Oxygen depolarized cathode (ODC) catalysts, especially for HCl electrolysis, face challenging corrosive environments that narrow the choice of materials to the current state-of-theart RhxSy/C. Nitrogen-coordinated Fe on carbon defect surfaces, commonly referred to as Fe-N-C, offers a low-cost, highly active, and Cl-poisoning-resistant alternative. However, its long-term durability remains unexplored under the unique operating conditions of the HCl electrolysis. To address this, we investigate the stability of Fe-N-C under simulated uncontrolled shutdowns, mimicking the harsh transients of industrial operation. Post-mortem analysis of Fe-N-C using Xray absorption and 57 Fe Mössbauer spectroscopy reveals a transition from the Fe-N4 coordinating environment to Fe2O3. Despite these structural changes, Fe-N-C maintained a competitive low voltage of 1.33 V at 0.5 A cm⁻ 2 , consistent with a relatively low fraction of sites being affected. Accelerated stress tests simulating uncontrolled shutdown conditions, combined with Raman spectroscopy, showed that Fe-N-C and RhxSy/C share a common carbon degradation mechanism. This work demonstrates the viability of Fe-N-C as a robust ODC catalyst and provides guidance for improving its durability by mitigating demetallation and carbon oxidation.

Abstract Nitrogen-coordinated Fe on carbon defect surfaces, commonly referred to as Fe–N–C, shows great potential as a highly active and Cl-poisoning-resistant catalyst for oxygen-depolarized cathode (ODC) HCl electrolysis. However, its durability remains unexplored under the corrosive operating conditions of the HCl electrolysis. To address this, we investigate the stability of Fe–N–C in HCl electrolysis via sustained constant current and uncontrolled shutdowns, mimicking the harsh transients of industrial operation. End-of-test analysis of Fe–N–C using X-ray absorption and 57Fe Mössbauer spectroscopy reveals stable intermediate-spin Fe(II)–N4 and high-spin Fe(II)–N4, allowing Fe–N–C to maintain its high activity. Despite these structural changes, Fe–N–C maintained a competitive low voltage of 1.33 V at 0.5 A cm–2. Accelerated stress tests simulating uncontrolled shutdown conditions, combined with Raman spectroscopy, showed that Fe–N–C and RhxSy/C share a common carbon degradation mechanism. This work identifies durable Fe–N4 moieties in the corrosive conditions of HCl electrolysis and demonstrates the resilience of Fe–N–C as a robust ODC catalyst, guiding improved catalyst design.

Lithium‑sulfur (LiS) batteries are limited by sluggish sulfur reduction reaction (SRR), lithium polysulfide (LPS) shuttling, and Li-metal instability, all governed by Li+ coordination. Yet solvation tuning alone cannot predict sulfur redox once LPS are involved. Here, by employing two structurally analogous sulfonate additives, methanesulfonate (MS) and trifluoromethanesulfonate (TFMS), paired with a weakly coordinating counter-cation, we decouple solvation effects from LPS-mediated Li+ association. Molecular dynamics simulations, density functional theory, and 7Li nuclear magnetic resonance confirm nearly identical perturbations to the Li+ solvation sheath in LPS-free electrolytes. Upon LPS formation, however, MS strengthens Li+-LPS association, restricting Li+ transport and moderating the liquid-to-solid sulfur conversion, whereas TFMS weakens Li+-LPS interactions, preserves Li+ mobility, and promotes more favorable sulfur-conversion behavior with reduced polarization and activation energy. Importantly, the electrochemical consequences of these divergent SRR pathways depend strongly on electrolyte availability. Under practical low electrolyte-to‑sulfur (E/S) conditions, the favorable sulfur-conversion behavior in TFMS enables superior sulfur utilization and stable cycling beyond 300 cycles at 87% capacity retention (695 mAh g−1). In contrast, flooded electrolyte conditions largely mask electrolyte-dependent differences, highlighting the dynamic coupling between sulfur-conversion behavior and electrolyte availability. Despite their opposite effects on SRR behavior, both additives enhance durability through distinct mechanisms: MS limits parasitic degradation by moderating SRR behavior, whereas TFMS uniquely induces polymerization of 1,3-dioxolane, forming a TFMS-associated polymer-rich interphase on Li metal. These findings identify LPS-mediated Li+ association as an important factor linking SRR behavior, electrolyte management, and interfacial stability, providing mechanistic guidance for additive design in practical LiS batteries.

