Enhancing Proton Co-Intercalation in Iron Ion Batteries Cathodes for Increased Capacity.

Recently, aqueous iron ion batteries (AIIBs) using iron metal anodes have gained traction in the battery community as low-cost and sustainable solutions for green energy storage. However, the development of AIIBs is significantly hindered by the limited capacity of existing cathode materials and the poor intercalation kinetic of Fe2+. Herein, we propose a H+ and Fe2+ co-intercalation electrochemistry in AIIBs to boost the capacity and rate capability of cathode materials such as iron hexacyanoferrate (FeHCF) and Na4Fe3(PO4)2(P2O7) (NFPP). This is achieved through an electrochemical activation step during which a FeOOH nanowire layer is formed in situ on the cathode. This layer facilitates H+ co-intercalation in AIIBs, resulting in a high specific capacity of 151 mAh g-1 and 93% capacity retention over 500 cycles for activated FeHCF cathodes. We found that this activation process can also be applied to other cathode chemistries, such as NFPP, where we found that the cathode capacity is doubled as a result of this process. Overall, the proposed H+/Fe2+ co-insertion electrochemistry expands the range of applications for AIBBs, in particular as a sustainable solution for storing renewable energy.

Layered Na2Ti3O7 as an Ultrastable Intercalation-Type Anode for Non-Aqueous Calcium-Ion Batteries.

Calcium ion batteries (CIBs) are a promising energy storage device due to the low redox potential of the Ca metal and the abundant reserves of the Ca element. However, the large radius and divalent nature of Ca2+ lead to its slow ion diffusion kinetics and the lack of suitable electrode materials for Ca storage. Here, a layered structure of Na2Ti3O7 (NTO) is presented as an anode material for nonaqueous CIBs. This NTO anode demonstrates a high discharge capacity of 165 mA h g-1 at 100 mA g-1 and a remarkable capacity retention rate of 80%, even after 2000 cycles at 500 mA g-1, surpassing the performance of all reported intercalation-type anode materials for CIBs. The NTO transfers to layered CaVIINaIXTi3O7 (CNTO) with intercalation of Ca2+ and extraction of Na+ during the first discharge process. Then, the CNTO undergoes the reversible insertion/extraction of Ca2+ during subsequent cycling. Additionally, density functional theory calculations reveal that NTO possesses a rapid two-dimensional diffusion pathway for Ca2+. Moreover, the full CIBs based on NTO as the anode further underscore its potential for CIBs. This work presents promising anode materials for CIBs, offering opportunities to promote the development of high-performance CIBs.

Organic solid-electrolyte interface layers for Zn metal anodes.

Zinc ion batteries (ZIBs) have emerged as promising candidates for renewable energy storage owing to their affordability, safety, and sustainability. However, issues with Zn metal anodes, such as dendrite growth, hydrogen evolution reaction (HER), and corrosion, significantly hinder the practical application of ZIBs. To address these issues, organic solid electrolyte interface (SEI) layers have gained traction in the ZIB community as they can, for instance, help achieve uniform Zn plating/stripping and suppress side reactions. This article summarizes recent advances in organic artificial SEI layers for ZIB anodes, including their fabrication methods, electrochemical performance, and degradation suppression mechanisms.

Electrode and Electrolyte Co-Energy-Storage Electrochemistry Enables High-Energy Zn-S Decoupled Batteries.

In the search for next-generation green energy storage solutions, Cu-S electrochemistry has recently gained attraction from the battery community owing to its affordability and exceptionally high specific capacity of 3350 mAh gs -1. However, the inferior conductivity and substantial volume expansion of the S cathode hinder its cycling stability, while the low output voltage limits its energy density. Herein, a hollow carbon sphere (HCS) is synthesized as a 3D conductive host to achieve a stable S@HCS cathode, which enables an outstanding cycling performance of 2500 cycles (over 9 months). To address the latter, a Zn//S@HCS alkaline-acid decoupled cell is configured to increase the output voltage from 0.18 to 1.6 V. Moreover, an electrode and electrolyte co-energy storage mechanism is proposed to offset the reduction in energy density resulting from the extra electrolyte required in Zn//S decoupled cells. When combined, the Zn//S@HCS alkaline-acid decoupled cell delivers a record energy density of 334 Wh kg-1 based on the mass of the S cathode and CuSO4 electrolyte. This work tackles the key challenges of Cu-S electrochemistry and brings new insights into the rational design of decoupled batteries.

