A Multi-Element Composition Modulation Strategy for Designing High-Capacity and Stable O3-Type Na-Layered Oxide.

Unstable high-capacity cathodes remain a substantial barrier to enhancing the energy density of Na-ion batteries (NIBs). While the high-entropy strategy has demonstrated significant advantages in improving the performance of layered oxide cathodes, the specific capacities of reported high-entropy oxides remain relatively low (<150 mAh g). This prompts a reconsideration toward leveraging not just high entropy, but also the synergy among multiple elements to meet the demands for higher energy density.

Cation-self-shielding strategy promises high-voltage all-Prussian-blue-based aqueous K-ion batteries.

Prussian blue analogues (PBAs) are promising electrode candidates for aqueous batteries because the inevitable interstitial water is generally thought to have little impact on battery performance. Currently, mounting researches have focused on optimizing PBA properties by varying transition metal composition, but less attention has been paid to interstitial water, especially in alkali metal-ion deficient PBAs with large cavities. Here, we employ the water-rich KMn[Cr(CN)]·4.

4.2 V O3-Layered Cathodes in Sodium-Ion Pouch Cells Enabled by an Intermolecular-Reinforced Ether Electrolyte.

To fulfill the requirements for practical applications, it is urgent to boost the gravimetric energy density of sodium-ion batteries. An effective way is to increase the charging voltage of O3-type layered cathodes preferably to 4.2 V versus Na/Na (V).

Decoupling the air sensitivity of Na-layered oxides.

Air sensitivity remains a substantial barrier to the commercialization of sodium (Na)-layered oxides (NLOs). This problem has puzzled the community for decades because of the complexity of interactions between air components and their impact on both bulk and surfaces of NLOs. We show here that water vapor plays a pivotal role in initiating destructive acid and oxidative degradations of NLOs only when coupled with carbon dioxide or oxygen, respectively.

Interannual fluctuations in precipitation shape the trajectory of ecosystem respiration along a grazing exclusion chronosequence in a typical steppe in Inner Mongolia.

Grazing exclusion (GE), as an effective strategy for revitalizing degraded grasslands, possesses the potential to increase ecosystem respiration (R) and significantly influence the capacity of grassland soils to sequester carbon. However, our current grasp of R dynamics in response to varying durations of GE, particularly in the context of precipitation fluctuations, remains incomplete. To fill this knowledge gap, we conducted a monitoring of R over a 40-year GE chronosequence within Inner Mongolia temperate typical steppe across two distinct hydrologically years.

Tailoring Electronic Structure to Achieve Maximum Utilization of Transition Metal Redox for High-Entropy Na Layered Oxide Cathodes.

Charge compensation from cationic and anionic redox couples accompanying Na (de)intercalation in layered oxide cathodes contributes to high specific capacity. However, the engagement level of different redox couples remains unclear and their relationship with Na content is less studied. Here we discover that it is possible to take full advantage of the high-voltage transition metal (TM) redox reaction through low-valence cation substitution to tailor the electronic structure, which involves an increased ratio of Na content to available charge transfer number of TMs.

Unraveling the Reaction Mystery of Li and Na with Dry Air.

Li and Na metals with high energy density are promising in application in rechargeable batteries but suffer from degradation in the ambient atmosphere. The phenomenon that in terms of kinetics, Li is stable but Na is unstable in dry air has not been fully understood. Here, we use environmental transmission electron microscopy combined with theoretical simulations and reveal that the different stabilities in dry air for Li and Na are reflected by the formation of compact LiO layers on Li metal, while porous and rough NaO/NaO layers on Na metal are a consequence of the different thermodynamic and kinetics in O.

Conversion of Surface Residual Alkali to Solid Electrolyte to Enable Na-Ion Full Cells with Robust Interfaces.

The deposition of volatilized Na on the surface of the cathode during sintering results in the formation of surface residual alkali (NaOH/Na CO NaHCO ) in layered cathode materials, leading to serious interfacial reactions and performance degradation. This phenomenon is particularly evident in O3-NaNi Cu Mn Ti O (NCMT). In this study, a strategy is proposed to transform waste into treasure by converting residual alkali into a solid electrolyte.

