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Ni-rich cathodes LiNixCoyMn1−x−yO2 (0.6 < x < 1) (NCM) with high energy density, environment friendliness, as well as low cost are widely used in Li-ion batteries. Li-ion batteries are required to operate at elevated temperatures in the application of electric vehicles or other special military occasions, which is a huge challenge for battery modules, particularly for batteries with Ni-rich cathodes due to their aggressive side reactions and large lattice volume changes at a high temperature. In this study, the failure mechanism of Ni-rich NCM at high temperatures was systematically investigated. Also, phosphorus doping LiNi0.83Co0.12Mn0.05O2 (Ni83) with excellent high-temperature performance was synthesized via a one-step high temperature diffusion process. Cation mixing is significantly reduced and the phase transformation reversibility evidently improved. As a result, phosphorus doped Ni83 exhibits an extraordinary capacity retention of 80.2% after 500 cycles between 2.7 and 4.3 V at 1C under 60 °C. The full cell also achieves an outstanding cycling stability with a capacity retention of 80.8% after 1000 cycles at 25 °C between 2.7 and 4.3 V. [ABSTRACT FROM AUTHOR]

Atomic ordering engineering has been a promising strategy to improve the catalytic activity and stability of Pt-based alloy catalysts for the oxygen reduction reaction (ORR) for proton exchange membrane fuel cells (PEMFCs). However, the synthesis of shape-controlled ordered nanocrystals, especially in a two-dimensional (2D) architecture, still remains a great challenge. Herein, 2D Pd2Sn nanosheets (NSs) with unique Pd–Sn ordering are developed as efficient ORR electrocatalysts for the first time. The ordered Pd2Sn NSs exhibit a mass activity of 2.5 A mgPd−1 at 0.9 ViR-freevs. the reversible hydrogen electrode and outstanding durability, much superior to that of their disordered counterparts, commercial Pt/C, and most of the reported Pd-based ORR catalysts. The outstanding activity and stability can be ascribed to the unique 2D defect-rich morphology, the thermodynamically stabilized intermetallic structure, and the optimized Pd–O binding due to Sn incorporation. [ABSTRACT FROM AUTHOR]

Aqueous sodium-ion batteries (ASIBs) show superior characteristics with high safety and low cost for large scale energy storage systems. However, easily occurring hydrogen evolution at a negative potential is a huge barrier to the application of anode materials in ASIBs. Even the most promising insert-type anode material, NaTi2(PO4)3 (NTP), cannot be commercialized due to its inadequate operating potential (−0.807 V vs. Ag/AgCl) that is close to the hydrogen evolution potential (−0.817 V vs. Ag/AgCl). Here, we report a redox potential regulation strategy to overcome this technical problem by integrating the redox couples of Ti4+/Ti3+ and Fe3+/Fe2+ to yield Na1.5Ti1.5Fe0.5(PO4)3 (NTFP) and increasing its operating potential up to −0.721 V vs. Ag/AgCl, which effectively prevents the potential overlap with the reductive decomposition of H2O. Importantly, the excellent electrochemical properties and low energy consuming synthetic route to NTFP open a new perspective to energetically develop low cost and highly stable ASIBs as a large-scale energy storage tool. [ABSTRACT FROM AUTHOR]

The use of redox-active organic materials in rechargeable batteries has the potential to achieve a high-energy, cheap and sustainable battery. Cuprous tetracyanoquinodimethane (CuTCNQ) is a novel metal organic cathode material with a highly reversible three-electron-transfer reaction, which has been demonstrated with high specific energy density. However, it also faces the challenge of the formation of highly soluble redox products that easily dissolve in the electrolyte and degrade the battery performance during cycling. Herein, a graphene oxide (GO) modified separator (GO separator) is used to immobilize the soluble active materials through π–π interaction between sp2-hybridized carbon rings in GO and aromatic rings in the soluble active material. The CuTCNQ-based Li-ion battery with the GO separator achieves an initial capacity as high as 252.2 mA h g−1 and also shows a significantly improved capacity retention over 100 cycles. Such an effective way to prevent the soluble organic redox materials from moving between the electrodes is applicable not only for Li–organic batteries but also for organic redox flow batteries. [ABSTRACT FROM AUTHOR]

Designing the architecture of 3D metal–organic frameworks (MOFs) is fascinating, but challenging. Using a simple and reliable method called TECSA – Template-Engaged Crystal Self-Assembly, we efficiently produced 3D hollow superstructures composed of nanosized ZIF-67 single crystals (HU-ZIF-67S). These superstructures are durable, withstanding sulfidation and pyrolysis when making a functional Co1−xS@C composite, HPHU-Co1−xS@C. The composite exhibits a superior pseudocapacitance performance as a cathode material for supercapacitors. Significantly, this study enables the rational assembly of 3D MOF superstructures and provides a real path to fabricate sophisticated MOF derivatives. [ABSTRACT FROM AUTHOR]