ABSTRACT Achieving stable interfacial chemistry in lithium–sulfur batteries under practical conditions remains a key barrier to commercialization. Here, we demonstrate that interfacial dynamics can be effectively regulated by coupling solvation‐power control with intrinsic heterogeneity of sulfur redox chemistry through the introduction of a weakly solvating fluorinated cosolvent, LIB 1200ET (1200ET). Compared with conventional fluorinated ethers, 1200ET efficiently shifts Li + solvation environment toward a more non‐coordinated configuration at low volume fractions, enabling substantial solvation modulation without significantly impairing sulfur redox kinetics. This solvation transition weakens Li + –solvent interactions while strengthening Li + –anion and Li + –lithium polysulfide (LPS) coordination, suppressing LPS solubility and promoting reconstruction of solid–electrolyte interphase (SEI). Regulated LPS chemistry, together with 1200ET, leads to formation of a S 4+ ‐rich, LiF‐reinforced SEI with enhanced ionic conductivity and mechanical robustness. Spatially resolved sulfur K‐edge X‐ray absorption spectroscopy on pouch cells reveals pronounced current‐density‐dependent chemical heterogeneity, distinguishing kinetically dominated and solvation‐controlled regions. Under practical conditions (3.7 mg cm −2 sulfur loading, E/S = 6 µL mg −1 ), a single‐layer pouch cell delivers 527 mAh g −1 over 200 cycles at C/3, while an Ah‐level multilayer pouch cell achieves an energy density of 358 Wh kg −1 . These results establish non‐coordinating cosolvent‐driven solvation engineering as a scalable strategy for practical Li–S batteries.

All-solid-state batteries (ASSBs) with a Si-based anode offer high energy density but suffer from sluggish mass transport and structural instability arising from large volume changes and electrochemical sintering. Here, we introduce a nitride-based solid electrolyte, vacancy-rich β-Li₃N, as a reactive anolyte for the Si anode, leveraging its high ionic conductivity (> 2 mS/cm) and unique reactivity within the Li–Si–N system. Beyond serving as an ion conductor, the nitride anolyte reacts in situ with Si during ball-milling mixing to form a novel lithium nitridosilicate (Li x Si y N z ) interlayer on the Si particle, thereby improving structural integrity, electrochemical stability, and charge transport. The interlayer also suppresses the electrochemical sintering between the Si, consequently avoiding the increase of the diffusion length in the Si phase during cycling. A further pre-lithiation process shifts the anode operation window away from the kinetically unfavorable regions. The pre-lithiated Si-Nitride-C anode with LiCoO₂ cathode delivers outstanding rate capability (up to a current density of 25.5 mA/cm²) and long cycling stability (over 5000 cycles). These findings provide novel insights into the interface and anolyte design principles for high-performance and long-lifespan ASSBs.

Lithium-sulfur batteries (LSBs) emerge as promising next-generation energy storage systems offering cost-effectiveness, environmental friendliness, and high theoretical energy density. The practical implementation of LSBs faces significant hindrances due to the shuttle effect and sluggish redox reactions. To address these challenges, single-atom catalyst (SAC) based combination materials from d-block elements can offer increased active catalytic sites, rapid charge transfer, accelerated electron migration, and fast sulfur redox conversion kinetics of lithium polysulfides (LiPSs). In this study, we fabricated three different LSB cathodes: pure S, S@MoS2/SnS2, and S@Fe-MoS2/SnS2. These cathodes were then used to explore the cycle life, capacity, rate capability, and redox kinetic reactions of LiPSs while assessing the influence of Fe-SACs on their performance. As a result, LSBs with S@Fe-MoS2/SnS2 cathodes demonstrate an extended cycle life of 1000 cycles at a C-rate of 0.2C, maintaining a capacity close to 500 mA h g-1, the highest initial discharge capacity of 1622 mA h g-1 and 1066 mA h g-1 at 0.05C and 0.2C, and excellent rate capabilities of 708 mA h g-1 and 558 mA h g-1 at 1C and 2C, respectively. The synergistic effect of the Fe-SAC-based combination cathode (S@Fe-MoS2/SnS2) creates plentiful adsorptive and highly active catalytic sites, resulting in substantially enhanced capacity for adsorbing soluble long-chain LiPSs. This facilitates ultra-fast redox kinetics, surpassing the performance of the S@MoS2/SnS2 and pure S cathodes. In the ex situ analysis, results from powder X-ray diffraction (XRD) to observe the new phase, soft X-ray absorption spectroscopy (XAS) to investigate the electronic structure, and hard X-ray photoelectron microscopy (HAXPES) with different energies (900 eV, 2000 eV, and 6000 eV) to track the chemical-state evolution of Fe-SACs in MoS2/SnS2 cathodes displayed notable electrochemical reversibility involving S8 -><- LiPSs -><- Li2S conversion even after 1000 cycles. Additionally, in situ, operando Raman analysis can unveil a novel catalytic mechanism of Fe-SACs in MoS2/SnS2 "facilitating rapid electron transfer" during the discharge and charge processes of LSBs involving the conversion of S8 -><- long-chain LiPSs -><- Li2S2/Li2S. This study elucidates the working mechanism of Fe-SAC cathodes, offering insights into overcoming the shuttle effect and facilitating sulfur redox kinetics to advance commercial LSBs.

