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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]

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]

Highlights: [•] An amorphized composite, Sb/Al2O3/C, is simply prepared by a straightforward mechanochemical reduction method. [•] Various analytical tools reveal that the composite is composed of amorphized Sb, amorphous Al2O3, and carbon. [•] The amorphized composite is investigated for use as an anode material for rechargeable Li-ion batteries. [•] The composite electrode shows a high energy density of more than 1800mAhcm−3 over 300 cycles. [Copyright &y& Elsevier]

Abstract: An anode material with improved electrochemical performances for Li-ion batteries is prepared using the disproportionation reaction of SiO followed by a high energy mechanical milling process. The modified SiO is composed of embedded Si nano-crystallites in a Si-oxide matrix. Si-oxide matrix could be divided into two parts by reactivity with Li-ion. The inactive Si-suboxide matrix would buffer the volume expansion of embedded Si nano-crystallites and active amorphous SiO2 during the lithiation. This modified SiO electrode shows a large reversible capacity, close to 1000 mAh g−1, and good cyclability, over 50 cycles. [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: The electrochemical behavior of the SiO (silicon monoxide) anode during its reaction with Li has been investigated using solid-state nuclear magnetic resonance (NMR) and high resolution transmission electron microscopy (HRTEM). It was mainly focused on identifying the intermediate and final phases formed with their microstructures of the electrochemically lithiated SiO at various voltage steps during the first cycle. A model for the reaction of SiO with lithium was suggested, which was consistent with the discharge capacity of about 2400mAhg−1. [Copyright &y& Elsevier]

Abstract: A Ge/Cu3Ge/C composite, prepared by pyrolysis and a high energy mechanical milling process, was investigated as an anode material for Li-ion batteries. Electron probe micro-analyzer images showed that Ge and Cu3Ge were well dispersed in the carbon matrix. Various analytical techniques were carried out to clarify the reaction mechanism of the Cu3Ge single phase and the Ge/Cu3Ge/C composite ex situ XRD and ex situ HRTEM analyses for Ge/Cu3Ge/C composite electrode were carried out and the final phase formed was Li15Ge4. For the case of pure Cu3Ge electrode, it reacted with Li at very low rate and the final product was probably a Li–Ge compound. Electrochemical tests showed that the Ge/Cu3Ge/C composite exhibited better capacity retention than that of the Ge/C composite anode probably due to the presence of amorphous carbon which acted as a buffering matrix during volume expansion and Cu that formed during the first discharge increased the electrical conductivity locally. [Copyright &y& Elsevier]

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: A Si–Zn–C composite material is prepared by mechanical ball-milling and investigated as an anode material for lithium-ion batteries. Electrochemical tests show that the first charge and discharge capacities are approximately 852 and 607mAhg−1, respectively, and that 91% of the initial discharge capacity of 607mAhg−1 can be maintained for up to 40 cycles. This improved cycling performance is attributed to the use of the third element Zn. Li2ZnSi is partially formed at the interface between Si and Zn and graphite to provide superior cycling performance compared with that of the binary system. [Copyright &y& Elsevier]

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]

A two-dimensional layered Sb 2 Se 3 -based amorphous composite (a –Sb 2 Se 3 /C) is synthesized using a simple solid-state ball-milling process, and its potential for Li- and Na-ion batteries is evaluated. Ex situ extended X-ray absorption fine structure analyses clearly indicate the electrochemical reaction mechanisms of Sb 2 Se 3 and a –Sb 2 Se 3 /C as anodes for Li- and Na-ion batteries. During Li- and Na-insertion, the Sb 2 Se 3 and a –Sb 2 Se 3 /C electrodes are converted into the final phases of Li 3 Sb/Na 3 Sb and Li 2 Se/Na 2 Se, respectively. During Li- and Na-extraction, the Li 3 Sb/Na 3 Sb and Li 2 Se/Na 2 Se in the Sb 2 Se 3 electrode are converted into Sb and Se, showing a non-recovery reaction, whereas a recovery to the original Sb 2 Se 3 in the a –Sb 2 Se 3 /C electrode occurs after full Li and Na extraction. Owing to the interesting conversion/recovery reaction, the a –Sb 2 Se 3 /C electrode exhibits excellent electrochemical performance, such as high reversible capacities (Li-ion battery: 662 mAh g−1; Na-ion battery: 407 mAh g−1), a long cycle life with highly reversible capacities (Li-ion battery: 662 mAh g−1 and 1,205 mAh cm−3, respectively, after 100th cycle; Na-ion battery: 378 mAh g−1 and 688 mAh cm−3, respectively, after 50th cycle), and high rate capabilities (Li-ion battery: 623 mAh g−1 and 1,133 mAh cm−3 at 3C; Na-ion battery: 270 mAh g−1 and 492 mAh cm−3 at 2C). Image 1 • A layered Sb 2 Se 3 and its amorphous Sb 2 Se 3 /C composite is synthesized simply. • The reaction mechanisms during Li- and Na-insertion/extraction is demonstrated. • The Sb 2 Se 3 had conversion/non-recovery reactions during Li- and Na-reactions. • The Sb 2 Se 3 /C had conversion/full-recovery reactions during Li- and Na-reactions. • The amorphous Sb 2 Se 3 /C exhibited excellent electrochemical performances. [ABSTRACT FROM AUTHOR]