Redesigning Solvation Structure toward Passivation-Free Magnesium Metal Batteries.

Simple magnesium (Mg) salt solutions are widely considered as promising electrolytes for next-generation rechargeable Mg metal batteries (RMBs) owing to the direct Mg2+ storage mechanism. However, the passivation layer formed on Mg metal anodes in these electrolytes is considered the key challenge that limits its applicability. Numerous complex halogenide additives have been introduced to etch away the passivation layer, nevertheless, at the expense of the electrolyte's anodic stability and cathodes' cyclability. To overcome this dilemma, here, we design an electrolyte with a weakly coordinated solvation structure which enables passivation-free Mg deposition while maintaining a high anodic stability and cathodic compatibility. In detail, we successfully introduce a hexa-fluoroisopropyloxy (HFIP-) anion into the solvation structure of Mg2+, the weakly [Mg-HFIP]+ contact ion pair facilitates Mg2+ transportation across interfaces. As a consequence, our electrolyte shows outstanding compatibility with the RMBs. The Mg||PDI-EDA and Mg||Mo6S8 full cells use this electrolyte demonstrating a decent capacity retention of ∼80% over 400 cycles and 500 cycles, respectively. This represents a leap in cyclability over simple electrolytes in RMBs while the rest can barely cycle. This work offers an electrolyte system compatible with RMBs and brings deeper understanding of modifying the solvation structure toward practical electrolytes.

Large-Scale Integration of the Ion-Reinforced Phytic Acid Layer Stabilizing Magnesium Metal Anode.

Rechargeable magnesium batteries (RMBs) have garnered significant attention for their potential in large-scale energy storage applications. However, the commercial development of RMBs has been severely hampered by the rapid failure of large-sized Mg metal anodes, especially under fast and deep cycling conditions. Herein, a concept proof involving a large-scale ion-reinforced phytic acid (PA) layer (100 cm × 7.5 cm) with an excellent water-oxygen tolerance, high Mg2+ conductivity, and favorable electrochemical stability is proposed to enable rapid and uniform plating/stripping of Mg metal anode. Guided by even distributions of Mg2+ flux and electric field, the as-prepared large-sized PA-Al@Mg electrode (5.8 cm × 4.5 cm) exhibits no perforation and uniform Mg plating/stripping after cycling. Consequently, an ultralong lifespan (2400 h at 3 mA cm-2 with 1 mAh cm-2) and high current tolerance (300 h at 9 mA cm-2 with 1 mAh cm-2) of the symmetric cell using the PA-Al@Mg anode could be achieved. Notably, the PA-Al@Mg//Mo6S8 full cell demonstrates exceptional stability, operating for 8000 cycles at 5 C with a capacity retention of 99.8%, surpassing that of bare Mg (3000 cycles, 74.7%). Moreover, a large-sized PA-Al@Mg anode successfully contributes to the stable pouch cell (200 and 750 cycles at 0.1 and 1 C), further confirming its significant potential for practical utilization. This work provides valuable theoretical insights and technological support for the practical implementation of RMBs.

Space dynamic target tracking method based on five-frame difference and Deepsort.

