Efficient pathways to improve electrode performance of P'2 NaMnO for sodium batteries.

A Mn-based sodium-containing layered oxide, P'2-type NaMnO, is revisited as a positive electrode material for sodium-ion batteries, and factors affecting its electrochemical performances are examined. The cyclability of NaMnO is remarkably improved by increasing the lower cut-off voltage during cycling even though the reversible capacity is sacrificed. Furthermore, the use of highly concentrated electrolytes, in which the presence of free solvent molecules is eliminated, effectively suppresses the dissolution of Mn ions, thus enabling stable cycling with >85% capacity retention for 300 continuous cycles.

Efficient Surface Passivation of Ti-Based Layered Materials by a Nonfluorine Branched Copolymer for Durable and High-Power Sodium-Ion Batteries.

There is a crucial need for low-cost energy storage technology based on abundant sodium ions to realize sustainable development with renewable energy resources. Poly(vinylidene fluoride) (PVDF) is applied as a binder in sodium-ion batteries (SIBs). Nevertheless, PVDF is also known to suffer from a larger irreversible capacity, especially when PVDF is used as the binder of negative electrode materials.

Virtues of Cold Isostatic Pressing for Preparation of All-Solid-State-Batteries with Poly(Ethylene Oxide).

All-solid-state-batteries (ASSBs) necessitate the preparation of a solid electrolyte and an electrode couple with individually dense and compact structures with superior interfacial contact to minimize overall cell resistance. A conventional preparation method of solid polymer electrolyte (SPE) with polyethylene-oxide (PEO) generally consists in employing uni-axial hot press (HP) to densify SPE. However, while uni-axial press with moderate pressure effectively densifies PEO with Li salts, excessive pressure also unavoidably results in perpendicular elongation and deformation for polymer matrix.

Anion-Induced Interfacial Liquid Layers on LiCoO in Salt-in-Water Lithium-Ion Batteries.

The incompatibility of lithium intercalation electrodes with water has impeded the development of aqueous Li-ion batteries. The key challenge is protons which are generated by water dissociation and deform the electrode structures through intercalation. Distinct from previous approaches utilizing large amounts of electrolyte salts or artificial solid-protective films, we developed liquid-phase protective layers on LiCoO (LCO) using a moderate concentration of 0.

Nanoscale domain imaging of Li-rich disordered rocksalt-type cathode materials with X-ray spectroscopic ptychography.

Lithium-rich disordered rocksalt-type cathode materials are promising for high-capacity and high-power lithium-ion batteries. Many of them are synthesized by mechanical milling and may have heterogeneous structures and chemical states at the nanoscale. In this study, we performed X-ray spectroscopic ptychography measurements of Li-rich disordered rocksalt-type oxide particles synthesized by mechanical milling before and after delithiation reaction at the vanadium K absorption edge, and visualized their structures and chemical state with a spatial resolution of ∼100 nm.

A near dimensionally invariable high-capacity positive electrode material.

Delivering inherently stable lithium-ion batteries is a key challenge. Electrochemical lithium insertion and extraction often severely alters the electrode crystal chemistry, and this contributes to degradation with electrochemical cycling. Moreover, electrodes do not act in isolation, and this can be difficult to manage, especially in all-solid-state batteries.

Unexpectedly Large Contribution of Oxygen to Charge Compensation Triggered by Structural Disordering: Detailed Experimental and Theoretical Study on a LiNbO-NiO Binary System.

Dependence on lithium-ion batteries for automobile applications is rapidly increasing. The emerging use of anionic redox can boost the energy density of batteries, but the fundamental origin of anionic redox is still under debate. Moreover, to realize anionic redox, many reported electrode materials rely on manganese ions through π-type interactions with oxygen.

Nanosized and metastable molybdenum oxides as negative electrode materials for durable high-energy aqueous Li-ion batteries.

The development of inherently safe energy devices is a key challenge, and aqueous Li-ion batteries draw large attention for this purpose. Due to the narrow electrochemical stable potential window of aqueous electrolytes, the energy density and the selection of negative electrode materials are significantly limited. For achieving durable and high-energy aqueous Li-ion batteries, the development of negative electrode materials exhibiting a large capacity and low potential without triggering decomposition of water is crucial.

Tomographic reconstruction of oxygen orbitals in lithium-rich battery materials.

The electrification of heavy-duty transport and aviation will require new strategies to increase the energy density of electrode materials. The use of anionic redox represents one possible approach to meeting this ambitious target. However, questions remain regarding the validity of the O/O oxygen redox paradigm, and alternative explanations for the origin of the anionic capacity have been proposed, because the electronic orbitals associated with redox reactions cannot be measured by standard experiments.

P2-type layered NaCrMgTiO for Na storage applications.

Na0.67Cr0.33Mg0.

Nanostructured LiMnO with LiPO Integrated at the Atomic Scale for High-Energy Electrode Materials with Reversible Anionic Redox.

Nanostructured LiMnO integrated with LiPO was successfully synthesized by the mechanical milling route and examined as a new series of positive electrode materials for rechargeable lithium batteries. Although uniform mixing at the atomic scale between LiMnO and LiPO was not anticipated because of the noncompatibility of crystal structures for both phases, our study reveals that phosphorus ions with excess lithium ions dissolve into nanosize crystalline LiMnO as first evidenced by elemental mapping using STEM-EELS combined with total X-ray scattering, solid-state NMR spectroscopy, and a theoretical study. The integrated phase features a low-crystallinity metastable phase with a unique nanostructure; the phosphorus ion located at the tetrahedral site shares faces with adjacent lithium ions at slightly distorted octahedral sites.