Abstract Engineering of a composite electrode containing Si-based anode materials is important for the practical applications of Si-based lithium-ion batteries. In this work, a hybrid composite anode of silicon/carbon/polymer was fabricated in situ by optimized heat treatment of the coating slurry containing silicon power and polyamic acid polymer, without adding any carbon agent. The resulting electrode has a three-component (silicon-carbon-polyamide) composite structure, wherein the nanohybrid carbon/polyamide matrix is in-situ generated from polyamic acid by optimized heat treatment. The hybrid Si composite electrode exhibits robust binding and conductive properties, and delivers promising battery performance even for high contents of the micron-sized Si powder (∼95 wt%). Consequently, the proposed method for Si anode engineering is another effective way to manufacture advanced lithium-ion batteries. Highlights • A Si/C/polyamide composite is fabricated from Si and polyamic acid coat. • The composite exhibits mechanically and electrically robust network. • The battery performance is resultingly promising. • This fabrication method can be an effective way for advanced LIB. [ABSTRACT FROM AUTHOR]

Potassium-ion batteries (PIBs) have emerged as promising alternatives to lithium-ion batteries owing to their various advantages. Among the various anode candidates for PIBs, black P (BP) has garnered attention owing to its high theoretical capacity and favorable reaction potential (vs. K+/K). Although several studies have reported on the reaction mechanism of BP during potassiation/depotassiation, it remains controversial. Therefore, the exact reaction mechanism needs to be clarified, and further enhancements in electrochemical performance are required. To thoroughly investigate the reaction mechanism of BP, a BP nanocomposite with amorphous carbon (BP@C) is synthesized to enhance its reversibility with K ions. A thorough investigation of the reaction mechanism employs various ex situ analytical tools for the potassiation/depotassiation process. During potassiation, BP sequentially transforms into the KP and K 4 P 3 phases, whereas the reaction is reversed during depotassiation. Based on the reaction mechanism, distinctive K quasi-intercalation is suggested using a similar structural relationship between the BP and KP phases. The K quasi-intercalation is applied to a BP@C anode, which consequently demonstrate a highly reversible capacity of 400 mAh g−1, exceptional cycle stability over 500 cycles, and superior rate capability. Consequently, we anticipate that K quasi-intercalation in BP will provide a high-performance P-based anode for PIBs. [Display omitted] • The K reaction pathway mechanism of black P is thoroughly demonstrated. • The concept of K quasi-intercalation in black P is newly introduced. • K quasi-intercalation in black P nanocomposite results in high electrochemical performance. • K quasi-intercalation leads to stable cycling performance and excellent rate capability. [ABSTRACT FROM AUTHOR]

[Display omitted] • A new synthesis method of black P-based composites is developed. • The composites are composed of nanocrystalline black P within the metal oxide matrices. • The composites are investigated as anode materials in rechargeable Li-ion batteries. • Black P@TiO 2 exhibited excellent electrochemical performance. A simple, inexpensive, and scalable method for transforming phosphorous pentoxide (P 2 O 5) into black phosphorus (BP)-based composites was developed. The BP-based composites of BP@MgO, BP@Al 2 O 3 , and BP@TiO 2 synthesized by a one-pot mechanochemical reduction of P 2 O 5 using Mg, Al, or Ti were composed of nanocrystalline BP within the metal oxide matrices of MgO, Al 2 O 3 , or TiO 2 , respectively. Subsequently, the potential of these composites as anode materials in rechargeable Li-ion batteries (LIBs) was investigated. BP@TiO 2 showed the highest electrochemical performance among the BP-based composites. Specifically, the BP@TiO 2 exhibited a high reversible capacity over 510 mAh g−1 after 300 cycles and a fast rate capability of ~ 400 mAh g−1 at the 3C rate. The superior electrochemical performance of BP@TiO 2 was attributed to the well-dispersed nanocrystalline BP and the Li-reactive TiO 2 matrix. Additionally, the formation of Li x TiO 2 in the Li-reactive TiO 2 matrix during Li cycling increased the electrochemical Li-ion conductivity and diffusivity, contributing to the enhanced electrochemical performance. Therefore, the BP@TiO 2 synthesized by the one-pot mechanochemical reduction has high potential as a superior LIB anode. [ABSTRACT FROM AUTHOR]

