Effect of Ni(2+) content on lithium/nickel disorder for Ni-rich cathode materials

Enhancing High-Voltage Performance of Ni-Rich Cathode by Surface Modification of Self-Assembled NASICON Fast Ionic Conductor LiZr2(PO4)3

Coating methodology is commonly employed in the enhancement of Ni-rich cathodes for Li-ion batteries as an efficient approach, while its strategy and effect are still great challenges to achieve success in surface modifications for comprehensive electrochemical properties. In this work, the surface of Ni-rich cathode LiNi_0.82Co_0.15Al_0.03O₂ (NCA) is modified by intimately coating NASICON-type solid electrolyte LiZr₂(PO₄)₃ (LZP) via a facile approach involving electrostatic attraction. With well-designed architecture and a uniform NASICON-type LZP nanolayer wrapping over the NCA microsphere, the entire electrode demonstrates exceptional Li⁺ diffusion and conductivity and suppresses the side reaction between electrolyte and electroactive NCA, stabilizing the phase interface with less Li⁺/Ni²⁺ cation mixing. As a result, the NCA@LZP can deliver a high reversible capacity of 182 mAh g^-1 at 1C in 2.7-4.3 V, maintaining the capacity retention of 84.6% after 100 cycles. More importantly, the structure stability of NCA is enhanced substantially by surface modification of LZP at high cutoff voltage. It achieves a reversible capacity of 204 mAh g^-1 and keeps 100.4 mAh g^-1 after 500 cycles at 1C in the potential range of 2.7-4.5 V. This effective strategy of using NASICON fast ionic conductor like LZP as a coating layer may provide a new insight to modify the surface of Ni-rich electrode, improving the rate capability and cyclic performance under high voltage.

Design and Synthesis of Double-Functional Polymer Composite Layer Coating To Enhance the Electrochemical Performance of the Ni-Rich Cathode at the Upper Cutoff Voltage

Graphene has been implemented as a desirable additive to improve the electrochemical performance of Ni-rich cathode materials. However, it is not only hard to ensure the intimate interaction between them in practice, which may affect the surface electronic conductivity of the composite, but also a challenge to fabricate cathodes with uniform graphene coating because of its two-dimensional planar structure. Besides, the graphene coating layer is easily peeled off from the cathode material during the cycling process, especially at the upper cutoff voltage. Therefore, we introduced a double-functional layer synergistically modified strategy to facilitate the electrochemical properties of LiNi_0.8Co_0.1Mn_0.1O₂ cathode materials. In the designed architecture, the LiNi_0.8Co_0.1Mn_0.1O₂ particles were uniformly enwrapped by a functional reduced graphene oxide (RGO)-KH560 polymer composite layer which consists of an inner high-flexibility epoxy-functionalized silane (KH560) layer and an outer RGO layer with high electronic conductivity. The KH560 layer, in the structural system, is especially critical in connecting the layer of outer RGO and the inner surface of the active material, which brings about the perfect and complete double-functional coating layer and in turn fully expresses the modification effect of both KH560 and RGO in the improvement of electrochemical performance. Consequently, higher capacity retention, better rate, and improved high-temperature performances (55 °C) at the upper cutoff voltage (4.5 V) of this composite are identified when compared with the RGO-coated and pristine samples. In particular, the cathode with RGO (0.5%)-KH560 (0.5%) coating exhibits capacity retentions of 95.2 and 81.5% after 150 cycles at 1 C, 4.5 V at room and high temperatures, respectively.