For the problem of space dynamic target tracking with occlusion, this paper proposes an online tracking method based on the combination between the five-frame difference and Deepsort (Simple Online and Realtime Tracking with a Deep Association Metric), which is to achieve the identification first and then tracking of the dynamic target. First of all, according to three-frame difference, the five-frame difference is improved, and through the integration with ViBe (Visual Background Extraction), the accuracy and anti-interference ability are enhanced; Secondly, the YOLOv5s (You Look Only Once) is improved using preprocessing of DWT (Discrete Wavelet Transformation) and injecting GAM (Global Attention Module), which is considered as the detector for Deepsort to solve the missing in occlusion, and the real-time and accuracy can be strengthened; Lastly, simulation results show that the proposed space dynamic target tracking can keep stable to track all dynamic targets under the background interference and occlusion, the tracking precision is improved to 93.88%. Furthermore, there is a combination with the physical depth camera D435i, experiments on target dynamics show the effectiveness and superiority of the proposed recognition and tracking algorithm in the face of strong light and occlusion.

Co single atom coupled oxygen vacancy on W18O49 nanowires surface to construct asymmetric active site enhanced peroxymonosulfate activation.

Enhancing the activation of peroxymonosulfate (PMS) is essential for generating more reactive oxygen species in advanced oxidation process (AOPs). Nevertheless, improving PMS adsorption and expediting interfacial electron transfer to enhance reaction kinetics pose significant challenges. Herein, we construct confined W18O49 nanowires with asymmetric active centers containing Co-Vo-W (Vo: oxygen vacancy). The design incorporates surface-rich Vo and single-atom Co, and the resulting material is employed for PMS activation in water purification. By coupling unsaturated coordinated electrons in Vo with low-valence Co single atoms to construct an the "electron fountainhead", the adsorption and activation of PMS are enhanced. This results in the generation of more active free radicals (SO4•-, •OH, •O2-) and non-free radicals (1O2) for the decomposition of micropollutants. Thereinto, the degradation rate of bisphenol A (BPA) by Co-W18O49 is 32.6 times faster that of W18O49 monomer, which is also much higher than those of other transition-metal-doped W18O49 composites. This work is expected to help to elucidate the rational design and efficient PMS activation of catalysts with asymmetric active centers.

Percolating Network of Anionic Vacancies in Prussian Blue: Origin of Superior Ammonium-Ion Storage Performance.

Emerging aqueous ammonium-ion batteries (AIBs) are considered inexpensive, highly safe, ecofriendly, and sustainable energy storage systems. Although some high-performance electrode materials have been reported for AIBs, a comprehensive understanding of the origin of the high ammonium-ion storage performance is still lacking. Herein, the percolating network of anionic vacancies is determined to be the origin of the superior ammonium-ion storage properties of the Prussian blue analogues based on ab initio molecular dynamics simulation and electrochemical kinetic analyses. Fe[Fe(CN)6] with a percolating anionic vacancy network delivers an outstanding rate of 64.7 mAh g-1 at 2000 mA g-1 in addition to a capacity retention of 94.5% after 10 000 cycles. The low-strain intercalation ammonium-ion storage mechanism of highly deficient Fe Prussian blue with Fe as the redox center is revealed by in situ X-ray diffraction and ex situ X-ray absorption fine structure analysis. The results provide insights into the mechanism of ammonium-ion storage in Prussian blue analogues and guidance in the development of aqueous AIBs.

Re-imagining the daniell cell: ampere-hour-level rechargeable Zn-Cu batteries.

The Daniell cell (Cu vs. Zn), was invented almost two centuries ago, but has been set aside due to its non-rechargeable nature and limited energy density. However, these cells are exceptionally sustainable because they do not require rare earth elements, are aqueous and easy to recycle. This work addresses key challenges in making Daniell cells relevant to our current energy crisis. First, we propose new approaches to stabilise Zn and Cu plating and stripping processes and create a rechargeable cell. Second, we replace salt bridges with an anion exchange membrane, or a bipolar membrane for alkaline-acid hybrid Zn-Cu batteries operating at 1.56 V. Finally, we apply these changes in pouch cells in order to increase energy and power density. These combined developments result in a rechargeable Daniell cell, which can achieve high areal capacities of 5 mA h cm-2 and can easily be implemented in 1 A h pouch cells.

Achieving highly reversible zinc metal anode via surface termination chemistry.

