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Summary: Bismuth has garnered attention as a promising anode material for Na‐ion batteries (NIBs) because of its high volumetric capacity and appropriate operating potential. However, the large and repeated volume variations of the Bi anode during sodiation/desodiation lead to a poor electrochemical performance; thus, a rational design for Bi‐based materials is essential for their application to NIB anodes. First, the Na reaction pathway of Bi was analyzed using various cutting‐edge ex situ analysis tools. Subsequently, two different types of Bi‐based nanocomposite materials were prepared to enhance the Na storage performance of Bi: one is an amorphous carbon (a‐C)‐modified Bi nanocomposite (Bi@a‐C) fabricated via mechanical treatment and the other is a metal–organic framework (MOF)‐derived polyhedral Bi nanocomposite (p‐Bi@C) fabricated via chemical treatment. The Na storage performance of p‐Bi@C is much higher than that of Bi@a‐C because of the homogeneous anchoring effect of Bi nanocrystals in the MOF‐derived polyhedral C matrices, which have robust and high Na‐ion conduction. The p‐Bi@C delivered a highly reversible capacity (302 mAh g−1 over 100 cycles) and high rate capability (205 mAh g−1 at 2C). Therefore, this study provides a rational design of Bi‐based nanocomposite materials for application to high‐performance NIB anodes. [ABSTRACT FROM AUTHOR]

A nanostructured FeSn 2 /SnO 2 composite was directly synthesized using a simple solid-state ball milling synthesis method by exploiting the disproportionation reaction of SnO and the thermodynamically stable formation of FeSn 2. The as-synthesized FeSn 2 /SnO 2 composite comprised small (∼10–20 nm) FeSn 2 and SnO 2 nanocrystallites, and as a lithium-ion battery anode, it exhibited better electrochemical performance than FeSn 2 and SnO 2. Furthermore, we prepared a C-decorated FeSn 2 /SnO 2 (FeSn 2 /SnO 2 /C) composite. Compared to FeSn 2 /SnO 2 , FeSn 2 /SnO 2 /C contained smaller nanocrystallites of FeSn 2 (∼10 nm) and SnO 2 (∼5 nm), which were present in the amorphous C matrix and provided enhanced electrochemical performance. The FeSn 2 /SnO 2 /C composite had a high reversible initial capacity of 843 mAh·g−1, a stable capacity retention of above 80% after 100 cycles, and a high C-rate performance of ∼610 mAh·g−1 at 3C rate. Moreover, its electrochemical reaction mechanism during lithium insertion/extraction was determined by ex situ extended X-ray absorption fine structure analysis. Owing to their high electrochemical performance, FeSn 2 /SnO 2 /C composites are promising as a new high-performance anode material for lithium-ion batteries. Image 1 • FeSn 2 /SnO 2 -based nanocomposites are synthesized by a simple solid-state ball milling. • A FeSn 2 /SnO 2 /C composite contains small FeSn 2 and SnO 2 nanocrystallites. • The FeSn 2 /SnO 2 /C composite is tested for its suitability as Li-ion battery anodes. • The FeSn 2 /SnO 2 /C composite exhibits excellent electrochemical performances. [ABSTRACT FROM AUTHOR]

To investigate the electrochemical reaction mechanism of As, which shows poor electrochemical reversibility with Li, an As/C nanocomposite was prepared using a straightforward high-energy mechanical milling technique. The electrochemical reaction mechanism of the As/C nanocomposite electrode with Li was elucidated by ex situ XRD and HRTEM analyses in combination with differential capacity plot analysis. Electrochemical tests showed that the As/C nanocomposite exhibited good reversibility between the LiAs (0.85 V) and As (2 V) phases showing quasi-intercalation reaction. [ABSTRACT FROM AUTHOR]