Li-sulfur (Li-S) batteries are promising as the next-generation energy storage technology but face challenges due to sluggish sulfur redox reaction (SRR) kinetics and a sulfur shuttling effect. While many studies have explored polycaprolactone (PCL)-based gel polymer electrolytes (GPEs) to address these issues, the influence of solvent properties, including dielectric constant (ϵ) and donor and acceptor numbers (DN and AN), remain unexplored despite their critical impact on performance and full-scale implementation. This study systematically compares three distinct electrolytes, dimethoxyethane (DME), dimethyl sulfoxide (DMSO), and tetraethylene glycol dimethyl ether (TEGDME)-paired with PCL, to correlate the varied solvent properties and their effects on the physical properties of the GPE, in terms of Li+ transport and solvation, and polysulfide's confinement. Among them, the DME-based GPE, with an intermediate DN, exhibited the lowest crystallinity (2.31%), highest ionic conductivity (7.49 mS/cm), and high Li+ transference number (0.77). As a result, it achieved a specific capacity of 795 mAh/g sulfur and an average Coulombic efficiency of 97.5% after 120 cycles at C/5, outperforming its competitors. Operando Raman and UV-vis spectroscopy confirmed that PCL effectively confines long-chain polysulfides within its network, mitigating the shuttle effect and facilitating reversible polysulfide conversion. These findings demonstrate that GPEs with moderate DN values and balanced ϵ significantly enhance stability, extend cycle life, and improve rate performance for Li-S batteries. This work provides valuable insights into the design of advanced electrolyte systems for practical energy storage applications.

Lithium-sulfur (Li-S) batteries stand promising for next-generation energy storage systems due to their high specific capacity and cost-effectiveness. However, their commercialization is hindered by sluggish sulfur reduction reaction (SRR) kinetics and polysulfide migration. To address these challenges, we introduce bis(4nitrophenyl) carbonate (BNC) as a bifunctional electrolyte additive. At an optimal concentration, BNC leverages its polar nature to anchor soluble polysulfides while simultaneously modifying the Li+ solvation structure at the molecular level, enhancing SRR kinetics. This dual functionality is confirmed through molecular dynamics simulations and electrochemical analyses. In situ electrochemical impedance spectroscopy (EIS) further shows that optimal BNC concentration reduces activation energy for polysulfides formation by 40.6%. Operando spectroscopic techniques, including Raman and X-ray absorption spectroscopy (XAS), demonstrate BNC's dual effect, with a focus on the middle-chain polysulfides conversion, supported by detailed polysulfide quantification. X-ray fluorescence (XRF) mapping reveals decreased sulfur deposition on lithium, indicating the effectiveness of shuttle suppression. These effects contribute to outstanding cycling performance under practical conditions, achieving 650.93 mAh gsulfur-1 and coulombic efficiency of 93% over 200 cycles at a C-rate of C/2. This work not only offers valuable insights into the use of unconventional carbonate-based additives but also provides a blueprint for advancing Li-S battery designs through targeted solvation structure modifications.

