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The advancement of electronic technology has led to increasing research on performance and stability. Continuous electrical pulse stimulation can cause crystal structure changes, affecting performance and accelerating aging. Controlled repair of these defects is crucial. In this study, we investigated crystal structure changes in van der Waals (vdW) InSe crystals under continuous electric pulses by using electron beam lithography (EBL) and spherical aberration corrected transmission electron microscopy (Cs-TEM). Results show that electrical pulses induce amorphous regions in the InSe lattice, increasing the device resistance. We used Cs-STEM probe scanning for precise repair, abbreviated SPRT, to optimize device performance. SPRT is related to electric fields induced by the electron beam and can be applied to other 2D materials like α-In2Se3and CrSe2, offering a potential approach to extend device lifespan.

Molybdenum disulfide (MoS2) is a promising anode material for sodium batteries due to its high theoretical capacity. While significantly improved electrochemical performance has been achieved, the reaction mechanism is still equivocal. Herein, we applied electron pair distribution function and X-ray absorption spectroscopy to investigate the desodiation/sodiation mechanism of MoS2electrodes. The results reveal that Mo–S bonds are well preserved and dominant in the sodiation product matrix but do not convert to metallic Mo and Na2S even at deep sodiation. The MoS2multilayer sheets break into disordered MoSxclusters with modified octahedral symmetry during discharging. The long-range order was not rebuilt during subsequent charging but with partial recovery of the Mo–S coordination symmetry. The mechanism of the reaction is independent of the carbon matrix, although it prevents the MoSxclusters from leaching into the electrolyte and thus contributes to an extended cycle life. This work refreshes the fundamental understanding of the desodiation/sodiation mechanism of MoS2materials.

The understanding of surface reactions at the electrode–electrolyte interfaces has been a longstanding challenge in Li-ion batteries. X-ray photoemission electron microscopy is used to throw light on the disputed aspects of the surface reactivity of high-energy Li-rich Li1+x(NiaCobMn1–a–b)1–xO2(HE-NCM) cycled in an aprotic electrolyte against Li4Ti5O12(LTO). Despite the highly oxidative potential of 5.1 V vs Li+/Li, there is no formation of a layer of oxidized electrolyte byproducts on any of the cathode particles; instead, a homogeneous organic–inorganic layer builds up across the particles of the LTO anode due to the electrolyte and poly(vinylidene fluoride) binder decomposition on HE-NCM. In addition, such a layer incorporates, already from the first charge, micrometer-sized agglomerates of transition metals (TMs). The presence of TMs on the anode is explained by the instability of the reduced Mn, Co, and Ni formed at the surface of HE-NCM mainly during delithiation. The reduced TMs are unstable and prone to be transported to the LTO, where they get further reduced to metallic-like clusters. These results demonstrate that a dual reaction takes place at the HE-NCM–electrolyte interface if subject to high potential, namely, degradation of the surface structure and decomposition of the electrolyte, affecting directly the anode surface through the migration–diffusion processes.

In view of the requirements for high-energy lithium ion batteries (LIBs), hierarchically layered LiNi1/3Co1/3Mn1/3O2 (NCM111) cathode materials have been prepared using a hydroxide coprecipitation method and subsequent high-temperature solid-state reaction. The diffraction results show that the synthesized NCM111 has a well-defined layered hexagonal structure. The initial specific discharge capacity of a Li/NCM111 cell is 204.5 mAh g[?]1 at a current density of 28 mA g[?]1 between 2.7 and 4.8 V. However, the cell suffers from poor capacity retention over extended charge-discharge cycles. The structural evolution of NCM111 electrode during electrochemical cycling is carefully investigated by in situ high-resolution synchrotron radiation diffraction. It is found that the nanodomain formation of a layered hexagonal phase H3 and a cubic spinel phase after charging to voltages above 4.6 V is the main source for the structural collapse in c direction and the poor cycling performance. This process is accompanied by the removal of oxygen, the transition metal (TM) migration and the crack generation in the nanodomains of the primary particles. These results may help to better understand the structural degradation of layered cathodes in order to develop high energy density LIBs.

Metallic nanohelices are extremely rare and, to date, have never been synthesized by a direct solution method. In this work, we report ultralong Au nanohelices grown in solution under ambient conditions. They are ultralong with several tens of micrometers in length, with extraordinary aspect ratio (length/diameter greater than 22 300) and the number of pitches (more than 22 000 pitches). The pitch and width are uniform within each helix but vary widely among the helices. Crystal analyses showed that the facets, twin boundaries, grain sizes, and orientations are aperiodic along the helices. The apparent smooth curving is only possible with a large number of surface steps, suggesting that these structural features are the mere consequence of the helix formation rather than the cause. We propose that the nanowires are formed by the active surface growth mechanism and that the helicity originates from the random and asymmetrical blocking of nuclei embedded within the floccules of ligand complexes, in the form of either asymmetric binding of ligands or asymmetric diffusion of growth materials through the floccules. The separate growth environment of these nuclei causes constant helicity within each helix but differing helicity among the individuals. The embedding also provides a robust environment for the sustained growth of the nanohelices, leading to their record length and consistency.

Borate chemistry offers attractive features for iron based polyanionic compounds. For battery applications, lithium iron borate has been proposed as cathode material because it has the lightest polyanionic framework that offers a high theoretical capacity. Moreover, it shows promising characteristics with an element combination that is favorable in terms of sustainability, toxicity, and costs. However, the system is also associated with a challenging chemistry, which is the major reason for the slow progress in its further development as a battery material. The two major challenges in the synthesis of LiFeBO3are in obtaining phase purity and high electrochemical activity. Herein, we report a facile and scalable synthesis strategy for highly pure and electrochemically active LiFeBO3by circumventing stability issues related to Fe2+oxidation state by the right choice of the precursor and experimental conditions. Additionally, we carried out a Mössbauer spectroscopic study of electrochemical charged and charged–discharged LiFeBO3and reported a lithium diffusion coefficient of 5.56 × 10–14cm2s–1for the first time.

Higher spheres:Hollow carbon nanospheres are prepared from glucose through a facile, sustainable hydrothermal method. Their morphology provides fast electron and lithium ion transport, which is reflected in a superior rate capability (100 mAh g−1at 50 C) and good cycle stability. Nevertheless, these results provide direct evidence that not only lithium‐ion insertion/extraction to the carbon layers occurs, but also that a surface reaction contributes to the high rate performance.

In view of the requirements for high-energy lithium ion batteries (LIBs), hierarchically layered LiNi1/3Co1/3Mn1/3O2(NCM111) cathode materials have been prepared using a hydroxide coprecipitation method and subsequent high-temperature solid-state reaction. The diffraction results show that the synthesized NCM111 has a well-defined layered hexagonal structure. The initial specific discharge capacity of a Li/NCM111 cell is 204.5 mAh g−1at a current density of 28 mA g−1between 2.7 and 4.8 V. However, the cell suffers from poor capacity retention over extended charge-discharge cycles. The structural evolution of NCM111 electrode during electrochemical cycling is carefully investigated by in situ high-resolution synchrotron radiation diffraction. It is found that the nanodomain formation of a layered hexagonal phase H3 and a cubic spinel phase after charging to voltages above 4.6 V is the main source for the structural collapse in cdirection and the poor cycling performance. This process is accompanied by the removal of oxygen, the transition metal (TM) migration and the crack generation in the nanodomains of the primary particles. These results may help to better understand the structural degradation of layered cathodes in order to develop high energy density LIBs.

Amorphous samples of MgF2are deposited on substrates below ‐100 °C and the structural transformations occurring upon warming are monitored by in situ powder XRD and TEM.