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An O3 type Li0.6[Li0.2Mn0.8]O2 lithium-rich material has a high reversible capacity due to the synergistic oxidation and reduction of anion and cation. However, the anion oxidation reaction that compensates the charge leads to a partial release of oxygen and the collapse of the structure inevitably. Here, we improve the structural stability of Li0.6[Li0.2Mn0.8]O2 by simultaneously introducing Al ions and B ions. Al ions and B ions randomly occupy octahedral and tetrahedral positions, hindering the migration of Mn ions and expanding the unit cell, resulting in a stable structure and promoting Li+ migration. The co-doped sample has better electrochemical performance than the bare material, and the capacity retention increases from 62.48% to 82.48% after 80 cycles at 0.1C rate, and still provides a capacity of 226 mAh g−1 between 2 and 4.8 V.

LiMn2 O4 (LMO) cathodes suffer from limited cycle life, resulting from Mn dissolution and side reactions between electrode and electrolyte. In this study, Sr-modified LMO is prepared by using a simple strategy. The nature and position of large-radius Sr ions are investigated, alongside their influence on the structural stability of the bulk. SrMnO3 (SMO) is found to be enriched at grain boundaries of LMO, with Mn-O-Sr bonds forming at the SMO/LMO interface. Furthermore, stable SMO alleviates the migration of Mn ions in LMO associated with structural integrity and suppresses side reactions between the electrode and electrolyte. The modified LMO cathodes maintain their structural integrity and display improved rate performance and cycling stability under harsh conditions. Remarkably, the discharge capacity of a Sr-modified LMO||Li half-cell maintains 94.8 % at 25 °C and 79.6 % at 55 °C after 500 cycles. Consequently, enrichment of strontium at grain boundaries presents a promising strategy for developing cathodes for long-term use.

The copper/graphene (Cu/Gr) composites made of Gr/Cu/Gr foils with a thickness of 25 μm were prepared using spark plasma sintering diffusion bonding (SPS) and hot press diffusion bonding (HP) in an Ar atmosphere at 900 °C for 20 min under a pressure of 50 MPa. The electrical conductivity of the prepared Cu/Gr composites was measured by the van der Pauw method, the microstructure was characterized using Raman spectroscopy, scanning electron microscope and transmission electron microscope, and the corresponding mechanism was analyzed by employing the first-principles calculations. The result indicates that, SPS process reduces the interfacial impurities of Cu/Gr composites, rendering a much higher electrical conductivity (108.6% IACS) than that prepared by using HP (98.8% IACS). This finding is correlated to the reduced oxygen (O) impurities on Gr/Gr interface, which is attributed to the high temperature plasma sputtering effect of SPS. In the prepared Cu/Gr composites, the impurity-free Gr/Gr interface has an ideal spacing of ∼3.3 A wherein carbon (C) across the interface do not bond. Despite the generated C–C covalent bonding within the same Gr layer bounds some of the electrons, the remaining electrons of the p orbital on each C atom are free electrons, leading to the excellent electrical conductivity. In contrast, absorption of O impurities on the Gr/Gr interface increases the spacing between the Gr layers to ∼3.8 A, and generates covalent C–O–C bonding across the interface due to p orbital hybridization. This reduces the free electron concentration and the corresponding electrical conductivity.

LiNi0.8Co0.1Mn0.1O2 cathode material for lithium-ion battery exhibits high capacity, but it suffers from interfacial side reactions and structural/thermodynamic instability, which leads to capacity reduction and safety problems. Cubic brick (Ni0.8Co0.1Mn0.1)C2O4·2H2O particles with micron size are synthesized by co-precipitation method. The oxalic precursor is sintered with lithium hydroxide to obtain cubic mono-dispersion LiNi0.8Co0.1Mn0.1O2 micrometer particles. Structural stability, cycling performance, rate capability and compacting density of the cubic mono-dispersion material are investigated. Conventional spherical and irregular mono-dispersion LiNi0.8Co0.1Mn0.1O2 are also prepared for comparison. The results reveal that the cubic mono-dispersion LiNi0.8Co0.1Mn0.1O2 dramatically enhances the structural stability and cycling performance at a little cost of capacity and rate capability.

All-solid-state Li-ion batteries (ASSLBs) are promising systems to power electronic devices and electric vehicles for their high-energy density and safety. PEO-based composite electrolytes containing lithium salts and various fillers have been regarded as the most attractive solid electrolytes for ASSLBs due to their high interfacial compatibility with electrodes, high mechanical flexibility, and easy fabrication. For PEO/lithium salt/ceramic composite electrolytes, both “ceramic-in-polymer” and “polymer in ceramic” can be applied to solid-state batteries. “Ceramic-in-polymer” can provide high ionic conductivity but narrow electrochemical window; “polymer in ceramic” can provide wide electrochemical window but low ionic conductivity. In order to combine the high conductivity of “ceramic in polymer” with the wide electrochemical window of “polymer in ceramic,” we designed multilayer PEO/ Li6.4La3Zr1.4Ta0.6O12(LLZTO) composite electrolytes with low content of LLZTO (10wt %) in the inside layer and high content of LLZTO (40wt %) in the surface layer (PCEs-40–10-40) by a simple solution casting method. The PCEs-40–10-40 showed high ionic conductivity(4.61 × 10–4 $${\mathrm{S}\cdot \mathrm{cm}}^{-1}$$ ) and a wide electrochemical window(> 5.1 V) at 60 ℃. Compared with monolayer composite electrolytes, solid-state LiFePO4|Li batteries with multilayer composite electrolytes showed much better cycling stability (capacity retention of 98.8% after 200 cycles) at 0.5C and 60 ℃. This work shall give practical insights for the applications of PEO-based composite electrolytes.