An oxidation layer on a Zn surface is considered to play a negative role in hindering the practical applications of aqueous zinc ion batteries (AZBs). Herein, we demonstrate the importance of Zn-surface termination on the overall electrochemical behavior of AZBs by revisiting the well-known bottleneck issues. Experimental characterizations in conjugation with theoretical calculations reveal that the formation of a dense Zn4(OH)6SO4·xH2O (ZSH) layer from the well-designed surface-oxide termination layer improves the interface stability of the Zn anode and reduces the dehydration energy of Zn(H2O)62+, thereby accelerating the interface transport kinetics of Zn2+. Moreover, instead of directly diffusing over the ZSH layer, a new "edge dehydration-along edge transfer" mechanism of Zn2+ is discovered. Owing to the presence of a Zn anode with a ZnO-derived ZSH layer, an ultrahigh stability of over 1200 h with a high cumulative-plated capacity of 6.24mAh cm-2 is achieved with a symmetrical cell. Furthermore, high cycling stability (over 1000 cycles) and Coulombic efficiency (99.07%) are obtained in the entire AZBs with a MnO2 cathode. An understanding of the oxygen surface termination mechanism is beneficial to Zn-anode protection and is a timely forward step toward the long-pursued practical application of AZBs.

Conductive MOF on ZIF-Derived Carbon Fibers as Superior Anode in Sodium-Ion Battery.

Superior specific capacity, high-rate capability, and long-term cycling stability are essential to anode materials in sodium-ion batteries, and conductive metal-organic frameworks (cMOF) with good electronic and ionic conductivity may satisfy these requirements. Herein, conductive neodymium cMOF (Nd-cMOF) produced in situ on the zeolitic imidazolate framework (ZIF)-derived carbon fiber (ZIF-CFs) platform is used to synthesize the Nd-cMOF/ZIF-CFs hierarchical structure. Four types of ZIFs with different pore diameters are prepared by electrospinning. In this novel structure, ZIF-CFs provide the electroconductivity, flexible porous structure, and mechanical stability, while Nd-cMOF provides the interfacial kinetic activity, electroconductivity, ample space, and volume buffer, consequently giving rise to robust structural integrity and excellent conductivity. The sodium-ion battery composed of the Nd-cMOF/ZIF-10-CFs anode has outstanding stability and electrochemical properties, such as a specific capacity of 480.5 mAh g-1 at 0.05 A g-1 as well as capacity retention of 84% after 500 cycles.

Mg2+ Ion Pre-Insertion Boosting Reaction Kinetics and Structural Stability of Ammonium Vanadates for High-Performance Aqueous Zinc-Ion Batteries.

Aqueous zinc-ion batteries (AZIBs) attract much attention owing to their high safety, environmentally friendliness and low cost. However, the unsatisfactory performance of cathode materials is one of the unsolved important factors for their widespread application. Herein, we report NH4 V4 O10 nanorods with Mg2+ ion preinsertion (Mg-NHVO) as a high-performance cathode material for AZIBs. The preinserted Mg2+ ions effectively improve the reaction kinetics and structural stability of NH4 V4 O10 (NHVO), which are confirmed by electrochemical analysis and density functional theory calculations. Compared with pristine NHVO, the intrinsic conductivity of Mg-NHVO is improved by 5 times based on the test results of a single nanorod device. Besides, Mg-NHVO could maintain a high specific capacity of 152.3 mAh g-1 after 6000 cycles at the current density of 5 A g-1 , which is larger than that of NHVO (only exhibits a low specific capacity of 30.5 mAh g-1 at the same condition). Moreover, the two-phase crystal structure evolution process of Mg-NHVO in AZIBs is revealed. This work provides a simple and efficient method to improve the electrochemical performance of ammonium vanadates and enhances the understanding about the reaction mechanism of layered vanadium-based materials in AZIBs.

Pore-forming mechanisms and sodium-ion-storage performances in a porous Na3V2(PO4)3/C composite cathode.

