Search

Within the academic and industrial communities there has been an increasing desire to better understand the sustainability of producing vehicles that contain embedded electrochemical energy storage. Underpinning a number of studies that evaluate different circular economy strategies for the electric vehicle (EV) or Hybrid electric vehicle (HEV) battery system are implicit assumptions about the retained capacity or State of Health (SOH) of the battery. International standards and best-practice guides exist that address the performance evaluation of both EV and HEV battery systems. However, a common theme is that the test duration can be excessive and last for a number of hours. The aim of this research is to assess whether energy capacity measurements of Li-ion cells can be accelerated; reducing the test duration to a value that may facilitate further EOL options. Experimental results are presented that highlight it is possible to significantly reduce the duration of the battery characterization test by 70–90% while still retaining levels of measurement accuracy for retained energy capacity in the order of 1% for cell temperatures equal to 25 °C. Even at elevated temperatures of 40 °C, the peak measurement error was found to be only 3%. Based on these experimental results, a simple cost-function is formulated to highlight the flexibility of the proposed test framework. This approach would allow different organizations to prioritize the relative importance of test accuracy verses experimental test time when grading used Li-ion cells for different end-of-life (EOL) applications. [ABSTRACT FROM AUTHOR]

Hierarchical CuCl with high economic value added (EVA) was successfully recycled with 85% recovery from the acid Cu printed circuit board (Cu-PCB) waste etchant via facile liquid chemical reduction. The micro-structure and morphology of the recycled hierarchical CuCl were systematically characterized in terms of scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), transmission electron microscopy (TEM) and Brunauer-Emmett-Teller (BET). Furthermore, the corresponding electrochemical performances as lithium ion battery (LIB) anode were also investigated in terms of galvanostatic charge/discharge, cyclic voltammetry (CV) and AC impedance. As expected, the recycled CuCl displayed a hierarchical tripod-like structure and large specific surface area of 21.2 m 2 /g. As the anode in LIB, the reversible discharge capacity was about 201.4 mAh/g even after 100 cycles, implying the satisfactory cycle performance. Clearly, the satisfactory results may open a new avenue to develop the sustainable industry, which is very important in terms of both the resource recovery and the environmental protection. [ABSTRACT FROM AUTHOR]

We unravel the role of flake dimensionality on the lithiation/de-lithiation processes and electrochemical performance of anodes based on few-(FLG) and multi-layer graphene (MLG) flakes prepared by liquid phase exfoliation (LPE) of pristine graphite. The flakes are sorted by lateral size (from 380 to 75 nm) and thickness from 20 (MLG) to 2 nm (FLG) exploiting a sedimentation-based separation in centrifugal field and, finally, deposited onto Cu disks for the realization of four binder-free anodes. The electrochemical results show that decreasing lateral size and thickness leads to an increase of the initial specific capacity from ≈590 to ≈1270mAhg −1 . However, an increasing irreversible capacity is also associated to the reduction of flakes’ size. We find, in addition, that the preferential Li ions storage by adsorption rather than intercalation in small lateral size (<100 nm) FLG flakes has a detrimental effect on the average de-lithiation voltage, resulting on low voltage efficiency of these anodes. We believe that the results reported in this work, provide the guidelines for the practical exploitation of graphene-based electrodes. [ABSTRACT FROM AUTHOR]

LiZnTiO/C nanocomposite has been synthesized using phenolic resin as carbon source in this work. The structure, morphology, and electrochemical properties of the as-prepared LiZnTiO samples were analyzed by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscope (TEM), Raman spectroscopy (RS), galvanostatic charge-discharge, and AC impedance spectroscopy. SEM images show that LiZnTiO/C was agglomerated with a primary particle size of ca. 40 nm. TEM images reveal that a homogeneous carbon layer (ca. 5 nm) formed on the surface of LiZnTiO particles which is favorable to improve the electronic conductivity and inhibit the growth of LiZnTiO during annealing process. The as-prepared LiZnTiO/C composite with 6.0 wt.% carbon exhibited a high initial discharge capacity of 425 and 159 mAh g at 0.05 and 5 A g, respectively. At a high current density of 1 A g, 95.5 % of its initial value is obtained after 100 cycles. [ABSTRACT FROM AUTHOR]

Core-shell nano-ring α-Fe 2 O 3 @Carbon (CSNR) composites with different carbon content (CSNR-5%C and CSNR-13%C) are synthesized using a hydrothermal method by controlling different amounts of glucose and α-Fe 2 O 3 nano-rings with further annealing. The CSNR electrodes exhibit much improved specific capacity, cycling stability and rate capability compared with that of bare nano-ring α-Fe 2 O 3 (BNR), which is attributed to the core-shell nano-ring structure of CSNR. The carbon shell in the inner and outer surface of CSNR composite can increase electron conductivity of the electrode and inhibit the volume change of α-Fe 2 O 3 during discharge/charge processes, and the nano-ring structure of CSNR can buffer the volume change too. The CSNR-5%C electrode shows super high initial discharge/charge capacities of 1570/1220 mAh g −1 and retains 920/897 mAh g −1 after 200 cycles at 500 mA g −1 (0.5C). Even at 2000 mA g −1 (2C), the electrode delivers the initial capacities of 1400/900 mAh g −1 , and still maintains 630/610 mAh g −1 after 200 cycles. The core-shell nano-rings opened during cycling and rebuilt a new flower-like structure consisting of α-Fe 2 O 3 @Carbon nano-sheets. The space among the nano-sheet networks can further buffer the volume expansion of α-Fe 2 O 3 and facilitate the transportation of electrons and Li + ions during the charge/discharge processes, which increases the capacity and rate capability of the electrode. It is the first time that the evolution of core-shell α-Fe 2 O 3 @Carbon changing to flower-like networks during lithiation/de-lithiation has been reported. [ABSTRACT FROM AUTHOR]

Micron-sized Co 3 O 4 hollow powders consisting of size controlled hollow nanospheres are prepared by applying Ostwald ripening and Kirkendall effect to the spray pyrolysis process. The Co-C composite powders uniformly dispersed with different sizes of metallic Co nanocrystals are formed by reduction of the cobalt oxide-carbon composite powders prepared using spray pyrolysis. Subsequent oxidation of the Co-C composite powders with filled structures forms the micron-sized Co 3 O 4 hollow powders consisting of size controlled hollow nanospheres. The mean sizes of the Co 3 O 4 hollow nanospheres oxidized from Co-C composite powders formed at reduction temperatures of 400, 600, and 800 °C are 37, 55, and 73 nm, respectively. The discharge capacities of the Co 3 O 4 powders formed from the Co-C composite powders reduced at temperatures of 400, 600, and 800 °C for the 300 th cycle are 644, 702, and 660 mA h g −1 , respectively, and their capacity retentions calculated from the second cycle are 81, 86, and 84%, respectively. The porous-structured Co 3 O 4 powders formed from the Co-C composite powders reduced at 800 °C show slightly better rate performance than those of the other two samples. [ABSTRACT FROM AUTHOR]