The large-scale and efficient synthesis of MnPO4·H2O is an urgent problem to be solved. In this paper, self-assembled dumbbell-shaped MnPO4·H2O particles were successfully synthesized just using KMnO4 and commercial concentrated H3PO4, and then employed as the precursor to prepare LiMnPO4/C composites. The XRD, SEM, TEM, and electrochemical performance tests were used to investigate MnPO4·H2O and the corresponding LiMnPO4/C. The formation mechanism of MnPO4·H2O was discussed. The results showed that temperature and water content have a significant effect on the yield, purity, and morphology of MnPO4·H2O. The synthesized LiMnPO4/C with reduced carbon content at 650 °C delivered a discharge capacity of 109.3 mA h g-1 at 1 C and 104.3 mA h g-1 at 2 C. This green and efficient synthesis method of MnPO4·H2O provides a new idea for the large-scale preparation of LiMnPO4/C cathode materials.

Titanium and boron are simultaneously introduced into LiNi0.8Co0.1Mn0.1O2 to improve the structural stability and electrochemical performance of the material. X-ray diffraction studies reveal that Ti4+ ion replaces Li+ ion and reduces the cation mixing; B3+ ion enters the tetrahedron of the transition metal layers and enlarges the distance of the [LiO6] layers. The co-doped sample has spherical secondary particles with elongated and enlarged primary particles, in which Ti and B elements distribute uniformly. Electrochemical studies reveal the co-doped sample has improved rate performance (183.1 mAh·g-1 at 1 C and 155.5 mAh·g-1 at 10 C) and cycle stability (capacity retention of 94.7% after 100 cycles at 1 C). EIS and CV disclose that Ti and B co-doping reduces charge transfer impedance and suppresses phase change of LiNi0.8Co0.1Mn0.1O2.

A feasible, environment-friendly and economical method to regenerate a graphite anode from discarded lithium-ion batteries is carried out. The regenerated graphite (G-A-T-SGT@C) was obtained after the treatment of scrapped graphite (SGT) via pyrolyzation, acid leaching, graphitization and coating by amorphous carbon. As a result, G-A-T-SGT@C has negligible impurities, smaller specific surface area, reduced pore defects and much higher degree of graphitization compared with SGT, which will enhance the electrochemical performance of G-A-T-SGT@C. Consequently, lithium-ion batteries with the G-A-T-SGT@C anode exhibited a high initial coulombic efficiency of 90.64%, a high specific capacity of 344 mA h g−1 at 0.2C, excellent rate capability and eximious cycling performance for more than 250 cycles at 0.5C, which is also outstanding compared with the performance of lithium-ion batteries using commercial graphite as the anode.

P2-type Na0.67Ni0.25Mn0.75O2 is considered as one of the most promising cathode materials for sodium-ion batteries due to its high initial capacity and operating voltage based on the Ni2+/Ni4+ redox reaction. However, it suffers from rapid capacity decay caused by P2–O2 phase transition when the cutoff voltage is above 4.2 V (vs. Na+/Na). Herein, a high-voltage phase transition from P2 to an amorphous phase with poor crystallinity has been proved to be the main cause of material deterioration and Mn redox process is another cause. Cu-substituted Na0.67(Ni0.25Mn0.75)1−xCuxO2 (x = 0, 0.05, 0.1, 0.2) with active redox couples of Ni2+/Ni4+ and Cu2+/Cu3+ has been fabricated for solving these issues. It is proved that Cu substitution can reduce the Mn3+/Mn4+ reaction below 3 V (vs. Na+/Na) and suppress the high-voltage phase transition effectively at deep de-sodiated state, resulting in the significantly enhanced cycle life and rate capability of Na0.67Ni0.25Mn0.75O2.

LiMn0.8Fe0.2PO4 is a potential candidate cathode material to balance the energy density, safety, and cost of power lithium ion batteries. However, the low electronic conductivity and ion diffusion coefficient limit its application. Here, bimetallic oxalate Mn0.8Fe0.2C2O4·2H2O/graphene oxide (Mn0.8Fe0.2C2O4·2H2O/GO) is designed to synthesize homogeneously distributed LiMn0.8Fe0.2PO4/reduced graphene oxide/carbon (LiMn0.8Fe0.2PO4/rGO/C) composite. The influence of rGO on the morphologies, structure, and electrochemical performance of the as-synthesized composite is investigated. The composite LiMn0.8Fe0.2PO4/rGO/C delivers discharge capacity of 153.2 mAh g−1 at 0.05 C and 127.3 mAh g−1 at 5 C, and 97.2% capacity retention even after 300 cycles at 1 C. The results confirm that the introduction of rGO sheets can alleviate the agglomeration of LiMn0.8Fe0.2PO4 particles. Furthermore, the conductive network composed of rGO sheets and pyrolytic organic carbon links the particles together to improve the migration pathways of electrons and lithium ions, thus enhancing the electrochemical performance of LiMn0.8Fe0.2PO4/rGO/C.

The MMS-200 thermal simulation testing machine was used to study the static softening behavior of low carbon high niobium microalloyed steel. The effect of niobium to the static recrystallization softening behavior of the microalloy steel had been analyzed by establishing the kinetics model of static recrystallization and the micro-morphology of precipitates. The results indicated that: the static softening behavior of the tested steel significantly influenced by the deformation temperature and the interval pass time of the rolling processing. At relatively high deformation temperature and long interval pass time, the ratio of static softening was increased. Then the deformation temperature was lower to 950°C, and the static softening behavior of the test steel was ceased. But when the deformation temperature was higher than 1000°C, the static softening behavior of the test steel completely occurred. The activation energy of the test steel was 325·mol-1 by the established model calculated.

The antialcoholic drug disulfiram (DSF) has attractive biomedical interests for its anticancer effects, particularly in combination use with copper. CuET, the complex of copper and diethyldithiocarbamate (DTC) that is derived from disulfiram, exhibits high redox stability against glutathione, cysteine, and hydrogen peroxide, but appears reactive to ascorbic acid and superoxide ions. By virtue of the copper binding property, apoferritin is developed as a carrier of CuET to alleviate concerns of poor water solubility and nonspecific toxicity and shows superior stability and protection over human serum albumin in nanocomposite manipulation. CuET and doxorubicin are codelivered by apoferritin with excellent efficiency (97%). The glutathione-responsive system demonstrates enhanced antitumor effect and potentials for combination tumor therapy.