We exploited the unstable characteristics of solid SnO at all temperatures to develop a simple, fast, inexpensive, and scalable method based on high-energy ball milling to transform SnO into a disproportionated nanocomposite that consists of amorphized Sn and nanocrystalline SnO2. In the first step of this process, nanostructured disproportionated SnO (d-SnO) made up of nanosized Sn and SnO2 crystallites is produced by ball milling pure SnO powder. The electrochemical performance of the d-SnO is then enhanced by creating a d-SnO/C nanocomposite through additional ball milling. This d-SnO/C nanocomposite was analyzed by various techniques, such as XRD, high-resolution transmission electron microscopy, and extended X-ray absorption fine structure analysis, and consists of amorphized Sn (≈sub-3 nm) and nanocrystalline SnO2 (≈5-15 nm) within an amorphous carbon matrix. This structure produces excellent electrochemical performances with a high initial energy density (first charge: 892 mA h g−1 or 1436 mA h cm−3), a relatively good initial Coulombic efficiency (≈73 %), long cycling stability (above 642 mA h g−1 or 1034 mA h cm−3 over 300 cycles), and a fast rate capability (3 C: 585 mA h g−1 or 942 mA h cm−3). Based on these results, we believe that d-SnO/C nanocomposite electrodes have the potential to create a new area of research in the field of high-performance Li-alloy-based anode materials. [ABSTRACT FROM AUTHOR]

Abstract: An Sb-based nanostructured composite with embedded TiO2 was prepared from Sb2O3, Ti, and carbon powders using a mechanochemical reduction method and was evaluated as an anode material in rechargeable Li-ion batteries. X-ray diffraction, X-ray photoelectron spectroscopy, and high-resolution transmission electron microscopy analyses reveal that the Sb/TiO2/C nanocomposite is composed of nanocrystalline Sb, rutile-TiO2, and amorphous carbon. Electrochemical tests show that the electrochemical performance of the Sb/TiO2/C nanocomposite electrode is superior to that of the pure Sb electrode. [Copyright &y& Elsevier]

Abstract: The suitability of silver sulfide (Ag2S) and its nanocomposite Ag2S/C, prepared by simple solid-state synthetic routes such as high-energy mechanical milling and heat treatment, for use as anode materials in rechargeable Li-ion batteries has been investigated. A well-developed Ag2S phase is identified from X-ray diffraction (XRD) patterns, and XRD and high-resolution transmission electron microscopy observations confirm that Ag2S nanocrystallites in Ag2S/C are uniformly distributed within an amorphous carbon matrix. The electrochemical reaction mechanism of Ag2S with Li is identified by ex situ XRD analyses of an Ag2S/C nanocomposite electrode. The Ag2S/C nanocomposite anode shows good cycling behavior and a high capacity of about 430mAhg−1 after 100cycles. [Copyright &y& Elsevier]

Abstract: Bi2S3 and Bi2S3/C nanocomposites prepared by high-energy mechanical milling were evaluated as electrode materials in lithium secondary batteries. For a Bi2S3/C nanocomposite, Bi2S3 nanocrystallites were well distributed in an amorphous carbon matrix. The reaction mechanism of the Bi2S3/C electrode was also examined during the first cycle. The Bi2S3/C nanocomposite anode showed superior electrochemical performance (ca. 500mAhg−1 and 85% of the capacity retention over 100 cycles). [Copyright &y& Elsevier]

Abstract: Intermetallic FeSb2 and CrSb2 and their nanocomposites (FeSb2/C and Sb/Cr3C2/C) were prepared using solid-state routes, such as heat-treatment and high-energy mechanical milling, in order to enhance the electrochemical properties of Sb. These electrodes were tested as anode materials for rechargeable Li-ion batteries. The reaction mechanism of intermetallic FeSb2 and CrSb2 was investigated using ex situ X-ray diffraction and high resolution transmission electron microscopy. The FeSb2/C and Sb/Cr3C2/C nanocomposite electrodes exhibited greatly enhanced electrochemical behaviors compared to the FeSb2 and CrSb2 electrodes. Additionally, the Sb/Cr3C2/C nanocomposite electrode showed a better electrochemical performance than the FeSb2/C nanocomposite electrode. [Copyright &y& Elsevier]

Intermetallic TiSb2 and Sb/TiC/C nanocomposites were prepared by alloying and dealloying reactions, respectively, and their potential as anode materials for rechargeable Li-ion batteries was investigated. The Sb/TiC/C nanocomposite was composed of nanocrystalline Sb and TiC, which were distributed uniformly in an amorphous carbon matrix. The reaction mechanism of intermetallic TiSb2 with Li was examined by ex Situ X-ray diffraction and high resolution transmission electron microscopy. The Sb/TiC/C nanocomposite exhibited good electrochemical performance, such as a high initial coulombic efficiency of 87% and a long cycle retention of 83% after 100 cycles.d. [ABSTRACT FROM AUTHOR]