Ionic liquids are often named solvents of the future because of flexibility in design. This statement has given credence that ionic liquids should simply replace the problematic electrolytes of lithium batteries. As a result, the promising potentials of ionic liquids in electrochemical systems are somehow obscured by inappropriate expectations. We summarize recent advancements in this field, especially, ionic liquids as standalone electrolytes, additives, plasticizers in gel polymer electrolytes, and binders; and attempt to shed light on the future pathway of this area of research. Ionic liquids are not dilute media to serve as pure solvents in electrochemical systems where mobility of ions is the priority; instead, they can contribute to the ionic conductivity of various components in a battery system. Owing to the enormous possibilities of ionic liquids, it is not merely a matter of choice. Ionic liquids can be used to design novel types of electrolytes for a new generation of lithium batteries. A promising possibility, which is still at a very early stage, is supercooled ionic liquid crystals for fast ion diffusion through the guided channels of a liquid-like medium. This, of course, will be a breakthrough in the realm of electrochemistry, far beyond lithium battery field, when materialized. [ABSTRACT FROM AUTHOR]

Cubic MnCO 3 @C composite was first synthesized using one-pot hydrothermal method. The prepared cubic MnCO 3 @C presented a homogeneous core-shell structure, which was composed of cubic MnCO 3 as core, a mixture of amorphous carbon and MnCO 3 as shell, and a separating interlayer. Compared to pure MnCO 3 , core-shell structured MnCO 3 @C exhibited better cycling stability, rate performance and recovery capability. It delivered a reversible capacity of 1020 mAh g −1 which was 94.7% of the initial capacity, and a recovery capacity of 862 mAh g −1 after 80 cycles under current density from 100 mA g −1 to 10000 mA g −1 . The superior electrochemical performance of MnCO 3 @C could be attributed to the improved electronic conductivity and suppressed particle aggregation during the conversion reaction. Voltage profile and cyclic voltammetry test results showed active material transformation in both anode materials during the cycling process. Furthermore, the infrared spectra at different discharge/charge states showed that the conversion reactions of MnCO 3 included not only the transition from MnCO 3 to Mn, but also a further reaction from Li 2 CO 3 to Li 2 O. [ABSTRACT FROM AUTHOR]

We have studied the effect of final annealing temperature on the formation of lithium zinc titanate, its electrical conductivity, and its electrochemical performance. LiZnTiO has been shown to form in a wide range of annealing temperatures, from 673 to 1073 K. Its particle size increases systematically with increasing annealing temperature, whereas its conductivity decreases. The highest electrochemical capacity at low currents is offered by the materials annealed at 773 and 873 K, and the highest cycling stability is offered by the material prepared at 873 K. [ABSTRACT FROM AUTHOR]

The synthesis and characterization of Mg-birnessite (Mg x MnO 2 ) with different crystallite sizes, prepared though low temperature precipitation and ion exchange was demonstrated. The influence of crystallite size on electrochemical performance of Mg-birnessite was studied for the first time, where material with smaller crystallite size was demonstrated to have enhanced capacity and rate capability in Li ion, Na ion, and Mg ion based electrolytes. Cation diffusion using GITT type testing demonstrated the ion diffusion coefficient of Mg 2+ was ∼10× lower compared with Li + and Na + . This work illustrates that tuning of inorganic materials properties can lead to significant enhancement of electrochemical performance in lithium, sodium as well as magnesium based batteries for materials such as Mg-birnessite and provides a deliberate approach to improve electrochemical performance. [ABSTRACT FROM AUTHOR]

MoO 2 has gained renewed attention as a safe oxide anode host material for lithium ion insertion because of its high gravimetric/volumetric capacity and highly stable cycling behavior. However, these recent results are completely contrary to previous reports. To confirm that MoO 2 is an appropriate anode material as well as further understand lithium ion reactions when inserted into MoO 2 , we combine electrochemical characterization of MoO 2 electrodes and ex situ X-ray diffraction analysis with first principle calculations. Theoretical capacity of the MoO 2 electrode (∼209 mAh g −1 ) and stable capacity retention up to 100 cycles are simultaneously attained using a proper particle size and type of binder. Ex situ XRD analysis with first principle calculations of the phase transformation of MoO 2 electrodes shows that MoO 2 undergoes reversible structural changes upon lithiation and subsequent delithiation, clearly demonstrating that nanostructured MoO 2 can be used as an anode material for highly reliable lithium ion batteries. [ABSTRACT FROM AUTHOR]

Lithium ion batteries (LIBs) for high performance require separators with auspicious reliability and safety. Keeping LIBs reliability and safety in view, microporous polyacrylonitrile (PAN)/polyurethane (PU) nonwoven composite separator have been developed by electrospinning technique. The physical, electrochemical and thermal properties of the PAN/PU separator were characterized. Improved ionic conductivity up to 2.07 S cm −1 , high mechanical strength (10.38 MPa) and good anodic stability up to 5.10 V are key outcomes of resultant membranes. Additionally, high thermal stability displaying only 4% dimensional change after 0.5 h long exposure to 170 °C in an oven, which could be valuable addition towards the safety of LIBs. Comparing to commercialized polypropylene based separators, resulting membranes offered improved internal short-circuit protection function, offering better rate capability and enhanced capacity retention under same observation conditions. These fascinating characteristics endow these renewable composite nonwovens as promising separators for high power LIBs battery. [ABSTRACT FROM AUTHOR]

