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Despite possessing a high gravimetric capacity above 230 mAh g–1, Li-rich NMC oxides suffer from the bottleneck of capacity fading and a decrease in the discharge voltage upon cycling. Therefore, suppressing the discharge voltage decay is a major concern for employing these cathodes in Li-ion cells. To understand the structural change during initial cycles, the ex-situ X-ray diffraction investigation of Li-rich NMC cathodes at different charged states (4.0, 4.4, and 4.6 V) after completing one cycle in the potential domain of 2.0–4.7 V is conducted, which reveals the generation of a spinel phase only when polarized to above 4.4 V. Hence, Li-rich Li1.2Ni0.13Mn0.54Co0.13O2 cathodes herein are investigated across three different voltage ranges: 2.0–4.6 V, 2.7–4.6 V, and 2.7–4.4 V versus Li, after being activated first by polarization up to 4.7 V, to assess the suitable operational voltage range for their stable cycling …

Zinc-bromine batteries (ZBBs) hold great potential for large-scale energy storage due to their high energy density, sustainability, and cost-effectiveness. However, the practical application of flowless ZBBs is hindered by self-discharge (SD) from uncontrolled bromine diffusion and the overlap of the Br⁻/Br2 redox potential with the oxygen evolution reaction (OER). Additionally, the limited solubility of bromine complexing agents (BCAs) in aqueous media poses a significant challenge. Here, we introduce a targeted localized presence (TLP) strategy, encapsulating hydrophobic BCAs within porous activated carbon electrodes to address these limitations. By examining three BCA structures, we demonstrate that TLP effectively reduces SD and increases coulombic efficiency. We show that the formation of hydrophobic phases within the pores can be controlled by manipulating the BCA alkyl chain length. This tailored TLP approach minimizes OER susceptibility and extends the voltage window to 2.7V (0.1M ZnBr2). Nuclear magnetic resonance analysis highlights the aggregation behavior of BCAs, elucidating their role in stabilizing the system. Remarkably, insoluble BCAs with hexyl side chains achieved >98% CE at 200 mAh/g over 1000 cycles at 1 A/g. This work presents a robust pathway for advancing aqueous zinc-halide batteries towards scalable and durable energy storage solutions.

Electrode–electrolyte interphases are critical determinants of the reversibility and longevity of lithium (Li)-metal batteries (LMBs). However, upon cycling, the inherently delicate interphases, formed from electrolyte decomposition, become vulnerable to chemomechanical degradation and corrosion, resulting in rapid capacity loss and thus short battery life. Here, we present a comprehensive analysis of the complex interplay between the thermodynamic and kinetic properties of interphases on Li-metal anodes, providing insights into interphase design to address these challenges. Direct measurements of ion-transport kinetics across various electrolyte chemistries reveal that interphases with high Li-ion mobility are essential for achieving dense Li deposits. Conversely, sluggish ion transport generates high-surface-area Li deposits that induce Li random stripping and the accumulation of isolated Li deposits. Surprisingly …

Combining Li‐metal anodes (LMAs) with high‐voltage Ni‐rich layered‐oxide cathodes is a promising approach to realizing high‐energy‐density Li secondary batteries. However, these systems experience severe capacity decay due to structural degradation of high‐voltage cathodes and side reactions of electrolyte solutions with both electrodes. Herein, the use of multi‐functional additives in fluoroethylene carbonate‐based electrolyte solutions that enable the operation of successfully rechargeable high‐voltage (4.5 V) Li‐metal batteries (LMBs) with high areal capacity (>4 mAh cm−2) are reported. Customized electrolyte solutions are pivotal in passivating the electrodes, minimizing microcrack formation, and ensuring that current is uniformly distributed within cathode particles. The developed electrolyte solution protects the LMA by forming a very stable and effective solid–electrolyte interphase. Together with the …

