Simultaneous modulation of cathode/anode and electrolyte interfaces a nitrile additive for high-energy-density lithium-metal batteries.

Nickel-rich layered oxides have great potential for commercial development applications, so it is critical to address their stability over long cycles. Ensuring long-term cycle stability relies heavily on the stability of the interface between the electrode and electrolyte in Li|LiNiCoMnO (NCM811) batteries. In this work, a denser, more stable and thinner nickel-rich cathode/electrolyte interface was constructed by electrolyte engineering with succinonitrile (SN) as an additive.

Off-Stoichiometry of Sodium Iron Pyrophosphate as Cathode Materials for Sodium-Ion Batteries with Superior Cycling Stability.

As one of the important devices for large-scale electrochemical energy storage, sodium-ion batteries have received much attention due to the abundant resources of raw materials. However, whether it is a base station power source, an energy storage power station, or a start-stop power supply, long energy cycle life (more than 5000 cycles), high stability, and safety performance are application prerequisites. Regrettably, currently, few sodium-ion batteries can meet this requirement, mainly due to shortcomings in positive electrode performance.

A High-Entropy Intergrowth Layered-Oxide Cathode with Enhanced Stability for Sodium-Ion Batteries.

Layered transition metal oxides are widely considered as ideal cathode materials for SIBs. However, the existing P2 and O3 structures possess specific issues, which limit their practical applications. To address these issues, this work designed a novel intergrowth layered oxide cathode with P2 and O3 phases by implementing Cu and Ti into the structure with the formation of high-entropy cathode materials with superior performance for SIBs.

Yolk-Shell Construction of NaV(PO)F with Copper Substitution Microsphere as High-Rate and Long-Cycling Cathode Materials for Sodium-Ion Batteries.

NaV(PO)F (NVPF) is emerging as a promising cathode material for high-voltage sodium-ion batteries. Whereas, the inferior intrinsic electrical conductivity leading to poor rate performance and cycling stability. To address this issue, a strategy of synthesizing unique yolk-shell structured NVPF with copper substitution via spray drying method is proposed.

Importance of Crystallographic Sites on Sodium-Ion Extraction from NASICON-Structured Cathodes for Sodium-Ion Batteries.

The V/V (3.4 V) redox couple has been well-documented in cathode material NaV(PO) for sodium-ion batteries. Recently, partial cation substitution at the vanadium site of NaV(PO) has been actively explored to access the V/V redox couple to achieve high energy density.

Elevating Energy Density for Sodium-Ion Batteries through Multielectron Reactions.

It remains a great challenge to explore desirable cathodes for sodium-ion batteries to satisfy the ever-increasing demand for large-scale energy storage systems. In this Letter, we report a NASICON-structured NaMnCr(PO) cathode with high specific capacity and operation potential. The reversible access of the Mn/Mn (3.

In Situ Formation of Liquid Metals via Galvanic Replacement Reaction to Build Dendrite-Free Alkali-Metal-Ion Batteries.

Galvanic replacement reactions have been studied as a versatile route to synthesize nanostructured alloys. However, the galvanic replacement chemistry of alkali metals has rarely been explored. A protective interphase layer will be formed outside templates when the redox potential exceeds the potential windows of nonaqueous solutions, and the complex interfacial chemistry remains elusive.

A Ternary Hybrid-Cation Room-Temperature Liquid Metal Battery and Interfacial Selection Mechanism Study.

The dendrite-free sodium-potassium (Na-K) liquid alloy composed of two alkali metals is one of the ideal alternatives for Li metal as an anode material while maintaining large capacity, low potential, and high abundance. However, Na- or K-ion batteries have limited cathode materials that can deliver stably large capacity. Combining advantages of both, a hybrid-cation liquid metal battery is designed for a Li-ion-insertion-based cathode to deliver stable high capacity using a Na-K liquid anode to avoid dendrites.

Size-, Water-, and Defect-Regulated Potassium Manganese Hexacyanoferrate with Superior Cycling Stability and Rate Capability for Low-Cost Sodium-Ion Batteries.

Potassium manganese hexacyanoferrate (KMHCF) is a low-cost Prussian blue analogue (PBA) having a rigid and open framework that can accommodate large alkali ions. Herein, the synthesis of KMHCF and its application as a high-performance cathode in sodium-ion batteries (NIBs) is reported. High-quality KMHCF with low amounts of crystal water and defects and with homogeneous microstructure is obtained by controlling the nucleation and grain growth by using a high-concentration citrate solution as a precipitation medium.