Si doping at high voltage spinel LiNi 0.5 Mn 1.5 O 4 are presented as an effective strategy to greatly increase the electrochemical performance. Well-crystallized LiNi 0.5 Mn 1.5-x Si x O 4 (x = 0.05, 0.10, 0.15, 0.20) with homogeneous Si distribution are successfully synthesized through solid-state reaction. Structural and electrochemical characteristics are investigated through FESEM, XRD, FTIR, Raman spectroscopy, cyclic voltammetry and galvanostatic charge/discharge testing. It can be demonstrated that Si doping significantly improves the electrochemical performance. LiNi 0.5 Mn 1.35 Si 0.15 O 4 exhibits reversible capacities of 123 mAh/g after the 100th cycle at 0.5C and LiNi 0.5 Mn 1.35 Si 0.15 O 4 as well as LiNi 0.5 Mn 1.3 Si 0.2 O 4 show superior electrochemical stability over the pristine LiNi 0.5 Mn 1.5 O 4 material. Since the Si-O bond exhibits high dissociation energy of 798 kJ/mol (298 K), which is far beyond of the dissociation energies of the Mn-O or Ni-O bonds, the excellent electrochemical performance might be associated with an increased structural and chemical stability caused by incorporation of Si into the Oxygen-rich crystal lattice. [ABSTRACT FROM AUTHOR]

In this study, we report a facile and novel method for preparing the porous Sb 2 S 3 /Sb composite. When the as-synthesized electrode is applied as an anode for lithium ion battery, it exhibits good cycling stability and rate capability. The capacity of the Sb 2 S 3 /Sb composite at a current density of 1.0 A g −1 for the 200th cycle is 387 mAh g −1 . Even when the current density is 10 A g −1 , the electrode still keeps a capacity of 250 mAh g −1 . To the best of our knowledge, the attractive electrochemical properties are much more distinguished than the Sb 2 S 3 -based anodes for li-ion batteries published to date. In addition, the simple synthesis method is applicable to the fabrication of a variety of chalcogenide electrode materials for batteries. [ABSTRACT FROM AUTHOR]

In this work we compare electrochemical cycling stability of Fe containing Li rich phase Li 1.2 Ni 0.13 Fe 0.13 Mn 0.54 O 2 (Fe–Li rich) with the well-known Co containing Li rich composition Li 1.2 Ni 0.13 Co 0.13 Mn 0.54 O 2 (Co–Li rich). During the first charge, the activation plateau corresponding to removal of Li 2 O from the structure is smaller (removal of 0.6 Li) in the case of Fe–Li rich compared to Co–Li rich composition (0.8 Li removal). Consequently, the Fe compound shows better capacity retention; for example, after 100 cycles Fe–Li rich compound exhibits 20% capacity degradation where as it is about 40% in the case of Co–Li rich phase. The electrochemical and microscopy studies support the fact that compared to Co–Li rich compound, the Fe–Li rich composition display smaller voltage decay and reduced spinel conversion. XPS studies on charged/discharged Fe–Li rich samples show participation of Fe +3 /Fe +4 redox during electrochemical cycling which is further supported by our first principles calculations. Also the temperature dependent magnetic studies on charge-discharged samples of Fe–Li rich compound point out that magnetic behavior is sensitive to cation oxidation states and Ni/Li disorder. [ABSTRACT FROM AUTHOR]

LiMn2O4 nanoparticles were successfully prepared using suitable dosage carbon nanotubles (CNTs) as a fuel through multiphase combustion synthesis. The effects of CNTs on the structure and electrochemical performance of LiMn2O4 were investigated. Rate performance test demonstrates that CNTs dosage greatly affect the electrochemical behaviour of LiMn2O4 and LiMn2O4 prepared by choosing suitable CNTs dosage (7%) as a fuel (C7%-LMO) shows high rate charge–discharge capability. X-ray diffraction results indicate that C7%-LMO has the smallest distortion degree in the crystal, compared to LiMn2O4 prepared without CNTs (C0%-LMO) and LiMn2O4 prepared with 10% CNTs (C10%-LMO). SEM results reveal that the average particle size of C7%-LMO is about 100 nm, which is the smallest among the three samples (C0%-LMO, C7%-LMO and C10%-LMO). This unique microscopic features guarantee C7%-LMO possesses the highest discharge capacity, the best cycling performance and the lowest charge transfer resistance among the three samples. [ABSTRACT FROM AUTHOR]

Li 2 FeSiO 4 was synthesized through Sol–Gel method and the effect of calcination temperature, time and chelating agent concentration were investigated. Appropriate calcination temperature above 550 °C was determined by TG/DTA analysis. Afterward, the dried gel powder was calcined at each temperature of 650 °C, 700 °C and 750 °C for 1, 2 and 3 h. XRD studies illustrated the most appropriate calcination temperature of 700 °C for 1 h. To compare the effect of chelating agent concentration, citric acid with molar ratio of 1/3, 2/3 and 1 were used which 1/3 was determined as the best concentration. FE-SEM observation showed that mean grain is size lower than 100 nm. By using this material, a three electrodes test cell was assembled and its electrochemical properties were investigated. The results showed high charge capacity which could be achieved at current density of 0.05C. [ABSTRACT FROM AUTHOR]

A novel facile strategy was developed to prepare the Fe 3 O 4 @graphene aerogel (Fe 3 O 4 @GA) composites. Fe 3 O 4 nanoparticles were uniformly dispersed into the 3D network of graphene aerogel and the resultant hybrid composites contained meso- and macro-scale pores with high specific surface area (276.9 m 2 g −1 ) and large pore volume (0.3230 cm 3 g –1 ). The electrochemical performance revealed that the Fe 3 O 4 @GA anode exhibited high reversible capacity (~941.5 mAh g −1 at a current density of 100 mA g −1 ), stable cycling performance, and excellent rate capability. [ABSTRACT FROM AUTHOR]

Introducing the Mg ion into host lattice is applied to improving the electrochemical performance of LiNi 0.6 Co 0.2 Mn 0.2 O 2 . The effect of Mg substitution for Co on the structure, morphology, electrochemical properties and Li + diffusion coefficients are investigated in details. Rietveld refinement results reveal that Mg is incorporated into the bulk lattice, which results in reduced cation mixing and expand c -lattice parameter. All Mg-doped sample exhibit better cycle and rate performances, although the Mg substitution for Co led to decreasing a part of capacity. The Li diffusion coefficients obtained by galvanostatic intermittent titration technique (GITT) are increased with increases of Mg content. [ABSTRACT FROM AUTHOR]

A novel air-stable titanium hexacyanoferrate (Ti 0.75 Fe 0.25 [Fe(CN) 6 ] 0.96 ·1.9H 2 O) with a cubic structure is synthesized simply by a solution precipitation method, which is first demonstrated to be a scalable, low-cost anode material for lithium-ion batteries exhibiting high capacity, long cycle life and good rate capability. Nevertheless, it has a low capacity of about 100 mAh g −1 as an anode material for sodium-ion batteries. [ABSTRACT FROM AUTHOR]