Rechargeable magnesium metal batteries (RMBs) represent a promising sustainable energy storage technology, complementary to lithium-ion and sodium-ion batteries due to their superior volumetric energy density, cost-effectiveness, and safety. However, their widespread adoption is hindered by limited electrolyte options due to the formation of Mg ion-insulating surface films that cannot behave as solid-electrolyte-interphases. Here, after considering the binding affinity with Mg²⁺ and steric hindrance, we report a single-solvent system based on commercial aminoacetaldehyde dimethyl acetal (ADMA). Our system effectively forms a Mg ion-conducting interphase and enhances the Mg plating-stripping efficiency, without severe corrosion. The average Coulombic efficiency is 97.3% over 500 hours upon galvanostatic cycling in Mg‖stainless steel cells at cycling conditions of 0.5 mA cm⁻² and 0.5 mAh cm⁻², along with capacity retention of 90.3% and 99.2% for 250 and 300 cycles in Mg‖Mo₆S₈ and Mg‖Tellurium full-cells, respectively. This study indicates that high-performance practical RMBs are achievable through solvation structure engineering with commercially available solvents and salts.

Rechargeable solid-state sodium batteries are considered important high-energy next-generation rechargeable batteries. Sodium, being abundant and affordable can be combined with safe and stable solid electrolytes, addressing safety issues encountered with high-energy batteries based on active metal anodes like Li and Na, which employ liquid aprotic electrolyte solutions. Solid electrolytes based on polymeric matrices provide flexibility and good adhesion to the electrodes without requiring external pressure during battery manufacturing and cycling. However, one drawback is the low conductivity at room temperature and high impedance at the interfaces. Here, we report on the development of Na||NVP solid batteries based on composite polymer electrolytes containing PEO:NaFSI matrices in which particles containing Na-X type zeolite, which has a stoichiometry of Na2[(SiO2)2.5(AlO2)], and approximately 20 …

The design of cathode/electrolyte interfaces in high‐energy density Li‐ion batteries is critical to protect the surface against undesirable oxygen release from the cathodes when batteries are charged to high voltage. However, the involvement of the engineered interface in the cationic and anionic redox reactions associated with (de‐)lithiation is often ignored, mostly due to the difficulty to separate these processes from chemical/catalytic reactions at the cathode/electrolyte interface. Here, a new electron energy band diagrams concept is developed that includes the examination of the electrochemical‐ and ionization‐ potentials evolution upon batteries cycling. The approach enables to forecast the intrinsic stability of the cathodes and discriminate the reaction pathways associated with interfacial electronic charge‐transfer mechanisms. Specifically, light is shed on the evolution of cationic and anionic redox in high …

LiCoO2 (LCO) has been the cathode material of choice for three decades for durable, lightweight Li‐ion storage systems. Being charged up to 4.2 V versus Li/Li+, LCO provides excellent cycling stability with a specific capacity of ≈140 mAh g−1. Raising the cut‐off voltage to 4.6 V improves capacity by up to 60% however, it leads to rapid degradation of the cathode structure. Here, a one‐pot dual coating of MgF2 and AlF3 with fluorinated electrolyte additives achieves 190 mAh g−1 at a 0.5 C rate after 400 cycles with a capacity retention of 93%. Various analytical tools are used to follow the structural and morphological changes during cycling. Synergistically, ion transport is improved, and detrimental interfacial side reactions with the electrolyte solutions are fully mitigated. Structural stability is thus improved by using this coating, with only a little loss of the active material. This work provides a brief guideline for …

The chemistry of the electrolyte solutions that enable reversible Mg deposition is not trivial. Such solutions are currently limited to ethereal solvents and most of them contain chlorides complexes. These ionic complexes have important role in the performance. However, the presence of chlorides in these solutions complicates the cathode side because such solutions are not compatible with the commonly used metallic current collectors for cathodes. Consequently, it is questionable whether it is possible to synthesize fully functional Cl-free electrolyte solutions suitable commercial Mg-ion batteries. Noked et al. reported that by adding DME to the precursor electrolyte [Mg2Cl3*6THF]+ [Ph3AlCl]- in THF, it was possible to create a new electroactive complex Mg salt, namely, [Mg-3.DME]2+ 2[AlPh3Cl]-, which solution performs better than the precursor’s solution. This solution introduces a new case of chlorides free …