Design of a 3D-Porous Structure with Residual Carbon for High-Performance Ni-Rich Cathode Materials

Recently, LiNi_0.8Co_0.1Mn_0.1O₂ has drawn much attention because of its high energy density. Here, 3D-porous LiNi_0.8Co_0.1Mn_0.1O₂ and the one with residual carbon have been synthesized using a resorcinol-formaldehyde-assisted sol-gel approach. Scanning electron microscopy images verify that the synthesized LiNi_0.8Co_0.1Mn_0.1O₂ possesses a 3D-porous morphology. X-ray photoelectron spectroscopy analysis and transmission electron microscopy-mapping images indicate the existence of residual carbon in the secondary particle of 3D-porous LiNi_0.8Co_0.1Mn_0.1O₂. Furthermore, 3D-porous LiNi_0.8Co_0.1Mn_0.1O₂ with residual carbon exhibits outstanding electrochemical properties. At a current density of 1900 mA g^-1, the 3D-porous LiNi_0.8Co_0.1Mn_0.1O₂ with residual carbon can still deliver a reversible capacity of 113 . Moreover, after 150 cycles at 0.2 C, the capacity retention of 3D-porous LiNi_0.8Co_0.1Mn_0.1O₂ with residual carbon reaches to 95%. The excellent electrochemical properties can be ascribed to the unique 3D-porous morphology and residual carbon in the secondary particle.

Effects of Cobalt Deficiency on Nickel-Rich Layered LiNi0.8Co0.1Mn0.1O2 Positive Electrode Materials for Lithium-Ion Batteries

The role of cobalt deficiency on the crystal structure, surface chemistry, and electrochemical performance of Ni-rich layered LiNi_0.8Co_0.1Mn_0.1O₂ (NCM811) positive electrode materials was experimentally studied possibly for the first time. We synthesized pristine and cobalt-deficient NCM811 samples by solid-state reaction. Using a variety of characterization techniques and electrochemical measurements, we show that cobalt nonstoichiometry can suppress Ni²⁺/Li⁺ cation mixing, but can simultaneously promote the formation of oxygen vacancies, leading to rapid capacity fade and inferior rate capability compared to pristine NCM811. This study provides new insights into the effects of cobalt deficiency on the cation mixing and electrochemical performance of a Ni-rich layered NCM compound.

Synthesis and electrochemical characterization of Mg–Al co-doped Li-rich Mn-based cathode materials

A novel synergistic strategy to improve electrochemical performance of Li-rich cathode by co-doping of magnesium and aluminium.

Enhancing the Structural Stability of Ni-Rich Layered Oxide Cathodes with a Preformed Zr-Concentrated Defective Nanolayer

Nickel-rich layered oxides (NLOs) exhibit great potential to meet the ever-growing demand for further increases in the energy density of Li-ion batteries because of their high specific capacities. However, NLOs usually suffer from severe structural degradation and undesired side reactions when cycled above 4.3 V. These effects are strongly correlated with the surface structure and chemistry of the active NLO materials. Herein, we demonstrate a preformed cation-mixed ( Fm3̅ m) surface nanolayer (∼5 nm) that shares a consistent oxygen framework with the layered lattice through Zr modification, in which Ni cations reside in Li slabs and play the role of a "pillar". This preformed nanolayer alleviates the detrimental phase transformations upon electrochemical cycling, effectively enhancing the structural stability. As a result, the Zr-modified Li(Ni_0.8Co_0.1Mn_0.1)_0.985Zr_0.015O₂ material exhibits a high reversible discharge capacity of ∼210 mA h/g at 0.1 C (1 C = 200 mA/g) and outstanding cycling stability with a capacity retention of 93.2% after 100 cycles between 2.8 and 4.5 V. This strategy may be further extended to design and prepare other high-performance layered oxide cathode materials.