We report a facile process to synthesize Mo 0.91 W 0.09 S 2 /amorphous carbon composites with mean thickness of only 5 nm ultrathin nanosheets and their improved electrochemical performance as anode materials for lithium ion batteries (LIBs). Structural and morphological characterizations of the nanocomposite have been investigated by XRD, SEM and TEM. It was found the amorphous carbon to be well dispersed on the ultrathin nanosheets surface. Due to the increased interlayer distance and the synergistic effects between Mo 0.91 W 0.09 S 2 nanosheets and amorphous carbon, the as-prepared Mo 0.91 W 0.09 S 2 /C electrode deliveres exhibit a high Li capacity, an excellent rate capability, and a stable cycling performance, which suggests the Mo 0.91 W 0.09 S 2 /C composites as promising electrode material for LIBs. [ABSTRACT FROM AUTHOR]

A strategy for the preparation of metal oxide-carbon composite powders with yolk-shell structure by simple spray pyrolysis is introduced. Mn–Sn–O–C composite powders with yolk-shell structure representing the first target material are prepared by one-pot spray pyrolysis and their formation mechanism is evaluated. Phase separation of polyvinylpyrrolidone (PVP), Sn, and Mn components during the drying stage of droplets plays a key role in the formation of yolk-shell structured composite powders. The repeated combustion and contraction processes of the dried powders under N 2 atmosphere produce the desired Mn–Sn–O–C composite powders with yolk-shell structure. The shell and core parts of the yolk-shell powders prepared directly by spray pyrolysis at 900 °C are MnO–Mn 2 SnO 4 –C and Sn–Mn 2 SnO 4 –C composites, respectively. The initial discharge capacities of the composite powders prepared at 700 and 900 °C at the current density of 1 A g −1 are 1058 and 1204 mA h g −1 , respectively. The discharge capacities of the composite powders prepared at 900 °C for the 2nd and 100 th cycle are 803 and 784 mA h g −1 , respectively. The structural stability of the Mn–Sn–O–C composite powders with yolk-shell structure during cycling results in good electrochemical performance. [ABSTRACT FROM AUTHOR]

Electrochemical performance of the 18650 lithium-ion batteries consisting lithium-rich layered oxides 0.5Li 2 MnO 3 ·0.5LiMn 0.33 Ni 0.33 Co 0.33 O 2 cathode material and soft carbon anode is investigated in detail. The cathode is synthesized by a spray drying process and the properties are studied by various methods, while the soft carbon is commercial available. The assembled batteries can exhibit excellent cyclic performance with a capacity retention of 90.2% even after 600 cycles in the voltage ranges of 2.0-4.5 V (at 1C-rate). Moreover, they can also deliver excellent rate capabilities as the discharge capacity under 40C is nearly equal to 83.9% of that under 1C (voltage range is in 2.0-4.5 V). Furthermore, in order to evaluate the mechanism of the superior performance exhibited by the full cells, cells after 300 cycles are disassembled in a glove box to assess the changes on the active materials by using a series of technique methods, including a scanning electron microscopy (SEM), X-ray diffraction (XRD), energy dispersive spectrometry (EDS), High-resolution transmission electron microscope (TEM) and selected area electron diffraction (SAED). [ABSTRACT FROM AUTHOR]

High-purity micro-rod β-Na 0.33 V 2 O 5 particles 2–5 μm in width and 3–10 μm in length are prepared by the chemical switch method. Electrochemical characterization demonstrates that micro-rod β-Na 0.33 V 2 O 5 as a cathode material for lithium ion batteries provides high discharge capacity, good rate-capability, and cyclic stability. It delivers high discharge capacities of 297, 245, 220, and 178 mAh g −1 at current densities of 0.1, 0.2, 0.5, and 1 C-rate, respectively. The capacity fading rate is less than 1% per cycle, with high volumetric discharge capacities (504 mAh cm −3 at 0.1C and 301 mAh cm −3 at 1 C). Scanning electron microscopy images of the micro-rods during cycling indicate that they have excellent crystal structural reversibility in the voltage range of 1.5–4.0 V. These superior electrochemical properties are attributed to the tunneled crystal structure and internal pores formed by crystal defects in the micro-rods. [ABSTRACT FROM AUTHOR]

The present study reports on the direct synthesis of LiFePO 4 nanoparticles and graphene nanosheets to form a composite cathode (LFP/GNs) in a one-step microwave-assisted polyol reaction. The polyol reaction induced by microwave irradiation for a few minutes produces nanocrystalline LFP and graphene nanosheets simultaneously from lithium, iron and phosphorus and carbon (5 wt% of graphite oxide) sources, respectively, used as starting precursors. Powder X-ray diffraction (XRD), electron microscopy, and atomic force microscopy (AFM) studies on microwave-reacted sample obtained using just graphite oxide confirms the formation of graphene nanosheets separately. Whereas, electron microscopy studies on the LFP/GNs composite reveals that olivine nanoparticles of average sizes ranging between 5 and 20 nm are well-dispersed on the graphene nanosheets. Electrochemical measurements reveal that the LiFePO 4 /GNs nanocomposite cathodes registered enhanced discharge capacities (79 and 108 mAh g −1 for the as-prepared and annealed composite cathodes, respectively) at 32 C rates with good capacity retention capabilities. The AC impedance measurements confirm that the enhanced cathode properties of the LFP/GNs nanocomposite are ascribed to the improved electronic conductivity of the graphene nanosheets and the nano-sized particles. The slightly better electrochemical properties of the annealed LFP/GNs are attributed to its higher crystallinity. [ABSTRACT FROM AUTHOR]

Natural graphite treated by mechanical activation can be directly applied to the preparation of LiV(PO). The carbon-coated LiV(PO) with monoclinic structure was successfully synthesized by using natural graphite as carbon source and reducing agent. The amount of activated graphite is optimized by X-ray diffraction, scanning electron microscope, transmission electron microscope, Raman spectrum, galvanostatic charge/discharge measurements, cyclic voltammetry, and electrochemical impedance spectroscopy tests. Our results show that LiV(PO) (LVP)-10G exhibits the highest initial discharge capacity of 189 mAh g at 0.1 C and 162.9 mAh g at 1 C in the voltage range of 3.0-4.8 V. Therefore, natural graphite is a promising carbon source for LVP cathode material in lithium ion batteries. [ABSTRACT FROM AUTHOR]

