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Among a variety of host materials for lithium storage, titanium-niobium oxides exhibit great potential in application. Herein, Ti 2 Nb 10 O 29 nanowire is synthesized via an electrospinning method. Compared with bulk Ti 2 Nb 10 O 29 prepared by solid-state approach, the electrochemical properties of Ti 2 Nb 10 O 29 nanowire is better. According to the galvanostatic charging-discharging test, the initial capacity of 232.8 mAh g−1 for Ti 2 Nb 10 O 29 nanowire is displayed. Besides, it exhibits superior rate performance. With the current density set as 0.5, 1, 2, 3, 4 and 5 C, the Ti 2 Nb 10 O 29 nanowire can deliver the specific capacity of 251.3, 240.3, 221.8, 205.3, 188.1 and 174.5 mAh g−1, respectively. Furthermore, its cycling performance is superior. The capacity retention of Ti 2 Nb 10 O 29 nanowire is 85.90% after 900 cycles at 12 C, which is obviously superior than that of bulk Ti 2 Nb 10 O 29 (25.16%). Finally, a Ti 2 Nb 10 O 29 /LiCoO 2 full cell is fabricated, which exhibits excellent electrochemical performance, demonstrating its potential for practical application. [ABSTRACT FROM AUTHOR]

Herein, we propose a new anode material, PbNb 2 O 6 , for use in lithium-ion batteries. PbNb 2 O 6 can be synthesized via a simple and traditional solid-state method. The as-prepared powder exhibits an average size distribution of about 0.5 μm. When tested in a lithium-ion cell, the PbNb 2 O 6 electrode can exhibit a charge capacity of 245.2 mAh g−1 at 200 mA g−1, and after 80 cycles, the capacity can retain a charge capacity of 181.4 mAh g−1, showing 0.32% capacity fading per cycle. Furthermore, the capacity of the PbNb 2 O 6 electrode is 223.1 mAh g−1, even when cycled at 1000 mA g−1, and a capacity of 150.7 mAh g−1 is maintained up to 500 cycles. In addition, the lithiation mechanism of PbNb 2 O 6 is investigated via various techniques. Interestingly, PbNb 2 O 6 exhibits high capacity without the contribution of two redox couples of niobium after the initial cycles. Finally, all Results suggest that PbNb 2 O 6 has potential for use as an electrode in lithium-ion batteries. [ABSTRACT FROM AUTHOR]

The GaNb 11 O 29 shows an open Wadsley-Roth shear structure, which is of great benefit to store ions in rechargeable batteries. In this work, we successfully synthesize GaNb 11 O 29 @C via a simple solid-state reaction method combined with carbon-coating modification. As anode for LIBs, the as-synthesized GaNb 11 O 29 @C sample exhibits wonderful electrochemical behaviors. It exhibits high reversible capacity (227.3 mA h g−1), outstanding rate capability (58.91% retention at 700 mA g−1) and excellent long cycle performance (0.036% capacity decay per cycle). The enhancement of diffusion kinetics and rate performance assigns to the increased surface reaction activity and electrical conductivity. The open and stable crystal framework structure guarantees rapid lithium-ion migration, excellent rate performance and long cycle performance. These results tell that GaNb 11 O 29 @C is promising anode material for the application in advanced LIBs. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • AgNb 13 O 33 is synthesized and applied as lithium host for the first time. • AgNb 13 O 33 shows a high storage capacity of 329.4 mAh g−1 above 1.0 V. • Structural evolutions of AgNb 13 O 33 are investigated by in-situ and ex-situ routes. Abstract Anode materials for lithium ion batteries with environmental benignity and great electrochemical performance are greatly desired. In this work, AgNb 13 O 33 with open framework is reported as an anode material for the first time. It shows a triclinic lattice with 4i, 4f sites and 8j sites for lithium storage. At the current density of 100 mA g−1, AgNb 13 O 33 delivers high initial charge/discharge capacity of 329.4/357.8 mAh g−1 with an initial Columbic efficiency of 92.06%. 500 cycles later, it still remains a reversible capacity of 214.2 mAh g−1. Moreover, at a higher rate of 1000 mA g−1, AgNb 13 O 33 still maintains an initial charge capacity of 203 mAh g−1. Ex-situ transmission electron microscope (TEM) and in-situ X-ray diffraction (XRD) tests are performed to study the lithiation and delithiation reactions of AgNb 13 O 33 during the cycling. The reversibility and structural stability of the AgNb 13 O 33 make contributions to its excellent performance. All results show the promising possibility of applying AgNb 13 O 33 as an anode material for lithium ion batteries. [ABSTRACT FROM AUTHOR]

Abstract La 2 (MoO 4) 3 is a kind of transition metal molybdate. It has been proved to be a possible anode material for lithium ion batteries due to the high theoretical capacity. In this work, molybdenum-based La 2 (MoO 4) 3 material is successfully synthesized through a traditional solid-state reaction method. Carbon-coated La 2 (MoO 4) 3 is designed by using glucose as carbon source. By comparing the carbon-coated La 2 (MoO 4) 3 with the carbon-free La 2 (MoO 4) 3 , carbon-coated La 2 (MoO 4) 3 delivers better cyclic stability and rate performance. Carbon-coated La 2 (MoO 4) 3 obtains a reversible charge capacity of 525.9 mA h g−1 at 100 mA g−1 after 100 cycles, corresponding to capacity retention of 75.2%. However, the capacity retention of carbon-free La 2 (MoO 4) 3 is only 33.4%. The results indicate that carbon layer can evidently alleviate the irreversibility of structure and improve capacity retention of La 2 (MoO 4) 3. It demonstrates that the carbon-coated La 2 (MoO 4) 3 composite can be a possible anode candidate for high capacity lithium ion batteries. In addition, in-situ X-ray diffraction investigation (XRD), ex-situ X-ray photoelectron spectroscopy (XPS), and ex-situ transmission electron microscopy (TEM) are employed to analyze the electrochemical behavior during process of cycling. These experimental results indicate that the conversion behavior of La 2 (MoO 4) 3 upon lithiation/delithiation is a process of structural pulverization. Based on that, our work provides guidance for the research of molybdenum-based electrode materials. [ABSTRACT FROM AUTHOR]

Abstract In this study, microsized WNb 60 O 153 bulks and nanostructured WNb 60 O 153 nanowires have been successfully prepared through solid-state reaction and electrospinning technique. Contributed to nanostructured architecture, WNb 60 O 153 nanowires have better performance than microsized WNb 60 O 153 bulks, which is verified by the comparison of galvanostatic charge/discharge experiment, cyclic voltammetry and electrochemical impedance spectroscopy and high-rate analysis. Revealed by electrochemical measurements, WNb 60 O 153 nanowires deliver a higher specific capacity of 174 mAh g−1 at 100 mA g−1 than that of microsized WNb 60 O 153 bulks (153 mAh g−1). Furthermore, it can reach a capacity of 134 mAh g−1 at a higher rate of 1000 mA g−1. It is worth mentioning that the longer cycle life, superior rate performance and higher reversible capacity is contributed to the great lithium-ion diffusion coefficient of WNb 60 O 153 nanowires, which are also higher than other Nb-based compounds and conventional Ti-based anode materials. In addition, in situ X-ray diffraction (XRD) technique is carried out to further elucidate the structural stability and reversibility for the WNb 60 O 153 nanowires. All the evidences prove that electrospun WNb 60 O 153 nanowires can be employed as an alternative electrode material for the lithium-ions batteries (LIBs). [ABSTRACT FROM AUTHOR]

Abstract The tungsten niobium oxides that belong to the well-known Wadsley-Roth shear structure have been already studied as the high-performance anode materials over the past several years since these materials can provide the additional vacuum site for accommodating lithium ions. Now, a novel anode material Nb 18 W 16 O 93 which has a tetragonal tungsten bronze type structure is firstly reported in this paper. This material exhibits the good electrochemical performance. Upon the modification of its surface morphology, the electrochemical performance for Nb 18 W 16 O 93 nanowire has been greatly improved. Nb 18 W 16 O 93 nanowire shows the reversible specific capacity of 195 mAh g−1 when the current density is 100 mA g−1 and it can reach 153 mAh g−1 even at 1000 mA g−1. Meanwhile, the lithiation/delithiation mechanism and its corresponding structural change during the charge and discharge process are also carried out by an in-situ XRD technique. The result shows that Nb 18 W 16 O 93 nanowire has excellent electrochemical reversibility and structural stability. Consequently, Nb 18 W 16 O 93 nanowire can be employed as a novel anode material for lithium ion batteries. Graphical abstract Image 1 Highlights • Nb 18 W 16 O 93 nanowires are prepared by a facile electrospinning method. • Nb 18 W 16 O 93 nanowires show better electrochemical performance than the bulks. • Nb 18 W 16 O 93 nanowires deliver a capacity of 153 mAh g−1 at 1000 mA g−1. • Structural evolution of Nb 18 W 16 O 93 during lithiation is analyzed by in-situ XRD. [ABSTRACT FROM AUTHOR]