Abstract: A nanostructured Sn/TiO2/C composite was prepared from SnO, Ti, and carbon powders using a mechanochemical reduction method and evaluated as an anode material in rechargeable Li-ion batteries. The Sn/TiO2/C nanocomposite was composed of uniformly dispersed nanocrystalline Sn and rutile TiO2 in amorphous carbon matrix. In addition, electrochemical Li insertion/extraction in rutile TiO2 was examined by ex situ XRD and extended X-ray absorption fine structure. The Sn/TiO2/C nanocomposite exhibited excellent electrochemical performance, which highlights its potential as a new alternative anode material in Li-ion batteries. [Copyright &y& Elsevier]

Abstract: At present, graphite (LiC6: 372mAhg−1, 840mAhcm−3) is used as the anode material for lithium-ion batteries. However, methods to enhance the energy density, cyclability, initial Coulombic efficiency, and rate capability of lithium-ion batteries are still actively being researched. Here, we report a simple, fast, and novel method for transforming micron-sized Sn and Sb powders into ca. 10nm- and 2–3nm-sized SnSb crystallites by mechanochemical synthesis and electrochemical reactions, respectively. These nanocrystallites are uniformly distributed in an amorphous carbon matrix, resulting in a SnSb/C nanocomposite structure. The fabricated SnSb/C nanocomposite showed excellent electrochemical properties, such as a high energy density (1st charge: 706mAhg−1), long cyclability (ca. 550mAhg−1 over 300 cycles), good initial Coulombic efficiency (ca. 81%), and a fast rate capability (1C: 590mAhg−1, 2C: 550mAhg−1). [Copyright &y& Elsevier]

• A new synthesis method comprising alloying and dealloying is developed. • Electrochemical sodiation/desodiation mechanism of Sb in Sb@C is demonstrated. • Electrochemical performance and mechanism of TiSb 2 and NbSb 2 is reported. • Sb@TiC@C and Sb@NbC@C nanocomposites show excellent Na storage performance. To achieve high-performance Sb-based anodes for Na-ion battery (NIB), various approaches for obtaining amorphous C-containing Sb composite (Sb@C), Sb-based intermetallic compounds (TiSb 2 and NbSb 2), and Na-inactive metal carbide and amorphous C-containing Sb composites (Sb@TiC@C and Sb@NbC@C) have been introduced. First, Sb@C was prepared using a simple solid-state ball-milling, and then its potential as a NIB anode material was investigated. The electrochemical phase change mechanism of Sb during the sodiation/desodiation of Sb@C was investigated using various ex situ analytical techniques. Sb was found to sequentially transform into NaSb and Na 3 Sb during sodiation and NaSb and Sb during desodiation. Second, as another trial to further improve the electrochemical performance of Sb, Sb-based intermetallic compounds of TiSb 2 and NbSb 2 were synthesized by alloying reaction via a simple solid state heat-treatment and their potential as NIB anode materials was investigated. Lastly, the Sb@TiC@C and Sb@NbC@C nanocomposites comprising tiny (~3–5 nm) Sb nanocrystallites and Na-inactive metal carbide (TiC/NbC) matrix embedded in buffering amorphous C were synthesized by alloying and dealloying reaction. The Sb@TiC@C and Sb@NbC@C demonstrated highly reversible, stable capacity (Sb@TiC@C: 746 mAh cm−3, Sb/NbC/C: 726 mAh cm−3 after 100 cycles) and fast rate capability with exceptional capacity retentions after 400 cycles (Sb@TiC@C: ~710 mAh cm−3 at 2 C rate, Sb@NbC@C: ~680 mAh cm−3 at 2 C rate). Therefore, the Sb-based nanocomposites synthesized by alloying and dealloying are considered to be possible new anode materials for use in high-performance NIBs. [ABSTRACT FROM AUTHOR]

Here, we report a simple, cheap, and rapid synthesis method combined with physical and chemical routes for porous structured metal-based carbon nanocomposites, which can be applicable to anode materials for high performance Li-ion batteries. [ABSTRACT FROM AUTHOR]

