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Cu and Fe are the main impurity elements in the hydrometallurgical regeneration of spent lithium‐ion batteries. Hence, it is important to study the effect of Cu and Fe doping on the structures and electrochemical properties of cathode materials. In this study, a series of Cu‐ and/or Fe‐doped LiNi0.8Co0.15Al0.05O2 cathode materials are synthesized by spray pyrolysis and high‐temperature solid‐state method. The inductively coupled plasma (ICP), X‐ray diffraction (XRD), and Rietveld refinement results reveal that Cu and Fe can incorporate into the crystal lattice and cation mixing is suppressed. The X‐ray photoelectron spectroscope (XPS) results show that the relative ratio of Ni2+/Ni3+ on the surface is effectively decreased. Electrochemical results display that the electrochemical performances of Cu‐ and/or Fe‐doped samples are improved when the atomic ratio of Ni to Cu and Ni to Fe is greater than 79.0 and 399.0, respectively. The dQ/dV, GITT, EIS, XRD, and XPS studies indicate that the structure stability, Li+ diffusion coefficient, and charge transfer can be increased by appropriate Cu and/or Fe substitution. The results suggest that appropriate Cu and Fe can be doped into LiNi0.8Co0.15Al0.05O2 as beneficial elements rather than removed as impurities. [ABSTRACT FROM AUTHOR]

To improve the stability of LiVPO 4 F electrode/electrolyte interface, Li 3 PO 4 is used to modify LiVPO 4 F composite (P-LVPF) for the first time. Morphological characterization shows that LiVPO 4 F particles are wrapped by amorphous carbon and lithium ionic conductor Li 3 PO 4 as the interlayer and outer layer, respectively. Compared to the pristine sample, the resultant P-LVPF exhibits greatly improved rate capability and elevated-temperature cycle performance when applied as the cathode material for lithium ion batteries. Specifically, the Li 3 PO 4 modified sample specific capacity maintains 77.6% at 1 C after 100 cycles under 55 °C. Such improvement is attributed to the fact that the Li 3 PO 4 coating layer not only acts as a good ionic conductor for LiVPO 4 F, but also serves as a physical barrier between electrode and electrolyte which can build a stable interface. [ABSTRACT FROM AUTHOR]

LiFe 0.6 Mn 0.4 PO 4 /C, due to its low cost and safety advantages, is gradually becoming a safe and reliable commercial lithium battery storage material. However, its lower capacity at high rates and poor cycle performance limit its further industrial application. To address this, this work used a one-step solvothermal method to prepare Li(Fe 0.6 Mn 0.4) 1‑x Nb x PO 4 (x = 0, 0.01, 0.02, 0.03) cathode materials to improve electrochemical performance. Characterization of the samples indicates that Nb doping promoted the growth of the material's [001] crystal orientation, thus enhancing the lithium ion diffusion rate, effectively reducing electrode polarization and charge transfer resistance, which helps to explain its excellent rate performance. More importantly, Nb doping increases the M-O bond energy, making the LMFP/C metal-oxygen framework more stable, and enhancing the stability of the crystal structure of lithium ions intercalating and deintercalating during cycling. The electrochemical test results further indicate that the LFMP/C Nb0.02 cathode exhibits excellent electrochemical performance. It has remarkable capacities of 156.9 mAh·g‑1 at 0.2 C and 135.9 mAh·g‑1 at 1 C, particularly showing an initial discharge specific capacity of 121.4 mAh·g‑1 at a high rate of 5 C. After 500 cycles, it still maintains a capacity of 114.3 mAh·g‑1, with a capacity retention rate of 94.15 %, significantly outperforming the original LMFP/C (initial discharge specific capacity of 109.8 mAh·g‑1) which only retains 61.47 % of its capacity after 300 cycles. [Display omitted] [ABSTRACT FROM AUTHOR]

In this paper, a material-oriented metallurgical electrolysis strategy, which is of such characteristics as short process, easy procedure, and nonpollution, is proposed to treat sodium sulfate wastewater and simultaneously prepare high value-added cathode material LiNi 1/3 Co 1/3 Mn 1/3 O 2 for lithium-ion batteries. The strategy is divided into two parts. First, the Ni 1/3 Co 1/3 Mn 1/3 (OH) 2 precursor is obtained by double membrane electrolyzing a mixed solution of Na 2 SO 4 , NiSO 4 , CoSO 4 , and MnSO 4 under the optimum electrolysis conditions (60 °C, 1.0 A). Furthermore, LiNi 1/3 Co 1/3 Mn 1/3 O 2 cathode is obtained through solid-sintering desulfurization. The change of sulfur content in the process and its effect on the morphology and electrochemical properties of the materials are investigated. Under optimum desulfurization conditions, the LiNi 1/3 Co 1/3 Mn 1/3 O 2 electrode delivers a high initial specific discharge capacity of 195.0 mAh·g−1 and a satisfying capacity retention of 85.0% after 120 cycles at 0.1 C in 2.5–4.5 V. This innovative strategy can realize the comprehensive utilization of sodium sulfate wastewater for preparation of Ni, Co, Mn-contained layered cathode materials. A material-oriented metallurgical electrolysis strategy, which is of such characteristics as short process, easy procedure, and nonpollution, is proposed to treat sodium sulfate wastewater and simultaneously prepare high value-added cathode material LiNi 1/3 Co 1/3 Mn 1/3 O 2 for lithium-ion batteries. [Display omitted] • A material-oriented metallurgical strategy is proposed for electrolysis of Na 2 SO 4 solution to prepare NCM. • A double-membrane electrolytic system is designed for simultaneously synthesis of precursor, NaOH and H 2 SO 4. • The correlation between the sulfur content of the material and its properties is verified. • Via desulfurization, the prepared cathode exhibits excellent electrochemical performance. [ABSTRACT FROM AUTHOR]