To fulfill the requirement for large-scale energy-storage systems, lithium ions batteries have been attracted great attentions. It is necessary to develop the anode material with high rate capability, long cycling life and outstanding safety. Here, N-doped carbon been successfully synthesized and estimated as an anode material for lithium ions batteries. PbLi 2 Ti 6 O 14 is isostructural with SrLi 2 Ti 6 O 14 . After nitrogen-doped carbon coating, PbLi 2 Ti 6 O 14 @NC delivers a high capacity of 143.2 mAh g −1 at a current density of 100 mA g −1 and remains 104.8 mAh g −1 even at 700 mA g −1 . In addition, PbLi 2 Ti 6 O 14 @NC also possesses excellent cyclic stability. The reversible capacity of PbLi 2 Ti 6 O 14 @NC can keep at 99.7 mAh g −1 after 1500 cycles. Such results are also proved by CV tests and EIS measurements. Meanwhile, the lithium storage mechanism of PbLi 2 Ti 6 O 14 @NC is investigated by an in situ XRD technique. It indicates that PbLi 2 Ti 6 O 14 @NC has a stable structural host. These aforementioned results suggest that PbLi 2 Ti 6 O 14 @NC has great potential working as an anode material for lithium ions batteries. [ABSTRACT FROM AUTHOR]

Silver and carbon coated NaTi 2 (PO 4 ) 3 is synthesized via a facile sol-gel method, with polyvinyl alcohol as carbon source and silver nitrate as Ag source. NaTi 2 (PO 4 ) 3 @C/Ag is characterized by XRD, SEM, TEM, EDS and XPS. It can be found that C/Ag composite layer is uniformly coated on the surface of NaTi 2 (PO 4 ) 3 . Compared with the pure NaTi 2 (PO 4 ) 3 , NaTi 2 (PO 4 ) 3 @C/Ag material demonstrates significantly higher rate capability and cycling stability. It can deliver an initial discharge capacity of 126.5 mA h g −1 at a current rate of 2 C with the capacity retention of 94.5% after 100 cycles. It can still deliver an initial discharge capacity of 97.5 mA h g −1 at a current rate of 5 C with a substantial capacity retention of 83.8% after 400 cycles. It is worth mentioning that NaTi 2 (PO 4 ) 3 @C/Ag also exhibits pretty good rate capacity. When the current density ranges from 1 C, 2 C, 5 C, 10 C and finally back to 1 C, NaTi 2 (PO 4 ) 3 @C/Ag electrode still retains a discharge capacity of 84.6 mAh g −1 after 200 cycles at 5 C corresponding to a capacity retention ratio of 83.5%. [ABSTRACT FROM AUTHOR]

Bismuth can alloy with lithium to generate Li 3 Bi with the volumetric capacity of about 3765 mAh cm −3 (386 mAh g −1 ), rendering bismuth-based materials as attractive alloying-type electrode materials for rechargeable batteries. In this work, bismuth-based material Bi 5 Nb 3 O 15 @C is fabricated as anode material through a traditional solid-state reaction with glucose as carbon source. Bi 5 Nb 3 O 15 @C composite is well dispersed, with small particle size of 0.5–2.0 µm. The electrochemical performance of Bi 5 Nb 3 O 15 @C is reinforced by carbon-coated layer as desired. The Bi 5 Nb 3 O 15 @C exhibits a high specific capacity of 338.56 mAh g −1 at a current density of 100 mA g −1 . And it also presents an excellent cycling stability with a capacity of 212.06 mAh g −1 over 100 cycles at 100 mA g −1 . As a comparison, bulk Bi 5 Nb 3 O 15 without carbon-coating only remains 319.62 mAh g −1 at 100 mA g −1 , revealing poor cycle and rate performances. Furthermore, in-situ X-ray diffraction experiments investigate the alloying/dealloying behavior of Bi 5 Nb 3 O 15 @C. These insights will benefit the discovery of novel anode materials for lithium-ion batteries. [ABSTRACT FROM AUTHOR]

The perovskite type oxide Ca 1-x Li x MnO 3-δ (x = 0, 0.02, 0.05, 0.1, 0.2) was prepared by a simple citric acid assisted sol-gel method and was investigated as a possible lithium ion anode material. XRD confirmed that up to 10% calcium element in the CaMnO 3 lattice can be replaced by lithium without the obvious corruption of lattice symmetry or the appearance of the secondary phase. Although pure CaMnO 3 exhibited poor electro-chemical performance, the introduction of lithium has greatly improved the electrochemical performance of Ca 1-x Li x MnO 3-δ . Without carbon coating, the specific capacity of Ca 0.95 Li 0.05 MnO 3-δ within the initial 10 cycles were maintained at ca. 480 mA h g −1 , and after 50 cycles of rate capability testing it was estimated to be around 350 mA h g −1 . The rate capability was also improved significantly. The detailed structural analysis of lithium doping CaMnO 3 revealed that this improvement in the electro-chemical performance mostly likely originated from the extra lithium diffusion path between two 8c sites mediated by the 36 f oxygen vacancy in between. Further EIS and CV tests demonstrated that the lithium doping reduced the charge transfer resistance effectively and increased the lithium ion diffusion coefficient accordingly. Although the performance of lithium doping CaMnO 3 was still inferior to the frequently investigated anode material like Si series or metal oxide series, the further improvement of the material was still possible by further modification of perovskite CaMnO 3 . [ABSTRACT FROM AUTHOR]

KNb 3 O 8 is a kind of layered niobium oxide material. In this work, it is the first time for KNb 3 O 8 to be investigated as anode active material for lithium-ion batteries. KNb 3 O 8 nanowires are successfully prepared by a feasible electro-spinning technique followed with a subsequent heat treatment. The KNb 3 O 8 nanowires exhibit a high charge capacity of 325.2 mA h g −1 at current density of 50 mA g −1 . At a higher rate of 500 mA g −1 , the charge capacity of KNb 3 O 8 nanowires can still be maintained at 155.9 mA h g −1 . In order to further investigate the electrochemical properties of KNb 3 O 8 nanowires, cyclic voltammetry and electrochemical impedance spectroscopy are used to reveal the diffusion kinetics in KNb 3 O 8 . In addition, the electrochemical reversibility of KNb 3 O 8 is also demonstrated by in-situ XRD investigation. All the results indicate that KNb 3 O 8 nanowires may be a potential anode material for rechargeable lithium-ion batteries. [ABSTRACT FROM AUTHOR]

In this work, hierarchical structure Nd 10 W 22 O 81 nanowires are successfully prepared by a feasible electro-spinning technique followed by heat treatment. The structure, morphology and electrochemical characteristics of Nd 10 W 22 O 81 nanowires are investigated and compared with Nd 10 W 22 O 81 particles fabricated by a high temperature solid state reaction. It can be observed that Nd 10 W 22 O 81 nanowires display a “nanoparticle-in-nanowire” architecture. For comparison, solid state formed Nd 10 W 22 O 81 is composed of irregular microsized particles. This hierarchical architecture makes Nd 10 W 22 O 81 nanowires have higher Li-storage capacity and better rate performance, contributing to the larger ion channels and shorter ion transportation pathways. In addition, an in-situ X-ray diffraction investigation is also operated to study the structural evolution and reaction mechanism during the charge/discharge process. All these evidences indicate that hierarchical structure Nd 10 W 22 O 81 nanowires could be a potential high capacity anode material for rechargeable lithium-ion batteries. [ABSTRACT FROM AUTHOR]