Ni-rich layered LiNi0.8 Mn0.1 Co0.1 O2 (NCM811) cathode material has promising prospects for high capacity batteries at acceptable cost. However, LiNi0.8 Mn0.1 Co0.1 O2 cathode material suffers from surface structure instability and capacity degradation upon cycling. In this study, in situ ZrP2 O7 coating is introduced to provide a protective structure. The optimum modification amount is 1.0 wt %. A series of characterization methods (X-ray diffraction, high-resolution transmission electron microscopy, and X-ray photoelectron spectroscopy) verify the generation and structure of the coating layer. Electrochemical performance tests demonstrate that the cycle retention rate increases from 66.35 to 86.92 % after 100 cycles at 1 C rate. The dense inorganic pyrophosphate layer not only has chemical stability against the electrolyte but also eliminates surface residual lithium. The protective layer and the matrix are strongly joined by high-temperature heating, thereby giving a certain mechanical strength and protecting the overall structure of the topography. Therefore, the cycle and rate performance are enhanced by the modification with ZrP2 O7 .

The lithium-rich manganese cathode material Li2MnO3·LiMO2 (M = Mn, Co, Ni, Fe, etc.) has been received extensive attention for Li-ion batteries owing to its ultra-high specific capacity (>250 mAh g−1) and lower cost. Nevertheless, it is still strictly challengeable to achieve encouraging Li-storage behaviors due to its poor cyclability, rate performance, and voltage decay. Li-rich manganese cathode material Li1.2Mn0.54Ni0.13Co0.13O2 (LRNCM) modified by a novel hybrid conductive layer constructed with Li1.4Al0.4Ti1.6(PO4)3 (LATP) and polyaniline (PANI) is prepared. The hybrid modification layer (LATP&PANI) not only serves as a physical barrier to protect the active material from the electrolyte, but also combines the high ionic conductivity of Li1.4Al0.4Ti1.6(PO4)3 with the excellent electronic conductivity of polyaniline, helping for facilitating the transfer of electrons and lithium ions. The hybrid modification cathode material (LRNCM@3 wt%LATP@1 wt%PANI) displays favorable rate capability and cycle performance, whose capacity retention (2.0–4.8 V at 0.2 C, 25 °C) deliveries 79% after 200 cycles. The hybrid modification is a promising route for remarkable enhancement in performance of the lithium-rich manganese-based cathode materials.

The (1-x)LiFePO4·xLiVPO4F/C (x = 0, 0.05, 0.10, 0.20, 0.40, 0.60, 0.80, 1) composites with high rate performance were successfully prepared by an improved solid-phase method. Their physicochemical properties were characterized by different test instruments. Through X-ray Diffractometer and structural refinement, it was found that modification with certain amount of LiVPO4F on the LiFePO4 material induced bi-phase co-existence with mutual doping. By Scanning Electron Microscope and Transmission Electron Microscopy detection assisted with Energy Dispersion Spectrum and Fast Fourier Transform analysis, it can be confirmed that the composite material was evenly distributed. Sample 0.9LiFePO4·0.1LiVPO4F/C had the highest specific capacity and specific energy in all samples, with its discharge capacity of 137.4, 129.0, 121.4, 109.6 and 94.0 mAh g−1 at the rate of 3C, 5C, 7C, 10C and 15C, respectively. Furthermore, at the rate of 15C, the specific energy of 0.9LiFePO4·0.1LiVPO4F/C was more than 2 times of that of sample LiFePO4/C. After 800 cycles at 10C, the capacity retention ratio still maintained at 91.42%. Compared with the untreated material, sample 0.9LiFePO4·0.1LiVPO4F/C possessed smaller impedance and larger lithium diffusion coefficient, which is conducive to improve the electrochemical properties of LiFePO4 materials. It indicated that the heterogeneous double active phase shows good synergistic effect.

WO3 modified LiNi0.8Co0.1Mn0.1O2 materials were got by a wet method. Structure parameters, micromorphology, element distribution of the modified and bare NCM materials were compared by different detection methods, such as XRD, SEM, EDS and TEM. The results reveal that there was no significant change in morphology before and after modification, and the distribution of tungsten was relatively uniform. In addition, tungsten oxide surface modification layer does exist by TEM, FFT and XPS analysis, and affects the distribution and valence states of surface elements. Furthermore, it is found that the micro amount of tungsten oxide modified NCM material is beneficial to the improvement of rate performance and cycle stability, especially at high cutoff voltage. Then the effect of modification on the electrochemical properties was conducted by CV, EIS and SEM detection after cycle. It is displayed that the particles after modification have no cracks, and the polarization and impedance decrease to varying degrees. This simple and feasible method has a good prospect for improving the cyclic stability of Ni-rich materials.

LiMnPO4 cathode material has a high voltage platform and matches the existing electrolyte window, and thus researchers are constantly shifting their focus from LiFePO4 to LiMnPO4. However, LiMnPO4 has lower electron (ion) conductivity than LiFePO4, and besides, its delithiated phase MnPO4 will suffer thermal decomposition at lower temperatures more easily than FePO4. In order to effectively solve the above problems by elements substitution, DFT calculations are employed to screen for suitable dopants from a series of transition metals including Fe, Mg, Ni, V, Nb, Ti. Properties such as electronic structure, atomic Bader charge, O2 evolution Gibbs free energy, average voltages, and lithium ion diffusion energy barrier were evaluated. Based on the calculation, Fe is the most effective doping element because Fe doping is able to reduce the band gap of the material and improve the electronic conductivity, suppress the O2 evolution reaction of the delithiation phase and improve the thermal stability. The reason for such a situation is that Fe can form a stronger covalent bond with the surrounding O atoms to bind the escape of O. Fe doping reduces ion diffusion energy barrier to promote lithium ion diffusion. Electrochemical tests show that Fe doping can improve the electrochemical properties of LiMnPO4.

