Natriumionenbatterien für die elektrochemische Energiespeicherung

Improving the Performance of Layered Oxide Cathode Materials with Football-Like Hierarchical Structure for Na-Ion Batteries by Incorporating Mg2+ into Vacancies in Na-Ion Layers

The development of advanced cathode materials is still a great interest for sodium-ion batteries. The feasible commercialization of sodium-ion batteries relies on the design and exploitation of suitable electrode materials. This study offers a new insight into material design to exploit high-performance P2-type cathode materials for sodium-ion batteries. The incorporation of Mg²⁺ into intrinsic Na⁺ vacancies in Na-ion layers can lead to a high-performance P2-type cathode material for sodium-ion batteries. The materials prepared by the coprecipitation approach show a well-defined morphology of secondary football-like hierarchical structures. Neutron power diffraction and refinement results demonstrate that the incorporation of Mg²⁺ into intrinsic vacancies can enlarge the space for Na-ion diffusion, which can increase the d-spacing of the (0 0 2) peak and the size of slabs but reduce the chemical bond length to result in an enhanced rate capability and cycling stability. The incorporation of Mg²⁺ into available vacancies and a unique morphology make Na_0.7 Mg_0.05 Mn_0.8 Ni_0.1 Co_0.1 O₂ a promising cathode, which can be charged and discharged at an ultra-high current density of 2000 mA g^-1 with an excellent specific capacity of 60 mAh g^-1 . This work provides a new insight into the design of electrode materials for sodium-ion batteries.

Vacancy-Controlled Na+ Superion Conduction in Na11 Sn2 PS12

Highly conductive solid electrolytes are crucial to the development of efficient all-solid-state batteries. Meanwhile, the ion conductivities of lithium solid electrolytes match those of liquid electrolytes used in commercial Li⁺ ion batteries. However, concerns about the future availability and the price of lithium made Na⁺ ion conductors come into the spotlight in recent years. Here we present the superionic conductor Na₁₁ Sn₂ PS₁₂ , which possesses a room temperature Na⁺ conductivity close to 4 mS cm^-1 , thus the highest value known to date for sulfide-based solids. Structure determination based on synchrotron X-ray powder diffraction data proves the existence of Na⁺ vacancies. As confirmed by bond valence site energy calculations, the vacancies interconnect ion migration pathways in a 3D manner, hence enabling high Na⁺ conductivity. The results indicate that sodium electrolytes are about to equal the performance of their lithium counterparts.

Two-Dimensional Metal Oxide Nanomaterials for Next-Generation Rechargeable Batteries

The exponential increase in research focused on two-dimensional (2D) metal oxides has offered an unprecedented opportunity for their use in energy conversion and storage devices, especially for promising next-generation rechargeable batteries, such as lithium-ion batteries (LIBs) and sodium-ion batteries (NIBs), as well as some post-lithium batteries, including lithium-sulfur batteries, lithium-air batteries, etc. The introduction of well-designed 2D metal oxide nanomaterials into next-generation rechargeable batteries has significantly enhanced the performance of these energy-storage devices by providing higher chemically active interfaces, shortened ion-diffusion lengths, and improved in-plane carrier-/charge-transport kinetics, which have greatly promoted the development of nanotechnology and the practical application of rechargeable batteries. Here, the recent progress in the application of 2D metal oxide nanomaterials in a series of rechargeable LIBs, NIBs, and other post lithium-ion batteries is reviewed relatively comprehensively. Current opportunities and future challenges for the application of 2D nanomaterials in energy-storage devices to achieve high energy density, high power density, stable cyclability, etc. are summarized and outlined. It is believed that the integration of 2D metal oxide nanomaterials in these clean energy devices offers great opportunities to address challenges driven by increasing global energy demands.

Rocking-Chair Ammonium-Ion Battery: A Highly Reversible Aqueous Energy Storage System

Aqueous rechargeable batteries are promising solutions for large-scale energy storage. Such batteries have the merit of low cost, innate safety, and environmental friendliness. To date, most known aqueous ion batteries employ metal cation charge carriers. Here, we report the first "rocking-chair" NH₄ -ion battery of the full-cell configuration by employing an ammonium Prussian white analogue, (NH₄ )_1.47 Ni[Fe(CN)₆ ]_0.88 , as the cathode, an organic solid, 3,4,9,10-perylenetetracarboxylic diimide (PTCDI), as the anode, and 1.0 m aqueous (NH₄ )₂ SO₄ as the electrolyte. This novel aqueous ammonium-ion battery demonstrates encouraging electrochemical performance: an average operation voltage of ca. 1.0 V, an attractive energy density of ca. 43 Wh kg^-1 based on both electrodes' active mass, and excellent cycle life over 1000 cycles with 67 % capacity retention. Importantly, the topochemistry results of NH₄⁺ in these electrodes point to a new paradigm of NH₄⁺ -based energy storage.