A series of SrLi 2-x Na x Ti 6 O 14 (x = 0.0, 0.05, 0.1, 0.15, 0.2) are synthesized and fabricated as lithium storage anodes for rechargeable batteries. Evaluations of the structure and electrochemical performance suggest that proper Li-site substitution by sodium could effectively improve the lithium-ion diffusion coefficient and reduce the particle size of SrLi 2 Ti 6 O 14 . Among them, it is known that the ideal number of sodium doping content is 0.1 per formula. SrLi 1.9 Na 0.1 Ti 6 O 14 reveals better electrochemical performance than bare SrLi 2 Ti 6 O 14 and other doped samples. It shows an initial charge capacity of 168 mAh g −1 at the current density of 100 mA g −1 . After 100 cycles, its reversible capacity is remained at 158 mAh g −1 with excellent capacity retention of 94%. In addition, it also has a good rate performance with the reversible charge capacity of 145 mAh g −1 at 500 mA g −1 , reflecting its excellence as lithium host. [ABSTRACT FROM AUTHOR]

SrLi 2 Ti 6 O 14 @C/N is synthesized by using a solid-state assisted solution method, with polyvinyl pyrrolidone (PVP) as carbon/nitrogen source. The morphology of SrLi 2 Ti 6 O 14 and SrLi 2 Ti 6 O 14 @C/N samples are characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and elemental mappings. According to the results, C/N layer is uniformly coated on the surface of SrLi 2 Ti 6 O 14 . Subsequently, the two samples are analyzed by using electrochemical measurements such as galvanostatic charge/discharge tests, rate performance, cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). SrLi 2 Ti 6 O 14 @C/N (initial charge capacity of 166.41 mAh g −1 ) shows enhanced electrochemical capability compared with SrLi 2 Ti 6 O 14 (156.06 mAh g −1 ). After 150 cycles, SrLi 2 Ti 6 O 14 @C/N can keep a reversible capacity of 156.58 mAh g −1 with only 5.98% capacity loss at 100 mA g −1 . The improvement is due to the increase of electronic conductivity and the decrease in the redox polarization after coating. Moreover, in-situ XRD is also used to investigate the structural stability of SrLi 2 Ti 6 O 14 @C/N. All the results prove that the C/N coating has a positive effect on the electrochemical performance of SrLi 2 Ti 6 O 14 . [ABSTRACT FROM AUTHOR]

A novel anode candidate, Sr(NO 3 ) 2 , has been studied as a potential host material in lithium-ion batteries. The phase composition, particle morphology and lithium storage capability of Sr(NO 3 ) 2 have been thoroughly investigated. Sr(NO 3 ) 2 ,could maintain its reversible charge capacity at 237.3 mA h g −1 along with a high capacity retention of 99.08% at 50 mA g −1 . Furthermore, it shows excellent cycling stability even at higher current density. Cycled at 500 mA g −1 , it can deliver an initial charge capacity of 103.0 mA h g −1 kept at 100.9 mA h g −1 after 500 cycles. Compared with other nitrates that have been reported before, Sr(NO 3 ) 2 proved to have a better capacity retention capability at low and high rates. The high stable electrochemical performance can be ascribed to the absence of crystal water in its structure. Most importantly, commercial Sr(NO 3 ) 2 in this work just needs to be ground uniformly before its use as anode material and does not need complicated pretreatment like doping, carbon coating, calcination or nanocrystallization. [ABSTRACT FROM AUTHOR]

The preparation and characterization of Pb 1- x Ba x Li 2 Ti 6 O 14 ( x = 0, 1/4, 1/2, 3/4, 1) as anode materials for lithium ion batteries are investigated in this research. The structure, morphology and electrochemical properties are compared with each other by changing the Pb/Ba atomic ratio in Pb 1- x Ba x Li 2 Ti 6 O 14 . It can be observed that each sample shows the same orthorhombic structure with Cmca space group. Moreover, it can also be found that the working potential, conductivity, cycling and rate performances of as-received samples gradually change along with the evolution of x in Pb 1- x Ba x Li 2 Ti 6 O 14 ( x = 0, 1/4, 1/2, 3/4, 1). Electrochemical evaluation shows that the operating potential of the as-received sample gradually decreases with increasing x value in Pb 1- x Ba x Li 2 Ti 6 O 14 and its initial charge capacity increases reversely. Moreover, different Pb/Ba atomic ratio also brings different cycling stability for Pb 1- x Ba x Li 2 Ti 6 O 14 . Especially for Pb 3/4 Ba 1/4 Li 2 Ti 6 O 14 , it presents better electrochemical properties than other samples. After 120 cycles, the reversible capacity of Pb 3/4 Ba 1/4 Li 2 Ti 6 O 14 is maintained at 129.7 mAh g −1 with capacity retention of 88.3%. In addition, its electrochemical reversibility is also demonstrated by in-situ X-ray investigation. [ABSTRACT FROM AUTHOR]

In this work, Li 5 Cr 7 Ti 6 O 25 as a new anode material for rechargeable batteries is fabricated through a simple sol-gel method at different calcination temperatures. The X-ray diffraction, scanning electron microscopy, high resolution transmission electron microscopy, charge/discharge curve and cyclic voltammograms are utilized to study the crystal structures, morphologies and electrochemical properties of as-obtained Li 5 Cr 7 Ti 6 O 25 samples. The impact of calcination temperatures on morphologies and electrochemical properties of Li 5 Cr 7 Ti 6 O 25 is discussed in detail. The test result shows that the 800 °C is a proper calcination temperature for Li 5 Cr 7 Ti 6 O 25 with excellent electrochemical properties. Cycled at 200 mA g −1 , it displays a high initial reversible capacity of 146.6 mA h g −1 and retains a considerable capacity of 130.8 mA h g −1 after 300 cycles. Even cycled at large current density of 500 mA g −1 , the initial reversible capacity of 129.6 mA h g −1 with the capacity retention of 88% after 300 cycles is achieved, which is obviously higher than that of Li 5 Cr 7 Ti 6 O 25 prepared at 700 °C (80.5 mA h g −1 and 68%) and 900 °C (98.4 mA h g −1 and 80%). In addition, in-situ XRD analysis reveals that Li 5 Cr 7 Ti 6 O 25 exhibits a reversible structural change during lithiation and delithiation processes. The above prominent electrochemical performance indicates the great potential of the Li 5 Cr 7 Ti 6 O 25 obtained at 800 °C as anode material for rechargeable batteries. [ABSTRACT FROM AUTHOR]

In this work, silver and carbon co-coated SrLi 2 Ti 6 O 14 is synthesized by using a solid-state assisted solution method, with glucose as carbon source and silver nitrate as Ag source. The structural and morphological properties of as-prepared samples are characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM), which confirm that C/Ag composite layer is uniformly coated on the surface of SrLi 2 Ti 6 O 14 . Electrochemical measurements like galvanostatic charge/discharge tests, rate performance, cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) analysis are also undertaken to evaluate and compare the lithium storage capability of SrLi 2 Ti 6 O 14 before and after coating. According to the results, SrLi 2 Ti 6 O 14 @C/Ag presents enhanced electrochemical capability compared with bare material. It can be found that bare SrLi 2 Ti 6 O 14 only delivers the reversible capacity of 140.32 mA h g −1 with capacity retention of 90.7% at 100 mA g −1 after 200 cycles. In contrast, SrLi 2 Ti 6 O 14 @C/Ag presents the reversible capacity of 151.20 mA h g −1 with only 6.7% capacity loss after 200 cycles. The improvement is owing to the increase of electronic conductivity and the decrease in the redox polarization after coating. In order to further investigate the structural stability of SrLi 2 Ti 6 O 14 @C/Ag, in-situ XRD was performed as well. All the results prove that the C/Ag co-coating has positive effect on the electrochemical performance of SrLi 2 Ti 6 O 14 . [ABSTRACT FROM AUTHOR]