Constructing a Protective Pillaring Layer by Incorporating Gradient Mn4+ to Stabilize the Surface/Interfacial Structure of LiNi0.815Co0.15Al0.035O2 Cathode

Nickel-rich layered oxides are regarded as very promising materials as cathodes for lithium-ion batteries because of their environmental benignancy, low cost, and high energy density. However, insufficient cycle performance and poor thermotic characteristics induced by structural degradation at high potentials and elevated temperatures pose challenging hurdles for nickel-rich cathodes. Here, a protective pillaring layer, in which partial Ni²⁺ ions occupy Li slabs induced by gradient Mn⁴⁺, is integrated into the primary particle of LiNi_0.815Co_0.15Al_0.035O₂ to stabilize the surface/interfacial structure. With the stable outer surface provided by the enriched Mn⁴⁺ gradient concentration and the pillar effect of the NiO-like phase, Mn-incorporated quaternary cathodes show enhanced structural stability and improved Li⁺ diffusion as well as lithium-storage properties. Compared with the severe capacity fade of a pure layered structure, the cathode with gradient Mn⁴⁺ exhibits more stable cycling behavior with a capacity retention of 80.0% after 500 cycles at 5.0 C.

Towards deriving Ni-rich cathode and oxide-based anode materials from hydroxides by sharing a facile co-precipitation method

Although intensive studies have been conducted on layered transition metal oxide(TMO)-based cathode materials and metal oxide-based anode materials for Li-ion batteries, their precursors generally follow different or even complex synthesis routes. To share one route for preparing precursors of the cathode and anode materials, herein, we demonstrate a facile co-precipitation method to fabricate Ni-rich hydroxide precursors of Ni0.8Co0.1Mn0.1(OH)2. Ni-rich layered oxide of LiNi0.8Co0.1Mn0.1O2 is obtained by lithiation of the precursor in air. An NiO-based anode material is prepared by calcining the precursor or multi-walled carbon nanotubes (MWCNTs) incorporated precursors. The pre-addition of ammonia solution can simplify the co-precipitation procedures and the use of an air atmosphere can also make the heat treatment facile. LiNi0.8Co0.1Mn0.1O2 as the cathode material delivers a reversible capacity of 194 mA h g-1 at 40 mA g-1 and a notable cycling retention of 88.8% after 100 cycles at 200 mA g-1. This noticeable performance of the cathode arises from a decent particle morphology and high crystallinity of the layered oxides. As the anode material, the MWCNTs-incorporated oxides deliver a much higher reversible capacity of 811.1 mA h g-1 after 200 cycles compared to the pristine oxides without MWCNTs. The improvement on electrochemical performance can be attributed to synergistic effects from MWCNTs incorporation, including reinforced electronic conductivity, rich meso-pores and an alleviated volume effect. This facile and sharing method may offer an integrated and economical approach for commercial production of Ni-rich electrode materials for Li-ion batteries.

Synthesis Method for Long Cycle Life Lithium-Ion Cathode Material: Nickel-Rich Core-Shell LiNi0.8Co0.1Mn0.1O2

High-nickel materials with core-shell structures, whose bulk is rich in nickel content and the outer shell is rich in manganese content, have been demonstrated to improve cycle stability. The high-nickel cathode material LiNi_0.8Co_0.1Mn_0.1O₂ is a very promising material for lithium-ion batteries; however, its low rate performance and especially cycle performance currently hamper further commercialization. This study presents a new synthesis method to prepare this core-shell material (LiNi_0.8Co_0.1Mn_0.1O₂@ x[Li-Mn-O], x = 0.01, 0.03, 0.06). Electrochemical data show that LiNi_0.8Co_0.1Mn_0.1O₂@ x[Li-Mn-O] ( x = 0.03, CS-0.03) exhibits the best high-rate performance, cycle stability, and thermal stability. The initial discharge capacity of the core-shell sample CS-0.03 is 118 mAh g^-1, which is almost the same as the discharge capacity of pristine LiNi_0.8Mn_0.1Co_0.1O₂ (117 mAh g^-1) at the rate of 10 C in the voltage range of 3.0-4.3 V. Notably the capacity decay of CS-0.03 is 18.4% after 200 cycles compared to 27% decay in capacity of the pristine sample. Furthermore, CS-0.03 exhibits better thermal cycling stability. The capacity retention of the CS-0.03 sample reached 65.1% which is over 1.3 times than that of the pristine one, whose capacity retention is 49.2% after 105 cycles (55 °C). Evidently, the core-shell structured CS-0.03 sample has excellent cycle stability and this synthesis method can be applied to other cathode materials.

