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Discovering suitable electrodes is a challenge for the development of sodium-ion batteries. Here the authors demonstrate a high-performance symmetric battery based on Na2VTi(PO4)3, highlighting its potential application in a smart grid.

The past decade has witnessed rapid advancements in chloride-ion batteries (CIBs), including the development of transition metal chlorides, oxychlorides and layered double hydroxide cathode materials, as well as organic, aqueous, and solid-state electrolyte systems. However, research on anode materials has still been limited to a few strong alkaline metals due to the high demand for Cl- affinity. The inherent insulating chlorinated phase and reconstructed chlorination process of these metallic anodes are the most severe obstacles to the practical application of CIBs. Herein, high-throughput screening is applied to explore the potential anode materials from the layered perovskite oxychlorides (A2TMO3Cl). The screened Ca2CoO3Cl and Ba2RhO3Cl are identified that can maintain their layered structure during electrochemical processes, thereby enabling a stable Cl- (de)intercalation reaction process. Strong alkaline metals in A2TMO3Cl are directly connected to Cl-, ensuring strong binding ability to meet the requirements of CIB anodes. Meanwhile, transition metal in A2TMO3Cl acts as a redox center, which provides Cl- storage capacity and good electrical conductivity. Based on such a layered framework, Ca2CoO3Cl and Ba2RhO3Cl possess low Cl- diffusion barriers of 0.50 and 0.52 eV, which are numerically and mechanically improved compared to those of the reported CIB anode materials. [ABSTRACT FROM AUTHOR]

Aprotic lithium–oxygen (Li–O2) batteries are receiving intense research interest by virtue of their ultra-high theoretical specific energy. However, current Li–O2 batteries are suffering from severe barriers, such as sluggish reaction kinetics and undesired parasitic reactions. Recently, molecular catalysts, i.e. redox mediators (RMs), have been explored to catalyse the oxygen electrochemistry in Li–O2 batteries and are regarded as an advanced solution. To fully unlock the capability of Li–O2 batteries, an in-depth understanding of the catalytic mechanisms of RMs is necessary. In this review, we summarize the working principles of RMs and their selection criteria, highlight the recent significant progress of RMs and discuss the critical scientific and technical challenges on the design of efficient RMs for next-generation Li–O2 batteries. [ABSTRACT FROM AUTHOR]

Layered Li[Ni.sub.0.4][Mn.sub.0.4][Co.sub.0.2][O.sub.2] is prepared by citrate precursor and its magnetic properties are examined by dc magnetization. The studies have shown that the cluster-spin-glass has resulted from the short-range structure disorder rather than the geometrical frustration.

LiCuVO4 with distorted inverse spinel structure is prepared by solid-state reaction and comprehensively examined as an intercalation anode material by means of cyclic voltammograms (CV), galvanostatic charge-discharge profiles, rate performance, and electrochemical impedance spectroscopy (EIS). LiCuVO4 shows a stable capacity of 447 mA h g-1 under 3-0.01 V at the current density of 200 mA g-1, and the capacity retention reaches 91% after 50 cycles. At high cutoff voltage, between 3 and 0.2 V, LiCuVO4 also delivers an average reversible capacity of 200 mA h g-1 at a current density of 2000 mA g-1, higher than the performance of the newly reported Li3VO4. Moreover, the lithium ion storage mechanism for LiCuVO4 is also explained on the basis of the ex situ X-ray diffraction (XRD) and high-resolution transmission electron microscopy (HRTEM) at different insertion/extraction depths. While being discharged to 0.01 V, LiCuVO4 decomposes into Li3VO4, whose surface is coated by Cu nanoparticles spontaneously. Interestingly, Li ions are suggested to be inserted into Li3VO4 in the subsequent cycles due to the intercalation mechanism, and Cu nanoparticles would not contribute to the reversible capacity. Our findings provide a strong supplemental insight into the electrochemical mechanism of the anode for lithium-ion batteries. In addition, LiCuVO4 is expected to be a potential anode material because of its low cost, simple preparation procedure, good electrochemical performance and safety discharge voltage. [ABSTRACT FROM AUTHOR]

Porous ZnMn2O4 microspheres were prepared via a facile co-precipitation method followed by calcination at various temperatures and evaluated as anode materials for lithium ion batteries. The sample prepared at 600 °C outperformed the other samples in terms of electrochemical performance with high reversible capacity, high-rate capability, and excellent cycling performance. The capacity of the sample remained as high as 999 mAh g−1 at a current rate of 100 mA g−1 after 50 cycles—one of the best ever reported for ZnMn2O4-based materials. A high reversible capacity of 400 mAh g−1 was retainable at a current density of 2000 mA g−1 after 2500 cycles. A novel electrochemical reaction mechanism of ZnMn2O4 anodes was established and investigated at length. The Mn3O4 observed during the charge process was largely responsible for the enhanced performance, as confirmed by x-ray photoelectron spectroscopy, scanning electron microscopy, and transmission electron microscopy. The relatively large surface area, abundant porosity, large ion exchange space, and strong mechanical stability of the porous connected 3D framework were responsible for the unique oxidation/reduction Mn2+ ↔ Mn3+ process we observed. [ABSTRACT FROM AUTHOR]