Metal doping is an effective way to improve the electrochemical properties of titanates. In this work, Ba-site substituted Ba 0.9 M 0.1 Li 2 Ti 6 O 14 (M = K, Zn, La) are synthesized to fabricate high performance titanate anode for lithium-ion batteries. Electrochemical evaluations reveal that introducing metal doping at Ba-site can result in higher ionic/electronic conductivity. As a result, Ba 0.9 M 0.1 Li 2 Ti 6 O 14 exhibits enhanced lithium storage capability. Especially for Ba 0.9 La 0.1 Li 2 Ti 6 O 14 , it shows the best electrochemical performance with a high reversible charge capacity of 151.3 mAh g −1 and high capacity retention of 94.21% at a current density of 100 mA g −1 . For comparison, the pristine BaLi 2 Ti 6 O 14 only exhibits a reversible charge capacity of 128.5 mAh g −1 with the capacity retention of 80.06% after 100 cycles. Further, the lithium storage process is investigated in detail by in-situ structural observation, which reveals a maximum volume expansion of 1.9% for Ba 0.9 La 0.1 Li 2 Ti 6 O 14 during charge-discharge cycle. It shows that Ba 0.9 La 0.1 Li 2 Ti 6 O 14 is a possible material with high structural reversibility for lithium storage. [ABSTRACT FROM AUTHOR]

In this work, Na 2 Ti 3 O 7 is fabricated as lithium storage material via one-step solid state reaction. Worked as anode material, Na 2 Ti 3 O 7 delivers a stable electrochemical performance with good lithium storage capability. Structural analyses show that Na 2 Ti 3 O 7 anode experiences slight volume change during electrochemical lithiation/delithiation process. Moreover, the reversibility of structural evolution is further demonstrated by in-situ X-ray diffraction technique. All these evidences prove the cycling stability of Na 2 Ti 3 O 7 as lithium storage material. Besides, the kinetic properties of the Li + ion storage in Na 2 Ti 3 O 7 are systematically investigated. The observed results reveal that Na 2 Ti 3 O 7 delivers the lithium ions diffusion coefficient in the range of 10 − 14 –10 − 12 cm 2 s − 1 during the discharge process and 10 − 15 –10 − 12 cm 2 s − 1 during the recharge process. It suggests that Na 2 Ti 3 O 7 has good lithiation/delithiation kinetics in rechargeable batteries. [ABSTRACT FROM AUTHOR]

Using Ag, Pb and Al as dopants, Ba 0.95 M 0.05 Li 2 Ti 6 O 14 is fabricated as advanced anode candidate for repeated lithium storage. Owing to smaller ionic radius, Ag + , Pb 2+ and Al 3+ are successfully introduced into the lattice of BaLi 2 Ti 6 O 14 , which results in the formation of high purity Ba-site doped Ba 0.95 M 0.05 Li 2 Ti 6 O 14 (M = Ag, Pb, Al). Compared with the pristine sample, M-doped BaLi 2 Ti 6 O 14 exhibits higher reversible capacity, better rate capability and superior cyclability. Especially for Ba 0.95 Ag 0.05 Li 2 Ti 6 O 14 , it presents the best electrochemical property among all the as-prepared samples. It can deliver a high reversible charge capacity of 149.1 mAh g −1 after 100 cycles at the current density of 100 mA g −1 with capacity retention of 92.27%. In contrast, BaLi 2 Ti 6 O 14 only provides a lithium storage capacity of 126.9 mAh g −1 with capacity retention of 80.83%. In addition, its high structural stability and electrochemical reversibility are also demonstrated by in-situ X-ray diffraction observation. All these evidences show that metal doping may be an effective method to enhance the lithium storage capability of BaLi 2 Ti 6 O 14 . Especially for Ba 0.95 Ag 0.05 Li 2 Ti 6 O 14 , it can be used as possible anode candidate for rechargeable batteries. [ABSTRACT FROM AUTHOR]

In order to investigate the lithiation-delithiation kinetics in BaLi 2 Ti 6 O 14 anode material, BaLi 2 Ti 6 O 14 is achieved by a solid-state reaction process in this work. The as-prepared BaLi 2 Ti 6 O 14 is high purity titanate and well crystallized with a particle size distribution in the range of 0.5–1.5 μm. Electrochemical analysis shows that BaLi 2 Ti 6 O 14 can deliver a reversible capacity of 126.1 mAh g − 1 at 5C, and the capacity retention is 74.1% after 1000 cycles. In addition, the electrochemical kinetics of BaLi 2 Ti 6 O 14 is investigated by cyclic voltammetry (CV), in-situ electrochemical impedance spectroscopy ( in-situ EIS) and galvanostatic intermittent titration (GITT) techniques. The D Li + values calculated from CVs are located in the range of 10 − 13 –10 − 12 cm 2 s − 1 . For comparison, the average D Li + values received from EIS and GITT methods are located in the range of 10 − 14 –10 − 12 cm 2 s − 1 and 10 − 14 –10 − 11 cm 2 s − 1 , respectively. Although the D Li + differs by several orders of magnitude from different measurement techniques, it still reveals higher value than that of Li 4 Ti 5 O 12 . Owing to the rapid diffusion kinetics of BaLi 2 Ti 6 O 14 , symmetrical structural evolutions can be observed via in-situ X-ray diffraction (XRD) study, which indicates that BaLi 2 Ti 6 O 14 is a promising high-power anode candidate. [ABSTRACT FROM AUTHOR]

As a novel anode material, PbLi 2 Ti 6 O 14 is prepared by a traditional solid state method at a calcination temperature of 900 °C. Structural analysis and electrochemical tests prove that PbLi 2 Ti 6 O 14 possesses a good crystallinity and superior performance. PbLi 2 Ti 6 O 14 , composed of particles with 400 nm in length and 300 nm in width, exhibits an initial charge capacity of 155.1 mAh g −1 at 100 mA g −1 and maintains at 147.9 mAh g −1 after 100 cycles, with capacity retention as high as 95.4%. Especially, the reversible capacity of PbLi 2 Ti 6 O 14 can stabilize at 101.6 mAh g −1 after 1000 cycles at a high current density of 1000 mA g −1 , with capacity retention of 87.5%. Besides, the lithium storage behavior in PbLi 2 Ti 6 O 14 is also studied by various in-situ and ex-situ methods. It is found that the lithiation/delithiation process in PbLi 2 Ti 6 O 14 is a highly reversible reaction. All these results demonstrate that PbLi 2 Ti 6 O 14 may be an impressive anode material in the near future. [ABSTRACT FROM AUTHOR]

In this paper, carbon coated Li 5 Cr 9 Ti 4 O 24 is prepared by using cystine as carbon source, which results in the formation of carbon co-doped with nitrogen/sulfur (CNS) coating layer after pyrolysis. Compared with carbon free Li 5 Cr 9 Ti 4 O 24 , the resulting Li 5 Cr 9 Ti 4 O 24 @CNS exhibits enhanced lithium storage capability. Cycled at 500 mA g −1 , it can be found that carbon free Li 5 Cr 9 Ti 4 O 24 can only deliver the reversible capacity of 97.8 mAh g −1 with capacity retention of 80.7% after 200 cycles. In contrast, Li 5 Cr 9 Ti 4 O 24 @CNS can maintain the reversible lithium storage capacity of 111.4 mAh g −1 with capacity retention of 91.9% after 200 cycles. This improvement is attributed to the introduction of nitrogen/sulfur dual-doped carbon coating layer, which significantly enhances the electronic/ionic conductivity and reduces the charge-transfer resistance of Li 5 Cr 9 Ti 4 O 24 . Hence, Li 5 Cr 9 Ti 4 O 24 @CNS may be a promising anode candidate for lithium-ion batteries. [ABSTRACT FROM AUTHOR]

With the Pb doping content at Sr-site increasing, a series of Sr 1-x Pb x Li 2 Ti 6 O 14 (x = 0, 0.25, 0.50, 0.75, 1.0) are synthesized by a simple solid-state reaction. It is found that the reversible capacity and rate capability experience a parabolic course from SrLi 2 Ti 6 O 14 to PbLi 2 Ti 6 O 14 . Among all the as-prepared samples, Sr 0.5 Pb 0.5 Li 2 Ti 6 O 14 shows the best cycling and rate properties. It delivers an initial charge capacity of 163.2 mAh g −1 at 100 mA g −1 with the capacity retention of 96.08% after 100 cycles. In addition, it can also deliver a reversible capacity of 141.8 mAh g −1 at 700 mA g −1 . The superior electrochemical properties of Sr 0.5 Pb 0.5 Li 2 Ti 6 O 14 are attributed to the reduced charge transfer resistance and increased lithium-ion diffusion coefficient after doping. Besides, in-situ X-ray diffraction is also performed to investigate the lithium-ion insertion/extraction behaviors of SrLi 2 Ti 6 O 14 , Sr 0.5 Pb 0.5 Li 2 Ti 6 O 14 and PbLi 2 Ti 6 O 14 . The observed results confirm that Sr 0.5 Pb 0.5 Li 2 Ti 6 O 14 has good structural stability and reversibility for repeated lithium storage. [ABSTRACT FROM AUTHOR]

