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There is a controversial issue based on the particle cracking of the Ni-rich layered oxide cathode materials whether it occurs at the primary particles or the grain boundary. Herein, we found that the microcracking of NMC811 does not occur at single crystalline primary particles even abused at a severe upper cell voltage of 4.7 V having a lot of gas evolution since the single-crystal NMC811 has superior mechanical stability. The capacity retentions determined at 1C rate and a 100% state of charge (SOC) are 80% and 50% after 1000 cycles for single crystal and polycrystal NMC811, respectively. [ABSTRACT FROM AUTHOR]

Understanding gas evolution during battery operation is pivotal for elucidating the underlying mechanisms of battery behavior, a cornerstone for fostering innovation in energy storage technologies. Despite the wealth of quantitative analyses available, the realm of large-scale, practical, full-cell investigations remains relatively unexplored. This study bridges this gap by unveiling a novel, robust gas chromatography methodology designed to meticulously quantify gas generation within 18650 cylindrical cells Li-ion and anode-free Li-metal Ni-rich batteries across a spectrum of operational conditions. Our approach not only reaffirms the capability for precise, reliable quantitative measurements but also illuminates new findings on the dynamics of gas evolution. This includes the significant impact of temperature and cathode material composition on gas generation, alongside a pioneering exploration into the behavior of anode-free Li-metal batteries. These insights not only advance our understanding of battery performance and safety at a practical cell level but also pave the way for the development of more efficient, durable, and safer energy storage solutions. [Display omitted] • Developed precise gas chromatography for Li-ion and Li-metal batteries. • Higher temperatures, nickel content significantly boost gas production, degradation. • Revealed unique gas evolution in anode-free Li-metal batteries. • Identified key conditions influencing gas production, battery design optimization. • Data links gas evolution to battery degradation, boosts safety, efficiency. [ABSTRACT FROM AUTHOR]

We present a novel, non-flammable electrolyte for Ni-rich 18650 cylindrical lithium-ion batteries (LIBs) based on a blend of triethyl phosphate (TEP) and fluorinated ethylene carbonate (FEC). We conducted a comprehensive analysis of the electrolyte, including electrochemical tests, safety evaluations, electrode surface characterizations, and quantum calculations, to elucidate its property-function relationship. We found that combining TEP with a concentrated FEC as a co-solvent (1.2 M LiPF 6 in TEP/FEC, 30/70 %v) resulted in a robust solid electrolyte interface (SEI) predominantly composed of lithium fluoride (LiF). This innovation improved the SEI's stability and suppressed electrolyte decomposition during extended cycling, leading to consistent battery performance. Our findings introduce a promising non-flammable electrolyte solution for LIBs that offers both thermal runaway prevention and seamless integration into existing battery manufacturing processes. This positions it as a potential alternative to solid-state electrolytes in advanced battery technology, with the potential to revolutionize the field. • Novel Electrolyte : Non-flammable blend for 18650 LIBs using TEP and FEC. • Rigorous Analysis : Comprehensive tests and calculations for electrolyte understanding. • Enhanced SEI : TEP and FEC create a stable, lithium fluoride SEI. • Consistent Performance : Approach reduces decomposition, ensuring prolonged battery life. • Future Applications : Solution integrates with existing processes, challenging solid-state alternatives. [ABSTRACT FROM AUTHOR]

Li–S batteries with a sulphur loading content of 5 mg cm−2 were produced as large-scale 18 650 cylindrical cells. We have found that a key failure mode of cylindrical Li–S battery cells is the severe capacity fading during the galvanostatic charge–discharge process due to the corrosion of the electrodes, the electrolyte decomposition, and the severe polysulphide shuttling effect. [ABSTRACT FROM AUTHOR]

The non-noble metal single-atom catalysts (SACs) of Fe, Co, Ni and Cu supported on graphitic carbon nitride (g-C 3 N 4) for CO 2 adsorption and hydrogenation to formic acid have been investigated with periodic density functional theory calculations. From our calculations, we found the adsorption energies of CO 2 in the range of −0.16 to −0.40 eV with the highest stability over Fe-g-C 3 N 4. The van der Waals interaction was included in the calculation due to its significant role in CO 2 adsorption. The 2-step proposed reaction mechanism involves the CO 2 hydrogenation to form a formate intermediate and hydrogen abstraction to formic acid as the end product. Based on the rate-determining step activation barrier, the catalytic activity order was found as Fe-g-C 3 N 4 > Co-g-C 3 N 4 > Cu-g-C 3 N 4 > Ni-g-C 3 N 4. From our findings, the better understanding of the effect of the non-noble metal coordination on CO 2 adsorption and hydrogenation provides hints to the rational catalyst design. Unlabelled Image • Fe-g-C 3 N 4 binds CO 2 stronger than other metals studied in this work. • The van der Waals interaction is found to be important for the CO 2 adsorption. • The catalytic activity order is found as Fe-g-C 3 N 4 > Co-g-C 3 N 4 > Cu-g-C 3 N 4 > Ni-g-C 3 N 4. [ABSTRACT FROM AUTHOR]