LiFePO4 cathode material is considered as prospective materials for lithium-ion batteries and attracted great interest because of excellent cyclic performance and environmentally friendliness. However, LiFePO4 material suffers from inferior electronic and Li+ conductivity, which restricts its performance at high rate. Improving the interfacial stability and the interfacial charge transfer of the electrode is a necessary method to enhance the cycle and rate capability. Herein, vanadium oxide decoration on LiFePO4/C composites was obtained via a simple wet chemical method. The results show that a moderate amount of vanadium oxide hybrid stabilizes the structure of the matrix LiFePO4 material. Vanadium oxide and the residual carbon coating construct a mixed conductive network, which optimizes the interface structure and reaction dynamics of the electrode. In addition, the charge transfer resistance of the decorated hybrid is smaller and the Li+ diffusion ability is better than pristine LiFePO4/C material. Moreover, the electrochemical performance exhibits a promising high rate capability and perfect cycle ability, showing the discharge specific capacities of 157.2, 150.6, and 131.1 mAh g−1 at 0.1 C, 1 C, and 3 C respectively. Furthermore, the capacity retention reached 90.9% after the 1000th cycle at 3 C.

Cracking carbon, grapheme as well as carbon nanotube co-modified LiVPO4F material (LiVPO4F/C/G/CNT) and cracking carbon modified LiVPO4F material (LiVPO4F/C) were respectively prepared by a two-step process. Physicochemical properties, electrochemical datas and kinetic parameters of LiVPO4F/C/G/CNT and LiVPO4F/C materials were obtained by various detection means. X-ray diffraction analysis (XRD) demonstrates that co-modification of multi-level carbon cannot change fundamental crystallographic structure of LiVPO4F/C/G/CNT material. Scanning electron microscopy (SEM) and High resolution transmission electron microscopy (HRTEM) synergistically reveal that cross-linked network structures formed by cracking carbon, grapheme and carbon nanotube are evenly distributed among the LiVPO4F particles, helping for charge transfer throughout the inside and outside of cathode materials. Compared with LiVPO4F/C material, the LiVPO4F/C/G/CNT material possesses many advantages such as higher discharge specific capacity, higher charge-discharge rate performance, smaller charge transfer impedance (Rct), and higher Li+ diffusion coefficient (DLi+), indicating that the LiVPO4F/C/G/CNT cathode material prepared by a two-step process shows better potential application prospect for lithium batteries.

In this paper, the micro-sized Fe2P2O7/C composites have been successfully prepared by rheological phase method using Fe2O3, H3PO4 and glucose as raw materials. Then, the prepared Fe2P2O7/C is used as a precursor to synthesize LiFePO4/C. The synthesis process of Fe2P2O7/C-dynamic composites is assisted by dynamic calcination. The corresponding LiFePO4/C-dynamic composites exhibit excellent physicochemical performance confirmed by XRD, SEM, TEM, CV, EIS, Elements detection and cyclic tests. The results indicate that the LiFePO4/C-dynamic sample is well-distributed in element level and possesses uniform monodisperse morphology. In addition, it delivers a discharge capacity of 157.1, 146.6, 138.0 and 130.2 mAh g−1 at the rate of 0.2, 1, 2 and 3 C, respectively. Meanwhile, it can retain 99.52% of the initial capacity after 300 cycles at 1 C, exhibiting an excellent cycling stability. The study reveals that the assisting method of dynamic calcination is highly efficient to synthesize Fe2P2O7/C materials with better performance, and eventually, fabricate high performance LiFePO4/C composites for lithium-ion batteries.

The surface-fluorinated Li4Ti5O12 nanowires/reduced graphene oxide composite is synthesized through a hydrothermal procedure. Lithium ion transport is promoted by forming a special morphology of lithium titanate nanowires, meanwhile, electronic transmission is facilitated by surface fluorination and conductive network of graphene coating. These three kinds of synergistic effects greatly improve the rate performance of lithium titanate. The surface-fluorinated Li4Ti5O12 nanowires/reduced graphene oxide composite exhibits high specific capacities (167.5 mAh g−1 at 1 C and even 132.6 mAh g−1 at 10 C) and good cyclic stability (95% capacity remain after 300 cycles at 5 C). The influences of surface fluorination and graphene coating on electrochemical performance of lithium titanate are investigated in detail in terms of reversible capacity, cyclability and rate capability. Its excellent electrochemical properties make it become possible to be a potential anode material for high-rate lithium-ion batteries applied in high power facilities.

Different content of Ti4+ has been successfully doped into the lattice sites of Cr3+ in NaCrO2 by the two step solid-state reaction. The analysis results of crystal structure demonstrate that the interslab (NaO2) spacing is increased with Ti doping content, which contributes to widening the sodium ion migration channel and then facilitating the rapid (de)intercalation capability of sodium ions. During charge-discharge processes, these O3-Na1-xCr1-xTixO2 (x = 0.03, 0.05, 0.1) layered oxides exhibit delayed O3-P3 phase transition and increased average discharge voltage due to stronger Ti-O bond relative to Cr-O bond. In particular, the Na0.95Cr0.95Ti0.05O2 shows the optimal electrochemical performance which releases a discharge specific capacity of 96.7 mAh g−1 at 1 C (100 mA g−1) with 80.1% capacity retention after 800 cycles. Even under the high rate of 30 C, it can deliver a discharge specific capacity of 67 mAh g−1.