Nanosize Cation-Disordered Rocksalt Oxides: Na TiO -NaMnO Binary System.

To realize the development of rechargeable sodium batteries, new positive electrode materials without less abundant elements are explored. Enrichment of sodium contents in host structures is required to increase the theoretical capacity as electrode materials, and therefore Na-excess compounds are systematically examined in a binary system of Na TiO -NaMnO . After several trials, synthesis of Na-excess compounds with a cation disordered rocksalt structure is successful by adapting a mechanical milling method.

Material Design Concept of Lithium-Excess Electrode Materials with Rocksalt-Related Structures for Rechargeable Non-Aqueous Batteries.

Dependence on lithium-ion batteries for automobile applications is rapidly increasing, and further improvement, especially for positive electrode materials, is indispensable to increase energy density of lithium-ion batteries. In the past several years, many new lithium-excess high-capacity electrode materials with rocksalt-related structures have been reported. These materials deliver high reversible capacity with cationic/anionic redox and percolative lithium migration in the oxide/oxyfluoride framework structures, and recent research progresses on these electrode materials are reviewed.

All-solid-state ion-selective electrodes with redox-active lithium, sodium, and potassium insertion materials as the inner solid-contact layer.

All-solid-state ion-selective electrodes as potentiometric ion sensors for lithium, sodium, and potassium have been demonstrated by installing a composite layer containing a powder of alkali insertion materials, LiFePO, NaMnO, and KMnO·nHO, respectively, as an inner solid-contact layer between the electrode substrate and plasticized poly(vinyl chloride) (PVC)-based ion-sensitive membrane containing the corresponding ionophores for Li, Na, and K ions. These double-layer ion-selective electrodes, consisting of the composite and PVC layers prepared by a simple drop cast method, exhibit a quick potential response (less than 5 s) to each alkali-metal ion with sufficient Nernstian slopes of calibration curves, ca. 59 mV per decade.

Origin of stabilization and destabilization in solid-state redox reaction of oxide ions for lithium-ion batteries.

Further increase in energy density of lithium batteries is needed for zero emission vehicles. However, energy density is restricted by unavoidable theoretical limits for positive electrodes used in commercial applications. One possibility towards energy densities exceeding these limits is to utilize anion (oxide ion) redox, instead of classical transition metal redox.

Thermal Stability of NaCrO for Rechargeable Sodium Batteries; Studies by High-Temperature Synchrotron X-ray Diffraction.

Thermal stability and phase transition processes of NaCrO and NaCrO are carefully examined by high-temperature synchrotron X-ray diffraction method. O3-type NaCrO shows anisotropic thermal expansion on heating, which is a common character as layered materials, without phase transition in the temperature range of 27-527 °C. In contrast, for the desodiated phase, in-plane distorted P3-type layered oxide (P'3 NaCrO), phase transition occurs in the following order.

Synthesis and electrochemical properties of Li(1.3)Nb(0.3)V(0.4)O2 as a positive electrode material for rechargeable lithium batteries.

The binary system, xLi3NbO4-(1 - x)LiVO2, was first examined as an electrode material for rechargeable lithium batteries. The sample (x = 0.43) crystallizes into a cation-disordered rocksalt structure and delivers a reversible capacity of ca.

High-capacity electrode materials for rechargeable lithium batteries: Li3NbO4-based system with cation-disordered rocksalt structure.

Rechargeable lithium batteries have rapidly risen to prominence as fundamental devices for green and sustainable energy development. Lithium batteries are now used as power sources for electric vehicles. However, materials innovations are still needed to satisfy the growing demand for increasing energy density of lithium batteries.

Electrochemical lithiation performance and characterization of silicon-graphite composites with lithium, sodium, potassium, and ammonium polyacrylate binders.

Poly(acrylic acid) (PAH), which is a water soluble polycarboxylic acid, is neutralized by adding different amounts of LiOH, NaOH, KOH, and ammonia (NH4OH) aqueous solutions to fix neutralization degrees. The differently neutralized polyacid, alkali and ammonium polyacrylates are examined as polymeric binders for the preparation of Si-graphite composite electrodes as negative electrodes for Li-ion batteries. The electrode performance of the Si-graphite composite depends on the alkali chemicals and neutralization degree.

Recent research progress on iron- and manganese-based positive electrode materials for rechargeable sodium batteries.

Large-scale high-energy batteries with electrode materials made from the Earth-abundant elements are needed to achieve sustainable energy development. On the basis of material abundance, rechargeable sodium batteries with iron- and manganese-based positive electrode materials are the ideal candidates for large-scale batteries. In this review, iron- and manganese-based electrode materials, oxides, phosphates, fluorides, etc, as positive electrodes for rechargeable sodium batteries are reviewed.

Negative electrodes for Na-ion batteries.

Research interest in Na-ion batteries has increased rapidly because of the environmental friendliness of sodium compared to lithium. Throughout this Perspective paper, we report and review recent scientific advances in the field of negative electrode materials used for Na-ion batteries. This paper sheds light on negative electrode materials for Na-ion batteries: carbonaceous materials, oxides/phosphates (as sodium insertion materials), sodium alloy/compounds and so on.