In this work, a novel lithium storage material Li 5 Cr 9 Ti 4 O 24 is reported as anode material for rechargeable lithium-ion batteries. We prepare Li 5 Cr 9 Ti 4 O 24 by two different routes, sol-gel method and solid state reaction. Li 5 Cr 9 Ti 4 O 24 nanocrystalline can be achieved by sol-gel method, while solid state reaction delivers micro-sized product. Electrochemical results show that Li 5 Cr 9 Ti 4 O 24 nanocrystalline exhibits reduced charge transfer resistance, decreased redox polarization and improved lithium-ion diffusion coefficient compared with micro-sized product. As a result, Li 5 Cr 9 Ti 4 O 24 nanocrystalline shows excellent lithium storage capability with 100% capacity retention after 200 cycles. Cycled at 600 mA g −1 , it still can deliver a charge specific capacity of 110.3 mAh g −1 . In contrast, micro-sized Li 5 Cr 9 Ti 4 O 24 only reveals the reversible capacity of 66.8 mAh g −1 at the same current density. In addition, Li 5 Cr 9 Ti 4 O 24 nanocrystalline also shows outstanding structural stability for repeated lithium storage. In-situ structural observation reveals that the entire volume expansion of Li 5 Cr 9 Ti 4 O 24 is only 0.62% during the charge/discharge process, which is similar with the zero-strain Li 4 Ti 5 O 12 . Therefore, Li 5 Cr 9 Ti 4 O 24 nanocrystalline can be used as high performance anode material for lithium-ion batteries. [ABSTRACT FROM AUTHOR]

Via Sr-site substitution, a series of Sr 0.95 M 0.05 Li 2 Ti 6 O 14 (M z+ = Na + , Cu 2+ , In 3+ ) are prepared as anode materials for lithium-ion batteries. It is found that the introduction of Na + , Cu 2+ or In 3+ into the crystal lattice can reduce the charge-transfer resistance and improve the lithium-ion diffusion coefficient of SrLi 2 Ti 6 O 14 . Especially for In 3+ -doping, it exhibits more obvious effect on these improvements. Furthermore, the substitution of Sr 2+ by In 3+ can also enhance the electronic conductivity via inducing a reduction of an equivalent number of Ti cations from Ti 4+ to Ti 3+ . As a result, Sr 0.95 In 0.05 Li 2 Ti 6 O 14 shows the best cycle and rate properties among all as-prepared samples. In addition, in-situ observation also proves that Sr 0.95 In 0.05 Li 2 Ti 6 O 14 is a zero-strain lithium storage compound during charge/discharge process. As a result, it delivers a lithium storage capacity of 136.4 mAh g −1 at 200 mA g −1 , 126.3 mAh g −1 at 400 mA g −1 and 121.0 mAh g −1 at 600 mA g −1 . In contrast, SrLi 2 Ti 6 O 14 only presents a charge capacity of 138.3 mAh g −1 at 200 mA g −1 , 120.3 mAh g −1 at 400 mA g −1 and 111.3 mAh g −1 at 600 mA g −1 . Therefore, In 3+ -doping is an effective method to enhance the electrochemical properties of SrLi 2 Ti 6 O 14 . [ABSTRACT FROM AUTHOR]

A series of Li 3− x Na x V 2 (PO 4 ) 3 /C (0≤ x ≤3) materials are successfully prepared by a simple solid-state reaction method and used for the first time as anode materials for Na-ion batteries. Powder X-ray diffraction (XRD) results show that the phase structures of Li 3− x Na x V 2 (PO 4 ) 3 /C evolve along with the change of Li/Na atomic ratio (0≤x≤3). With increasing x in Li 3− x Na x V 2 (PO 4 ) 3 /C from 0.0 to 3.0, the main phase in as-prepared sample transforms from monoclinic Li 3 V 2 (PO 4 ) 3 to rhombohedral Li 3 V 2 (PO 4 ) 3 , and finally to rhombohedral Na 3 V 2 (PO 4 ) 3 , which results in different sodium storage behavior and performance between Li 3− x Na x V 2 (PO 4 ) 3 /C (0≤ x ≤3) materials. Electrochemical results show that Li 3− x Na x V 2 (PO 4 ) 3 /C ( x =0.0, 0.5, 1.0, 1.5, 2.0, 2.5 and 3.0) can deliver the initial charge capacities of 21.1, 35.9, 33.8, 41.7, 43.3, 43.9 and 47.7 mAh g −1 at a current density of 10 mA g −1 , respectively. After 45 cycles, the reversible capacities can be kept at 16.9, 45.1, 32.6, 44.6, 43.7, 37.8 and 27.3 mAh g −1 for Li 3 V 2 (PO 4 ) 3 /C, Li 2.5 Na 0.5 V 2 (PO 4 ) 3 /C, Li 2 NaV 2 (PO 4 ) 3 /C, Li 1.5 Na 1.5 V 2 (PO 4 ) 3 /C, LiNa 2 V 2 (PO 4 ) 3 /C, Li 0.5 Na 2.5 V 2 (PO 4 ) 3 /C and Na 3 V 2 (PO 4 ) 3 /C, respectively. Furthermore, the structural reversibility of Li 3− x Na x V 2 (PO 4 ) 3 /C ( x =1.0, 2.0, and 3.0) is also observed by in-situ XRD observation during sodiation/de-sodiation process. All these observed evidences indicate that only some of Li 3− x Na x V 2 (PO 4 ) 3 /C (0≤ x ≤3) can be used as possible sodium storage materials. [ABSTRACT FROM AUTHOR]

In this paper, a series of Li 3-x Na x V 2 (PO 4 ) 3 (0 ≤ x ≤ 3) are prepared by a solid state reaction and systematically evaluated as anode materials for lithium-ion batteries. Structural analysis shows that the phase structure of Li 3-x Na x V 2 (PO 4 ) 3 changes along with the evolution of Na content. Charge-discharge tests exhibit that Li 3 V 2 (PO 4 ) 3 shows the highest initial charge specific capacity as high as 88.3 mAh g −1 among all the seven samples, and the reversible capacity is kept at 68.3 mAh g −1 after 45 cycles, corresponding to 77.3% of the initial charge capacity. With increasing of Na content in Li 3-x Na x V 2 (PO 4 ) 3 , the as-obtained sample show poorer lithium storage capability than Li 3 V 2 (PO 4 ) 3 . As a result, Na 3 V 2 (PO 4 ) 3 shows the inferior cycling performance than other Li 3-x Na x V 2 (PO 4 ) 3 . It can only deliver a reversible capacity of 20.9 mAh g −1 after 45 cycles, corresponding to 45.9% of the initial charge capacity. In-situ X-ray diffraction observations demonstrate that the poor electrochemical property of Na 3 V 2 (PO 4 ) 3 anode is due to the irreversible structural evolution during charge-discharge process. Therefore, reducing the Na 3 V 2 (PO 4 ) 3 phase in as-obtained sample is a feasible route to improve the lithium storage capability of Li 3-x Na x V 2 (PO 4 ) 3 . [ABSTRACT FROM AUTHOR]

Due to the characteristics of an electronic insulator, Na 2 Li 2 Ti 6 O 14 always suffers from low electronic conductivity as anode material for lithium storage. Via Ag coating, Na 2 Li 2 Ti 6 O 14 @Ag is fabricated, which has higher electronic conductivity than bare Na 2 Li 2 Ti 6 O 14 . Enhancing the Ag coating content from 0.0 to 10.0 wt%, the surface of Na 2 Li 2 Ti 6 O 14 is gradually deposited by Ag nanoparticles. At 6.0 wt%, a continuous Ag conductive layer is formed on Na 2 Li 2 Ti 6 O 14 . While, particle growth and aggregation take place when the Ag coating content reaches 10.0 wt%. As a result, Na 2 Li 2 Ti 6 O 14 @6.0 wt% Ag displays better cycle and rate properties than other samples. It can deliver a lithium storage capacity of 131.4 mAh g −1 at 100 mA g −1 , 124.9 mAh g −1 at 150 mA g −1 , 119.1 mAh g −1 at 200 mA g −1 , 115.8 mAh g −1 at 250 mA g −1 , 111.9 mAh g −1 at 300 mA g −1 and 109.4 mAh g −1 at 350 mA g −1 , respectively. [ABSTRACT FROM AUTHOR]