Y-doped Li 2 Fe 1−x Y x SiO 4 /C (x = 0, 0.02, 0.04) composites are successfully synthesized via a sol-gel method. X-ray diffraction, field emission scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, Raman spectrometry and UV-visible spectroscopy are used to investigate the effect of yttrium doping on the characteristics of Li 2 FeSiO 4 /C. The results show that yttrium (Y) does enter the crystal structure of Li 2 FeSiO 4 and negligibly affect the morphology of the composites as well as the structural properties of the coated carbon. The electrochemical performance is evaluated by galvanostatic charge-discharge and electrochemical impedance spectra. Li 2 Fe 0.98 Y 0.02 SiO 4 /C exhibits the best rate capability and cycle stability among the three samples. The enhanced electrochemical performance is attributed to its enhanced electronic conductivity, higher lithium ion diffusion coefficient and better structure stability due to the proper amount of Y doping in Fe sites. [ABSTRACT FROM AUTHOR]

The severe capacity fading and poor rate performance under high voltage of LiNi 0.5 Co 0.2 Mn 0.3 O 2 are the vital barriers for their large scale application. In order to solve above issues, zirconium doped LiNi 0.5 Co 0.2 Mn 0.3 O 2 materials were prepared by solid state method. The effects of the zirconium content on the structure and electrochemical properties of Li(Ni 0.5 Co 0.2 Mn 0.3 ) 1- x Zr x O2 were extensively studied. Though the zirconium doped samples delivered lower initial capacities, the cycling stability are dramatically enhanced. Notably, Li(Ni 0.5 Co 0.2 Mn 0.3 ) 0.99 Zr 0.01 O 2 showed a capacity retention of 83.78% at 1C after 100 repeated cycle in a high voltage of 4.6 V, while that of bare sample remains only 69.35%. Moreover, the rate capability of Li(Ni 0.5 Co 0.2 Mn 0.3 ) 0.99 Zr 0.01 O 2 is also greatly reinforced especially at high current density. The improved electrochemical performances could be ascribed to the less cation mixing degree, better lithium transportation kinetic and lower impedance, which were confirmed by Rietveld refinement, X-ray photoelectron spectroscopy and electron impedance spectroscopy. [ABSTRACT FROM AUTHOR]

A novel nano/micro-structured pSi@C composite with buffer void was successfully synthesized via a simple and scalable process with combination of the calcination, spray drying, carbonization and HF etching. The obtained pSi@C composite with this particular structure exhibits high reversible capacity of ca. 2200 mA h g −1 and excellent cycling stability with 90.3% capacity retention after 300 cycles, which benefits from its void spaces between silicon and carbon layer and highly conductive carbon-layer. The simple and scalable synthesis technique and good electrochemical performance of this nano/micro-structured pSi@C composite make it a promising candidate for large capacity lithium ion battery anode material. [ABSTRACT FROM AUTHOR]

Li[Li 0.2 Mn 0.54 Ni 0.13 Co 0.13 ]O 2 materials doped with different Zr contents are studied using X-ray diffractometry (XRD), energy dispersive X-ray analysis (EDX), scanning electron microscopy (SEM), charge–discharge measurements, AC impedance spectroscopy as well as cyclic voltammetry. These results demonstrate that the element Zr is distributed uniformly in these materials. With the increase of Zr content, the lattice parameters a , c and lattice volume V become larger. The discharge cycling curves of cells show that Zr doping enhances cycle life compared with the undoped one. The sample with x =0.01 shows the highest capacity and best cycling performance, especially at high current density. The Li[Li 0.2 Mn 0.54− x /3 Ni 0.13− x /3 Co 0.13− x /3 Zr x ]O 2 ( x =0.01) delivers a capacity of 133.6 mA h g −1 (after 100 cycles) at the current density of 250 mA g −1 , corresponding to the capacity retention of 83.8%. The favorable performance of the doped samples could be attributed to its enhanced structural stability and Li + mobility. [ABSTRACT FROM AUTHOR]

In this study, we prepared a kind of composite solid polymer electrolyte (CSPE) based on montmorillonite (MMT) nano-clay fillers, lithium-bis(trifluoromethanelsulfonyl) (LiTFSI), polyvinylidenedifluoride (PVDF) and polyvinyl alcohol (PVA) copolymer by the casting method. Effect of the montmorillonite on ionic conductivity and electrochemical properties of the polymer electrolyte was demonstrated. The result CSPE obtained a higher ionic conductivity up to 4.31 × 10 −4 S cm −1 at room temperature when 4.0 wt% MMT was contained, and the maximum lithium ions transference number of 0.40 was achieved. Electrochemical performance of the polymer solid electrolyte was evaluated in Li/polymer electrolyte/LiFePO 4 coin cell. Good performance with low capacity fading on charge–discharge cycling was achieved, indicating the potential application of the as-prepared CSPE in lithium ion batteries. [ABSTRACT FROM AUTHOR]

We simulate the electrochemical properties of Li-ion cells consisting of a blended cathode composed of LiMn 2 O 4 and LiNi 0.6 Co 0.2 Mn 0.2 O 2 and an artificial graphite anode using the Li-ion battery model available in COMSOL MULTIPHYSICS 4.4 along with a capacity fade model. The discharge profiles of the pure and blended cathodes at various current rates obtained through simulations and experimental results are well matched. By combining two capacity fade models available in literature, namely the solid electrolyte interphase (SEI) growth model and the Mn 2+ dissolution model, the cycling performance of the pure LiMn 2 O 4 cells at 25 °C are successfully simulated and found to be in a good agreement with the experimental results. The blended cathode exhibits better capacity retention than the pure LiMn 2 O 4 during cycling. We also observed that at high powers, the gravimetric energy density of the LiMn 2 O 4 cathode exceeds that of the LiNi 0.6 Co 0.2 Mn 0.2 O 2 cathode; the reverse effect is seen at low powers. Further, we were able to easily modulate the energy and power densities of the blended cathode system by changing the blend ratio in our simulation model. [ABSTRACT FROM AUTHOR]

Li 3 V 2 (PO 4 ) 3 /C (LVP/C) cathode materials for lithium ion batteries have been successfully synthesized via carbon thermal reduction method using pitch as both a new carbon source and a reduction agent. The influences of different carbon sources (pitch, Super P, KS15 and Vulcan-XC72) and heat treatments between 650 and 950 °C on the LVP/C materials have also been investigated. The structural and electrochemical properties of the samples are characterized by X-ray powder diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscope (TEM) and high resolution transmission electron microscopy (HRTEM) as well as charge-discharge experiments. The LVP/C synthesized with pitch have smooth surface with uniform residue carbon distribution and presents the best electrochemical performance. In addition, the oxidation of carbon has been discussed. The results indicate that carbons obtained from four carbon sources are tended to be oxidized to CO 2 than CO. Electrochemical tests show the LVP/C-750 °C exhibits the highest discharge capacity and the most excellent capacity retention. Spherical LVP/C particles are obtained using the spray drying method. The spray drying-LVP/C composite deliver higher discharge capacity than those of LVP/C composites obtained by carbon thermal reduction method or by drying with oven. [ABSTRACT FROM AUTHOR]

