Ni-rich layered oxides are extensively employed as a promising cathode material in lithium ion batteries (LIBs) due to their high energy density and reasonable cost. However, the hierarchical ...structure of secondary particles with grain boundaries inevitably induces the structural collapse and severe electrode/electrolyte interface parasitic reactions as the intergranular crack arises from the anisotropic shrink and expansion. Herein, the single-crystalline LiNi0.83Co0.11Mn0.06O2 (SC-NCM) with primary particles of 3–6 μm diameter is developed and comprehensively investigated, which exhibits superior cycling performance at both room temperature and elevated temperature (55 °C) as well as significantly improved structural integrity after long-term cycling. Remarkably, the SiO-C||SC-NCM pouch-type full cell with a practical loading (8.7 mAh cm−2) delivers a capacity retention of 84.8 % at 45 °C after 600 cycles at a current rate of 1C (1C = 200 mA g−1), retaining a high specific energy density of 225 Wh/kg. Using a combination of X-ray photoelectron spectroscopy, time-of-flight secondary-ion mass spectrometry and scanning transmission electron microscopy, we reveal that SC-NCM particles with micron-sizes effectively mitigate the undesired electrode/electrolyte side interactions and prevent the generation of intergranular cracks, thereby alleviating irreversible structural degradation. The strategy of developing single-crystalline micron-sized particles may offer a new path for maintaining the structural stability and improving cycling life of Ni-rich layered NCM cathodes even under high temperature.
Integrated single-crystalline Ni-rich NCM cathode is rationally designed and successfully fabricated, which effectively mitigate undesired electrode/electrolyte interactions, avoid intergranular cracks, and significantly alleviate irreversible phase transformation. Investigation of the relationship between phase transformation and intergranular crack unambiguously reveals that the enhanced prolonged cyclic life and thermal stability are attributed to the intrinsic structure of single-crystalline Ni-rich NCM. Display omitted
•The single-crystalline Ni-rich NCM with 3-6 μm diameter is developed and systematically investigated for the first time.•The pouch-type full cell with a practical loading (8.7mAh/cm) delivers capacity retention of 84.8% at 45°C after 600 cycles.•SC-NCM exhibits superior cycling performance at both 25 and 55 °C as well as enhanced thermal stability.•SC-NCM effectively mitigate undesired side interactions and significantly prevent the generation of intergranular cracks.
Sodium is first introduced to modify Ni-rich LiNi0.8Co0.15Al0.05O2 cathode material in this work, and Li1–x Na x Ni0.8Co0.15Al0.05O2 (x = 0, 0.01, 0.02, 0.05) is successfully synthesized by using ...Na2CO3 as sodium resource through coprecipitation and solid state calcination route. The morphology of the samples analyzed with SEM, EDS. and TEM show that all the samples maintain sphere-like morphology and the main elements are uniformly distributed. X-ray diffraction (XRD) results show that all the synthesized materials have typical hexagonal structure without impurities. The lattice parameters calculated from the XRD data are also refined by Rietveld refinement methods, confirming that the position of Na in the NCA is occupying the Li slab as designed. Despite a slight decrease in the initial discharge capacities, the sodium doped materials display improved capacity retention as well as superior performance at high rates. The Li0.99Na0.01Ni0.8Co0.15Al0.05O2 exhibits an initial discharge specific capacity of 184.6 mAh g–1 at 0.1 C and a capacity retention of 90.71% after 200 cycles when cycled at 1 C between 2.8 and 4.3 V, which is greatly superior to the pristine one, owing to the enlarged Li layer spacing, decreased Li+ migration activation energy, the low cation mixing, and enhanced structural stability brought by sodium treatment.