Disproportionation of SnO: The cover image shows a simple, fast, inexpensive, and scalable method of transforming solid tin oxide (SnO) into a Sn/SnO2/C nanocomposite, which consists of disproportionated amorphous Sn (sub 3 nm) and nanocrystalline SnO2 (5–15 nm) within an amorphous carbon matrix. Specifically, the disproportionated Sn/SnO2/C nanocomposite was developed based on the unstable characteristics of solid SnO at all temperatures. As described in the Full Paper on page 658 by Jae‐Wan Park and Cheol‐Min Park of the Kumoh National Institute of Technology, Korea, the process is aimed at obtaining high‐performance anode materials for rechargeable Li‐ion batteries. Upon use as an anode material in rechargeable Li‐ion batteries, the disproportionated Sn/SnO2/C nanocomposite showed excellent electrochemical performance, with high initial energy density, a relatively good initial coulombic efficiency, long cycling stability, and a fast rate capability. Additionally, the disproportionation reaction of SnO was thoroughly investigated using various analytical techniques, which should be of broad interest to the field of materials chemistry. [ABSTRACT FROM AUTHOR]

Herein, we describe a simple solid-state synthesis of zinc sulfide (ZnS) and its amorphous carbon–modified nanocomposite (ZnS/C) and examine their performance as high-capacity anode materials for rechargeable Li-ion batteries, probing lithiation/delithiation mechanisms by ex situ X-ray diffraction and extended X-ray absorption fine structure analyses. The ZnS converted into LiZn and Li 2 S during lithiation, being subsequently incompletely recombined into ZnS during delithiation and thus resulting in traces of Zn and S. Based on the above investigation of reaction mechanism, the ZnS/C electrode was electrochemically tested within a potential range of 0–2.0 V vs. Li + /Li and exhibited a high reversible capacity of 681 mAh g −1 , excellent cycling stability (>150 cycles), and high rate capability. [ABSTRACT FROM AUTHOR]

New battery systems having high energy density are actively being researched in order to satisfy the rapidly developing market for longer-lasting mobile electronics and hybrid electric vehicles. Here, we report a new Li-Te secondary battery system with a redox potential of ~1.7 V (vs. Li+/Li) adapted on a Li metal anode and an advanced Te/C nanocomposite cathode. Using a simple concept of transforming TeO2 into nanocrystalline Te by mechanical reduction, we designed an advanced, mechanically reduced Te/C nanocomposite electrode material with high energy density (initial discharge/charge: 1088/740 mA h cm−3), excellent cyclability (ca. 705 mA h cm−3 over 100 cycles), and fast rate capability (ca. 550 mA h cm−3 at 5C rate). The mechanically reduced Te/C nanocomposite electrodes were found to be suitable for use as either the cathode in Li-Te secondary batteries or a high-potential anode in rechargeable Li-ion batteries. We firmly believe that the mechanically reduced Te/C nanocomposite constitutes a breakthrough for the realization and mass production of excellent energy storage systems. [ABSTRACT FROM AUTHOR]

[Display omitted] • Nanocrystalline Ge exhibited higher Li reversibility than bulk Ge. • Li reaction pathways in nanocrystalline Ge were definitively established. • Ge/Al 2 O 3 /C was synthesized by one-pot mechanical solid-state reduction. • Ge/Al 2 O 3 /C exhibited good cyclic behavior, rate capability, and reversible capacity. Ge is a highly researched anode material for Li-ion batteries (LIBs) owing to its high theoretical Li storage capacity and higher electrical conductivity compared to that of Si. However, Li reaction pathways in Ge have not been definitively established due to the formation of various and complicated Li-Ge alloy phases during lithiation/delithiation. Evaluation of the Li storage characteristics of bulk and nanocrystalline Ge demonstrated that nanocrystalline Ge showed higher Li reversibility than bulk Ge. Various cutting-edge ex situ techniques were used to analyze nanocrystalline Ge, and the Li reaction pathways in Ge were thoroughly demonstrated. To enhance the electrochemical Li storage characteristics of Ge, a Ge-based nanocomposite, Ge/Al 2 O 3 /C, was synthesized via simple one-pot mechanical solid-state reduction using GeO 2 , Al, and C. Ge/Al 2 O 3 /C exhibited very stable cyclic behavior at a current density of 100 mA g−1 over 300 cycles (capacity retention after 300 cycles: ∼95 %). Moreover, Ge/Al 2 O 3 /C exhibited excellent rate capability with high reversible capacity and stable cyclic behavior at a high 1C-rate. The superior electrochemical performance of Ge/Al 2 O 3 /C was attributed to the nanoscale dimensions of Li-active nanocrystalline Ge (∼10 nm) and Li-inactive Al 2 O 3 (∼12 nm) embedded uniformly in the amorphous carbon matrices. The size of nanocrystalline Ge in nanocomposite was consistently maintained during repeated cycles owing to the anti-agglomeration effect of the uniformly distributed Li-inactive Al 2 O 3 and amorphous carbon matrices. We anticipate that the electrochemical Li reaction pathways in Ge and the resulting high-performance nanocomposite anodes will be highly useful in investigating high-performance Ge-based anodes for LIBs. [ABSTRACT FROM AUTHOR]