Manganese dioxide/cabon nanotubes (MnO 2 /CNTs) composites with tunable density of MnO 2 nanosheets on the surface of CNTs were synthesized by a facile room temperature solution method. When applied in lithium-ion batteries (LIBs) as anode materials, the spacial density of MnO 2 nanosheets in the MnO 2 /CNT composite was verified to be crucial for the lithium storage performance. The optimized composite with moderate spatial density of MnO 2 nanosheets delivered a reversible capacity of 903 mA h g −1 at the current rate of 0.24 A g −1 . Moreover, this composite exhibited a high stable capacity of 540 mA h g −1 even at a high current density of 2.4 A g −1 after 1500 cycles, demonstrating its potential for applications in LIBs with long cycling life and high power density. The enhanced electrochemical performance of the optimized composite was ascribed to sufficient space between the MnO 2 nanosheets on the CNTs, which not only allows the effective electrical contact between the CNT backbones and the conductive carbon but also accommodates the large volume changes upon repeated lithiation/delithiation. [ABSTRACT FROM AUTHOR]

Transition metal oxides have been considered as promising lithium storage materials that undergo a conversion reaction, exhibiting high specific capacity. However, capacity fading during cycling is the most serious obstacle for their commercialization. In order to overcome this, we have added PEDOT:PSS (poly(3,4-ethylenedioxythiophene) polystyrene sulfonate) to Mn 2 O 3 nanowires. PEDOT:PSS was successfully coated onto Mn 2 O 3 nanowires while maintaining the structure of Mn 2 O 3 . The coating of PEDOT:PSS reduced the resistance of the surface and protected the surface electron channels from the pulverization effect of the charge–discharge operation. α-Mn 2 O 3 /PEDOT:PSS showed excellent cyclability with a reversible capacity of 1450 mAh g −1 after 200 cycles at a current density of 100 mA g −1 . An increase in capacity was observed with continuous cycling, which may be attributed to further oxidation of the manganese species and a reversible reaction of the gel-like polymer on the manganese surface. The results demonstrate that PEDOT:PSS enhances the electrochemical activity by providing electron channels and prevents pulverization caused by the charge and discharge process. [ABSTRACT FROM AUTHOR]

A series of lithium borate added electrolyte compounds, x Li 3 BO 3 -(1− x )Li 3.5 Si 0.5 P 0.5 O 4 (0 ≤ x ≤ 0.2), are synthesized and characterized. This so-called LISICON electrolyte system is analyzed by using X-ray diffraction (XRD), scanning electron microscopy (SEM), solid state nuclear magnetic resonance (ss-NMR), electrochemical impedance spectra (EIS), and direct current (DC) polarization methods. From 11 B MAS NMR spectra, it is demonstrated that a small fraction of boron exists in the form of BO 4 , while its majority settles at grain boundaries in the form of BO 3 , indicating that lithium borate glasses play a role as sintering assistant. This prominently increases the relative density of samples, and is beneficial to the ionic conductivity. Further results show that the electrical conduction of lithium borate added LISICONs is dominated by Li + ions, with a transference number of t Li + ≥ 0.996 and a corresponding ionic conductivity of about 6.5 × 10 −6 S cm −1 at room temperature, almost two times that of pristine Li 3.5 Si 0.5 P 0.5 O 4 . [ABSTRACT FROM AUTHOR]

The open terminal voltage of a lithium ion battery is measured at temperatures ranging from 0 °C to 50 °C in increments of 10 °C. Primary focus is on three states of charge of the battery (full charge, late life, charge depletion). Estimates of the enthalpy, ΔH, and the entropy, ΔS, of the battery reaction are made using the established thermochemical relationship between the open terminal voltage and the Gibbs free energy, ΔG. As expected, ΔS is found to be dependent on the state of charge. The enthalpy also shows some dependence on the state of charge, which is at variance with the ideal Nernstian behavior. This may attributed to non-equivalence of intercalation sites as well as near neighbor interactions. Furthermore, the rate of discharge has little apparent effect on these results. An equilibration time well in excess of 20 hours is also observed. [ABSTRACT FROM AUTHOR]

LiNi 1/3 Co 1/3 Mn 1/3 O 2 is successfully coated with MnO 2 by a chemical deposition method. The X-ray diffraction (XRD), scanning electron microscope (SEM) and high resolution transmission electron microscope (HRTEM) results demonstrate that MnO 2 forms a thin layer on the surface of LiNi 1/3 Co 1/3 Mn 1/3 O 2 without destroying the crystal structure of the core material. Compared with pristine LiNi 1/3 Co 1/3 Mn 1/3 O 2 , the MnO 2 -coated sample shows enhanced electrochemical performance especially the rate capability. Even at a current density of 750 mA g −1 , the discharge capacity of MnO 2 -coated LiNi 1/3 Co 1/3 Mn 1/3 O 2 is 155.15 mAh g −1 , while that of the pristine electrode is only 132.84 mAh g −1 in the range of 2.5–4.5 V. The cyclic voltammetry (CV) and X-ray photoelectron spectroscopy (XPS) curves show that the MnO 2 coating layer reacts with Li + during cycling, which is responsible for the higher discharge capacity of MnO 2 -coated LiNi 1/3 Co 1/3 Mn 1/3 O 2 . Electrochemical impedance spectroscopy (EIS) results confirmed that the MnO 2 coating layer plays an important role in reducing the charge transfer resistance on the electrolyte–electrode interfaces. [ABSTRACT FROM AUTHOR]

A ZnO/activated carbon nanofiber (ACNF) composite is fabricated by electrospinning and subsequent thermal treatment as a novel anode material for lithium-ion batteries (LIBs). A ZnO(20)–ACNF sample prepared with a weight ratio of 20 wt% zinc acetate to polyacrylonitrile (PAN) exhibits stable capacity retention and a reversible capacity of above 380 mAh g −1 at 0.1 C rate after 100 cycles, which is much larger than the equivalent values of 266 and 224 mAh g −1 for ACNF and pure ZnO electrodes, respectively. ZnO(20)–ACNF retains a reversible discharge capacity of 334 mAh g −1 at 2.0 C rate. The high rate capability and cycling stability are attributed to the structural buffering offered by the introduction of ACNF, good electrical conductivity, and short diffusion path for ions and electrons due to the synergistic effect between the nanosized ZnO and ACNF during charging/discharging. [ABSTRACT FROM AUTHOR]