Abstract α-MoO 3 coated Li[Li 0.2 Mn 0.54 Ni 0.13 Co 0.13 ]O 2 electrode materials were obtained via a simple and effective wet chemical method. The results of X-ray diffraction (XRD), high-resolution transmission electron microscope (HR-TEM) and X-ray photoelectron spectroscopy (XPS) indicated that α-MoO 3 had been successfully coated on the surface of pristine materials. Charge-discharge measurements demonstrated that the α-MoO 3 thin layer could enhance the electrochemical performances. The initial coulombic efficiency improved from 75.7% to 89.6%, and the modified sample exhibited good cyclic performance of 87.0% at 100 mA g−1 after 100 cycles and 85.3% at 200 mA g−1 after 100 cycles with the excellent discharge properties. According to the analysis of electrochemical impedance spectroscopy (EIS) and cyclic voltammogram (CV), the largely enhanced electrochemical performance are mainly due to the restrain of the side reactions between electrode and electrolyte and the increased migration rate of Li+ between the electrode/electrolyte interface by α-MoO 3 film. Highlights • α-MoO 3 -coated sample shows significantly improved initial coulombic efficiency. • A Li+-free insertion host, α-MoO 3 , is coated on Li-rich Mn-based electrode material. • Superior cyclic performance and rate capability are obtained after Mo coating. • The mechanisms of Mo composites coating layer on improved performances are discussed in detail. [ABSTRACT FROM AUTHOR]

Li 2 ZrO 3 with three dimensional tunnels for Li + diffusion is introduced to improve the electrochemical performance of LiNi 0.8 Co 0.1 Mn 0.1 O 2 . The coating process is carried on the precursor rather than on the product. The Li 2 ZrO 3 coating layer with thickness of 10 nm has been detected by morphological observation. Electrochemical tests indicate that the Li 2 ZrO 3 -coating samples display better electrochemical performance than the bare sample. Especially, the 2% Li 2 ZrO 3 coated sample delivers desirable capacity retention of 94.5% after 200 cycles at 1C, which is superior to the bare one (82.5%). Furthermore, the 1% Li 2 ZrO 3 coated sample exhibits superior specific capacity of 144.3 mAh g −1 at 10C, much greater than the bare sample (107.4 mAh g −1 ). The cyclic voltammograms and electrochemical impedance spectra tests demonstrate that the Li 2 ZrO 3 -coated layer can cut down the electrochemical polarization of the materials and decrease the charge-transfer resistance in the cycling process. The XRD patterns and SEM images of the electrodes before and after 200 cycles reveal the Li 2 ZrO 3 -coated samples have more stable structure during cycling. [ABSTRACT FROM AUTHOR]

Developing thick electrodes is vital to achieving the requirement of next-generation of lithium-ion batteries (LIBs) with high energy density. However, the thick electrode suffers from severe polarization, which makes the investigation of its internal impedance and dynamics crucial. Herein, the three types of resistances (ionic transmission resistance, ohmic resistance, and contact resistance) dominated by the composition and microstructure of thick graphite anodes are systematically explored by utilizing electrochemical impedance spectroscopy measurements on the symmetrical cell. Firstly, the relationship between tortuosity (τ) calculated from ionic transmission resistance and porosity (ε) of electrodes is studied, which conforms to the deformed Bruggeman equation (τ = f ε − α ). And the effect of different morphologies of mesocarbon microbeads (MCMB) and flake graphite (FG) on tortuosity is analyzed, then the mechanism of improving the dynamics of thick graphite anodes through constructing vertical electrolyte channels is clarified. Secondly, the ohmic resistance produced by electronic transmission and by ionic transmission are quantitatively characterized separately. Thirdly, the factors affecting the contact resistance of electrodes are also discussed in detail, revealing that the contact area and electronic resistivity govern the contact resistance. This work contributes to preparing the thick electrodes with low resistances. • The relationship between tortuosity and porosity of electrodes was clarified. • Vertical electrolyte channels can improve the dynamics of thick electrodes. • The ohmic resistance was quantitatively characterized. • The contact area and electronic resistivity govern the contact resistance. [ABSTRACT FROM AUTHOR]

