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.

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.

Realizing the Multi-electron Reaction in the NaV(PO) Cathode via Reversible Insertion of Dihydrogen Phosphate Anions.

Dual-ion battery (DIB) is an up-and-coming technology for the energy storage field. However, most of the current cathodes are still focused on the graphite hosts, which deliver a limited specific capacity. In this work, we demonstrated for the first time that HPO can be used as the charge carrier for NaV(PO) under an aqueous electrolyte, which enabled the V/V and V/V multielectron reactions in the NaV(PO) electrode.

Fluorine Triggered Surface and Lattice Regulation in Anatase TiO F Nanocrystals for Ultrafast Pseudocapacitive Sodium Storage.

Sodium-ion batteries (SIBs) have been considered as one of the most promising secondary battery techniques for large-scale energy storage applications. However, developing appropriate electrode materials that can satisfy the demands of long-term cycling and high energy/power capabilities remains a challenge. Herein, a fluorine modulation strategy is reported that can trigger highly active exposed crystal facets in anatase TiO F , while simultaneously inducing improved electron transfer and Na diffusion via lattice regulation.

Reversible Insertion of Mg-Cl Superhalides in Graphite as a Cathode for Aqueous Dual-Ion Batteries.

Oxidative anion insertion into graphite in an aqueous environment represents a significant challenge in the construction of aqueous dual-ion batteries. In dilute aqueous electrolytes, the oxygen evolution reaction (OER) dominates the anodic current before anions can be inserted into the graphite gallery. Herein, we report that the reversible insertion of Mg-Cl superhalides in graphite delivers a record-high reversible capacity of 150 mAh g from an aqueous deep eutectic solvent comprising magnesium chloride and choline chloride.

Ultrastable Sodium-Sulfur Batteries without Polysulfides Formation Using Slit Ultramicropore Carbon Carrier.

The formation of the soluble polysulfides (NaS , 4 ≤ ≤ 8) causes poor cycling performance for room temperature sodium-sulfur (RT Na-S) batteries. Moreover, the formation of insoluble polysulfides (NaS , 2 ≤ < 4) can slow down the reaction kinetics and terminate the discharge reaction before it reaches the final product. In this work, coffee residue derived activated ultramicroporous coffee carbon (ACC) material loading with small sulfur molecules (S) as cathode material for RT Na-S batteries is reported.

Birnessite Nanosheet Arrays with High K Content as a High-Capacity and Ultrastable Cathode for K-Ion Batteries.

Potassium-ion batteries (PIBs) are one of the emerging energy-storage technologies due to the low cost of potassium and theoretically high energy density. However, the development of PIBs is hindered by the poor K transport kinetics and the structural instability of the cathode materials during K intercalation/deintercalation. In this work, birnessite nanosheet arrays with high K content (K MnO ⋅0.

Few-Layered Tin Sulfide Nanosheets Supported on Reduced Graphene Oxide as a High-Performance Anode for Potassium-Ion Batteries.

Anodes involving conversion and alloying reaction mechanisms are attractive for potassium-ion batteries (PIBs) due to their high theoretical capacities. However, serious volume change and metal aggregation upon potassiation/depotassiation usually cause poor electrochemical performance. Herein, few-layered SnS nanosheets supported on reduced graphene oxide (SnS @rGO) are fabricated and investigated as anode material for PIBs, showing high specific capacity (448 mAh g at 0.

Research Advances of Amorphous Metal Oxides in Electrochemical Energy Storage and Conversion.

Amorphous metal oxides (AMOs) have aroused great enthusiasm across multiple energy areas over recent years due to their unique properties, such as the intrinsic isotropy, versatility in compositions, absence of grain boundaries, defect distribution, flexible nature, etc. Here, the materials engineering of AMOs is systematically reviewed in different electrochemical applications and recent advances in understanding and developing AMO-based high-performance electrodes are highlighted. Attention is focused on the important roles that AMOs play in various energy storage and conversion technologies, such as active materials in metal-ion batteries and supercapacitors as well as active catalysts in water splitting, metal-air batteries, and fuel cells.

Highly Porous Mn O Micro/Nanocuboids with In Situ Coated Carbon as Advanced Anode Material for Lithium-Ion Batteries.

The electrochemical performance of most transition metal oxides based on the conversion mechanism is greatly restricted by inferior cycling stability, rate capability, high overpotential induced by the serious irreversible reactions, low electrical conductivity, and poor ion diffusivity. To mitigate these problems, highly porous Mn O micro/nanocuboids with in situ formed carbon matrix (denoted as Mn O @C micro/nanocuboids) are designed and synthesized via a one-pot hydrothermal method, in which glucose plays the roles of a reductive agent and a carbon source simultaneously. The carbon content, particle size, and pore structure in the composite can be facilely controlled, resulting in continuous carbon matrix with abundant pores in the cuboids.

Cobalt Sulfide Quantum Dot Embedded N/S-Doped Carbon Nanosheets with Superior Reversibility and Rate Capability for Sodium-Ion Batteries.

Metal sulfides are promising anode materials for sodium-ion batteries due to their large specific capacities. The practical applications of metal sulfides in sodium-ion batteries, however, are still limited due to their large volume expansion, poor cycling stability, and sluggish electrode kinetics. In this work, a two-dimensional heterostructure of CoS (CoS and CoS) quantum dots embedded N/S-doped carbon nanosheets (CoS@NSC) is prepared by a sol-gel method.

Controllable Synthesis of TiO@FeO Core-Shell Nanotube Arrays with Double-Wall Coating as Superb Lithium-Ion Battery Anodes.

Highlighted by the safe operation and stable performances, titanium oxides (TiO) are deemed as promising candidates for next generation lithium-ion batteries (LIBs). However, the pervasively low capacity is casting shadow on desirable electrochemical behaviors and obscuring their practical applications. In this work, we reported a unique template-assisted and two-step atomic layer deposition (ALD) method to achieve TiO@FeO core-shell nanotube arrays with hollow interior and double-wall coating.