N-Allyl- N, N-Bis(trimethylsilyl)amine as a Novel Electrolyte Additive To Enhance the Interfacial Stability of a Ni-Rich Electrode for Lithium-Ion Batteries

Enhancing the electrode/electrolyte interface stability of high-capacity LiNi_0.8Co_0.15Al_0.05O₂ (LNCA) cathode material is urgently required for its application in next-generation lithium-ion battery. Herein, we demonstrate that enhanced interfacial stability of LNCA can be achieved by simply introducing 2 wt % N-allyl- N, N-bis(trimethylsilyl)amine (NNB) electrolyte additive. Electrolyte oxidation reactions and electrode structural destruction are greatly suppressed in the electrolyte with NNB additive, leading to improved cyclic stability of LNCA from 72.8 to 86.2% after 300 cycles. The mechanism of NNB on improving the cyclic stability of LNCA has been verified to its excellent solid electrolyte interface (SEI) film-forming capability. Moreover, the X-ray diffraction and X-ray photoelectron spectroscopy results indicate that the NNB-derived Si-containing SEI film restrains the Li/Ni disorder of LNCA during cycling, which further improves the cyclic stability of Ni-rich LNCA. Importantly, the charging/discharging test reveals that the NNB additive effectively improves the cyclic stability of the LNCA/graphite full cell.

Exposing the {010} Planes by Oriented Self-Assembly with Nanosheets To Improve the Electrochemical Performances of Ni-Rich Li[Ni0.8Co0.1Mn0.1]O2 Microspheres

A modified Ni-rich Li[Ni_0.8Co_0.1Mn_0.1]O₂ cathode material with exposed {010} planes is successfully synthesized for lithium-ion batteries. The scanning electron microscopy images have demonstrated that by tuning the ammonia concentration during the synthesis of precursors, the primary nanosheets could be successfully stacked along the [001] crystal axis predominantly, self-assembling like multilayers. According to the high-resolution transmission electron microscopy results, such a morphology benefits the growth of the {010} active planes of final layered cathodes during calcination treatment, resulting in the increased area of the exposed {010} active planes, a well-ordered layer structure, and a lower cation mixing disorder. The Li-ion diffusion coefficient has also been improved after the modification based on the results of potentiostatic intermittent titration technique. As a consequence, the modified Li[Ni_0.8Co_0.1Mn_0.1]O₂ material exhibits superior initial discharges of 201.6 mA h g^-1 at 0.2 C and 185.7 mA h g^-1 at 1 C within 2.8-4.3 V (vs Li⁺/Li), and their capacity retentions after 100 cycles reach 90 and 90.6%, respectively. The capacity at 10 C also increases from 98.3 to 146.5 mA h g^-1 after the modification. Our work proposes a novel approach for exposing high-energy {010} active planes of the layered cathode material and again confirms its validity in improving electrochemical properties.

Ab Initio Study on Surface Segregation and Anisotropy of Ni-Rich LiNi1-2yCoyMnyO2 (NCM) (y ≤ 0.1) Cathodes

Advances in ex situ and in situ (operando) characteristic techniques have unraveled unprecedented atomic details in the electrochemical reaction of Li-ion batteries. To bridge the gap between emerging evidences and practical material development, an elaborate understanding on the electrochemical properties of cathode materials on the atomic scale is urgently needed. In this work, we perform comprehensive first-principle calculations within the density functional theory + U framework on the surface stability, morphology, and elastic anisotropy of Ni-rich LiNi_1-2yCo_yMn_yO₂ (NCM) (y ≤ 0.1) cathode materials, which are strongly related to the emerging evidence in the degradation of Li-ion batteries. On the basis of the surface stability results, the equilibrium particle morphology is obtained, which is mainly determined by the oxygen chemical potential. Ni-rich NCM particles are terminated mostly by the (012) and (001) surfaces for oxygen-poor conditions, whereas the termination corresponds to the (104) and (001) surfaces for oxygen-rich conditions. Besides, Ni surface segregation predominantly occurs on the (100), (110), and (104) nonpolar surfaces, showing a tendency to form a rocksalt NiO domain on the surface because of severe Li-Ni exchange. The observed elastic anisotropy reveals that an uneven deformation is more likely to be formed in the particles synthesized under poor-oxygen conditions, leading to crack generation and propagation. Our findings provide a deep understanding of the surface properties and degradation of Ni-rich NCM particles, thereby proposing possible solution mechanisms to the factors affecting degradation, such as synthesis conditions, coating, or novel nanostructures.