In this work, Na 2 Ti 6 O 13 nanorods are prepared by a traditional solid state reaction and reported as anode materials for advanced lithium-ion batteries. The effect of calcining temperature on the size and electrochemical behavior of nanorodes is thoroughly described and compared within the temperature range of 800-1000 °C. It can be found that the size of nanorodes increases with the enhancing of calcining temperature. At 1000 °C, Na 2 Ti 6 O 13 nanorodes melt into big bulks, which exhibit poor ionic conductivity and low lithium storage capacity. Although Na 2 Ti 6 O 13 nanorodes with smaller size can be formed at 800 °C, its capacity retention is poor. In contrast, Na 2 Ti 6 O 13 nanorodes obtained at 900 °C reveal high reversible capacity, rapid lithium ion diffusion behavior and outstanding rate property. In-situ and ex-situ analyses reveal that the structural evolution of Na 2 Ti 6 O 13 during lithiation and delithiation process is quasi-reversible, which ensures the excellent electrochemical performance of Na 2 Ti 6 O 13 nanorods for repeated lithium storage. [ABSTRACT FROM AUTHOR]

In this work, Na 2 Li 2 Ti 6 O 14 and its Li-site substitution Na 2 Li 1.9 M 0.1 Ti 6 O 14 (M n+ = Na + , Mg 2+ , Cr 3+ , Ti 4+ , V 5+ ) samples are synthesized by a simple solid state reaction route and evaluated as anode materials for lithium-ion batteries. Their crystal structures and ion doping behaviors are described and verified by Rietveld refinement. Electrochemical results exhibit that Na + , Mg 2+ and Cr 3+ dopings can effectively improve the lithium storage capability of Na 2 Li 2 Ti 6 O 14 . Especially for Na 2 Li 1.9 Cr 0.1 Ti 6 O 14 , it shows the best cycling and rate properties among all the as-prepared samples, with a cycling reversible capacity of 262.2 mAh g −1 at 100 mA g −1 and a rate charge capacity of 233.3 mAh g −1 at 700 mA g −1 . The enhanced electrochemical properties are contributed to the reduced particle size, decreased charge transfer resistance and improved ionic diffusion coefficient of Na 2 Li 2 Ti 6 O 14 via Cr 3+ doping. Furthermore, the zero-strain characteristic should also be responsible for the outstanding lithium storage capability of Na 2 Li 1.9 Cr 0.1 Ti 6 O 14 . Besides, in-situ X-ray diffraction also reveals that Na 2 Li 1.9 Cr 0.1 Ti 6 O 14 has high structural stability and reversibility during charge–discharge process. Therefore, Na 2 Li 1.9 Cr 0.1 Ti 6 O 14 may be a probable high performance anode material for lithium-ion batteries. [ABSTRACT FROM AUTHOR]

Li 2 Na 2 Ti 6 O 14 and its Ti-site substitution Li 2 Na 2 Ti 5.9 M 0.1 O 14 (M = Al, Zr, V) are prepared by a solid-state reaction method and used as anode materials for lithium-ion batteries. It is found that metal doping can effectively enhance the electronic conductivity and ionic diffusion coefficient of Li 2 Na 2 Ti 6 O 14 . Especially for Li 2 Na 2 Ti 5.9 Al 0.1 O 14 , it reveals the highest electronic conductivity (1.02 × 10 −9 S cm −1 ) and lithium ion diffusion coefficient (8.38 × 10 −15 cm 2 s −1 ) among all the samples. As a result, Li 2 Na 2 Ti 5.9 Al 0.1 O 14 reveals the best electrochemical performance. It can deliver a charge specific capacity of 270.3 mAh g −1 at 50 mA g −1 . Even cycled at 1000 mA g −1 , it still can present a charge capacity of 180.7 mAh g −1 . All these enhanced lithium storage capabilities of Li 2 Na 2 Ti 5.9 Al 0.1 O 14 should be attributed to the increased electronic/ionic conductivities and the decreased charge transfer resistance induced by Al doping. Besides, in-situ X-ray diffraction observation also confirms that the structural change of Li 2 Na 2 Ti 5.9 Al 0.1 O 14 is highly reversible process for lithium storage. [ABSTRACT FROM AUTHOR]

SrLi 2 Ti 6 O 14 is a novel lithium storage host material. In this work, a series of SrLi 2 Ti 6 O 14 are prepared by a simple solid state reaction method at different calcination temperatures and then used as probable host materials for lithium storage. Evaluations of the electrochemical performance in combination with structural analysis suggest that the calcination temperature dramatically affects the phase purity, particle size and lithium storage capability of SrLi 2 Ti 6 O 14 . It can be found that the optimum calcination temperature for SrLi 2 Ti 6 O 14 is 950 °C. SrLi 2 Ti 6 O 14 formed at 950 °C exhibits the highest lithium storage capacity, the fastest lithium-ion diffusion behavior, the best cycling and rate properties among all the five samples. It reveals an initial charge capacity of 170.3 mAh g −1 at the current density of 50 mA g −1 . After 50 cycles, the reversible capacity can be kept at 155.9 mAh g −1 with excellent capacity retention of 91.9%. Even cycled at 300 mA g −1 , it still can deliver a charge capacity of 141.6 mAh g −1 . In contrast, the SrLi 2 Ti 6 O 14 formed at 800 °C can only deliver a reversible capacity of 71.5 mAh g −1 at 300 mA g −1 . Besides, the electrochemical reaction mechanism between SrLi 2 Ti 6 O 14 and Li is thoroughly investigated by various in-situ and ex-situ techniques. It is found that SrLi 2 Ti 6 O 14 is a zero-strain compound for lithium storage. For the lithium storage process, Rietveld refinement results reveal that lithium ions occupy the 8c, 4b and 4a vacant sites in turns during the discharge process, and the stable framework ensures the structural reversibility during repeated cycles, which is important for SrLi 2 Ti 6 O 14 as a probable host material for high performance lithium-ion batteries. [ABSTRACT FROM AUTHOR]

In this work, novel nano/micro structure nitrates are reported for sodium storage for the first time. By using a facile solution route, carbon black (CB) and carbon nanotube (CNT) are introduced to incorporate with copper nitrate hydrate (Cu(NO 3 ) 2 ·2.5H 2 O) to form Cu(NO 3 ) 2 ·2.5H 2 O/CB and Cu(NO 3 ) 2 ·2.5H 2 O/CNT composites for high capacity sodium storage, respectively. Morphological and structural investigations show that CB or CNT coating does not obviously change the particle size and phase composition of Cu(NO 3 ) 2 ·2.5H 2 O, while, the electrochemical performance of Cu(NO 3 ) 2 ·2.5H 2 O is significantly improved by introducing CB or CNT as a conductive network. Moreover, carbon matrix can also provide a buffer for suppressing particle pulverization during sodiation/desodiation process. Especially for CNT, it builds a three-dimensional conductive network for active particles. As a result, Cu(NO 3 ) 2 ·2.5H 2 O/CNT exhibits higher reversible specific capacity and better cycling stability than bare Cu(NO 3 ) 2 ·2.5H 2 O and Cu(NO 3 ) 2 ·2.5H 2 O/CB. After 30 cycles, Cu(NO 3 ) 2 ·2.5H 2 O/CNT can deliver a reversible charge capacity of 140.7 mAh g − 1 at a current density of 50 mA g − 1 . This result demonstrates that CNT reinforced Cu(NO 3 ) 2 ·2.5H 2 O composite could be a probable anode material for sodium-ion batteries. Besides, the probable sodium storage mechanism in Cu(NO 3 ) 2 ·2.5H 2 O is also proposed by using various ex-situ analytical methods. [ABSTRACT FROM AUTHOR]