Single-atom catalysts (SACs) are highly promising for electrochemical CO₂ reduction due to their excellent activity, selectivity toward CO, and efficient use of metal centers. However, the fundamental mechanisms driving their performance, particularly the rate-limiting step, remain unclear, limiting the ability to design more effective catalysts. This project seeks to understand how surface modifications influence the electronic structure and coordination environment of SACs to identify which steps in the CO₂ reduction pathway are rate-determining. Dopants will be used to modify Fe- and Ni-based SACs to tune their local chemical environments. These modifications influence intermediate binding energies and proton availability at the catalyst surface. Electron-withdrawing or electron-donating characteristics of the added groups may change the binding energy of key intermediates such as *COOH formation or CO desorption. To probe these effects, a combination of ex situ X-ray photoelectron spectroscopy (XPS) and operando X-ray absorption spectroscopy (XAS) will be employed. XPS will characterize surface composition, chemical bonding, and oxidation states before and after the reaction. Operando XAS will provide real-time insight into the oxidation state and coordination changes of the active metal centers under working electrochemical conditions. By correlating catalyst structure with changes in reaction behavior, this study aims to uncover how specific modifications impact activity and selectivity. The results will contribute to a deeper mechanistic understanding of SACs and guide the rational design of next-generation catalysts for efficient and selective CO₂ electroreduction.

Chemically doped carbon-based candidates have emerged as a significant driving force across multifarious research domains including oxygen reduction reaction (ORR), electrochemical sensing, energy storage and conversion, and solar cell technologies, etc., This comprehensive review takes a critical stance, shedding light on the exceptional supercapacitance performance found within heteroatom-doped/enriched carbon derivatives. This includes an array of candidates such as graphene, carbon nanotubes, carbon nanofibers, boron carbonitride, g-C3N4, mesoporous carbon, ordered mesoporous carbon, and oxygen-enriched porous carbon. The review delves into diverse synthetic methodologies, encompassing chemical vapor deposition, thermal annealing, hydrothermal, microwave routes, and arc discharge techniques for each of these carbon-based materials. Furthermore, an in-depth exploration of the underlying electrochemical mechanisms governing supercapacitive performance is provided. Notably, the synthesis and energy storage proficiency of heteroatom-enriched materials like g-C3N4 and BCN are meticulously scrutinized. The influence of heteroatom doping on crucial characteristics like wettability, and porosity is deeply examined, boosted by compelling empirical substantiation. Adding intrigue, the merits, and drawbacks inherent to each synthetic approach are thoughtfully presented systematically. As a result, this article stands as a highly valuable resource, offering substantial support and insightful information tailored to young researchers. By furnishing a panoramic survey of diverse synthetic avenues and an in-depth analysis of supercapacitive performances across distinct classes of heteroatom-doped/enriched carbon materials, we aspire for this work to become an indispensable reference.

Lithium-sulfur (Li-S) batteries offer substantial promise for next-generation energy storage but suffer from rapid capacity decay, primarily due to polysulfide dissolution and slow conversion kinetics. Metal-nitrogen-carbon (M-N-C) single-atom catalysts (SACs) involving nitrogen‐coordinated transition metals embedded into a carbon matrix have been explored to address these challenges by enhancing sulfur redox kinetics and trapping polysulfides. However, the observed performance improvements with SACs are not permanent, prompting an investigation into their degradation mechanisms during cycling. In this work, we systematically examine the degradation pathways of various M-N-C catalysts (Fe-N-C, Co-N-C, Ni-N-C, Sn-N-C, and Mo-N-C) via operando and in situ X-ray absorption spectroscopy (XAS) at the National Synchrotron Light Source II. While these catalysts initially improved battery performance, increasing capacity retention by over 50% compared to catalyst-free controls, structural degradation during cycling was evident. Transmission electron microscopy (TEM) revealed a significant (>50%) reduction in the density of active metal centers within the catalysts after extended cycling. Hard XAS analysis of Fe-N-C catalysts showed a progressive reduction in iron valence from Fe³⁺ to Fe²⁺, ultimately leading to the formation of metallic Fe nanoparticles, a major contributor to catalyst degradation and capacity fade. Our findings provide critical insights into the stability limitations of M-N-C SACs and their interactions with polysulfides. Understanding these degradation mechanisms is essential for designing more durable SACs, ultimately advancing Li-S battery technology toward commercial viability. Figure 1