• Monoclinic VP 2 synthesized and tested as LIB anodes. • VP 2 undergoes topotactic/conversion and recombination during Li-insertion and extraction. • VP 2 shows high electrochemical performance in topotactic reaction potential region. • Graphite-modified composite VP 2 @G shows excellent Li storage performance. Vanadium diphosphide (VP 2) and its graphite-modified composite (VP 2 @G) were fabricated using a fast and simple solid-state manner, and evaluated as Li-ion battery (LIB) anodes. The electrochemical Li-mechanism of VP 2 was investigated using various ex situ tools. During Li-insertion, VP 2 underwent a topotactic-reaction by the formation of Li x VP 2 (x ≤ 1.5), and then was converted to Li 3 P and V phases with a partially unconverted Li x VP 2 phase at the Li-inserted state of 0 V via a partial conversion reaction. Conversely, during Li-extraction, Li 3 P, V, and unconverted Li x VP 2 phases recombined fully into VP 2. First, when VP 2 was used the topotactic-reaction between Li x VP 2 and VP 2 (potential region: 0.3–2.0 V), stable cycling performance with a high volumetric-capacity (595 mAh cm–3 after 100 cycles) and fast rate performance (~555 mAh cm–3 at 2 C and ~530 mAh cm–3 at 3 C) were attained. Additionally, the graphite-modified composite VP 2 @G (potential region: 0–2.0 V) also exhibited stable cycling performance with a high gravimetric-capacity (602 mAh g−1 after 100 cycles) and fast rate performance (~530 mAh g−1 at 1 C and ~470 mAh g−1 at 2 C), which was attributed to the well-dispersed nanocrystalline (~10–20 nm) VP 2 in the Li-buffering graphite matrix. Therefore, the VP 2 and VP 2 @G have high potential as a superior LIB anode. [ABSTRACT FROM AUTHOR]

Rechargeable K-ion batteries (KIBs) have attracted tremendous attention as a replacement for Li-ion batteries because potassium is earth-abundant and inexpensive. Although the formation of K-ion intercalated graphite compounds gives graphite a reasonable capacity, its capacity is insufficient, and its initial Coulombic efficiency (ICE) is low because of the slow kinetics of the large K ion. In this study, to address the shortcomings of graphite anodes for KIBs, we obtained a high-performance C-based anode by a simple, scalable two-step approach of amorphization and prepotassiation of carbon black (CB). CB was amorphized to provide numerous K-ion insertion sites and thus improve the K storage properties. However, the ICE and reversible capacity (RC) remained low. Therefore, to enhance the electrochemical performance, the amorphized CB (a-CB) was prepotassiated. The prepotassiated/amorphized CB showed a high RC (>300 mAh g−1) with an extraordinarily high ICE (>100%), high rate capability (255 mAh g−1 at 1C, 210 mAh g−1 at 2C), and remarkable cycling stability after 300 cycles at a high rate of 1C. Its electrochemical performance is among the best reported for C-based anode materials for KIBs, which suggests that it is a promising material for next-generation KIB anodes. [Display omitted] [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]

Amorphous ZnSb/MgO/C (I) and ZnSb/Al2O3/C (II) nanocomposite anodes are prepared via high-energy ball milling of ZnO and Sb2O3, Mg or Al, and C in molar ratios of 2:1:5 and 6:3:10 under Ar, respectively. [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]