Na 2 Li 2 Ti 6 O 14 is synthesized by a simple solid state method between 500 and 900 °C. It is found that pure Na 2 Li 2 Ti 6 O 14 is only formed at 800 °C or above. The tap density of as-prepared Na 2 Li 2 Ti 6 O 14 is about 1.52 g cm −3 . Particle morphology analysis shows that the size of Na 2 Li 2 Ti 6 O 14 gradually increases with the increase of sintering temperature. Calcined at 900 °C, Na 2 Li 2 Ti 6 O 14 shows slight particle aggregation and melting. As a result, Na 2 Li 2 Ti 6 O 14 formed at 800 °C reveals higher electrochemical activity than the sample obtained at 900 °C. Therefore, the suitable preparation temperature for Na 2 Li 2 Ti 6 O 14 by solid state reaction is 800 °C. Charge–discharge results show that Na 2 Li 2 Ti 6 O 14 prepared at 800 °C can deliver a reversible capacity of 89.9 mAh g −1 at 100 mA g −1 , 81.3 mAh g −1 at 200 mA g −1 , 75.2 mAh g −1 at 300 mA g −1 , 69.6 mAh g −1 at 400 mA g −1 and 65.5 mAh g −1 at 500 mA g −1 . Besides, the lithium storage mechanism in Na 2 Li 2 Ti 6 O 14 is also studied by various in-situ and ex-situ methods, which prove that the structural evolution is highly reversible for Na 2 Li 2 Ti 6 O 14 during lithiation/delithiation process. [ABSTRACT FROM AUTHOR]

By using carbon nanotube (CNT), Pb(NO 3 ) 2 /CNT is fabricated by a solution method and investigated for the first time as probable anode materials for sodium-ion batteries. For comparison, pristine Pb(NO 3 ) 2 and Pb(NO 3 ) 2 /carbon black (CB) are also prepared by the same solution method. Electrochemical results show that Pb(NO 3 ) 2 /CNT can deliver an initial charge capacity of 285.7 mA h g −1 , which is much higher than the pristine Pb(NO 3 ) 2 (203.8 mA h g −1 ) and Pb(NO 3 ) 2 /CB (252.1 mA h g −1 ). After 50 cycles, Pb(NO 3 ) 2 /CNT still maintains a sodium storage capacity of 112.9 mA h g −1 . Furthermore, it also shows outstanding rate property compared with other two samples. All the enhanced results can be attributed to the introduction of crosslinked CNTs in the composite, which provide good electronic conductive pathways interconnecting Pb(NO 3 ) 2 particles and maintain the whole nano-micro structure upon repeated cycles. The reaction mechanism of Pb(NO 3 ) 2 with Na is studied by various in-situ and ex-situ techniques. It can be found that Pb(NO 3 ) 2 /CNT irreversibly decomposes into Pb, NaNO 3 , NaN 3 , and Na 2 O, and then the resulting metal Pb will further react with Na to form Na x Pb alloys during the initial discharge process. In contrast, the charge process is mainly associated with the de-alloying reaction of Na x Pb to the formation of Pb. [ABSTRACT FROM AUTHOR]

PbSbO 2 Cl@C nanocomposite is synthesized via a simple one-step hydrothermal route and tested as a lithium storage material. The as-prepared PbSbO 2 Cl@C nanocomposite presents a core–shell structure composing of PbSbO 2 Cl nanoparticles (20–200 nm) as inner core and amorphous carbon coating layer as outer shell. The core–shell structure of PbSbO 2 Cl@C can restrict the structural breakdown of nanocomposite with carbon coating layer on the surface, and avoid the pulverization and aggregation of PbSbO 2 Cl nanoparticles during repeated lithiation–delithiation process. Moreover, the induction of carbon layer can also improve the electronic conductivity and reduce the charge transfer resistance of PbSbO 2 Cl. As a result, PbSbO 2 Cl@C nanocomposite exhibits improved electrochemical performances compared to pristine PbSbO 2 Cl. [ABSTRACT FROM AUTHOR]

A series of Li 2 BaTi 6 O 14 samples are synthesized by a traditional solid-state method by calcining at different temperatures from 800 to 1000 °C. Structural analysis and electrochemical evaluation suggest that the optimum calcining temperature for Li 2 BaTi 6 O 14 is 950 °C. The Li 2 BaTi 6 O 14 calcined at 950 °C exhibits a high purity phase with an excellent reversible capacity of 145.7 mAh g −1 for the first cycle at a current density of 50 mA g −1 . After 50 cycles, the reversible capacity can be maintained at 137.7 mAh g −1 , with the capacity retention of 94.51%. Moreover, this sample also shows outstanding rate property with a high reversible capacity of 118 mAh g −1 at 300 mA g −1 . The excellent electrochemical performance is attributed to the stable lithium storage host structure, decreased electrochemical resistance and improved lithium-ion diffusion coefficient. In-situ and ex-situ structure analysis shows that the electrochemical reaction of Li 2 BaTi 6 O 14 with Li is a highly reversible lithiation–delithiation process. Therefore, Li 2 BaTi 6 O 14 may be a promising alternative anode material for lithium-ion batteries. [ABSTRACT FROM AUTHOR]

Using carbon nanotube (CNT) as conductive additive, (NH 4 ) 2 Ce(NO 3 ) 5 ·4H 2 O/CNT is prepared from (NH 4 ) 2 Ce(NO 3 ) 6 by a facile solution method and used as high capacity anode material for the first time. Morphology and structure investigation shows that (NH 4 ) 2 Ce(NO 3 ) 5 ·4H 2 O/CNT exhibits high purity phase with particle size of 0.1–1.0 μm. In the composite, CNT provides a three-dimensional conductive network for electron transportation and can maintain the whole structure upon electrochemical cycles. For comparison, (NH 4 ) 2 Ce(NO 3 ) 5 ·4H 2 O and (NH 4 ) 2 Ce(NO 3 ) 5 ·4H 2 O/carbon black ((NH 4 ) 2 Ce(NO 3 ) 5 ·4H 2 O/CB) are also prepared by the same method. Impurity phase of (NH 4 ) 3 Ce 2 (NO 3 ) 9 can be detected in both (NH 4 ) 2 Ce(NO 3 ) 5 ·4H 2 O and (NH 4 ) 2 Ce(NO 3 ) 5 ·4H 2 O/CB. Electrochemical testing results reveals that (NH 4 ) 2 Ce(NO 3 ) 5 ·4H 2 O/CNT shows lower initial discharge capacity (1683.6 mAh g −1 ) than (NH 4 ) 2 Ce(NO 3 ) 5 ·4H 2 O (1972.8 mAh g −1 ) in the first cycle. However, (NH 4 ) 2 Ce(NO 3 ) 5 ·4H 2 O/CNT shows the highest reversible capacity among all the three samples. After 30 cycles, it can deliver a reversible capacity of 818.5 mAh g −1 , which is much higher than that of (NH 4 ) 2 Ce(NO 3 ) 5 ·4H 2 O (50.6 mAh g −1 ) and (NH 4 ) 2 Ce(NO 3 ) 5 ·4H 2 O/CB (208.8 mAh g −1 ). It suggests that the enhanced electrochemical properties are attributed to the introduction of CNT, which improves the electronic conductivity and structural stability during repeated cycles. [ABSTRACT FROM AUTHOR]

A series of Na x Li 4−x Ti 6 O 14 (0 ≤ x ≤ 4) are prepared by solid-state method and their structures, morphologies and electrochemical properties are compared by changing the Na/Li atomic ratio. It can be found that two single-phase samples of Na 2 Li 2 Ti 6 O 14 and Na 4 Ti 6 O 14 and three multi-phase samples of Li 4 Ti 6 O 14 (Li 4 Ti 5 O 12 /TiO 2 ), NaLi 3 Ti 6 O 14 (Na 2 Li 2 Ti 6 O 14 /Li 4 Ti 5 O 12 /TiO 2 ) and Na 3 LiTi 6 O 14 (Na 2 Li 2 Ti 6 O 14 /Na 2 Ti 3 O 7 ) can be formed by using a stoichiometric ratio of starting materials based on the formula of Na x Li 4−x Ti 6 O 14 . Besides, different Na/Li atomic ratios in Na x Li 4−x Ti 6 O 14 also induce the morphology evolution shifting from round-shape to polyhedron-shape, and then to square-shape with the increase of Na content. Electrochemical tests show that Li 4 Ti 6 O 14 delivers the highest charge capacities of 116 mAh g −1 at 100 mA g −1 , 91.5 mAh g −1 at 200 mA g −1 , 77.5 mAh g −1 at 300 mA g −1 and 66.9 mAh g −1 at 400 mA g −1 among five samples. For comparison, Na 4 Ti 6 O 14 only reveals the reversible capacities of 38.6 mAh g −1 at 100 mA g −1 , 30.2 mAh g −1 at 200 mA g −1 , 24.8 mAh g −1 at 300 mA g −1 and 20.9 mAh g −1 at 400 mA g −1 . It suggests that Li 4 Ti 6 O 14 is the most potential lithium storage material among all the Na x Li 4−x Ti 6 O 14 samples. [ABSTRACT FROM AUTHOR]