Solid electrolytes are critical to enabling safe and high-energy-density batteries; yet, their practical deployment is impeded by poor electrochemical stability, inadequate interfacial contact, and challenging manufacturing processes. Here, we introduce a novel "solid-in-solid" electrolyte architecture comprising a porous Li zeolite electrolyte (LiX) infiltrated with a melt-processable plastic crystal electrolyte (PCE). This LiX-PCE electrolyte achieves an ionic conductivity of 0.55 mS/cm at 20 °C, alongside improved electrochemical stability over pure PCE. Solid-state nuclear magnetic resonance reveals three Li+ transport pathways: through LiX, through PCE, and via ion exchange at phase boundaries. Leveraging the melt-processability of the PCE, we proposed a roll-to-roll-compatible melt infiltration strategy for scalable solid-state battery (SSB) fabrication with the LiX-PCE electrolyte. The SSBs demonstrate excellent rate performance (up to 10 C), 93% capacity retention after 200 cycles at 2C, and 4.5 V compatibility. This work elucidates critical design principles for high-performance solid-state electrolytes and presents a viable path toward practical, fast-charging, high-power SSBs.

Lithium-sulfur (Li–S) batteries promise ultra-high energy densities but suffer from sluggish sulfur reduction reaction (SRR) kinetics and polysulfide shuttling. Here, we demonstrate that bis(4-nitrophenyl) carbonate (BNC), a previously overlooked carbonate additive, exhibits concentration-dependent bifunctionality in practical Li–S cells (4 mg cm -2 sulfur loading, E/S = 8 µL mg -1 ). At an optimized concentration of 0.01 M, BNC simultaneously modifies the Li + solvation environment and anchors soluble polysulfides, thereby enhancing SRR kinetics and suppressing shuttle effects. We validate these dual mechanisms through an integrated suite of molecular simulations and operando techniques. Ab initio molecular dynamics (AIMD) and 7 Li NMR spectroscopy reveal that BNC induces a redistribution of solvent molecules in the Li + solvation shell, weakening DME coordination and facilitating desolvation for faster reaction kinetics. Operando Raman spectroscopy indicates that middle- and long-chain polysulfide peaks diminish earlier in BNC-containing cells, while operando X-ray absorption spectroscopy (XAS) captures the formation and transformation of short-chain polysulfides (Li 2 S x , x<4), culminating in enhanced Li 2 S formation. Quantitative deconvolution using MCR-ALS confirms a more complete 16-electron conversion under BNC regulation. Electrochemical studies further corroborate these findings. Randles–Sevcik analysis and potentiostatic Li 2 S nucleation tests show a 46% increase in Li-ion diffusion and a 30 mAh g s -1 enhancement in Li 2 S nucleation capacity. In situ EIS reveals that BNC lowers the SRR activation energy by 40.6%, particularly at the most kinetically hindered stages. Galvanostatic cycling achieves 650.93 mAh g s -1 with 93% coulombic efficiency over 200 cycles at C/2. Meanwhile, XRF mapping and shuttle current measurements confirm reduced sulfur deposition on the Li anode, directly linking BNC’s function to suppressed parasitic reactions. This work not only reveals BNC’s unique ability to simultaneously optimize solvation structure and immobilize polysulfides but also sets a blueprint for additive design in high-loading, lean-electrolyte Li–S systems, advancing their viability for commercial applications. Figure 1

Alkaline water and anion-exchange membrane electrolyzers are considered leading solutions for the large-scale production of hydrogen due to their lower capital costs. In recent years, numerous hydrogen evolution electrocatalysts have been developed, primarily by alloying nickel with other transition metals. Despite these advancements, stability remains a challenge due to the low intrinsic corrosion resistance of these alloys. In this work, we present an advanced synthesis method that incorporates an amorphous copper hydroxide phase within a nickel-copper alloy using a pH-trap mechanism. This approach prevents the formation of long-range ordered and dense catalysts, resulting in a significantly higher surface area and enhanced catalytic activity. A detailed mechanism was proposed to explain this deposition process. The use of copper eliminates corrosion risks due to its thermodynamic stability in alkaline conditions, even at relatively high potentials. Accelerated stress tests demonstrate that the NiCu catalyst is stable under both continuous and intermittent conditions, in both inert and oxygen atmospheres, positioning it as one of the most active and stable HER catalysts in alkaline media. Furthermore, the pH-trap deposition (pTD) method developed here can be applied to a variety of materials to tailor their physical and chemical properties.