Eco-Efficient Synthesis of Highly Porous CoCO3 Anodes from Supercritical CO2 for Li+ and Na+ Storage

An eco-efficient synthetic route for the preparation of high-performance carbonate anodes for Li⁺ and Na⁺ batteries is developed. With supercritical CO₂ (scCO₂ ) as the precursor, which has gas-like diffusivity, extremely low viscosity, and near-zero surface tension, CoCO₃ particles are uniformly formed and tightly connected on graphene nanosheets (GNSs). This synthesis can be conducted at 50 °C, which is considerably lower than the temperature required for conventional preparation methods, minimizing energy consumption. The obtained CoCO₃ particles (ca. 20 nm in diameter), which have a unique interpenetrating porous structure, can increase the number of electroactive sites, promote electrolyte accessibility, shorten ion diffusion length, and readily accommodate the strain generated upon charging/discharging. With a reversible capacity of 1105 mAh g^-1 , the proposed CoCO₃ /GNS anode shows an excellent rate capability, as it can deliver 745 mAh g^-1 in 7.5 min. More than 98 % of the initial capacity is retained after 200 cycles. These properties are clearly superior to those of previously reported CoCO₃ -based electrodes for Li⁺ storage, indicating the merit of our scCO₂ -based synthesis, which is facile, green, and can be easily scaled up for mass production.

An Electrolyte for Reversible Cycling of Sodium Metal and Intercalation Compounds

Na battery chemistries show poor passivation behavior of low voltage Na storage compounds and Na metal with organic carbonate-based electrolytes adopted from Li-ion batteries. Therefore, a suitable electrolyte remains a major challenge for establishing Na batteries. Here we report highly concentrated sodium bis(fluorosulfonyl)imide (NaFSI) in dimethoxyethane (DME) electrolytes and investigate them for Na metal and hard carbon anodes and intercalation cathodes. For a DME/NaFSI ratio of 2, a stable passivation of anode materials was found owing to the formation of a stable solid electrolyte interface, which was characterized spectroscopically. This permitted non-dentritic Na metal cycling with approximately 98 % coulombic efficiency as shown for up to 300 cycles. The NaFSI/DME electrolyte may enable Na-metal anodes and allows for more reliable assessment of electrode materials in Na-ion half-cells, as is demonstrated by comparing half-cell cycling of hard carbon anodes and Na₃ V₂ (PO₄ )₃ cathodes with a widely used carbonate and the NaFSI/DME electrolyte.

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 1.4 V in an aqueous electrolyte with a stable cycle performance and superior rate capability. The advent of aqueous symmetric sodium-ion battery with high safety and low cost may provide a solution for large-scale stationary energy storage.

Layered Na-Ion Cathodes with Outstanding Performance Resulting from the Synergetic Effect of Mixed P- and O-Type Phases

Herein, the synthesis of new quaternary layered Na-based oxides of the type Na _x Mn _y Ni _z Fe_0.1Mg_0.1O₂ (0.67≤ x ≤ 1.0; 0.5≤ y ≤ 0.7; 0.1≤ z ≤ 0.3) is described. The synthesis can be tuned to obtain P2- and O3-type as well as mixed P-/O-type phases as demonstrated by structural, morphological, and electrochemical properties characterization. Although all materials show good electrochemical performance, the simultaneous presence of the P- and O-type phases is found to have a synergetic effect resulting in outstanding performance of the mixed phase material as a sodium-ion cathode. The mixed P3/P2/O3-type material, having an average elemental composition of Na_0.76Mn_0.5Ni_0.3Fe_0.1Mg_0.1O₂, overcomes the specific drawbacks associated with the P2- and O3-type materials, allowing the outstanding electrochemical performance. In detail, the mixed phase material is able to deliver specific discharge capacities of up to 155 mAh g^-1 (18 mA g^-1) in the potential range of 2.0-4.3 V. In the narrower potential range of 2.5-4.3 V the material exhibits high average discharge potential (3.4 V versus Na/Na⁺), exceptional average coulombic efficiencies (>99.9%), and extraordinary capacity retention (90.2% after 601 cycles). The unexplored class of P-/O-type mixed phases introduces new perspectives for the development of layered positive electrode materials and powerful Na-ion batteries.

Photopolymer Electrolytes for Sustainable, Upscalable, Safe, and Ambient-Temperature Sodium-Ion Secondary Batteries

The first example of a photopolymerized electrolyte for a sodium-ion battery is proposed herein. By means of a preparation process free of solvents, catalysts, purification steps, and separation steps, it is possible to obtain a three-dimensional polymeric network capable of efficient sodium-ion transport. The thermal properties of the resulting solid electrolyte separator, characterized by means of thermogravimetric and calorimetric techniques, are excellent for use in sustainable energy systems conceived for safe large-scale grid storage. The photopolymerized electrolyte shows a wide electrochemical stability window up to 4.8 V versus Na/Na(+) along with the highest ionic conductivity (5.1 mS cm(-1) at 20 °C) obtained in the field of Na-ion polymer batteries so far and stable long-term constant-current charge/discharge cycling. Moreover, the polymeric networks are also demonstrated for the in situ fabrication of electrode/electrolyte composites with excellent interfacial properties, which are ideal for all-solid-state, safe, and easily upscalable device assembly.

FeV2S4as a high capacity electrode material for sodium-ion batteries

FeV₂S₄synthesizedviaa solid state reaction showing a high area capacity of 2.7 mA h cm⁻²for sodium ion batteries at room temperature.