The cave-embedded porous Mn 2 O 3 hollow microsphere is synthesized from aqueous manganese chloride by a facile one-step spray pyrolysis. When evaluated as anode materials for LIBs, the as-obtained Mn 2 O 3 microsphere easily allows the electrolyte to penetrate into the hollow interior through the cave, providing more active sites and a shortened Li + diffusion pathway. As a result, the enhanced charge transfer and lithium ion diffusion kinetics is achieved. Furthermore, the special structure is able to mitigate the stress led by enormous volume variation and maintain the structural integrity during conversion reaction process. Benefiting from the special structural features, the Mn 2 O 3 microspheres with such smart architecture delivers a reversible capacity of ∼1000 mAh g −1 at 300 mA g −1 after 100th cycle, and maintains a high reversible capacity of 639 mAh g −1 at 1600 mA g −1 , showing better electrochemical performance than the conventional Mn 2 O 3 microspheres. [ABSTRACT FROM AUTHOR]

Because of the rich sodium reserves in nature, low cost, and high initial sodium content, O3-NaNi 0.5 Mn 0.5 O 2 material stands out from other cathode materials. However, O3-NaNi 0.5 Mn 0.5 O 2 shows poor kinetics and undergoes serious irreversible phase transitions, resulting in structural collapse and deteriorated cyclic performance. Herein, NaNi 0.5 Mn 0.5 O 2 material with distinguished cyclic and rate performance was prepared via spray pyrolysis combined with a high-temperature solid-phase sintering method, which can deliver a specific capacity of 98.4 mAh g−1 at 1 C between 2.0 and 4.0 V. After 100 cycles, it shows outstanding capacity retention of 89.1 %. Moreover, it can recover 70.4 % of the capacity of 0.1 C even at a high rate of 10 C. This newly proposed synthesis method provides an alternative method to prepare superior electrode materials for sodium-ion batteries. • A new synthesis method for NaNi 0.5 Mn 0.5 O 2 material is proposed. • The sintering temperature of NaNi 0.5 Mn 0.5 O 2 material is explored and optimized. • The reason of excellent kinetic properties of NaNi 0.5 Mn 0.5 O 2 material is investigated by EIS measurements and GITT tests. [ABSTRACT FROM AUTHOR]

The x LiVPO 4 F– y Li 3 V 2 (PO 4 ) 3 composite cathode materials have been synthesized through a soft chemical route with mechanical activation assistance followed by low-temperature calcination. Structural analysis indicates that two phases, i.e. monoclinic Li 3 V 2 (PO 4 ) 3 and triclinic LiVPO 4 F coexist in the composites. With the addition of LVP, the average particle size becomes smaller. The prepared composite materials show good electrochemical performance, and especially a good cyclic performance, the most suitable x / y ratio being 1:5 where the sample can deliver a reversible capacity of 139 mA h g −1 . [ABSTRACT FROM AUTHOR]

The effects of adding vinylene carbonate (VC) and vinyl ethylene carbonate (VEC) in a 1:1:1 (weight ratio) ethylene carbonate (EC)/diethy carbonate (DEC)/dimethyl carbonate (EMC) on the performance of LiMn 2 O 4 /Li cells at elevated temperature are studied. Linear sweep voltammetry (LSV), cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), inductively coupled plasma-atomic emission spectrometry (ICP-AES), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS) were used for the analyses. These results confirm the capability of the 1 wt.% VEC electrolyte additive to more effectively improve the cell cycling performance and stability in the (EC and DEC)-based electrolyte of LiMn 2 O 4 /Li cells. [ABSTRACT FROM AUTHOR]

Synthesizing spinel/layer Li-rich materials (SLLRs) is a promising way to improve the electrochemical performance of Li-rich material. In this work, the influence of introducing spinel phase into layered one on the coulombic efficiency is studied by electrochemical method. During CV testing, the composite exhibits no oxidation peak around 2.5–3.0 V when it starts with positive scanning, while demonstrates a reduction peak at ∼2.57 V as it begins with negative scanning. This means the spinel phase formed during the synthetic process is lithium-deficient, consuming lithium from lithium metal anode during discharge in Li-half cell. Charge-discharge results show that this spinel phase contributes to extra capacities when cells are discharged below 3.0 V, leading to a higher initial coulombic efficiency (ICE) of SLLRs in half cells. However, when tested in full cell using graphite as anode, ICE of SLLRs equals to that of Li-rich material while the capacity is lower. This is because that the graphite anode in full cell is unable to provide extra lithium ions and to compensate lithium deficiency of cathode material. Strategy like electrochemical pre-lithiation is suggested to improve the electrochemical performance of SLLRs in full cell. • The introduced spinel phase into layered one was lithium-deficient. • The fake high ICE in spinel-layer composite in half-cell was revealed by CV. • Electrochemical pre-lithiation promoted the application of SLLR in full cell. [ABSTRACT FROM AUTHOR]