NaMnZr(PO): A High-Voltage Cathode for Sodium Batteries.

Sodium batteries have been regarded as promising candidates for large-scale energy storage application, provided cathode hosts with high energy density and long cycle life can be found. Herein, we report NASICON-structured NaMnZr(PO) as a cathode for sodium batteries that exhibits an electrochemical performance superior to those of other manganese phosphate cathodes reported in the literature. Both the Mn/Mn and Mn/Mn redox couples are reversibly accessed in NaMnZr(PO), providing high discharge voltage plateaus at 4.

Polyanthraquinone-Triazine-A Promising Anode Material for High-Energy Lithium-Ion Batteries.

A novel covalent organic framework polymer material that bears conjugated anthraquinone and triazine units in its skeleton has been prepared via a facile one-pot condensation reaction and employed as an anode material for Li-ion batteries. The conjugated units consist of C═N groups, C═O groups, and benzene groups, which enable a 17-electron redox reaction with Li per repeating unit and bring a theoretical specific capacity of 1450 mA h g. The polymer also shows a large specific surface area and a hierarchically porous structure to trigger interfacial Li storage and contribute to an additional capacity.

Selective CO Evolution from Photoreduction of CO on a Metal-Carbide-Based Composite Catalyst.

A selective CO evolution from photoreduction of CO in water was achieved on a noble-metal-free, carbide-based composite catalyst, as demonstrated by a CO selectivity of 98.3% among all carbon-containing products and a CO evolution rate of 29.2 μmol h, showing superiority to noble-metal-based catalyst.

Room-Temperature Liquid Na-K Anode Membranes.

The Na-K alloy is a liquid at 25 °C over a large compositional range. The liquid alloy is also immiscible in the organic-liquid electrolytes of an alkali-ion rechargeable battery, providing dendrite-free liquid alkali-metal batteries with a liquid-liquid anode-electrolyte interface at room temperature. The two liquids are each immobilized in a porous matrix.

A High-Energy-Density Potassium Battery with a Polymer-Gel Electrolyte and a Polyaniline Cathode.

A safe, rechargeable potassium battery of high energy density and excellent cycling stability has been developed. The anion component of the electrolyte salt is inserted into a polyaniline cathode upon charging and extracted from it during discharging while the K ion of the KPF salt is plated/stripped on the potassium-metal anode. The use of a p-type polymer cathode increases the cell voltage.

Cathode Dependence of Liquid-Alloy Na-K Anodes.

Alkali ions can be plated dendrite-free into a liquid alkali-metal anode. Commercialized Na-S battery technology operates above 300 °C. A low-cost Na-K alloy is liquid at 25 °C from 9.

Nitrogen-Doped Perovskite as a Bifunctional Cathode Catalyst for Rechargeable Lithium-Oxygen Batteries.

In this work, nitrogen-doped LaNiO perovskite was prepared and studied, for the first time, as a bifunctional electrocatalyst for oxygen cathode in a rechargeable lithium-oxygen battery. N doping was found to significantly increase the Ni contents and oxygen vacancies on the bulk surface of the perovskite, which helped to promote the oxygen reduction reaction and oxygen evolution reaction of the cathode and, therefore, enabled reversible LiO formation and decomposition on the cathode surface. As a result, the oxygen cathodes loaded with N-doped LaNiO catalyst showed an improved electrochemical performance in terms of discharge capacity and cycling stability to promise practical Li-O batteries.

A Plastic-Crystal Electrolyte Interphase for All-Solid-State Sodium Batteries.

The development of all-solid-state rechargeable batteries is plagued by a large interfacial resistance between a solid cathode and a solid electrolyte that increases with each charge-discharge cycle. The introduction of a plastic-crystal electrolyte interphase between a solid electrolyte and solid cathode particles reduces the interfacial resistance, increases the cycle life, and allows a high rate performance. Comparison of solid-state sodium cells with 1) solid electrolyte Na Zr (Si PO ) particles versus 2) plastic-crystal electrolyte in the cathode composites shows that the former suffers from a huge irreversible capacity loss on cycling whereas the latter exhibits a dramatically improved electrochemical performance with retention of capacity for over 100 cycles and cycling at 5 C rate.