NASICON-structure Na3V2(PO4)3 (NVP) is a potential cathode material for sodium ion battery, which is still confronted with low rate performance because of its poor conductivity. To address this problem, high-valance Mo6+ ion was introduced into NVP. The crystal structure, electrochemical performances, sodium ion diffusion kinetics and ion transfer mechanism of high valence Mo-doped Na3−5xV2−xMox(PO4)3/C (0 ＜ x ＜ 0.04) were investigated. X-ray diffraction, electron microscopy and XPS data confirmed high purity NASICON phosphate phases. The Na ion diffusion process was identified through CV measurement, which clearly shows rapid sodium ion transportation in the Mo-doped NASICON materials. Moreover, DFT calculations proved that Na ion diffusion is promoted by Mo doping. Benefiting from the superior Na ion kinetics, Na2.9V1.98Mo0.02(PO4)3 exhibited a performance of 90 mA h g−1 at 10C and preserved 83.5% of the original capacity after 500 cycles. Our studies demonstrate that high-valence Mo doped Na3V2(PO4)3/C is a promising cathode material for sodium ion batteries with super-high rate capability and stable cycle life. [ABSTRACT FROM AUTHOR]

Transition metal phosphides are often studied as hydrogen evolution reaction cathode catalysts, but scarcely as oxygen evolution reaction (OER) anode catalysts for water oxidation. Herein, we report a new amorphous Co0.63Fe0.21P0.16 OER catalyst, which was prepared through a one-step solvothermal process. This catalyst exhibits extraordinary OER catalytic activity in alkaline media and is superior to the state of the art IrO2 in 1.0 M KOH, capable of yielding a current density of 10 mA cm−2 at an overpotential of only 217 mV. This newly achieved high activity outperforms most reported transition metal phosphide catalysts. During the OER, the surface layers of the Co0.63Fe0.21P0.16 nanospheres (200–500 nm) are oxidized, which show the typical Tafel slope of oxides around 40 mV dec−1. The in situ formation of surface Co oxides in the catalysts during the OER along with an optimal doping of Fe are found to be crucial for their remarkable activity. In particular, the metal-rich amorphous phosphide cores, i.e., substrates, probably contribute to OER performance of the catalysts due to their high electrical conductivity. This new type of surface oxidized amorphous transition metal phosphide would provide a new pathway for the design of high-performance OER electrocatalysts. [ABSTRACT FROM AUTHOR]

Currently, it is a great challenge to find suitable electrode materials for sodium-ion batteries (SIBs) with large capacity, long cycle life, and high rate capability. Herein, we report a new layered titanate, Na2Li2Ti5O12 (NLT), derived from K2Li2Ti5O12 (KLT) via an ion-exchange method as a SIB anode material. KLT is prepared by a low-temperature solid-state reaction and then transformed into NLT by replacing potassium with sodium in a NaCl solution at room temperature. NLT provides a sodium-ion intercalation voltage at ∼0.5 V versus Na/Na+ and a reversible capacity of 175 mA h g−1 at a current density of 100 mA g−1. It also shows a high sodium-ion diffusion coefficient of 3.0 × 10−10 cm2 s−1, ensuring a high rate capability. For NLT, extremely high discharging rate capability is achieved with a capacity of more than 80 mA h g−1 at a 60 second full discharge and even with 70 mA h g−1 at a 34 second charge. Kinetics analysis based on cyclic voltammogram reveals a typical sodium-ion intercalation behavior in NLT. Furthermore, the first-principle calculation shows a lower migration energy barrier for sodium ions in NLT than that in other layered titanates. These results suggest that NLT is a very promising anode material for high-performance SIBs, especially for fast-charging stable SIBs. [ABSTRACT FROM AUTHOR]

Antimony (Sb) based materials are regarded as promising anode materials for Li-ion batteries (LIBs) because of the high capacity, appropriate working potential, and earth abundance of antimony. However, the quick capacity decay due to the huge volume expansion during the cycling process seriously hinders its practical applications. Here, a nanocomposite of core@shell Sb@Sb 2 O 3 particles anchored on 3D porous nitrogen-doped carbon (3DNC) nanosheets is synthesized by freeze drying and sintering in a reducing atmosphere. Structural characterization shows that the developed Sb@Sb 2 O 3 /3DNC electrode has a high surface area (839.8 m 2 g -1 ) and unique Sb-O-C bonding, both contributing to the excellent electrochemical performance. The initial charge and discharge specific capacities of the Sb@ Sb 2 O 3 /3DNC anode in LIB tests are 1109 mA h g -1 and 1810 mA h g -1 , respectively. Also, it shows a charge capacity of 696.9 mA h g -1 after 500 cycles at 1 A g -1 and 458 mA h g -1 at a current density of 5 A g -1 . Moreover, the assembled Sb@Sb 2 O 3 /3DNC‖LiNi 0.6 Co 0.2 Mn 0.2 O 2 battery exhibits a discharge capacity of more than 100 mA h g -1 after 25 cycles at 100 mA g -1 . The synthetic method can be extended to obtain other nanocomposites of metal and carbon materials for high-performance energy storage devices., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

The evolution of the Li-ion displacements in the 3D interstitial pathways of the cubic garnet-type Li(7)La(3)Zr(2)O(12), cubic Li(7)La(3)Zr(2)O(12), was investigated with high-temperature neutron diffraction (HTND) from RT to 600 °C; the maximum-entropy method (MEM) was applied to estimate the Li nuclear-density distribution. Temperature-driven Li displacements were observed; the displacements indicate that the conduction pathways in the garnet framework are restricted to diffusion through the tetrahedral sites of the interstitial space.