High-voltage performance of concentration-gradient Li[Ni0.6Co0.2Mn0.2]O2 layered oxide cathode materials for lithium batteries

High-voltage performance concentration-gradient Li[Ni_0.6Co_0.2Mn_0.2]O₂ (CG-NCM622) layered oxide cathodes consisting of Li[Ni_0.8Co_0.1Mn_0.1]O₂ cores and stable outer layers of Li[Ni_1/3Co_1/3Mn_1/3]O₂ were synthesized via co-precipitation.

Surface Modification of Li(Ni0.6Co0.2Mn0.2)O₂ Cathode Materials by Nano-Al₂O₃ to Improve Electrochemical Performance in Lithium-Ion Batteries

Al₂O₃-coated Li(Ni_0.6Co_0.2Mn_0.2)O₂ cathode materials were prepared by simple surface modification in water media through a sol-gel process with a dispersant. The crystallinity and surface morphology of the samples were characterized through X-ray diffraction analysis and scanning electron microscopy observation. The Li(Ni_0.6Co_0.2Mn_0.2)O₂ cathode material was of a polycrystalline hexagonal structure and agglomerated with particles of approximately 0.3 to 0.8 μm in diameter. The nanosized Al₂O₃ particles of low concentration (0.06–0.12 wt %) were uniformly coated on the surface of Li(Ni_0.6Co_0.2Mn_0.2)O₂. Measurement of electrochemical properties showed that Li(Ni_0.6Co_0.2Mn_0.2)O₂ coated with Al₂O₃ of 0.08 wt % had a high initial discharge capacity of 206.9 mAh/g at a rate of 0.05 C over 3.0–4.5 V and high capacity retention of 94.5% at 0.5 C after 30 cycles (cf. uncoated sample: 206.1 mAh/g and 90.8%, respectively). The rate capability of this material was also improved, i.e., it showed a high discharge capacity of 166.3 mAh/g after 5 cycles at a rate of 2 C, whereas the uncoated sample showed 155.8 mAh/g under the same experimental conditions.

Stabilizing the Electrode/Electrolyte Interface of LiNi0.8Co0.15Al0.05O2 through Tailoring Aluminum Distribution in Microspheres as Long-Life, High-Rate, and Safe Cathode for Lithium-Ion Batteries

The unstable electrode/electrolyte interface of high-capacity LiNi_0.8Co_0.15Al_0.05O₂ (NCA) cathodes, especially at a highly delithiated state, usually leads to the transformation of layered to spinel and/or rock-salt phases, resulting in drastic capacity fade and poor thermal stability. Herein, the Al-increased and Ni-,Co-decreased electrode surface is fabricated through tailoring element distribution in micrometer-sized spherical NCA secondary particles via coprecipitation and solid-state reactions, aimed at stabilizing the electrode/electrolyte interface during continuous cycles. As expected, it shows much extended cycle life, 93.6% capacity retention within 100 cycles, compared with that of 78.5% for the normal NCA. It also delivers large reversible capacity of about 140 mAh g^-1 even at 20 C, corresponding to energy density of around 480 Wh kg^-1, which is enhanced by 45% compared to that of the normal NCA (about 330 Wh kg^-1). Besides, the delayed heat emission temperature and reduced heat generation mean remarkably improved thermal stability. These foregoing improvements are ascribed to the Al-increased spherical secondary particle surface that stabilizes the electrode/electrolyte interface by protecting inner components from directly contacting with electrolyte and suppressing the side reaction on electrode surface between high oxidizing Ni⁴⁺ and electrolyte.

