metal electrode exhibits exceptional electrochemical reversibility in both carbonate and ether-based electrolytes. Paired with LiFePO4 and sulfurized polyacrylonitrile (S@pPAN) cathodes, the full cells deliver highly stable and long-term cycling performance. Therefore, the proposed strategy to fabricate Li metal anodes could promote the practical application of Li metal batteries.

Sulfur-/Nitrogen-Rich Albumen Derived "Self-Doping" Graphene for Sodium-Ion Storage.

The development of sodium-ion batteries (SIBs) is hindered by the rapid reduction in reversible capacity of carbon-based anode materials. Outside-in doping of carbon-based anodes has been extensively explored. Nickel and NiS2 particles embedded in nitrogen and sulfur codoped porous graphene can significantly improve the electrochemical performance. Herein a built-in heteroatom "self-doping" of albumen-derived graphene for sodium storage is reported. The built-in sulfur and nitrogen in albumen act as the doping source during the carbonization of proteins. The sulfur-rich proteins in albumen can also guide the doping and nucleation of nickel sulfide nanoparticles. Additionally, the porous architecture of the carbonized proteins is achieved through removable KCl/NaCl salts (medium) under high-temperature melting conditions. During the carbonization process, nitrogen can also reduce the carbonization temperature of thermally stable carbon materials. In this work, the NS-graphene delivered a specific capacity of 108.3 mAh g-1 after 800 cycles under a constant current density of 500 mA g-1 . In contrast, the Ni/NiS2 /NS-graphene maintained a specific capacity of 134.4 mAh g-1 ; thus the presence of Ni/NiS2 particles improved the electrochemical performance of the whole composite.

Publisher Correction: Aligning academia and industry for unified battery performance metrics.

The original PDF version of this Article contained an error in Fig. 2, in which only the central part of the figure, between 'Mass loading' and 'Gravimetric performance', was visible. This has been corrected in the PDF version of the Article. The HTML version was correct from the time of publication.