Herein, we introduce a multifunctional materials dry coating strategy on LiNi 0.8 Mn 0.1 Co 0.1 O 2 (NMC811) at 1 wt% with a thickness of ca. 100 nm. The materials included high chemical stable Al 2 O 3 (0.33 wt%) to reduce parasitic reactions, high electrical carbon black (0.33 wt%) to reduce internal charge transfer resistance, and high ionic conductive Li 7 La 3 Zr 2 O 12 (0.33 wt%) to enhance Li+ diffusion. The scalable dry coating mechanofusion used can also generate a smooth surface of spherical NMC811 particles enhancing its stability. With an exceptional property of mixed multi-functional materials, the cell of encapsulated NMC811 can perform up to 1000 cycles with 80% capacity retention. Whilst the pristine NMC811 cell can maintain only 39%. The coated NMC811 provides a two-fold specific capacity at a high C-rate (2.0C) compared to the pristine one. Moreover, it also offers excellent safety based on the UN38.3 standard at 18650 cylindrical cells. This multifunctional coating concept may lead to the further development of high-performance Li-ion batteries. [Display omitted] • Reducing intrinsic drawbacks of NMC811with a multifunctional materials coating. • Carbon black-Al 2 O 3 – Li 7 La 3 Zr 2 O 12- NMC811 strong bond at the interface. • Carbon black can reduce internal resistance of NMC811 Li-ion batteries. • Al 2 O 3 can reduce parasitic reactions of NMC811. • Li 7 La 3 Zr 2 O 12 can enhance Li-ion diffusion. [ABSTRACT FROM AUTHOR]

Electrolyte decomposition significantly impacts the long-term stability of Li-ion batteries, generating liquid and gaseous byproducts. This study focuses on formaldehyde formation, a critical byproduct from CO 2 reduction in Ni-rich Li-ion batteries. Through experimental and computational analyses, formaldehyde emerges from carbonate-based electrolyte decomposition. Examining overcharge, over-discharge, and fast charging conditions, formaldehyde concentration sharply increases under overcharge, indicating severe electrolyte breakdown, while over-discharge shows a gradual rise. Fast charging similarly elevates formaldehyde levels, underscoring the link between electrolyte decomposition and abusive conditions. Importantly, this research proposes utilizing formaldehyde concentration from the initial cycle as a predictive marker for assessing long-term Ni-rich Li-ion battery stability trends. Elevated initial formaldehyde indicates potential capacity fade and accelerated degradation, enabling proactive mitigation strategies. The study elucidates mechanisms governing formaldehyde formation, providing a foundation for developing electrolyte formulations and electrode materials with enhanced decomposition resistance and improved stability. This investigation contributes to the fundamental understanding of electrolyte decomposition in Ni-rich Li-ion batteries and presents a novel approach to predicting long-term performance based on initial formaldehyde measurements, advancing high-performance and reliable energy storage solutions. [Display omitted] • Formaldehyde predicts stability in Ni-rich Li-ion batteries under stress. • CO 2 reduction to formaldehyde marks electrolyte decomposition's critical pathway. • Overcharge significantly accelerates formaldehyde production, hinting at rapid degradation. • Precise formaldehyde measurement via NMR improves battery health evaluation. • Research inspires advanced battery designs limiting formaldehyde generation. [ABSTRACT FROM AUTHOR]

This study investigates the impact of fluorinated ethylene carbonate (FEC) as a co-solvent in the electrolytes of large-scale lithium-ion capacitors (LICs), an area previously unexplored. Our comprehensive analysis integrates electrochemical analysis, gas detection, and surface chemical examination to assess the performance and stability of a 1.2 M LiPF 6 electrolyte system. We explored various formulations, including a standard EC/EMC/DEC mixed solvent and newly designed electrolytes with FEC additions, such as EC/EMC/DEC/FEC and DMC/FEC blends. Our findings demonstrate that the DMC/FEC blend matches and even surpasses the capacity retention of traditional electrolytes, suggesting enhanced long-term stability. FEC's presence significantly reduces electrolyte decomposition, as confirmed by in situ Differential Electrochemical Mass Spectrometry and ex-situ gas chromatography. Further, surface chemical analysis highlighted the formation of a stable, LiF-rich solid electrolyte interface (SEI) when FEC is included, thereby improving the chemical stability of the system. These results underline FEC's crucial role in optimizing electrolyte compositions, thus advancing the development of more efficient and durable LIC systems. FEC's integration into LIC electrolytes represents a significant breakthrough, enhancing overall performance and longevity, with broad implications for the application of LICs in various technologies. [Display omitted] • FEC as a co-solvent significantly reduces electrolyte decomposition. • DMC/FEC blend outperforms traditional formulations in capacity retention. • FEC forms a stable, LiF-rich SEI, improving the chemical stability of LICs. • FEC lowers gas production during electrolyte decomposition. • FEC-based electrolytes boost thermal stability and safety under abusive conditions. [ABSTRACT FROM AUTHOR]