LiNi0.8Co0.15Al0.05O2: Enhanced Electrochemical Performance From Reduced Cationic Disordering in Li Slab

Sub-micron sized LiNi_0.8Co_0.15Al_0.05O₂ cathode materials with improved electrochemical performance caused by the reduced cationic disordering in Li slab were synthesized through a solid state reaction routine. In a typical process, spherical precursor powder was prepared by spray drying of a uniform suspension obtained from the ball-milling of the mixture of the starting raw materials. Then the precursor powders were pressed into tablets under different pressures and crushed into powder. The pressing treated powders were finally calcinated under oxygen atmosphere to obtain the target cathode materials. XRD investigation revealed a hexagonal layered structure without impurity phase for all samples and significant increase in the diffraction intensity ratio of I₍₀₀₃₎/I₍₁₀₄₎ was observed. Rietveld refinement further confirmed the reduced cationic disordering in Li slab by such pressing treatment, and the smallest disordering was observed for sample S4 with only 1.3% Ni ions on Li lattice position. The electrochemical testing showed an improvement in electrochemical behavior for those pressing treated samples. The calculation of diffusion coefficients using EIS data showed improved Li diffusion coefficient after pressing treatment. The sample S4 presented a diffusion coefficient of 4.36 × 10⁻¹¹ cm²·s⁻¹, which is almost 3.5 times the value of untreated sample.

Multishelled Ni-Rich Li(Ni x Co y Mn z )O2 Hollow Fibers with Low Cation Mixing as High-Performance Cathode Materials for Li-Ion Batteries

A simple seaweed biomass conversion strategy is proposed to synthesize highly porous multishelled Ni-rich Li(Ni x Co y Mn z )O2 hollow fibers with very low cation mixing. The low cation mixing results from the cation confinement by the novel "egg-box" structure in the alginate template. These hollow fibers exhibit remarkable energy density, high-rate capacity, and long-term cycling stability when used as cathode material for Li-ion batteries.

Cyanide bridged coordination polymer nanoflakes thermally derived Ni3C and fcc-Ni nanoparticles for electrocatalysts

We have reported a controlled crystal growth process, which allows the formation of NiCNNi CP nanoflakes derived Ni₃C and fcc-Ni nanoparticles.

Alleviating Surface Degradation of Nickel-Rich Layered Oxide Cathode Material by Encapsulating with Nanoscale Li-Ions/Electrons Superionic Conductors Hybrid Membrane for Advanced Li-Ion Batteries

Nickel-rich layered oxide cathode materials for advanced lithium-ion batteries have received much attention recently because of their high specific capacities and significant reduction of cost. However, these cathodes are facing a fundamental challenge of loss in performance as a result of surface lithium residue, side reactions with the electrolyte and structure rearrangement upon long-term cycling. Herein, by capturing the lithium residue on the surface of LiNi_0.8Co_0.1Mn_0.1O₂ (NCM) cathode material as Li source, we propose a hybrid coating strategy incorporating lithium ions conductor Li_xAlO₂ with superconductor Li_xTi₂O₄ to overcome those obstinate issues. By taking full advantage of this unique hybrid nanomembrane coating architecture, both the lithium ion diffusion ability and electronic conductivity of LiNi_0.8Co_0.1Mn_0.1O₂ cathode material are improved, resulting in remarkably enhanced electrochemical performances during high voltage operation, including good cycle performance, high reversible capacity, and excellent rate capability. A high initial discharge capacity of 227 mAh g^-1 at 4.4 V cutoff voltage with Coulombic efficiency of 87.3%, and reversible capacity of 200 mAh g^-1 with 98% capacity retention after 100 cycles at a current density of 0.5 C can be attained. The improved electrochemical performance can be attributed to the synergetic contribution from the removal of lithium residues and the unique hybrid nanomembrane coating architecture. Most importantly, this surface modification technique could save some cost, simplify the technical procedure, and show great potential to optimize battery performance, apply in a large scale and extend to all nickel-rich cathode material.