Na3V2(PO4)3 (NVP) is regarded as one of the most promising cathode materials for sodium-ion batteries (SIBs). However, it suffers from a dense bulk structure and low intrinsic electronic conductivity, which lead to limited electrochemical performances. Herein, we propose a surfactant-assisted molding strategy to regulate the pore-forming process in NVP/C composite cathode materials. More precisely, the forming process of the pores in NVP could be easily controlled by utilizing the huge difference in critical micelle concentration of a surfactant (cetyltrimethylammonium bromide, CTAB) in water and ethanol. By reasonably modulating the ratio of water and ethanol in the solution, the as-synthesized NVP/C sample exhibited a three-dimensional interconnected structure with hierarchical micro/meso/macro-pores. Benefiting from these hierarchical porous structures in NVP/C, the structural stability, contact surface with the electrolyte, and electronic/ionic conductivity were improved simultaneously; whereby the optimized porous NVP/C sample exhibited an excellent high-rate performance (61.3 mA h g-1 at 10 C) and superior cycling stability (90.2% capacity retention after 500 cycles at 10 C).

Mg-substituted Prussian blue as a low-strain cathode material for aqueous Fe-ion batteries.

Aqueous Fe-ion batteries (FIBs) have gradually emerged in recent years due to their inherent merits. Herein, we constructed a Mg-substituted Prussian blue analogue (MgFeHCF) as cathode for FIBs, achieving higher capacity (96 mA h g-1) and better stability (70.9% capacity retention over 500 cycles). The Fe-ion storage mechanism was revealed using the in situ XRD technique and DFT calculations were employed to analyse the battery performance.

Revealing the Interfacial Chemistry of Fluoride Alkyl Magnesium Salts in Magnesium Metal Batteries.

Exploring promising electrolyte-system with high reversible Mg plating/stripping and excellent stability is essential for rechargeable magnesium batteries (RMBs). Fluoride alkyl magnesium salts (Mg(ORF )2 ) not only possess high solubility in ether solvents but also compatible with Mg metal anode, thus holding a vast application prospect. Herein, a series of diverse Mg(ORF )2 were synthesized, among them, perfluoro-tert-butanol magnesium (Mg(PFTB)2 )/AlCl3 /MgCl2 based electrolyte demonstrates highest oxidation stability, and promotes the in situ formation of robust solid electrolyte interface. Consequently, the fabricated symmetric cell sustains a long-term cycling over 2000 h, and the asymmetric cell exhibits a stable Coulombic efficiency of 99.5 % over 3000 cycles. Furthermore, the Mg||Mo6 S8 full cell maintains a stable cycling over 500 cycles. This work presents guidance for understanding structure-property relationships and electrolyte applications of fluoride alkyl magnesium salts.

NH4 + Deprotonation at Interfaces Induced Reversible H3 O+ /NH4 + Co-insertion/Extraction.

Ion insertions always involve electrode-electrolyte interface process, desolvation for instance, which determines the electrochemical kinetics. However, it's still a challenge to achieve fast ion insertion and investigate ion transformation at interface. Herein, the interface deprotonation of NH4 + and the introduced dissociation of H2 O molecules to provide sufficient H3 O+ to insert into materials' structure for fast energy storages are revealed. Lewis acidic ion-NH4 + can, on one hand provide H3 O+ itself via deprotonation, and on the other hand hydrolyze with H2 O molecules to produce H3 O+ . In situ attenuated total reflection-Fourier transform infrared ray method probed the interface accumulation and deprotonation of NH4 + , and density functional theory calculations manifested that NH4 + tend to thermodynamically adsorb on the surface of monoclinic VO2 , and deprotonate to provide H3 O+ . In addition, the inserted NH4 + has a positive effect for stabilizing the VO2 (B) structure. Therefore, high specific capacity (>300 mAh g-1 ) and fast ionic insertion/extraction (<20 s) can be realized in VO2 (B) anode. This interface derivation proposes a new path for designing proton ion insertion/extraction in mild electrolyte.

Interfacial Chemistry Modulation via Amphoteric Glycine for a Highly Reversible Zinc Anode.