As representative next-generation secondary battery systems, sodium-ion batteries (SIBs) and potassium-ion batteries (PIBs) are key candidates to achieve zero-carbon emission. Herein, we introduce a versatile GaSb nanocomposite anode for SIBs and PIBs. The performance and phase transition mechanism for GaSb, pure Ga, and Sb with Na and K ions are evaluated. Furthermore, three-step nanoconfinement and stabilization of GaSb crystallites are achieved in the GaSb nanocomposite. The nanostructure of the GaSb nanocomposite, consisting of approximately 2–4 nm GaSb crystallites uniformly distributed in an amorphous carbon matrix, promotes the electrochemical reaction kinetics with Na and K ions, and the chemical and mechanical stabilities of the GaSb nanocomposite electrodes. The GaSb nanocomposite anode possesses highly reversible initial volumetric and gravimetric capacities and superior high-rate capabilities. In this study, we offer new insights into the phase transition mechanisms of GaSb with Na and K ions and promising performance GaSb nanocomposite anodes for SIBs and PIBs. [Display omitted] • GaSb is newly introduced as high-performance anode materials for SIBs and PIBs. • The GaSb and its nanocomposite are synthesized using simple solid-state methods. • The GaSb nanocomposite exhibits high electrochemical performance. • The high performance is achieved by the three-step nanoconfinement process. [ABSTRACT FROM AUTHOR]

• A Si-based composite interconnected by multiple matrices is developed. • The Si-based composite is fabricated by a combination of two simple solid-state methods. • The Si-based composite contains Si, a Li-inactive Cu 3 Si, and multiple carbon-based matrices. • The Si-based composite exhibits excellent electrochemical performances. To obtain anode materials with high performance Li-ion batteries, a nanostructured Si-based composite, including Si, a Li-inactive conducting Cu 3 Si matrix, and multiple carbon-based matrices (carbon nanotube, graphite, and a pyrolytic carbon coating) is developed by facile step-by-step combination of solid-state synthetic technologies. First, various Si x Cu y alloys with different weight compositions are synthesized by a simple ball-milling process. Among the Si x Cu y alloys, Si 80 Cu 20 , which is comprised of Si and Cu 3 Si, displays the highest electrochemical performance. To further improve the electrochemical performance of Si-Cu 3 Si, an interconnected composite with 1D-structured CNT and 3D-structured graphite, Si-Cu 3 Si-CNT/G, is prepared via an additional ball-milling process. The Si-Cu 3 Si-CNT/G composite is finally coated via the pyrolysis of polyvinyl chloride, thus forming the carbon-coated Si-Cu 3 Si-CNT/G-C composite. This final product, Si-Cu 3 Si-CNT/G-C, is comprised of well-dispersed nanocrystalline Si and Cu 3 Si (Li-inactive conducting matrix) within the multiple interconnected carbon matrices. The Si-Cu 3 Si-CNT/G-C displays excellent electrochemical performance, with a high first reversible capacity of 1237 mA h g−1, a high initial coulombic efficiency of 82.8%, a long cycle durability of 1084 mAh g−1 over 100 cycles, and a high rate capability of ~1000 mAh g−1 at 1C-rate, which confirms its commercial application as a high-performance Si-based anode for Li-ion batteries. [ABSTRACT FROM AUTHOR]