High-Rate and Cycling-Stable Nickel-Rich Cathode Materials with Enhanced Li(+) Diffusion Pathway

The nickel-rich LiNi0.7Co0.15Mn0.15O2 material was sintered by Li source with the Ni0.7Co0.15Mn0.15(OH)2 precursor, which was prepared via hydrothermal treatment after coprecipitation. The intensity ratio of I(110)/I(108) obtained from X-ray diffraction patterns and high-resolution transmission electronmicroscopy confirm that the particles have enhanced growth of (110), (100), and (010) surface planes, which supply superior inherent Li(+) deintercalation/intercalation. The electrochemical measurement shows that the LiNi0.7Co0.15Mn0.15O2 material has high cycling stability and rate capability, along with fast charge and discharge ability. Li(+) diffusion coefficient at the oxidation peaks obtained by cyclic voltammogram measurement is as large as 10(-11) (cm(2) s(-1)) orders of magnitude, implying that the nickel-rich material has high Li(+) diffusion capability.

Improved electrochemical performances of layered lithium rich oxide 0.6Li[Li1/3Mn2/3]O2·0.4LiMn5/12Ni5/12Co1/6O2 by Zr doping

HRTEM patterns of undoped and Zr4% doped samples, (0a) x = 0 before cycle, (0a1) x = 0 after 101 cycles, (4a) x = 4% before cycle, (4a1) x = 4% after 101 cycles.

Facile strategy of NCA cation mixing regulation and its effect on electrochemical performance

The cation mixing of LiNi_0.8Co_0.15Al_0.05O₂ materials was regulated by a facile strategy via oxygen flow rate control during sintering, and the effect of cation mixing on the electrochemical performance was investigated by CR2025 coin cells tests.

Improvement of the Cycling Performance and Thermal Stability of Lithium-Ion Cells by Double-Layer Coating of Cathode Materials with Al₂O₃ Nanoparticles and Conductive Polymer

We demonstrate the effectiveness of dual-layer coating of cathode active materials for improving the cycling performance and thermal stability of lithium-ion cells. Layered nickel-rich LiNi0.6Co0.2Mn0.2O2 cathode material was synthesized and double-layer coated with alumina nanoparticles and poly(3,4-ethylenedioxythiophene)-co-poly(ethylene glycol). The lithium-ion cells assembled with a graphite negative electrode and a double-layer-coated LiNi0.6Co0.2Mn0.2O2 positive electrode exhibited high discharge capacity, good cycling stability, and improved rate capability. The protective double layer formed on the surface of LiNi0.6Co0.2Mn0.2O2 materials effectively inhibited the dissolution of Ni, Co, and Mn metals from cathode active materials and improved thermal stability by suppressing direct contact between electrolyte solution and delithiated Li(1-x)Ni0.6Co0.2Mn0.2O2 materials. This effective design strategy can be adopted to enhance the cycling performance and thermal stability of other layered nickel-rich cathode materials used in lithium-ion batteries.

Structural and electrochemical properties of Mg-doped nickel based cathode materials LiNi0.6Co0.2Mn0.2−xMgxO2 for lithium ion batteries

Combined with experiments and ab initio calculations, we investigated the impact of the substitution of Mn with Mg in LiNi_0.6Co_0.2Mn_0.2O₂.

Promoting the cyclic and rate performance of lithium-rich ternary materials via surface modification and lattice expansion

Nickel-rich layered lithium transition-metal oxides have been studied intensively as high-energy positive-electrode materials for lithium batteries because of their high specific capacity and relatively low-cost.