LiMnPO4/C with hierarchical spindle structures was synthesized by a facile solvothermal method at 180 ℃ for 10 h. The morphology and structure of the prepared materials were controlled through the adjustment of hexamethylenetetramine (HMT). The synthesized materials were investigated by means of X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Quantachrome instrument(Quabrasorb SI-3MP) and Fourier transform infrared spectroscopy (FTIR), and so on. The prepared LiMnPO4/C exhibits good electrochemical performance, for instance, there are 153.2, 126.3, 110.2 mA h g−1 at 0.05 C, 1 C, 2 C respectively. The promising properties of the materials results from unique hierarchical nanostructures and the uniform thin carbon coating of particle surface, which improve the ionic and electronic transfer of LiMnPO4.

The micro-nanosized LiFePO4/carbon particles have been successfully prepared via a novel mechanical milling process and subsequently carbothermal reduction reaction, using Fe powder, H3PO4, Li2CO3 and glucose as the reactants. Notably, the milling process is assisted by ultrasonic treatment. XRD, SEM, TEM and particle size detection are operated to investigate the structure, morphology and particle size distribution of the as-prepared products. The electrochemical performances are studied by CV, EIS and cyclic tests. The results show that the LiFePO4/carbon-ultrasonic-assisted particles are granular and uniformly distributed with high crystallinity, and the mean size of LiFePO4 powder is about 220 nm. The composite exhibits an excellent electrochemical performance and its initial discharge capacity reaches approximately 156.8, 149, 138, 128 and 119 mAh g−1 at rates of 0.2, 1, 2, 3 and 5 C, respectively. Meanwhile, it can keep the discharge capacity retention of 99.7% over 300 charge/discharge cycles at 1 C.

Herein, partially reduced graphite oxide (PRGO) was prepared by the thermal reduction of GO at 220 °C and investigated as a cathode material for lithium-ion batteries. After an initial galvanostatic charging process to 5.2 V, the PRGO shows a high capacity of 230 mA h g−1, and the capacity retention can reach approximately 90% even after 8000 cycles at 1 A g−1. XPS, Raman spectroscopy, FTIR spectroscopy and TEM analysis showed that the active oxygen functional groups obviously increased after electrochemical activation; this was considered the reason for the increase in capacity. In this study, we demonstrated a novel strategy for the preparation of high-performance organic cathode materials for lithium-ion batteries.

Lithium vanadium fluorophosphate (LiVPO4F) composite with three-dimensional conductive networks architecture is synthesized with synergistic modification of pyrolytic carbon (C), multi-walled carbon nanotubes (MWCNTs) and graphene sheets (rGO). The differences between LiVPO4F@C, LiVPO4F@C/MWCNTs, LiVPO4F@C/rGO and LiVPO4F@C/MWCNTs/rGO composites are compared through a variety of characterization means. By means of SEM and TEM analysis, it can be seen that pyrolyzed C, MWCNTs and rGO are interwoven, which forms a three-dimensional conductive network structure wrapping the LiVPO4F particles. The difference of discharge specific capacity between LiVPO4F@C and LiVPO4F@C/MWCNTs/rGO composites is becoming larger and larger with the increase of charge-discharge rate. Additionally, CV and EIS results indicate that the LiVPO4F@C/MWCNTs/rGO has the smallest polarization value and charge transfer impedance (Rct) as well as the highest diffusion coefficient of lithium ion (DLi+) in all samples. Consequently, LiVPO4F@C/MWCNTs/rGO composite exhibits a high rate capability (97.9 mAh/g cycles at 10 C) and cycling stability (93.74% capacity retention over 800 cycles at 10 C)，showing potential application for high power LIB with high voltage.

We show the first experimental implementation of biosensing using high contrast reporter cleavage detection (HCRCD). HCRCD makes use of dramatic signal amplification caused by cleavage of high-contrast nanoparticle labeled reporters instead of the capture of low-index bio- molecules.

A highly time-efficient approach based on liquid nitrogen quenching technique has been developed to synthesize over-lithiated oxide Li[Li 0.2 Mn 0.54 Ni 0.13 Co 0.13 ]O 2 . The improved morphology and crystal structure, as confirmed by X-ray diffraction (XRD) patterns, scanning and high-resolution transmission electron microscope (SEM and HRTEM), endow the material with impressive electrochemical performance. The as-prepared material shows a capacity of 265 mAh g −1 at 0.1 C. It almost exhibits no capacity fading and its working voltage is stabilized within a decaying variation of 0.05 V after 100 cycles at 0.1 C. The results indicate an immense potential of application of this technique for over-lithiated oxide as cathode material for lithium ion batteries.

Ni-rich cathode material attracts a substantial amount of attention due to its high specific capacity, superior energy density and low cost. Nonetheless, there are still a few intrinsic issues which need to be solved including rate performance, cycling stability, elevated-temperature performance, etc. In this paper, the graphene-analogous structural MoS2 with chemical stability and acceptable conductivity is purposefully introduced to modify LiNi0.8Co0.1Mn0.1O2 cathode material via a facile wet-chemical approach followed by low-temperature reaction. In addition, lithium-active MoS2 coating layer can provide an interconnected and stable tunnel for the insertion and extraction of lithium ions. Characterizations by X-ray diffraction, X-ray photoelectron spectroscopy, Raman, scanning electron microscopy and transmission electron microscopy demonstrate that MoS2 coating layer is uniformly deposited on the surface of LiNi0.8Co0.1Mn0.1O2 material. The electrochemical results indicate that the modified cathode material displays excellent structure stability, superior rate performance and outstanding cycling properties.

WO3-coated Li1.2Ni0.2Mn0.6O2 cathode materials have been synthesized by using co-precipitation method along with a liquid-evaporation coating process. Investigations via X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS) reveal that a WO3 layer is uniformly distributed on the surface of bulk Li1.2Ni0.2Mn0.6O2. After coating appropriate amount of WO3, the Li-rich cathode materials exhibit improved electrochemical performance. In particular, the 2 wt% WO3 coated sample (WO3-0.02 LLNMO) can deliver an initial discharge capacity of 252.2 mA h g-1 with a low irreversible capacity loss of 44.6 mA h g-1 and remarkable cycling stability of 97% capacity retention after 100 cycles at a current density of 52 mA g−1. This is mainly due to the effects of the WO3 coating layer which can suppress the initial activation of Li2MnO3 and improve the stability of surface structure of Li-rich materials by protecting it from corrosion by HF and other side reactions.