To improve the electrochemical performance of Na 2 Li 2 Ti 6 O 14 , carbon black (CB), graphene (GN) and carbon nanotube (CNT) are introduced to fabricate high conductive Na 2 Li 2 Ti 6 O 14 /CB, Na 2 Li 2 Ti 6 O 14 /GN, Na 2 Li 2 Ti 6 O 14 /CNT and Na 2 Li 2 Ti 6 O 14 /CB/GN/CNT by a solid state method. It can be found that only CNT forms a complete three-dimensional conductive network which embeds the randomly distributed Na 2 Li 2 Ti 6 O 14 particles, leading to an improvement of electronic conductivity. The results of cyclic voltammetry, electrochemical impedance spectroscopy and charge–discharge tests reveal that Na 2 Li 2 Ti 6 O 14 /CNT obtains the lowest redox polarization and the highest peak current among all the five samples. As a result, Na 2 Li 2 Ti 6 O 14 /CNT shows the best cycling and rate performances among all the five samples. It reveals a charge capacity of 111.4 mAh g −1 at 100 mA g −1 , 110 mAh g −1 at 200 mA g −1 , 103.9 mAh g −1 at 300 mA g −1 and 98.9 mAh g −1 at 400 mA g −1 . For comparison, bare Na 2 Li 2 Ti 6 O 14 only displays a charge capacity of 89.9 mAh g −1 at 100 mA g −1 , 79.7 mAh g −1 at 200 mA g −1 , 73.7 mAh g −1 at 300 mA g −1 and 69.4 mAh g −1 at 400 mA g −1 . It indicates that the introduction of CNT is more effective to improve the performance of Na 2 Li 2 Ti 6 O 14 than CB, GN and CB/GN/CNT. [ABSTRACT FROM AUTHOR]

H 3 NOHCl is used for the first time as anode material for lithium-ion batteries. Electrochemical results show that H 3 NOHCl with particle size of 4–12 μm can deliver an initial charge capacity of 1018.6 mAh g −1 , which is much higher than commercial graphite. After 30 cycles, the reversible capacity can be kept at 676.1 mAh g −1 at 50 mA g −1 . Up to 50 cycles, H 3 NOHCl still maintains a lithium storage capacity of 368.9 mAh g −1 . Even cycled at 200 mA g −1 , H 3 NOHCl can deliver a charge capacity of 715.7 mAh g −1 . It suggests that H 3 NOHCl has high lithium storage capacity, excellent cycling stability and outstanding rate performance. Besides, the electrochemical reaction between H 3 NOHCl and Li is also investigated by various ex-situ techniques. It can be found that H 3 NOHCl irreversibly decomposes into Li 3 N and LiCl during the initial discharge process and LiNO 2 can be formed after a reverse charge process. [ABSTRACT FROM AUTHOR]

By using multi-wall carbon nanotube (MWCNT), a well-dispersed composite of Cu(NO 3 ) 2 · xH 2 O/MWCNT (2.5

Copper nitrate hydrate (Cu(NO3)2·2.5H2O) exhibits superior high lithium storage capacity (2285 mAh g−1) as anode material for lithium-ion batteries. The structural transformation and lithium storage mechanism of Cu(NO3)2·2.5H2O are thoroughly studied by various advanced analytical techniques. It is found that the lithium storage process of Cu(NO3)2·2.5H2O is associated with a quasi-reversible electrochemical conversion reaction. During the discharge process, the electrochemical reaction of Cu(NO3)2·2.5H2O with lithium results in the formation of Cu, LiNO3, Li3N, Li2O and H2O. In the reverse charge process, Cu(NO3)2 can be generated by a conversion reaction. As a result, Cu(NO3)2·2.5H2O shows the reversible charge capacities of 1632.1 mAh g−1 in 0.0–3.4 V and 689.1 mAh g−1 in 1.0–3.4 V, respectively. [ABSTRACT FROM AUTHOR]

Abstract: Core–shell Li2Na2Ti6O14@Cu/C is prepared by a preliminary formation of Li2Na2Ti6O14 by solid state reaction and a following coating process with Cu/C layer by thermal decomposition. The amorphous Cu/C coating layer reveals a thickness of 5 nm on the surface of Li2Na2Ti6O14, which improves the electronic conductivity and charge transfer rate of active materials. As a result, Li2Na2Ti6O14@Cu/C shows lower electrochemical polarization and quicker kinetic behavior compared to bare Li2Na2Ti6O14. Cycled at 50 mA g−1, Li2Na2Ti6O14@Cu/C can deliver a reversible capacity of 120.3 mAh g−1 after 50 cycles, which is much higher than the value of 96.8 mAh g−1 obtained by Li2Na2Ti6O14. Even kept at 400 mA g−1, a reversible lithium storage capacity of 76.3 mAh g−1 can be delivered by Li2Na2Ti6O14@Cu/C. The improved electrochemical properties of Li2Na2Ti6O14 are attributed to the electronic conductive Cu/C coating layer on the surface. [Copyright &y& Elsevier]

Abstract: In this paper, Cr2O3@Ag2O composite is prepared by a simple chemical decomposition method and then used as anode material for lithium-ion batteries. It can be found that Ag2O coating can effectively enhance the electrochemical property of Cr2O3. For bare Cr2O3, a discharge capacity of 1123.5mAhg−1 can be delivered during the first lithiation process. After Ag2O coating, the initial discharge capacity of Cr2O3@Ag2O is improved to 1357.8mAhg−1. The reversible lithium storage capacity of Cr2O3@Ag2O is 694.5mAhg−1 after 80 cycles with a capacity retention of 98.5%, which is also much higher than that (139.6mAhg−1, 21.7%) of Cr2O3. It indicates that Cr2O3@Ag2O shows good cycling stability with high reversible capacity as anode material for lithium-ion batteries. [Copyright &y& Elsevier]

[Bi6O4](OH)4(NO3)6·4H2O, [Bi6O4](OH)4(NO3)6·H2O and [Bi6O4](OH)4(NO3)6·H2O/C, derivated from Bi(NO3)3·5H2O, are firstly investigated for the electrochemical activity as anode materials for lithium-ion batteries. Electrochemical results show that [Bi6O4](OH)4(NO3)6·4H2O can deliver a higher initial discharge specific capacity (2792.9 mAh g−1) than that of [Bi6O4](OH)4(NO3)6·H2O (832.2 mAh g−1) and [Bi6O4](OH)4(NO3)6·H2O/C (1169.3 mAh g−1). However, the capacity retention (60.3%) and reversible specific capacity (365.5 mAh g−1) of [Bi6O4](OH)4(NO3)6·H2O/C are much higher than those of [Bi6O4](OH)4(NO3)6·H2O (4.75% and 39.6 mAh g−1) and [Bi6O4](OH)4(NO3)6·4H2O (15.9% and 289.4 mAh g−1) in the first 30 cycles. The improved electrochemical properties are attributed to the decrease of crystal water in the structure and the introduction of carbon black as conductive additive and volume change buffer. The reaction mechanism of [Bi6O4](OH)4(NO3)6·H2O/C with Li is also studied in detail by using various ex-situ and in-situ techniques during the initial charge-discharge cycle. It can be found that the electrochemical reaction of [Bi6O4](OH)4(NO3)6·H2O with Li leads to the preliminary formation of metal Bi, LiNO3, LiOH, Li2O and H2O and then the alloying reaction to form Li–Bi alloys. [ABSTRACT FROM AUTHOR]

Highlights: [•] Li4Ti5O12@C is prepared by a facile carbon coating strategy. [•] Amorphous carbon coating layer shows a thickness of 4–6nm. [•] Li4Ti5O12@C delivers a capacity of 160.6mAhg−1 at 20mAg−1 in 1.0–2.0V. [•] Li4Ti5O12@C displays a capacity of 205.1mAhg−1 at 1500mAg−1 in 0.0–2.0V. [ABSTRACT FROM AUTHOR]