Li-Sulfur (Li-S) batteries stand promising as the next-generation energy storage technology but are hindered by sluggish sulfur redox reaction kinetics and sulfur shuttling effect. Many studies tried to address these issues by adopting polycaprolactone (PCL) based gel polymer electrolytes (GPEs), but often overlooked solvent properties, including dielectric constant (ϵ), donor and acceptor numbers (DN and AN), impact performance and prevent the full implementation of GPE-based Li-S batteries. This work compares three distinct electrolytes paired with PCL, namely, dimethoxyethane (DME), dimethyl sulfoxide (DMSO), and tetraethylene glycol dimethyl ether (TEGDME), due to their varied solvent properties, to evaluate their effects on the physical properties of the GPE, Li⁺ transport and solvation, and polysulfide's confinement. The DME-based GPE, with an intermediate DN, exhibited the lowest crystallinity (2.31%), highest ionic conductivity (7.49 mS/cm), and high Li⁺ transference number (0.77), achieving a specific capacity of 795 mAh/g sulfur and an average coulombic efficiency of 97.5% after 120 cycles at C/5, outperforming its competitors. Moreover, operando Raman and UV-Vis spectroscopy confirmed that PCL effectively confines long-chain polysulfides within its network, mitigating the shuttle effect and facilitating reversible polysulfide conversion. These findings highlight that GPEs with moderate DN values and balanced ϵ enhance stability, extend cycle life, and improve rate performance for Li-S batteries, providing unique insights for designing advanced electrolyte systems for practical applications.

Enhancing photocatalytic oxygen evolution is vital for renewable energy. In this work, we demonstrate how plasmon-induced resonant energy transfer (PIRET) from gold nanoparticles (AuNPs) to Fe- and Co-doped nickel hydroxide (Ni(OH)2) can improve this process. PIRET involves the transfer of energy from excited AuNPs to nearby molecules, boosting their reactivity. We show that doping Ni(OH)2 with Fe or Fe/Co results in a significant enhancement in photocatalytic activity, achieving a 72% increase in oxygen evolution reaction (OER) performance compared to pristine Ni(OH)2 layered double hydroxide (LDH). In addition, a reduced optical band gap from 2.8 eV (pristine Ni(OH)2 LDH) to 2.3 eV and the formation of flat bands was observed, enabling efficient energy transfer upon plasmonic nanoparticle integration and enhancing electronic properties. This supports that the PIRET mechanism is responsible for the increased OER performance. This study demonstrates the crucial role of PIRET in enhancing plasmonic energy transfer and the synergistic effects of doping and AuNP coupling. These findings highlight the broader potential of material engineering in advancing efficient and sustainable energy technologies.

Lithium-sulfur (Li-S) batteries offer significant potential for high-energy-density applications due to sulfur’s exceptional theoretical specific capacity (1,675 mAh/g) and energy density (~2,600 Wh/kg), surpassing current Li-ion technologies. However, commercialization remains hindered by sluggish reaction kinetics, polysulfide dissolution, Li-metal corrosion, and limited cycle life. Addressing these challenges, we introduce a novel family of tetrabutylammonium-based (TBA) organosulfur counter-anion additives, soluble in standard electrolytes, to enhance the stability and performance of the solid electrolyte interphase (SEI). Cells incorporating TBA-based additives (0.01 to 0.25M) demonstrated superior cycling performance, achieving up to a 52% improvement in capacity retention after 100 cycles at C/5 and maintaining coulombic efficiencies around 98%. Rate capability tests further revealed improved performance at higher current densities (up to 53% higher capacity at C/2 compared to the baseline). Among the additives tested, the role of counter anions was specifically explored: Trifluoromethanesulfonate (TFMS) supports the polymerization of DOL, enhancing Li-metal protection; Methanesulfonate (MS) interacts favorably with intermediate polysulfides (Li₂S₄ and Li₂S₆), promoting high-rate performance; and bis-Trifluoromethanesulfonimidate (TFSI) reduces polysulfide solubility, mitigating the shuttle effect by increasing solution anion concentration. Although TBA is electrochemically inactive, it may function as a surfactant, further influencing Li-S battery performance. Significantly, TFMS and TFSI directly impact the solubility of long-chain polysulfides, decreasing conversion kinetics and improving battery stability. These findings highlight the critical role of anions in enhancing SEI formation through ring-opening polymerization of 1,3-dioxolane (DOL), significantly improving the quality of the SEI and cycling stability, thus advancing practical Li-S battery applications in electric vehicles and grid storage systems. Figure 1: The RDFs and corresponding major coordination complex for A) 1MLiTFSI with 1:1 DME:DOL solvent and 0.1 M TBA-TFMS and B) 1MLiTFSI with 1:1 DME:DOL solvent and 0.1 M TBA-MS. Atom color code: white – H, Li – purple, cyan – C, red – O, lime – F, yellow – S. Figure 1