Abstract
High nickel content in LiNi
x
Co
y
Mn
z
O
2
(NCM, x ≥ 0.8, x + y + z = 1) layered cathode material allows high specific energy density in lithium-ion batteries (LIBs). However, Ni-rich NCM ...cathodes suffer from performance degradation, mechanical and structural instability upon prolonged cell cycling. Although the use of single-crystal Ni-rich NCM can mitigate these drawbacks, the ion-diffusion in large single-crystal particles hamper its rate capability. Herein, we report a strategy to construct an in situ Li
1.4
Y
0.4
Ti
1.6
(PO
4
)
3
(LYTP) ion/electron conductive network which interconnects single-crystal LiNi
0.88
Co
0.09
Mn
0.03
O
2
(SC-NCM88) particles. The LYTP network facilitates the lithium-ion transport between SC-NCM88 particles, mitigates mechanical instability and prevents detrimental crystalline phase transformation. When used in combination with a Li metal anode, the LYTP-containing SC-NCM88-based cathode enables a coin cell capacity of 130 mAh g
−1
after 500 cycles at 5 C rate in the 2.75-4.4 V range at 25 °C. Tests in Li-ion pouch cell configuration (i.e., graphite used as negative electrode active material) demonstrate capacity retention of 85% after 1000 cycles at 0.5 C in the 2.75-4.4 V range at 25 °C for the LYTP-containing SC-NCM88-based positive electrode.
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.
High-capacity Ni-rich layered oxides are promising cathode materials for secondary lithium-based battery systems. However, their structural instability detrimentally affects the battery performance ...during cell cycling. Here, we report an Al/Zr co-doped single-crystalline LiNi
Co
Mn
O
(SNCM) cathode material to circumvent the instability issue. We found that soluble Al ions are adequately incorporated in the SNCM lattice while the less soluble Zr ions are prone to aggregate in the outer SNCM surface layer. The synergistic effect of Al/Zr co-doping in SNCM lattice improve the Li-ion mobility, relief the internal strain, and suppress the Li/Ni cation mixing upon cycling at high cut-off voltage. These features improve the cathode rate capability and structural stabilization during prolonged cell cycling. In particular, the Zr-rich surface enables the formation of stable cathode-electrolyte interphase, which prevent SNCM from unwanted reactions with the non-aqueous fluorinated liquid electrolyte solution and avoid Ni dissolution. To prove the practical application of the Al/Zr co-doped SNCM, we assembled a 10.8 Ah pouch cell (using a 100 μm thick Li metal anode) capable of delivering initial specific energy of 504.5 Wh kg
at 0.1 C and 25 °C.
Nominal Na
0.6
(Li
0.2
Mn
0.8
)O
2
with the layered P3 structure (s.g.
R
3
m
) showed XPS evidence of holes in the O-2p bands on removal of Na
+
ions. A large voltage plateau at 4.1 V
versus
Na
+
/Na ...faded significantly over 50 cycles although the capacity in the range 20 ≤
V
< 4.5 V remained unchanged. Oxidation of the O-2p bands is not reversible.
Oxidation of layered P3-Na
0.6
(Li
0.2
Mn
0.8
)O
2
by electrochemical removal of Na
+
introduces holes into the O-2p bands at 4.2 V, but the voltage plateau fades on cycling.
•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.
With the development of nanotechnology, significant progress has been made in the design, and manufacture of nanoparticles (NPs) for use in clinical treatments. Recent increases in our understanding ...of the central role of macrophages in the context of inflammation and cancer have reinvigorated interest in macrophages as drug targets. Macrophages play an integral role in maintaining the steady state of the immune system and are involved in cancer and inflammation processes. Thus, NPs tailored to accurately target macrophages have the potential to transform disease treatment. Herein, we first present a brief background information of NPs as drug carriers, including but not limited to the types of nanomaterials, their biological properties and their advantages in clinical application. Then, macrophage effector mechanisms and recent NPs-based strategies aimed at targeting macrophages by eliminating or re-educating macrophages in inflammation and cancer are summarized. Additionally, the development of nanocarriers targeting macrophages for disease diagnosis is also discussed. Finally, the significance of macrophage-targeting nanomedicine is highlighted, with the goal of facilitating future clinical translation.
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.
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