Robust hierarchical nanocube framework CoS 2 -based composites comprising of nanocrystalline CoS 2 (∼8–10 nm) encapsulated in a robust carbon-core matrix entangled in carbon nanotubes (CNTs) were synthesized, and their performance as electrodes for Li-ion batteries (LIBs) and Na-ion batteries (NIBs) was evaluated. The robust nanocube framework CoS 2 -C-CNT composites were synthesized from Co-based metal-organic frameworks by an efficient two-step synthesis process of carbonization and sulfidation. The structural phase change mechanism of CoS 2 was systematically characterized by ex situ analysis tools, which revealed that it involved a conversion during Li/Na-insertion and a recombination reaction during Li/Na-extraction. The unique structural characteristics of the nanocube framework CoS 2 -C-CNT composites and the unique structural phase change mechanism of CoS 2 are attributed to the superior Li/Na-storage performances. The nanocube framework CoS 2 -C-CNT composites delivered a large reversible capacity (LIB: 770 mAh g−1 and NIB: 629 mAh g−1), excellent cycling (LIB: 726 mAh g−1 after 250 cycles and NIB: 531 mAh g−1 after 100 cycles), and fast rate behavior (LIB: 613 mAh g−1 at 3C and NIB: 391 mAh g−1 at 2C rates). This remarkable robust nanocube framework composite structure is highly applicable to various LIB/NIB electrode materials owing to their excellent Li/Na-ion storage characteristics. [Display omitted] • Nanocube framework CoS 2 -based composite is synthesized by efficient two step method. • Li- and Na-reaction mechanism of CoS 2 anode is fully demonstrated. • The robust nature of nanocube framework CoS 2 -C-CNT is demonstrated by ex situ TEM. • Nanocube framework CoS 2 -C-CNT exhibits excellent Li- and Na-storage performance. [ABSTRACT FROM AUTHOR]

[Display omitted] • A superior carbon black as conducting additive and LIB and NIB anodes is developed. • The superior carbon black is synthesized by amorphization and pre-lithiation/sodiation. • Electrochemical mechanism of the superior carbon black is elucidated using various analytical techniques. • The superior carbon black compensates ICE and increases the reversible capacity of anode materials. Carbon black (CB) is an inexpensive and widely used carbonaceous material. However, the reversibility between CB and Li or Na is very poor, and the initial coulombic efficiency (ICE) is so low that it cannot be used as an electrode material for rechargeable batteries. In this study, we successfully designed superior CB as a high-performance conducting additive for Li-ion batteries (LIBs) and Na-ion batteries (NIBs) using a simple two-step strategy: amorphization and pre-lithiation/sodiation. The Li- and Na-reversible capacities of amorphized CB increased significantly from 213 to 564 mAh g−1 for LIB and from 92 to 209 mAh g−1 for NIB; however, the corresponding ICEs of 61.5% for LIB and 33.5% for NIB are poor. The poor ICEs are supplemented via pre-lithiation/sodiation in the amorphized CB, which show over 100% ICEs with high Li- and Na-reversible capacities. Specifically, the modified CB has highly reversible capacities (>500 mAh g−1 for LIB, >300 mAh g−1 for NIB) with exceptionally high ICEs (133% ICE for LIB, 160% ICE for NIB), stable reversible capacities for over 100 cycles (470 mAh g−1 for LIB, 278 mAh g−1 for NIB), fast rate capabilities with highly reversible capacities at a 3C rate (~330 mAh g−1 for LIB, ~190 mAh g−1 for NIB), and excellent cycling behavior for over 300 cycles at a 1C rate. When used as a conducting additive, this CB contributes to high electrical conductivity and increase of ICE and the reversible capacity for LIB and NIB anode materials. These results are expected to have a significant impact on LIBs and NIBs. [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]

Germanium telluride (GeTe) with a layered structure and a GeTe nanocomposite modified by amorphous carbon (GeTe/C) are prepared via a simple solid-state synthesis, and their electrochemical performance for sodium-ion batteries is evaluated. To determine the electrochemical sodiation/desodiation mechanism of the GeTe and GeTe/C, various ex situ analytical methods are employed. During sodiation, GeTe in both electrodes is converted into NaGe and Na 2 Te phases. By contrast, during desodiation, the converted NaGe and Na 2 Te phases in the only GeTe/C are completely recombined into the original GeTe phase. Because of the repeated conversion/recombination reactions during sodiation/desodiation, GeTe/C displays outstanding Na-ion storage characteristics, such as a high reversible first volumetric capacity of 662 mAh cm−3, a stable capacity retention of 98.5% up to after 100 cycles, and rapid rate capabilities of 704 mAh cm−3 at 1C and 630 mAh cm−3 at 3C. Therefore, the GeTe/C is expected to perform well as a high–capacity anode in rechargeable sodium-ion batteries. Image 1 • Rhombohedral GeTe with layer structure is synthesized in a straightforward manner. • Phase change mechanisms during Na-insertion/extraction is demonstrated fully. • GeTe/C composite is tested for their suitability as a Na-ion battery anode. • GeTe/C composite exhibits excellent electrochemical performances. [ABSTRACT FROM AUTHOR]

Review: focus on metallic Li anodes, but Mg, Na, Al, and Zn electrodes are included; 286 refs. [ABSTRACT FROM AUTHOR]