Zn metal is thermodynamically unstable in aqueous electrolytes, which induces dendrite growth and ongoing parasitic reactions at the interface during the plating process and even during shelf time, resulting in rapid battery failure and hindering the practical application of aqueous Zn ion batteries. In this work, glycine, a common multifunctional additive, is utilized to modulate the solvation shell structure and enhance the interfacial stability to guard the reversibility and stability of the Zn anode. Apart from partially replacing the original SO42- in the contact ion pair of Zn2+[H2O]5·OSO32- complexes to suppress the formation of Zn4(OH)6SO4·xH2O byproducts at the interface, glycine molecules can also form a water-poor electrical double layer on the zinc metal surface during resting and be further reduced to build in situ a ZnS-rich solid electrolyte interphase (SEI) layer during cycling, which further suppresses side reactions and the random growth of Zn dendrites in the whole process. As expected, the cycle life of the symmetrical cells reaches over 3200 h in glycine-containing electrolytes. In addition, the Zn//NVO full cell shows exceptional cycling stability for 3000 cycles at 5 A g-1. Given the low-cost superiority of glycine, the proposed strategy for interfacial chemistry modulation shows considerable potential in promoting the commercialization progress of aqueous batteries.

Serrated lithium fluoride nanofibers-woven interlayer enables uniform lithium deposition for lithium-metal batteries.

The uncontrollable formation of Li dendrites has become the biggest obstacle to the practical application of Li-metal anodes in high-energy rechargeable Li batteries. Herein, a unique LiF interlayer woven by millimeter-level, single-crystal and serrated LiF nanofibers (NFs) was designed to enable dendrite-free and highly efficient Li-metal deposition. This high-conductivity LiF interlayer can increase the Li+ transference number and induce the formation of 'LiF-NFs-rich' solid-electrolyte interface (SEI). In the 'LiF-NFs-rich' SEI, the ultra-long LiF nanofibers provide a continuously interfacial Li+ transport path. Moreover, the formed Li-LiF interface between Li-metal and SEI film renders low Li nucleation and high Li+ migration energy barriers, leading to uniform Li plating and stripping processes. As a result, steady charge-discharge in a Li//Li symmetrical cell for 1600 h under 4 mAh cm-2 and 400 stable cycles under a high area capacity of 5.65 mAh cm-2 in a high-loading Li//rGO-S cell at 17.9 mA cm-2 could be achieved. The free-standing LiF-NFs interlayer exhibits superior advantages for commercial Li batteries and displays significant potential for expanding the applications in solid Li batteries.

Ni-Containing Electrolytes for Superior Zinc-Ion Aqueous Batteries with Zinc Hexacyanoferrate Cathodes.

A one-step coprecipitation process is designed to synthesize zinc hexacyanoferrate (ZnHCF) cathodes in aqueous zinc-ion batteries (ZIBs). The morphology of the cathode is influenced by the concentration of the precursor solution and valence of iron ions. The rhombohedral ZnHCF sample exhibits high crystallinity on the microscale in the cut-angle cubic structure, whereas Na-rich NaZnHCF contains many interstitial water molecules in the rhombic nanoplates. Both samples show effective insertion of Zn ions in the aqueous ZnSO4 solution. ZnHCF shows a specific capacity of 66.7 mA h g-1, a redox voltage of 1.73 V, and fast decline in a few cycles. On the other hand, NaZnHCF has a lower specific capacity of 48.2 mA h g-1, showing two voltage platforms and robust cycling stability. However, owing to serious side reactions, both samples have low Columbic efficiency. To improve the properties such as Coulombic efficiency, specific capacity, and cycling stability, Ni ions are introduced by adding 10 wt % NiSO4 to the ZnSO4 electrolyte. The ZnHCF cathode in the Ni-containing electrolyte has the best properties such as a high specific capacity of 71.2 mA h g-1 at a current density of 100 mA g-1, 93% retention of the Coulombic efficiency, and a good rate performance manifested by a reversible capacity of 58.2 mA h g-1 at 1 A g-1. The results reveal a strategy to improve the electrochemical properties of aqueous ZIBs by modifying the electrolytes.