Role of Defects, Pores, and Interfaces in Deciphering the Alkali Metal Storage Mechanism in Hard Carbon.

There are several questions and controversies regarding the Na storage mechanism in hard carbon. This springs from the difficulty of probing the vast diversity of possible configurational environments for Na storage, including surface and defect sites, edges, pores, and intercalation morphologies. In the effort to explain the observed voltage profile, typically existing of a voltage slope section and a low-voltage plateau, several experimental and computational studies have provided a variety of contradicting results.

Using High-Entropy Configuration Strategy to Design Na-Ion Layered Oxide Cathodes with Superior Electrochemical Performance and Thermal Stability.

Na-ion layered oxide cathodes (NaTMO, TM = transition metal ion(s)), as an analogue of lithium layered oxide cathodes (such as LiCoO, LiNiCoMnO), have received growing attention with the development of Na-ion batteries. However, due to the larger Na radius and stronger Na-Na electrostatic repulsion in NaO slabs, some undesired phase transitions are observed in NaTMO. Herein, we report a high-entropy configuration strategy for NaTMO cathode materials, in which multicomponent TMO slabs with enlarged interlayer spacing help strengthen the whole skeleton structure of layered oxides through mitigating Jahn-Teller distortion, Na/vacancy ordering, and lattice parameter changes.

Screening Heteroatom Configurations for Reversible Sloping Capacity Promises High-Power Na-Ion Batteries.

Heteroatom doping has been proved to effectively enhance the sloping capacity, nevertheless, the high sloping capacity almost encounters a conflict with the disappointing initial Coulombic efficiency (ICE). Herein, we propose a heteroatom configuration screening strategy by introducing a secondary carbonization process for the phosphate-treated carbons to remove the irreversible heteroatom configurations but with the reversible ones and free radicals remaining, achieving a simultaneity between the high sloping capacity and ICE (≈250 mAh g and 80 %). The Na storage mechanism was also studied based on this "slope-dominated" carbon to reveal the reason for the absence of the plateau.

Rational design of layered oxide materials for sodium-ion batteries.

Sodium-ion batteries have captured widespread attention for grid-scale energy storage owing to the natural abundance of sodium. The performance of such batteries is limited by available electrode materials, especially for sodium-ion layered oxides, motivating the exploration of high compositional diversity. How the composition determines the structural chemistry is decisive for the electrochemical performance but very challenging to predict, especially for complex compositions.

Pitch-Derived Soft Carbon as Stable Anode Material for Potassium Ion Batteries.

Potassium ion batteries (KIBs) have emerged as a promising energy storage system, but the stability and high rate capability of their electrode materials, particularly carbon as the most investigated anode ones, become a primary challenge. Here, it is identified that pitch-derived soft carbon, a nongraphitic carbonaceous species which is paid less attention in the battery field, holds special advantage in KIB anodes. The structural flexibility of soft carbon makes it convenient to tune its crystallization degree, thereby modulating the storage behavior of large-sized K in the turbostratic carbon lattices to satisfy the need in structural resilience, low-voltage feature, and high transportation kinetics.

Revealing an Interconnected Interfacial Layer in Solid-State Polymer Sodium Batteries.

Replacing the commonly used nonaqueous liquid electrolytes in rechargeable sodium batteries with polymer solid electrolytes is expected to provide new opportunities to develop safer batteries with higher energy densities. However, this poses challenges related to the interface between the Na-metal anode and polymer electrolytes. Driven by systematically investigating the interface properties, an improved interface is established between a composite Na/C metal anode and electrolyte.

Intercalation chemistry of graphite: alkali metal ions and beyond.

Reversibly intercalating ions into host materials for electrochemical energy storage is the essence of the working principle of rocking-chair type batteries. The most relevant example is the graphite anode for rechargeable Li-ion batteries which has been commercialized in 1991 and still represents the benchmark anode in Li-ion batteries 30 years later. Learning from past lessons on alkali metal intercalation in graphite, recent breakthroughs in sodium and potassium intercalation in graphite have been demonstrated for Na-ion batteries and K-ion batteries.