Super-hydrophobic materials for oil/water separation are usually prepared from non-renewable feedstocks, which does not coincide with the sense of sustainable development. Herein, we report a sustainable super-hydrophobic material fabricated via a simple spray-coating method from biobased feedstocks including epoxidized soybean oil, sebacic acid, stearic acid, zinc oxide and cotton fabric. Rough surface structure was successfully constructed by spraying epoxidized soybean oil (ESO) with sebacic acid (SA) and nano-ZnO. After modification with stearic acid (STA), the surface became super-hydrophobic with a water contact angle (WCA) of 155°. The super-hydrophobic fabric shows excellent stability without losing super-hydrophobicity after immersion in water and oil for several days. The super-hydrophobic fabric can selectively separate water mixtures with various oily liquids with separation efficiency higher than 97.5%. With high separation efficiency and excellent stability, the biobased super-hydrophobic fabric can be used as a sustainable and eco-friendly oil/water separation material.

The LiV1-xCoxPO4F/C (x = 0, 0.01, 0.03 and 0.05) composite cathode material for lithium ion batteries has been successfully prepared through the modified solid state method assisted by sonication and mechanical activation. Here, the influence of cobalt doping on the physical and electrochemical performances are investigated. In this paper, we adopted the X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscope (SEM)/energy dispersive spectrometer (EDS), cycle voltammetry (CV), electrochemical impedance spectrum (EIS) and charge-discharge test to investigate the influence of cobalt doping on the different aspects of the materials, including the physical and electrochemical properties. Compared with the original simple, the cycle and rate performance of cobalt doped samples has increased to some extent. We found that the LiV0.97Co0.03PO4F/C sample showed the best electrochemical performance. The lithium ions diffusion constant (DLi+) of the LiV0.97Co0.03PO4F/C (1.86321 × 10−13 cm2 s−1) is much higher than that of LiVPO4F/C (2.06453 × 10−14 cm2 s−1).

Using traditional co-precipitation method accompanied by the subsequent calcination treatment, spherical pristine LiNi0.6Co0.2Mn0.2O2 (P-LNCM), and LiNi0.6Co0.2Mn0.2O2 co-doped with Zr and Er (EZ-LNCM) cathode materials are successfully synthesized. Powder X-ray diffraction (XRD), scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), and X-ray photoelectron spectrometry (XPS) reveal that EZ-LNCM material exhibits some better potential crystal structural feature than P-LNCM material, mainly including the decreased Li+/Ni2+ disorder, the enlarged migration tunnel of Li+, the reduced content of Ni2+ in the surface and lower residual impurities. Within the voltage range of 2.8–4.5 V, the initial discharge capacity of EZ-LNCM at 0.1C is 208 mAh g−1, and the cycle retention at 1C after 200 cycles for EZ-LNCM electrodes maintains 90.03%, which are higher than those of P-LNCM. Results based on cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) measurements, morphology and structure of cathode material reveal that co-doping can alleviate irreversible phase transformation and stabilize structural integrity, which benefits rapid speed for Li+ transfer and reduces impedance rise for the better electrochemical properties of EZ-LNCM.

In order to improve the electrochemical performance of LiMn2O4 at elevated temperatures, a series of Li1.2Ni0.2Mn0.6O2-modified LiMn2O4 samples have been synthesized by a facile sol-gel method. The structure and morphology of pristine and modified LiMn2O4 are investigated by X-ray diffraction (XRD) and scanning electron microscopy (SEM), respectively. The Li1.2Ni0.2Mn0.6O2 coating layer is identified by transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS), which plays an important role in reducing the dissolution of manganese, thereby improving the cycle performance and rate capability of the material. The 2 wt% Li1.2Ni0.2Mn0.6O2-modified LiMn2O4 sample exhibits a higher capacity retention of 95.88% than that of the pristine one (81.2%) after 200 cycles at 1C and 25 °C. Furthermore, a capacity retention of 89.74% is obtained for the 2 wt%-modified LiMn2O4 sample after 200 cycles at 1C and 55 °C, compared to 66.34% for the pristine one. Surface modification with a Li-rich Li1.2Ni0.2Mn0.6O2 material is a good way to improve the elevated temperature performance of LiMn2O4.

Herein, for the first time, the visible-light-driven 2D/1D Ti3C2/CdS nanorods composites were fabricated by electrostatic assembly strategy to achieve efficient uranium(VI) photoreduction without any sacrificial agents. While CdS is the main catalyst, Ti3C2 in the composites acts as a Janus co-catalyst for the photoreduction of uranium(VI), in view of the fact that it can simultaneously enhance the photocatalytic performance and the stability of CdS. With the initial uranium(VI) concentration at 50 ppm, 97% uranium(VI) reduction efficiency was achieved by the optimal Ti3C2/CdS composites during 40 min visible light irradiation without any sacrificial agents. The kinetic reaction rate reaches as high as 1520 μmol/(g·h). Meanwhile, the Ti3C2/CdS composites keep high performance regardless of acidic, neutral and alkali conditions. The findings of this work highlight the vast opportunities for Ti3C2/CdS composites in the treatment of radioactive wastewater.