Low-Cost High-Energy Potassium Cathode.

Potassium has as rich an abundance as sodium in the earth, but the development of a K-ion battery is lagging behind because of the higher mass and larger ionic size of K than that of Li and Na, which makes it difficult to identify a high-voltage and high-capacity intercalation cathode host. Here we propose a cyanoperovskite KMnFe(CN) (0 ≤ x ≤ 2) as a potassium cathode: high-spin Mn/Mn and low-spin Fe/Fe couples have similar energies and exhibit two close plateaus centered at 3.6 V; two active K per formula unit enable a theoretical specific capacity of 156 mAh g; Mn and Fe are the two most-desired transition metals for electrodes because they are cheap and environmental friendly.

NaMV(PO) (M = Mn, Fe, Ni) Structure and Properties for Sodium Extraction.

NASICON (Na super ionic conductor) structures of NaMV(PO) (M = Mn, Fe, Ni) were prepared, characterized by aberration-corrected STEM and synchrotron radiation, and demonstrated to be durable cathode materials for rechargeable sodium-ion batteries. In NaMnV(PO), two redox couples of Mn/Mn and V/V are accessed with two voltage plateaus located at 3.6 and 3.

Liquid K-Na Alloy Anode Enables Dendrite-Free Potassium Batteries.

A K-Na liquid alloy allows a dendrite-free high-capacity anode; its immiscibility with an organic liquid electrolyte offers a liquid-liquid anode-electrolyte interface. Working with a sodiated Na MnFe(CN) cathode, the working cation becomes K to give a potassium battery of long cycle life with an acceptable capacity at high charge/discharge rates.

An Aqueous Symmetric Sodium-Ion Battery with NASICON-Structured Na3 MnTi(PO4 )3.

A symmetric sodium-ion battery with an aqueous electrolyte is demonstrated; it utilizes the NASICON-structured Na3 MnTi(PO4 )3 as both the anode and the cathode. The NASICON-structured Na3 MnTi(PO4 )3 possesses two electrochemically active transition metals with the redox couples of Ti(4+) /Ti(3+) and Mn(3+) /Mn(2+) working on the anode and cathode sides, respectively. The symmetric cell based on this bipolar electrode material exhibits a well-defined voltage plateau centered at about 1.

2D and 3D graphene materials: Preparation and bioelectrochemical applications.

The attractive properties of graphene materials have stimulated intense research and development in the field of bioelectrochemistry. In particular, the construction of 2D and 3D graphene architectures provides new possibilities for developing flexible and porous carbon scaffolds, which not only inherit some of the key properties of individual graphene sheets, but also develop additional functions that are of considerable interest for bioelectrochemical applications. In this review article, we will first summarize the recently developed approaches to preparing graphene sheets, and then focus on the methods to assemble them into macroscopic 2D and 3D structures.

Mussel-inspired synthesis of polydopamine-functionalized graphene hydrogel as reusable adsorbents for water purification.

We present a one-step approach to polydopamine-modified graphene hydrogel, with dopamine serving as both reductant and surface functionalization agents. The synthetic method is based on the spontaneous polymerization of dopamine and the self-assembly of graphene nanosheets into porous hydrogel structures. Benefiting from the abundant functional groups of polydopamine and the high specific surface areas of graphene hydrogel with three-dimensional interconnected pores, the prepared material exhibits high adsorption capacities toward a wide spectrum of contaminants, including heavy metals, synthetic dyes, and aromatic pollutants.

Flexible all-solid-state asymmetric supercapacitors based on free-standing carbon nanotube/graphene and Mn3O4 nanoparticle/graphene paper electrodes.

We report the design of all-solid-state asymmetric supercapacitors based on free-standing carbon nanotube/graphene (CNTG) and Mn(3)O(4) nanoparticles/graphene (MG) paper electrodes with a polymer gel electrolyte of potassium polyacrylate/KCl. The composite paper electrodes with carbon nanotubes or Mn(3)O(4) nanoparticles uniformly intercalated between the graphene nanosheets exhibited excellent mechanical stability, greatly improved active surface areas, and enhanced ion transportation, in comparison with the pristine graphene paper. The combination of the two paper electrodes with the polymer gel electrolyte endowed our asymmetric supercapacitor of CNTG//MG an increased cell voltage of 1.