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High-energy nickel (Ni)–rich cathode will play a key role in advanced lithium (Li)–ion batteries, but it suffers from moisture sensitivity, side reactions, and gas generation. Single-crystalline Ni-rich cathode has a great potential to address the challenges present in its polycrystalline counterpart by reducing phase boundaries and materials surfaces. However, synthesis of high-performance single-crystalline Ni-rich cathode is very challenging, notwithstanding a fundamental linkage between overpotential, microstructure, and electrochemical behaviors in single-crystalline Ni-rich cathodes. We observe reversible planar gliding and microcracking along the (003) plane in a single-crystalline Ni-rich cathode. The reversible formation of microstructure defects is correlated with the localized stresses induced by a concentration gradient of Li atoms in the lattice, providing clues to mitigate particle fracture from synthesis modifications.

Nanoscale ferroelectrics are expected to exhibit various exotic domain configurations, such as the full flux-closure pattern that is well known in ferromagnetic materials. Here we observe not only the atomic morphology of the flux-closure quadrant but also a periodic array of flux closures in ferroelectric PbTiO3 films, mediated by tensile strain on a GdScO3 substrate. Using aberration-corrected scanning transmission electron microscopy, we directly visualize an alternating array of clockwise and counterclockwise flux closures, whose periodicity depends on the PbTiO3 film thickness. In the vicinity of the core, the strain is sufficient to rupture the lattice, with strain gradients up to 10(9) per meter. Engineering strain at the nanoscale may facilitate the development of nanoscale ferroelectric devices.

Tetrahexahedral particles (~10 to ~500 nanometers) composed of platinum (Pt), palladium, rhodium, nickel, and cobalt, as well as a library of bimetallic compositions, were synthesized on silicon wafers and on catalytic supports by a ligand-free, solid-state reaction that used trace elements [antimony (Sb), bismuth (Bi), lead, or tellurium] to stabilize high-index facets. Both simulation and experiment confirmed that this method stabilized the {210} planes. A study of the PtSb system showed that the tetrahexahedron shape resulted from the evaporative removal of Sb from the initial alloy—a shape-regulating process fundamentally different from solution-phase, ligand-dependent processes. The current density at a fixed potential for the electro-oxidation of formic acid with a commercial Pt/carbon catalyst increased by a factor of 20 after transformation with Bi into tetrahexahedral particles.

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The sodium ion battery (NIB) is a promising alternative technology for energy storage systems because of the abundance and low cost of sodium in the Earth’s crust. However, the limited cycle life and safety concerns of NIBs hinder their large-scale applications. Here, we report a nonflammable localized high concentration electrolyte (sodium bis­(fluorosulfonyl)­imide-triethyl phosphate/1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether (1:1.5:2 in molar ratio)) for highly reversible NIBs. By using a cryo-transmission electron microscope, it was found that an ultrathin (3 nm) and robust interphase layer formed on the cathode surface can block transition metal dissolutions and minimize surface reconstructions of the cathode. The inorganic-rich solid electrolyte interphase formed on the hard carbon (HC) surface minimized undesirable reactions between HC and the electrolyte. These stable interphases enabled high Coulombic efficiency and long-term stable cycling of the HC anode and the NaCu1/9Ni2/9Fe1/3Mn1/3O2 cathode. The insights obtained in this work can be used to further improve the cycling stability and safety of rechargeable batteries.

In the pursuit of urgently needed, energy dense solid-state batteries for electric vehicle and portable electronics applications, halide solid electrolytes offer a promising path forward with exceptional compatibility against high-voltage oxide electrodes, tunable ionic conductivities, and facile processing. For this family of compounds, synthesis protocols strongly affect cation site disorder and modulate Li + mobility. In this work, we reveal the presence of a high concentration of stacking faults in the superionic conductor Li 3 YCl 6 and demonstrate a method of controlling its Li + conductivity by tuning the defect concentration with synthesis and heat treatments at select temperatures. Leveraging complementary insights from variable temperature synchrotron X-ray diffraction, neutron diffraction, cryogenic transmission electron microscopy, solid-state nuclear magnetic resonance, density functional theory, and electrochemical impedance spectroscopy, we identify the nature of planar defects and the role of nonstoichiometry in lowering Li + migration barriers and increasing Li site connectivity in mechanochemically synthesized Li 3 YCl 6 . We harness paramagnetic relaxation enhancement to enable 89 Y solid-state NMR and directly contrast the Y cation site disorder resulting from different preparation methods, demonstrating a potent tool for other researchers studying Y-containing compositions. With heat treatments at temperatures as low as 333 K (60 °C), we decrease the concentration of planar defects, demonstrating a simple method for tuning the Li + conductivity. Findings from this work are expected to be generalizable to other halide solid electrolyte candidates and provide an improved understanding of defect-enabled Li + conduction in this class of Li-ion conductors.

the energy density of LIBs because Si has ten times higher theoretical capacity (3579 mAh g −1 ) comparing with those of conventional graphite (372 mAh g −1 ). [9][10][11] However, large-scale applications of Si anodes still face several significant challenges, including pulverization of Si particles, continuous growth of a solid electrolyte interface (SEI) layer during the charge/discharge processes, and large swelling of the Si-based anode. [12,13] Without successfully overcoming those challenges, Si can be used only as a limited additive in graphite-based anodes to incrementally increase the energy density of LIBs.Several approaches have been developed in recent years to address those challenges. [14][15][16][17] In this regard, Si nanocomposites stabilized by heterogeneous elements has been used as one of most effective approaches to accommodate large volume changes and prevent side reactions between the electrolyte and Si. [15,16,[18][19][20] Moreover, practical issues associated with the use of nanoengineered Si anodes [21] (e.g., high surface area, low density, and high interparticle resistance) have been addressed by building the nanostructure in a local scale within micrometersized particles. [14,[22][23][24] Representative design of nanostructured Si includes the pomegranate-inspired Si/C anode [23] and Si nanolayer embedded graphite. [24] These nanostructure materials form micrometer (µm) size particles that can be used in practical applications and that are compatible with conventional battery manufacturing process. However, as the primary particle size decreases to nanometer-scale, it is increasingly difficult to assemble nanostructured Si into micrometer-sized material. [25][26][27][28] In this work, we demonstrate a facile method for preparing a Si/C composite containing micrometer-sized nanoporous Si (denoted Np-Si) that is protected by pitch-derived carbon (denoted PC). The resulting PC/Np-Si not only successfully retains its single nanometer-sized Si primary particle without sintering in micrometer-scale, but also exhibits favorable powder properties for conventional battery manufacturing process such as narrow particle size distribution, high density, strong mechanical strength, and small surface area. It also exhibits low swelling upon lithiation at both particle-and Porous silicon (Si)/carbon nanocomposites have been extensively explored as a promising anode material for high-energy lithium (Li)-ion batteries (LIBs). However, shrinking of the pores and sintering of Si in the nanoporous structure during fabrication often diminishes the full benefits of nanoporous Si. Herein, a scalable method is reported to preserve the porous Si nano structure by impregnating petroleum pitch inside of porous Si before high-temperature treatment. The resulting micrometer-sized Si/C composite maintains a desired porosity to accommodate large volume change and high conductivity to facilitate charge transfer. It also forms a stable surface coating that limits the penetration of electrolyte into nanoporous Si and ...