The nickel-rich layered Li[Ni0.8Co0.1Mn0.1]O2, popularly known as NCM811, is considered a high-performance cathode material in lithium-ion batteries (LIBs) due to its high specific capacity and energy density. However, because of its poor structural stability, it suffers from long-run performance in LIBs. The surface coating technique can enhance the performance of the NCM811 cathode by preventing its surface degradation during prolonged contact with electrolytes. Herein, we report a uric acid-derived nitrogen-doped carbon-coated NCM811 cathode to enhance the cathodic performance. The materials were prepared by a facile one-step calcination in which different weights of uric acid are mixed well with NCM811 through ball milling followed by sintering. The XRD peaks confirm the formation of a pure phase in both the bare and modified NCM811 materials. The morphological characteristics and coating thickness are observed by FE-SEM and FE-TEM analysis, respectively. Electrochemical characterizations such as galvanostatic charge-discharge (GCD), cyclic performance, and rate capability studies show that the 0.1-NCM811 material can effectively tailor the electrochemical performance of the cathode in LIBs. The capacity retention of 0.1-NCM811 material is 92.7% and 85.8% at 100 cycles in 0.1 C and 300 cycles in 1 C, respectively. The improved electrochemical performance of coated NCM811 cathode is associated with the effective coating of nitrogen-doped carbon, which can hinder the electrode dissolution process while amplifying the ionic conductivity.

Although lithium-ion battery (LIB) technology has been the primary choice for the everyday applications due to its high-energy-density, high-stability, and longer cycle-life, depletion of lithium reserve has prompted battery researchers to search for new alternatives to LIB. Sodium, in this respect, can be a viable solution because it is the sixth most abundant element in the earth's crust and has similar structure and electrochemical working mechanisms to lithium. Among all the prevailing cathode materials for Sodium-ion battery (SIB), the manganese and iron rich P2 type [[EQUATION]] has attracted broad attention as a promising cathode candidate due to natural abundancy of Fe and Mn along with high redox couple of Fe3+/Fe4+ and Mn3+/ Mn4+. Despite all these merits, NFM suffers from structural instability during cycling arising from the destructive Jahn-Teller (JT) distortion effect of Mn3+/ Mn4+ during charging and Fe4+/ Fe3+ during discharging. Although numerous strategies proposed by researchers to address the JT effect, this issue still persists. In this research, a novel P2-type transition metal-oxide cathode Na0.6Fe0.5-2xMn0.5TixVxO2 was synthesized by doping a tiny fraction two electrochemically inactive elements, Titanium (Ti) and Vanadium (V) into Mn-rich Na0.6Fe0.5Mn0.5O2 (NFM) that mitigated the JT effect substantially and ameliorated the stability of the SIB during cycling. A moderate amount of doping preserves the lattice structure and similar morphology to pristine NFM. Besides, the Ti/V co-doping in place of Fe not only effectively reduces the amount of JT prone Mn3+, which is observed through in-depth material analysis such as XRD and XPS, but also increases the specific capacity by expanding the d-spacing between the transition metal oxide layers for better Na ion transport that are reflected through various electrochemical analysis. These exhaustive structural and morphological comparisons provided insights on the effects of V and Ti doping on stabilizing surface structures, reducing Jahn Teller distortion, enhancing stability and capacity retention and promoting Na+ carrier transport mechanism. Moreover, the electrochemical analysis such as galvanostatic charge/discharge profile validates the capacity improvement via Ti and V co-doping into NFM cathode. The initial discharge capacity of the 2% Ti/V doped [[EQUATION]] was found to be 187.12 mAh g-1 at a rate of 0.1C, which was greater than the discharge capacity of 175.15 mAh g-1 observed for pure NFM [[EQUATION]] In contrast, 2NFMTV exhibited a noteworthy capacity retention of 46.1% when evaluated for its original capacity after undergoing 150 cycles at a rate of 0.1C. This research also established a structural doping approach as a feasible technique for advancing the progress of next generation SIBs.