Sodium-ion batteries (SIBs) are considered as the most promising complementary energy storage system for large-scale application due to the high abundance of sodium. However, the irreversible phase transition and slow diffusion kinetics in O3-type layered transition metals oxides cathodes impede the development of advanced SIBs. Here we address this issue by introducing high-entropy doping regulation strategies, a series of NaNi0.4Mn0.3-xFe0.1Ti0.1SnxLi0.05Sb0.05O2 cathodes exhibit an excellent rate performance (>60 mAh g−1 at 6 A g−1) and prolonged cycle performance (capacity retention >80 % after 300 cycles, at 120 mA g−1). The correlations between the chemical compositions and the electrochemical properties in the designed high-entropy transition metal oxides cathodes were elucidated using a combination of analytical tools including all kinds of electrochemical techniques including …

LiCoO2 (LCO) has been the cathode material of choice for three decades for durable, lightweight Li‐ion storage systems. Being charged up to 4.2 V versus Li/Li+, LCO provides excellent cycling stability with a specific capacity of ≈140 mAh g−1. Raising the cut‐off voltage to 4.6 V improves capacity by up to 60% however, it leads to rapid degradation of the cathode structure. Here, a one‐pot dual coating of MgF2 and AlF3 with fluorinated electrolyte additives achieves 190 mAh g−1 at a 0.5 C rate after 400 cycles with a capacity retention of 93%. Various analytical tools are used to follow the structural and morphological changes during cycling. Synergistically, ion transport is improved, and detrimental interfacial side reactions with the electrolyte solutions are fully mitigated. Structural stability is thus improved by using this coating, with only a little loss of the active material. This work provides a brief guideline for …

The development of efficient electrolytes is crucial for advancing magnesium (Mg) batteries, which hold promise for next‐generation energy storage systems. Previously, electrolytes such as [Mg2(μ‐Cl)3 ⋅ 6THF]+ [Ph4Al]−, A, and [Mg2(μ‐Cl)3 ⋅ 6THF]+ [Ph3AlCl]−, B, have been studied, but their performance has been limited by issues related to ion dissociation and electrochemical stability. In this study, we report the synthesis of novel electrolytes by introducing polydentate ligands to these known systems, leading to the formation of [DME ⋅ MgCl ⋅ 3THF]+ [Ph4Al]− 1 and [DG ⋅ MgCl ⋅ 2THF]+ [Ph4Al]− 2, [Mg ⋅ 3DME]2+ 2[Ph3AlCl−] 3 and [Mg ⋅ 2DG]2+ 2[Ph3AlCl−] 4. These firstly discovered compounds were thoroughly characterized using X‐ray crystallography and NMR spectroscopy. Our findings reveal that the choice of counter anion plays a pivotal role in the products and mechanism of the …

The design of cathode/electrolyte interfaces in high‐energy density Li‐ion batteries is critical to protect the surface against undesirable oxygen release from the cathodes when batteries are charged to high voltage. However, the involvement of the engineered interface in the cationic and anionic redox reactions associated with (de‐)lithiation is often ignored, mostly due to the difficulty to separate these processes from chemical/catalytic reactions at the cathode/electrolyte interface. Here, a new electron energy band diagrams concept is developed that includes the examination of the electrochemical‐ and ionization‐ potentials evolution upon batteries cycling. The approach enables to forecast the intrinsic stability of the cathodes and discriminate the reaction pathways associated with interfacial electronic charge‐transfer mechanisms. Specifically, light is shed on the evolution of cationic and anionic redox in high …

Developing polymer electrolytes as an alternative to aprotic liquid electrolytes for lithium and sodium-ion batteries aims to enhance their safety, durability, and cost. Among these, polyethylene oxide (PEO) is a favorite choice due to its wide availability, excellent versatility, and mechanical properties. PEO: NaTFSI and PEO: NaFSI are stable and efficient ion-conducting solid polymer electrolytes compared to other PEO: NaX matrices (for instance, X=[PF 6]−,[ClO 4]−). We tested Na/PEO: NaTFSI/NVP cells at low temperatures (40 C) and carried out a series of electrochemical measurements to extract vital performance metrics such as diffusion coefficient, transference number, conductivity, and activation energy. Our findings emphasize the important role of the anions' nature in the properties of polymeric electrolytes like those based on PEO, in which there are strong interactions between the ions and the oxygen atoms …