Customized hierarchical porous metal oxide arrays is of great importance for construction of high-performance electrochemical devices. In this work, we report hierarchical porous (HP)-NiO sheets arrays by a facile hydrothermal method. Interestingly, the obtained NiO sheets arrays show HP systems, and are composed of cat-ear-like sheets main structure and interconnected nanosheets secondary structure. Moreover, the secondary nanosheets are highly porous and consist of cross-linked nanoparticles of 30–100 nm. The electrochemical performances of the HP-NiO sheets arrays are evaluated as anode for Li ion batteries. Compared with the normal NiO sheets arrays, enhanced electrochemical performances are achieved for the HP-NiO sheets, including higher capacity, better cycling life and high-rate capability. The HP-NiO sheets can deliver a specific capacity of 511 mAh g −1 at 3 A g −1 , higher than the normal NiO sheets arrays (374 mAh g −1 at 3 A g −1 ), due to the hierarchical porous array configuration with large surface area, fast ion diffusion path and better accommodation of volume change. [ABSTRACT FROM AUTHOR]

Lithium chromium pyrophosphate (LiCrP2O7) and carbon-coated LiCrP2O7 (LiCrP2O7/C) were synthesized by solid-state and sol-gel routes, respectively. The materials were characterized by X-ray diffraction (XRD), thermogravimetric analysis (TGA), scanning electron microscopy (SEM) and conductivity measurements. LiCrP2O7 powder has a conductivity of ∼ 10−8 S cm−1, ∼ 104 times smaller than LiCrP2O7/C (∼ 10−4 S cm−1). LiCrP2O7/C is electrochemically active, mainly between 1.8 and 2.2 V versus Li+/Li (Cr3+/Cr2+ redox couple), whereas LiCrP2O7 has limited electrochemical activity. LiCrP2O7/C delivers a reversible specific charge up to ∼ 105 mAh g−1 after 100 cycles, close to the theoretical limit of 115 mAh g−1. Operando XRD experiments show slight peak shifts between 2.2 and 4.8 V versus Li+/Li, and a reversible amorphization between 1.8 and 2.2 V versus Li+/Li, suggesting an insertion reaction mechanism. [ABSTRACT FROM AUTHOR]

Li 2 MnO 3 is known to be electrochemically inactive due to Mn in tetravalent oxidation state. Several compositions such as Li 2 MnO 3 , Li 1.5 Al 0.17 MnO 3 , Li 1.0 Al 0.33 MnO 3 and Li 0.5 Al 0.5 MnO 3 were synthesized by a sol–gel Pechini method. All the samples were characterized with XRD, Raman, XPS, SEM, Tap density and BET analyzer. XRD patterns indicated the presence of monoclinic phase for pristine Li 2 MnO 3 and mixed monoclinic/spinel phases (Li 2 − x Mn 1 − y Al x + y O 3 + z ) for Al-substituted Li 2 MnO 3 compounds. The Al substitution seems to occur both at Li and Mn sites, which could explain the presence of spinel phase. XPS analysis for Mn 2p orbital reveals a significant decrease in binding energy for Li 1.0 Al 0.33 MnO 3 and Li 0.5 Al 0.5 MnO 3 compounds. Cyclic voltammetry, charge/discharge cycles and electrochemical impedance spectroscopy were also performed. A discharge capacity of 24 mAh g −1 for Li 2 MnO 3 , 68 mAh g −1 for Li 1.5 Al 0.17 MnO 3 , 58 mAh g −1 for Li 1.0 Al 0.33 MnO 3 and 74 mAh g −1 for Li 0.5 Al 0.5 MnO 3 were obtained. Aluminum substitutions increased the formation of spinel phase which is responsible for cycling. [ABSTRACT FROM AUTHOR]

The internal distributed physicochemical characteristics of a battery significantly affect its performance. However, these properties are difficult to measure experimentally. This study presents a validated three-dimensional (3D) battery model covering the conservation of charge, mass, and energy and the electrochemical reaction of a laminated 10 Ah lithium iron phosphate battery. Using this 3D battery model, the space and time distributions of the internal physicochemical properties of the battery are investigated. The results indicate that the maximum gradients of the properties are at the transition region between the tabs and electrode plates. Thus, the tabs in a battery should be reasonably designed. For this LiFePO 4 /Graphite battery, anode plays a more important role than cathode in the overall overpotential and is likely to be crucial in the sharp decrease of output voltage at the later discharge process. And a higher battery capacity can be obtained by increasing the amount of anode material. [ABSTRACT FROM AUTHOR]

TiO 2 is one of the most promising anode candidates for novel lithium ion batteries which combines the advantage of state of art anode graphite and the safety of Li 4 Ti 5 O 12 . However, the low intrinsic conductivity limits its electrochemical properties. In this paper, a sol-gel based route is presented to produce nanosize TiO 2 /CNT core-shell composite fibers. Fiber diameter is 253 ± 63 nm as-spun and 126 ± 35 nm with subsequent calcination to obtain crystalline phase. Crystallite size is between 13–18 nm. The as-prepared core-shell fibers exhibited ∼1.5 time higher electronic conductivity, 1.6–3 times greater lithium diffusivity which resulted in 25% more galvanostatic capacity at C/10 compared to bare TiO 2 nanofibers. The enhancement in high-rate performance at 10C was over 80% which was crucial for fast charging applications. CNT additives were found to enhance the electronic conductivity, lithium diffusivity and electrochemical properties of the TiO 2 nanofibers by both providing an alternative electron and lithium ion conducting mechanism as well as synergistic effects, which were systematically reviewed. [ABSTRACT FROM AUTHOR]

W-doped Li 7 La 3 Zr 2 O 12 electrolytes with composition of Li 7-2x La 3 Zr 2-x W x O 12 (LLZWO, x = 0-0.55) were prepared by conventional solid state reaction. The incorporation of W proves beneficial to stabilization of cubic phase and densification of the ceramic, resulting in relative density of 96% and ionic conductivity of 6.6 × 10 −4 S cm −1 at 25 °C. Further analysis indicates that the LLZWO is not only chemically but also electrochemically (at least up to 4.5 V) stable against Li metal anodes. The batteries consisting of Li/LLZWO/Electrolyte-soaked separator/LiNi 0.33 Mn 0.33 Co 0.33 O 2 at 25 °C exhibit the capacity of 142 mAh g −1 at a constant current of 15 mA g −1 at the first discharge, which could run for 20 cycles with capacity retention of 94%. These results indicate that the W-doped LLZO ceramics are promising electrolytes for solid state lithium ion batteries. [ABSTRACT FROM AUTHOR]