Nitrogen-doped porous carbon embedded with cobalt nanoparticles for excellent oxygen reduction reaction.

Nitrogen-doped hierarchical porous carbon (CN-Co) samples embedded with cobalt nanoparticles are selectively prepared with polyethylenimine (PEI) as both the carbon and nitrogen sources. By processing at different temperature, CN-Co-800 and CN-Co-1000 are selectively prepared and the materials exhibit excellent electrocatalytic activity in the oxygen reduction reaction (ORR). The ORR measurements show that sample processed at the higher temperature delivers better performance due to the larger Co and graphitic nitrogen concentrations.

Slope-Dominated Carbon Anode with High Specific Capacity and Superior Rate Capability for High Safety Na-Ion Batteries.

The comprehensive performance of carbon anodes for Na-ion batteries (NIBs) is largely restricted by their inferior rate capability and safety issues. Herein, a slope-dominated carbon anode is achieved at a low temperature of 800 °C, which delivers a high reversible capacity of 263 mA h g at 0.15C with an impressive initial Coulombic efficiency (ICE) of 80 %.

High-temperature treatment induced carbon anode with ultrahigh Na storage capacity at low-voltage plateau.

Sodium-ion batteries (NIBs) show great prospect on the energy storage applications benefiting from their low cost and the abundant Na resources despite the expected lower energy density compared with lithium-ion batteries (LIBs). To further enhance the competitive advantage, especially in energy density, developing the high-capacity carbon anode materials can be one of the effective approaches to realize this goal. Herein, we report a novel carbon anode made from charcoal with a high capacity of ∼400 mAh g, wherein about 85% (>330 mAh g) of its total capacity is derived from the long plateau region below ∼0.

Design and Comparative Study of O3/P2 Hybrid Structures for Room Temperature Sodium-Ion Batteries.

Rechargeable sodium-ion batteries have drawn increasing attention as candidates for the post lithium-ion batteries in large-scale energy storage systems. Layered oxides are the most promising cathode materials and their pure phases (e.g.

Advanced Nanostructured Anode Materials for Sodium-Ion Batteries.

Sodium-ion batteries (NIBs), due to the advantages of low cost and relatively high safety, have attracted widespread attention all over the world, making them a promising candidate for large-scale energy storage systems. However, the inherent lower energy density to lithium-ion batteries is the issue that should be further investigated and optimized. Toward the grid-level energy storage applications, designing and discovering appropriate anode materials for NIBs are of great concern.

A Fluorescent Switch Sensor for Glutathione Detection Based on Mn-doped CdTe Quantum Dots - Methyl Viologen Nanohybrids.

In the work, a fluorescence switch sensor consists of Mn-doped CdTe quantum dots (QDs) - methyl viologen (MV(2+)) nanohybrid is fabricated. In the sensor, MV(2+) plays a role in turning the QDs fluorescence to the "OFF" state due to the efficient electron transfer process while glutathione (GSH) could turn "ON" the native QDs fluorescence by effectively releasing QDs from the QDs-MV(2+) nanohybrids. In addition, the recovery level of QDs fluorescence is closely related to the amount of GSH.

A Simple Fluorescence Quenching Method for the Determination of Vanillin Using TGA-capped CdTe/ZnS Nanoparticles as Probes.

Based on the quenching of the fluorescence intensity of thioglycolic acid (TGA)-capped core-shell CdTe/ZnS nanoparticles (NPs) by vanillin, a novel, simple and rapid method for the determination of vanillin was proposed. In aqueous medium, the functionalized core-shell CdTe/ZnS NPs were successfully synthesized with TGA as the capping ligand. TGA-capped core-shell CdTe/ZnS NPs were characterized by using X-ray diffraction (XRD), transmission electron microscopy (TEM) and Fourier transform infrared (FTIR) spectroscopy.