Ni0.6Co0.2Mn0.2(OH)2 with unique morphology of dispersed hexagonal slab particles is synthesized via the hydrothermal method, which reacts with lithium hydroxide to form single-crystalline LiNi0.6Co0.2Mn0.2O2 (SC-NCM) after a simple sintering process. Scanning electron microscopy, X-ray diffraction and transmission electron microscopy testify the micrometer-sized SC-NCM particles display well-ordered layered structure with excellent crystallinity. Electrochemical characterization demonstrates that the LiNi0.6Co0.2Mn0.2O2 sample performs excellent capacity retentions of 93.2% (2.8–4.3 V) and 89.6% (2.8–4.5 V) after 100 cycles at a current rate of 1 C. In particular, LiNi0.6Co0.2Mn0.2O2 displays extraordinary rate property (174.5 mAh g−1 at 0.1 C and 130.7 mAh g−1 at 5 C). Therefore, it may provide a new method for the preparation of single-crystalline LiNixCoyMnzO2 materials with superior electrochemical performance.

A green strategy is designed for synthesizing LiMn0.8Fe0.2PO4/C composites bases on mechano-chemical liquid-phase activation technique. The micro-nano spherical precursor is prepared by the effective redox reaction between MnO2 and H2O2 in H3PO4 aqueous solution with subsequent addition FeC2O4•2H2O and Li2CO3, which is followed by spray drying. The dense LiMn0.8Fe0.2PO4/C microspheres are formed from conformal carbon coating connected with primary nano-sized particles, which provides rapid electron and ion transport pathways during the electrode reaction. The obtained LiMn0.8Fe0.2PO4/C cathode exhibits reduced electrochemical polarization with high voltage platform and high discharge capacity of 159 mAh g −1 at 0.1 C. Even at high rate of 10 C, the composite shows an impressing discharge capacity of 130 mAh g −1 with obviously stable plateau. Besides, uniformly conductive carbon network distributed all over the primary nano-sized particles effectively inhibits the occurrence of interfacial side reactions during electrode cycling, and the electrode exhibits good cycling stability with capacity retention rate of 95% after 500 cycles at 1 C. This work provides a scalable route to fabricate high energy density LiMn0.8Fe0.2PO4/C cathode with excellent rate performance for Li-ion battery.

A facile in-situ hydrolytic coating strategy has been suggested to architecture LiAlSiO4 (LASO)-coated LiNi0.8Co0.1Mn0.1O2 (LNCM) cathode material for lithium-ion batteries. Homogeneous LASO coating layer, as an one-dimensional lithium ion conductor, on the surface of LNCM is observed clearly and ascertained jointly by several testing methods. The effects of LASO coating layer on physicochemical properties, electrochemical properties and electrochemical kinetics of LNCM cathode material have been rigorously investigated by various tests. The cycling stability, rate capability and Li+ ion diffusion rate are enhanced evidently after LASO coating. Moreover, the polarization, impedance increase and particles cracking after cycles under the high cut-off voltage are greatly improved. These effective and obvious improvements are ascribed to the LASO coating layer, which could effectively inhibit the occurrence of side reactions and HF erosion and provide a fast ion diffusion channel for lithium ions on the surface of LNCM.

Graphene oxide (GO) is the key for the large-scale production of graphene by chemical oxidation-thermal reduction route. However, the current synthesis methods of GO involve concentrated sulfuric acid and potassium permanganate, which poses a risk of explosion and potential environmental pollution. Furthermore, a large number of oxygen-containing functional groups cause GO sheets to swell, posing a major challenge to the purification process. In this paper, a one-pot hydrothermal method is developed to synthesize pre-reduced graphene oxide (PRGO). The precursor is then employed to produce reduced graphene oxide (RGO) by further high-temperature thermal reduction. It not only avoids the complex temperature control and dilution operations during the oxidation and exfoliation processes but also enables the recycling of sulfuric acid. The synthesized weakly hydrophilic PRGO is highly conducive to achieve rapid filtration, which simplifies the purification process. The obtained reduced graphene oxide exhibits high rate capability and stable long cycling performance as the anode of lithium-ion batteries. This simple, safe and green synthesis route paves the way to large-scale preparation of graphene and its application for Li-ion storage.

Copper and cobalt are two of the most valuable metals that can be recovered from copper converter slag. In the reduction–vulcanization process, copper is reduced before cobalt, while FeS vulcanizes Cu2O into Cu2S and forms the matte phase. The matte phase can dissolve the reduced metals as solvent. In this study, the distribution coefficient of cobalt between metallic cobalt in matte and CoO in slag, namely L Co, was calculated to be 5000–8500 at the reaction temperature of 1600–1700 K, while the distribution coefficient between CoS and CoO, namely $$L_{\text{Co}}^{{^{\prime } }}$$ , was calculated to be between 6 and 8. The distribution coefficient of copper between metallic copper in matte and Cu2O in slag, namely L Cu, was calculated to be in the range of 7500–8500, while the coefficient between Cu2S and Cu2O, namely $$L_{\text{Cu}}^{{^{\prime } }}$$ , was calculated to be in the range of 60,000–75,000.

Ni-based layered LiNi0.5Co0.2Mn0.3O2 (NCM) compounds coated with lithium titanium oxide for lithium ion batteries were successfully achieved through a simple solid state synthesis process using TiO2 powder and CH3COOLi. Systematical measurements in structure, morphology and electrochemical properties have been applied. X-ray diffraction patterns showed the existence and conversion of lithium titanium oxide (Li4Ti5O12 and Li7Ti5O12 are labeled as LTO). A coating layer in the form of LTO could be observed and the thickness was approximately 10 nm with uniform distribution. Similarly, XPS was performed to confirm the existence of LTO. 1.0 wt.% LTO-coated NCM material exhibited higher capacity retentions of 91.0% than that of the bare one (64.3%) after 100 cycles at cutoff voltages of 4.5 V. Meanwhile, the LTO-coated NCM material showed significantly improved thermal stability compared with the pristine sample at an elevated 60 °C. In addition, it has proved that it is effective to enhance the electrochemical performances of electrodes by LTO modification.