Pompon-like MnO/carbon nanotube (CNT) composite microspheres have been prepared by the pyrolysis of Mn 3 O 4 and CNT mixtures. These microspheres are constructed by combining MnO nanocrystallines with CNT scaffolds to form the interconnected MnO-modified CNT networks. The three-dimensional composite structures are superior to the simple mixture of MnO and CNT in combination with each advantage, such as the inhibited aggregation, large porosity, high conductivity and enhanced mechanical strength. The lithium ion batteries based on MnO/CNT composite microspheres as anodes exhibit a high specific capacity of 841 mAh g −1 after 200 cycles at 0.1 A g −1 . Even at 0.38 A g −1 , the capacity could be still kept at 741 mAh g −1 after 250 cycles. The significant results might be attributed to the unique space grid structure and specific composition, including the CNT crossing-linked MnO for high dispersion of nanoparticles, abundant porous channels for electrolyte diffusion, excellent electronic conductivity for electron transport and durable structure for repeated electrochemical reactions. [ABSTRACT FROM AUTHOR]

To realize electrochemical impedance spectroscopy (EIS) using a simple measurement system, application of a square potential/current waveform to the input signals of EIS was investigated. The impedance of a simple redox reaction of [Fe(CN) 6 ] 4− /[Fe(CN) 6 ] 3− solution was measured by the potentio-EIS using a square waveform as the input signal, which was generated by a potentiostat system without a frequency response analyzer (FRA). A steady impedance response in the frequency range of 40 Hz–3.5 kHz was obtained, and the impedance was obtained by the potentiostat system with an FRA. The errors—the differences between the impedance measured by EIS with a square potential waveform and that of conventional EIS—were sufficiently low to allow impedance analysis. The impedance of a lithium-ion battery (LIB) was measured by galvano-EIS using a square waveform input signal generated by a power controller. A steady impedance response in the frequency range of 5 Hz–2.5 kHz was obtained, and the errors were sufficiently low to allow impedance analysis. It was demonstrated that both square potential-EIS (SP-EIS) and square current-EIS (SC-EIS) have great potential as simple systems for measuring impedance. Moreover, it was demonstrated that SC-EIS has potential as a simple measurement system for analyzing the state of an LIB. Thus, the potential of the SP/SC-EIS methodology was confirmed for electrochemical systems. [ABSTRACT FROM AUTHOR]

Construction of high-capacity anode is highly important for the development of next-generation high-performance lithium ion batteries (LIBs). Herein we fabricate Si/Ag nanowires/reduced graphene oxide (Si/Ag NWs/rGO) integrated composite film by introducing binary conductive networks (Ag NWs and rGO) into Si active materials with the help of a facile vacuum-filtration method. Active Si nanoparticles are homogeneously encapsulated by binary Ag NWs-rGO conductive network, in which Ag NWs are interwoven among the rGO sheets. The electrochemical properties of the integrated Si/Ag NWs/rGO composite film are thoroughly characterized as anode of LIBs. Compared to the Si/rGO composite film, the integrated Si/Ag NWs/rGO composite film exhibits enhanced electrochemical performances with higher capacity, better high-rate capability and cycling stability (1269 mAh g −1 at 50 mA g −1 up to 50 cycles). The binary conductive network plays a positive role in the enhancement of performance due to its faster ion/electron transfer, and better anti-structure degradation caused by volume expansion during the cycling process. [ABSTRACT FROM AUTHOR]

Layered-spinel composite cathode material Li 1.1 Ni 0.25 Mn 0.75 O 2.3 has been synthesized and cooled by different methods (naturally cooled within the furnace and cooled in liquid nitrogen). The effect of cooling methods on physical and electrochemical properties are discussed using the characterizations of X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM), X-ray photoelectron spectroscopy (XPS), electrochemical impedance spectroscopy (EIS), charge/discharge, cyclic and rate tests. The layered-spinel composite structure has been detected in Li 1.1 Ni 0.25 Mn 0.75 O 2.3 electrodes from the XRD patterns and TEM images. XPS results show that the content of Mn 3+ in the Li 1.1 Ni 0.25 Mn 0.75 O 2.3 cooled in liquid nitrogen is more than that of Li 1.1 Ni 0.25 Mn 0.75 O 2.3 cooled with furnace. The electrochemical performance results show that the Li 1.1 Ni 0.25 Mn 0.75 O 2.3 cooled in liquid nitrogen has higher initial discharge capacity, coulomb efficiency, better cyclic and rate performance compared with Li 1.1 Ni 0.25 Mn 0.75 O 2.3 cooled with furnace. EIS results show that the charge transfer resistance ( R ct ) of Li 1.1 Ni 0.25 Mn 0.75 O 2.3 cooled in liquid nitrogen is lower than that of Li 1.1 Ni 0.25 Mn 0.75 O 2.3 cooled with furnace. The improved cyclic and rate performances of Li 1.1 Ni 0.25 Mn 0.75 O 2.3 cooled in liquid nitrogen cathode are attributed to the lower R ct and more content of Mn 3+ . [ABSTRACT FROM AUTHOR]

Coordinated electrochemical effect between Li 3 VO 4 and NiO occurs in Li 3 VO 4 /NiO/Ni electrodes owing to the close potential regions of lithiation and delithiation for Li 3 VO 4 and NiO. Remarkably, Li 3 VO 4 /NiO/Ni with bottom nanowalls and upper micro-flowers architecture undergoes a novel coordinated electrochemical reconstruction owing to well coordinated morphology variation of Li 3 VO 4 and NiO in lithiation and delithiation process, which leads to the formation of a new symmetrical porous architecture in cycling, resulting in superior electrochemical performance. At a specific current of 70 mA g −1 , it exhibits discharge and charge capacity of 860 and 631 mAh g −1 in the initial cycle, maintaining of 612 and 604 mAh g −1 after 100 cycles. After 60 cycles at various specific currents from 54 to 2700 mA g −1 , the discharge and charge capacity can restore to 612 mAh g −1 when reverting the specific current to 54 mA g −1 . [ABSTRACT FROM AUTHOR]