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.
•Tungsten oxide modified LiNi0.8Co0.1Mn0.1O2 material were first put forward.•This simple and feasible method has a good prospect for improving the cyclic stability of Ni-rich materials.•The different amounts of tungsten oxide were compared, the addition of 0.25% has the best effect.
LiNi1−x−yCoxAlyO2 is a commonly used Ni-rich cathode material because of its relatively low cost, excellent rate capability and high gravimetric energy density. Surface modification is an efficient ...way to overcome the shortcomings of Ni-rich cathodes such as poor cycling stability and poor thermal stability. A high-powered concentration-gradient cathode material with an average composition of LiNi0.815Co0.15Al0.035O2 (LGNCAO) has been successfully synthesized by using spherical concentration-gradient Ni0.815Co0.15Al0.035(OH)2 (GNCA)as the starting material. An efficient design of the Al3+ precipitation method is developed, which enables obtaining spherical GNCA with ∼10 μm particle size and high tap density. In LGNCAO, the nickel and cobalt concentration decreases gradually whereas the aluminum concentration increases from the centre to the outer layer of each particle. Electrochemical performance and storage properties of LGNCAO have been investigated comparatively. The LGNCAO displays better electrochemical performance and improved storage stability than LNCAO.
•Al gradient doping is investigated to modify LiNiO2-based materials.•Al gradient doped cathode material is formed via a promoted precipitation method.•Al rich surface retards phase transformation and cation mixing.•LGNCAO displays better electrochemical performance and promoted storage property.
•LiMnPO4 was introduced to modify Ni-rich cathode materials.•LiMnPO4 uniformly coated NCA composite has been constructed successfully.•Olivine structured skin restrains the formation of residues on ...NCA during cycling.•LiMnPO4 improves the structural and thermal stability of NCA@LMP.
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 211.0mAhg−1 at 0.2C 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.
LiNi0.8Co0.15Al0.05O2 crystals with ∼4 μm particle size have been synthesized from spherical Ni0.8Co0.15Al0.05(OH)2 precursors via a two-step treatment strategy. A specific surface area controllable ...precipitation method was introduced to synthesize Ni1-x-yCoxAly(OH)2 hydroxides with large specific surface area. Spherical hydroxides with large specific area and excess LiOH calcination technique ensure the LiNi0.8Co0.15Al0.05O2 crystals with mono dispersed micrometer scaled particle distribution and perfect α-NaFeO2 layered structure. Water washing process wipes off the LiOH and Li2CO3 impurities from the cathodes efficiently without structural degradation. The LiNi0.8Co0.15Al0.05O2 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.
•NCA precursors with large specific surface area have been synthesized.•Mono dispersed micron scaled LNCAO is prepared by an excessive lithium treatment.•Morphology modified samples endows a higher compacting density than commercial NCA.•Mono dispersed micron scaled Ni rich cathode shows promoted cycling capability.
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.
LiNi0.5Co0.2Mn0.3O2 has been functionally coated with Li2SiO3 via a two-step method. The Li2SiO3-coated sample shows improved electrochemical properties. Display omitted
•LiNi0.5Co0.2Mn0.3O2 has been functionally coated with Li2SiO3 via a two-step method.•Li2SiO3 possesses a high Li+-ion conduction and excellent structural stability.•The Li2SiO3-coated sample shows improved electrochemical properties.
Highlights
A red blood cell-mimic nanocatalyst with photodynamic/chemodynamic-like, catalase-like and glutathione peroxidase-like activities was developed to boost radical storms for tumor ...eradication.
Combined with the Tim-3 immune checkpoint blockade, such radical therapy can systematically evoke a robust systemic antitumor immune response to eliminate residual cancer cells.