A high performance 9LiFePO4–Na3V2(PO4)3/C composite is successfully prepared by a sol–gel technique followed by subsequent carbonthermal reduction process. The structure and performance of 9LiFePO4–Na3V2(PO4)3/C composite have been investigated by XRD, SEM, TEM, EDS, CV and EIS. The result shows that the Na3V2(PO4)3 acting as ionic conductor improves the lithium ion transmission rate, while a thin amorphous carbon layer on the surface of nanoparticles and interfacial structure between the two phase enhances the electronic transmission rate of the composite. The synergistic effect of continual conductive carbon network and Na3V2(PO4)3 phase facilitates the diffusion of lithium ion and electron, ensures the stability of the LiFePO4 nanoparticles by limiting the direct contact of LiFePO4 particle with the electrolyte and ultimately improve the rate capability and long-cycling life of the material. The 9LiFePO4–Na3V2(PO4)3/C composite delivers discharge capacities of 151.2, 144.9 and 118.1 mA h g− 1 at 1.0, 2.0, 5.0 C, respectively, with high capacity retention up to 88.2% after 2000 cycles at 2.0 C, exhibiting good electrochemical performance compared with that of the pristine one.

To improve the operating voltage and the rate performance of LiFePO4, the different ratios of the xLiFePO4·(1−x)Na3V2(PO4)2F3/C (LFP-NVPF/C) are synthesised via a carbothermal reduction method. The structure and morphology of the composite are analysed by X-ray diffraction (XRD) and electron microscopy. The as-prepared material is composed of a mixture of two phases: V-doped LFP and Fe-doped NVPF. Electrochemical tests show that the molar ratio of 9:1 is the optimum composition and the LFP-NVPF/C (x = 0.9) composite exhibits excellent performance with an initial discharge capacity of 151.2, 146.5, 120.6 and 100.2 mAh g−1 at 1.0, 2.0, 5.0 and 10 C, respectively, which is higher than that of single phase LFP/C, especially at high rates. According to the cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS), the introduction of NVPF improves charge transfer and Li+ diffusion of LFP/C and provides excellent cycle stability at high rates.

Ni-based LiNi0.6Mn0.2Co0.2O2 cathode material is successfully clothed by an ordered olivine-type and homogeneously distributed LiCoPO4 nano-coating layer via a convenient sol-gel method. The olivine structured skin with superior chemical and thermal stabilities can restrain oxidative decomposition of the electrolytes, avoid detrimental crystal structure transformation and improve diffusion kinetics of Li ions and charge transfer dynamic on the interface. Consequently, in comparison with the uncoated sample, the cyclic properties of the modified material is enhanced dramatically even at high rate under high charge cut-off voltage. A capacity retention of 93.6% during 100 cycles is obtained from LCP-coated electrode between 3.0 and 4.5 V at 2 C rate, which is obviously higher than the pristine one.

LiNi 0.8 Co 0.15 Al 0.05 O 2 crystals with ∼4 μm particle size have been synthesized from spherical Ni 0.8 Co 0.15 Al 0.05 (OH) 2 precursors via a two-step treatment strategy. A specific surface area controllable precipitation method was introduced to synthesize Ni 1-x-y Co x Al y (OH) 2 hydroxides with large specific surface area. Spherical hydroxides with large specific area and excess LiOH calcination technique ensure the LiNi 0.8 Co 0.15 Al 0.05 O 2 crystals with mono dispersed micrometer scaled particle distribution and perfect α-NaFeO 2 layered structure. Water washing process wipes off the LiOH and Li 2 CO 3 impurities from the cathodes efficiently without structural degradation. The LiNi 0.8 Co 0.15 Al 0.05 O 2 prepared via 15% excess lithium calcination presents an improved compacting density of 3.8 g cm −3 . The modified cathode material shows an initial discharge capacity of 174.5 mAh g −1 at 1C rate and 91.7% capacity retention after 100 cycles. The mono dispersed micron scaled morphology together with high structural stability endows the LNCAO material with superior compacting density and cycling capability for lithium ion batteries with high energy density.

Layered LiNi0.5Co0.2Mn0.3O2 (NCM523) material has been functionally coated with a uniform and thin layer of Li2SiO3 via a two-step method. Owing to its high lithium ion conduction and excellent structural stability against electrolyte decomposition, Li2SiO3 could greatly improve the Li+ ion diffusion rate and ameliorate the electrochemical capability of the layered oxide materials. Electrochemical tests illustrate that Li2SiO3 used as a Li+-ion conductor greatly improves electrochemical performance of the NCM523 cathode at high current density under high cutoff voltage. Particularly, the Li2SiO3-modified sample delivers an initial capacity of 140.0 mAh g−1 and remains 134.1 mAh g−1 even at a high current density of 10 C after 100 cycles, while the capacity of the pristine decreased sharply to 81.5 mAh g−1. The capacity retention of Li2SiO3-modified NCM523 is 96.1%, while only 55.3% for the bare sample. This result demonstrates an efficient method for the Li2SiO3-modified NCM523 cathode with enhanced electrochemical performance, which has a certain reference for other cathode materials of Li-ion batteries.

Abtract LiNi0.80Co0.15Al0.05O2 has been widely pursued as an alternative to LiCoO2 cathode materials for lithium ion batteries because of its high capacity and acceptable cycling property. However, that NCA can react with commercialized electrolyte during cycling restrains its wide use. Here, olivine structured LiMnPO4 has been introduced to modify the surface of NCA by a sol-gel method. Characterizations from structure, morphology and composition analysis technologies demonstrate that a LiMnPO4 layer has been uniformly coated on NCA particles. The electrochemical performance and thermo stability of modified samples are characterized by electrochemical tests, XRD and metallic nail penetration tests. The olivine structured skin, which provides structural and thermal stability, is used to encapsulate the high powered core via using the effective coating technique. The modified material displays a high discharge capacity of 211.0 mAh g−1 at 0.2 C and better rate performance and promoted cycling stability than the uncoated control sample. Furthermore, the thermal stability of coated sample in the delithiated state is upgraded to the pristine powders remarkably.