Ni-rich cathodes are essential for the advancement of high-energy lithium-ion batteries but encounter significant challenges at elevated voltages, including oxygen liberation and enhanced surface reactivity, which precipitate electrolyte decomposition. This study explores the intricate reaction mechanisms of electrolyte decomposition linked to the pronounced release of oxygen from the cathode lattice in large-scale 18650 cylindrical cells employing Ni-rich LiNi 0.90 Mn 0.05 Co 0.05 O 2 (NMC90)//graphite configurations, focusing on electrode crosstalk effects at high voltages. Notably, acetals such as methoxy methanol (49.93 %) and methane diol (50.07 %) were identified at 4.7 V, with their presence escalating at 4.9 V. Formaldehyde, present at 7.21 %, along with methanol (22.77 %), methane diol (36.35 %), and methoxy methanol (33.67 %), begins to manifest at 4.9 V. The dissolution of transition metals was analyzed using Inductively Coupled Plasma Atomic Emission Spectrometry, and changes in the double-layer capacitance were assessed through electrochemical impedance spectroscopy, further validating the link between these decomposition products and cathode failure associated with oxygen release. These insights reveal the complex relationship between electrolyte decomposition and cathode degradation due to oxygen release, highlighting a critical failure mechanism in large-scale cylindrical lithium-ion batteries. [Display omitted] • Formaldehyde, acetals indicate high-voltage cathode degradation. • Cathode oxygen release correlates with electrolyte decomposition, impacts battery. • Spectroscopic analysis connects transition metal dissolution, cathode failure. • Capacitance variation used for precise battery diagnostics, indicates degradation. • Increased metal dissolution linked to microcracking, expands surface area. [ABSTRACT FROM AUTHOR]

The safety of Li-ion batteries is one of the most important factors, if not the most, determining their practical applications. We have found that free carbonate-based solvent molecules in the hybrid electrolyte system can cause severe safety concerns. Mixing ionic liquids with a carbonate-based solvent as the co-solvent at a fixed salt concentration of 1 M LiPF6 can lead to free carbonate-based molecules causing poor charge storage performance and safety concerns. [ABSTRACT FROM AUTHOR]

Although supercapcitors have been widely studied, large-scale 18650 cylindrical supercapacitor cells have been rarely investigated and reported. Here, we investigated the effects of polymer separators, electrode thickness, electrolyte additives, testing protocols, reproducibility, and stability of the supercapacitors at the large-scale pilot plant. The supercapacitor cells with polyethylene (PE) and Al 2 O 3 -coated PE separators are good at low and high specific currents, respectively. The Al 2 O 3 -coated PE exhibits better stability than the one with the PE separator. The supercapacitor with a thickness of 250 μm has a cell capacitance of over 120 F from 100 to 1000 mA, which is higher than that of the other cells studied in this work. Also, the cell capacitances of supercapacitors can be enhanced by having redox mediator additives. 25 mM hydroquinone and ferrocene methanol are the optimized concentrations. We also found that the cell capacitance and equivalent series resistance of the supercapacitors are sensitive to the testing protocol, for which the highest capacitance was observed using the IEC62391-1 standard method, followed by the Maxwell method and conventional galvanostatic charge discharge method without dwell time. High reproducibility and stability of the as-fabricated supercapacitors in this work may lead to the further development of practical large-scale supercapcitors in the future. [Display omitted] • Large-scale production of cylindrical supercapacitors. • Supercapacitors with Al 2 O 3 -coated PE separator are good at high specific currents. • Supercapacitors with a thickness of 250 μm has a cell capacitance of over 120 F. • 25 mM of hydroquinone and ferrocene methanol additives is the optimized concentration. • Cell capacitance and equivalent series resistance are sensitive to the testing protocal [ABSTRACT FROM AUTHOR]

• Oxygen vacancies play an important role to electrocatalytic activity. • Bifunctional electrocatalyst towards ORR and OER. • Bifunctional electrocatalyst for Li–O 2 batteries. • Electronic bandgap depends on the oxygen vacancies controlling electrocatalytic activity. The Co 3 O 4 , which is on the top of volcano plot, having high oxygen vacancy of ca. 30% finely tuned promotes narrow band gap, resulting in the facilitation of the electron and charge transportation. The as-synthesized Co 3 O 4 catalyst can improve the electrocatalytic activity towards oxygen evolution reaction (OER) and oxygen reduction reaction (ORR). The as-prepared catalyst exhibits the superior ORR/OER stability for which the relative current decays only 7% and 14% for OER and ORR, respectively. By contrast, the OER stability of the RuO 2 catalyst presents the significant decay in relative current about 20%. The ORR stability of Pt/C also remarkably decreases to 29%. The catalyst here can be used as an efficient bifunctional catalyst at the cathode of Li–O 2 battery. It provides the superior performance as compared to that using the state-of-the-art Pt/C and RuO 2 /C electrocatalysts. Image, graphical abstract [ABSTRACT FROM AUTHOR]