Red blood cells (RBCs) have recently emerged as promosing candidates for cancer treatment in terms of relieving tumor hypoxia and inducing oxidative damage against cancer cells, but they are still far from satisfactory due to their limited oxygen transport and reactive oxygen species generation rate in tumor tissue. Herein, artificial RBCs (designated FTP@RBCM) with radical storm production ability were developed for oncotherapy through multidimensional reactivity pathways of Fe-protoporphyrin-based hybrid metal–organic frameworks (FTPs, as the core), including photodynamic/chemodynamic-like, catalase-like and glutathione peroxidase-like activities. Meanwhile, owing to the advantages of long circulation abilities of RBCs provided by their cell membranes (RBCMs), FTP with a surface coated with RBCMs (FTP@RBCM) could enormously accumulate at tumor site to achieve remarkably enhanced therapeutic efficiency. Intriguingly, this ROS-mediated dynamic therapy was demonstrated to induce acute local inflammation and high immunogenic cancer death, which evoked a systemic antitumor immune response when combined with the newly identified T cell immunoglobulin and mucin-containing molecule 3 (Tim-3) checkpoint blockade, leading to not only effective elimination of primary tumors but also an abscopal effect of growth suppression of distant tumors. Therefore, such RBC-mimic nanocatalysts with multidimensional catalytic capacities might provide a promising new insight into synergistic cancer treatment.
LiMn2O4 (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.
Sr service: Sr‐modified LiMn2O4 cathodes are prepared by using a simple strategy and the effect of Sr ions on structural stability is investigated. SrMnO3 is found to be enriched at grain boundaries of LiMn2O4 with Mn−O−Sr bonds forming at the interface, enhancing structural integrity and suppressing side reactions between the electrode and electrolyte.
LiNi0.8Co0.15Al0.05O2 cathode material for lithium-ion batteries is synthesized by sintering the precursor Ni0.8Co0.15Al0.05OOH, which is prepared from the corresponding metal sulphates solution by a ...co-oxidation-controlled crystallization method. The effects of calcination temperature and time on the electrochemical performance of the material are investigated on the basis of TG-DSC analysis. XRD analyses show that the powders obtained by calcination at 700 ?C for 6 h have the best-ordered hexagonal layer structure. SEM images show that these powders are spherical particles with diameter in the 5--12 Delta *mm range. The XPS measurement and the chemical titration display that Ni ions of these powders are in the form of Ni3+. The charge--discharge tests demonstrate that these powders have the best electrochemical properties, with an initial discharge capacity of 196.8 mAh g-1 and capacity retention of 96.1% after 50 cycles when cycled at a current density of 0.2 C between 2.8 and 4.3 V. Besides, these powders have also exhibited excellent rate capability and high-temperature performance.
LiMn
O
(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. SrMnO
(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 storage properties of LiNi0.8Co0.15Al0.05O2 and LiCoO2-coated LiNi0.8Co0.15Al0.05O2 have been investigated comparatively. It is found that the latter exhibits better storage stability than the ...former. After storage in air at different relative humidities, LiCoO2-coated LiNi0.8Co0.15Al0.05O2 shows little changes in the aspects of weight, nickel oxidation state, moisture and carbon contents and electrochemical performance. However, for LiNi0.8Co0.15Al0.05O2, the higher the air humidity is, the bigger these aspects change. Fourier transformed infrared (FTIR) spectrum reveals that LiCoO2-coated LiNi0.8Co0.15Al0.05O2 is resistant to H2O and CO2 in air. X-ray photoelectron spectroscopy gives evidence that the LiCoO2 coating layer suppresses effectively the reactions between LiNi0.8Co0.15Al0.05O2 and atmosphere, which contributes to the enhancement of storage performance of LiCoO2-coated LiNi0.8Co0.15Al0.05O2.
► LiCoO2-coated LiNi0.8Co0.15Al0.05O2 shows better storage stability compared to LiNi0.8Co0.15Al0.05O2. ► The properties of LiCoO2-coated LiNi0.8Co0.15Al0.05O2 have almost nothing to do with the air humidity. ► LiCoO2-coated LiNi0.8Co0.15Al0.05O2 is resistant to H2O and CO2 in air. ► The LiCoO2 coating layer suppresses effectively the reactions between LiNi0.8Co0.15Al0.05O2 and atmosphere.
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