Stability Of Lithium-ion Batteries Research Articles

Preparation of lithium ferromanganese phosphate by non-stoichiometric strategy

LixFexMn1-xPO4 exhibits low production costs, environmental friendliness, high energy density, thermal stability, and cycling stability in lithium-ion batteries (LIBs), presenting broad application prospects. Furthermore, studies have shown that adopting a non-stoichiometric ratio strategy can reduce particle size, decrease anti-site defects, and generate a conductive impurity phase on the material surface. This leads to an enhancement in the electrochemical performance of the material, making it an effective approach to achieving high-performance olivine-type cathode materials. In this study, three materials were successfully prepared using the solid-phase method: Li1.05Fe0.5Mn0.475PO4/C, Li1.05Fe0.5Mn0.5PO4/C, and Li1.05Fe0.475Mn0.5PO4/C. The physical properties of the materials were characterized using X-ray diffraction (XRD), transmission electron microscopy (TEM), and scanning electron microscopy (SEM). The electrochemical performance including specific capacity, rate performance, and cycling performance were studied through charge-discharge tests, with Li1.05Fe0.5Mn0.475PO4/C exhibiting the best specific capacity at all rates. At rates of 0.1 C, 0.5 C, 1 C, 2 C, and 5 C, its average reversible specific capacities were 143.5, 129.5, 122.1, 112.8, and 97.3 mAh·g−1, respectively. Furthermore, differences in electrochemical performance of three materials were discussed in detail through cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS).

Designing high-chaos mixed-salt electrolytes for enhancing graphite-electrolyte interfacial stability in lithium-ion batteries

The interfacial stability between graphite anodes and electrolytes is crucial for the electrochemical performance of lithium-ion batteries, particularly at low temperatures. This study investigates the effect of incorporating four common Solid-Electrolyte Interphase (SEI) components—LiF, LiNO3, Li2O, and Li2CO3—directly into two types of commercial electrolytes: carbonate-based (1.0 M LiPF6-EC/DMC, LP30) and ether-based (1 M LiTFSI-DOL/DME+2 % LiNO3, LDD) both with 5 % FEC (v/v) to create high-chaos mixed-salt electrolytes (LP30-FEC-4S and LDD-FEC-4S). Our findings show that Li/graphite cells exhibit significantly enhanced rate performance in both LP30-FEC-4S and LDD-FEC-4S electrolytes, compared to commercial LP30 and LP57 electrolytes. LiFePO4/graphite full cells using LP30-FEC-4S and LDD-FEC-4S electrolytes also showed excellent electrochemical performance (124.73 mAh g−1 and 119.21 mAh g−1 specific capacities at 0.5C). Remarkably, stable SEIs form rapidly on the graphite anode surfaces in the designed electrolytes even at low temperatures of −10 °C. Moreover, we demonstrate that the Li+ solvation structure is fundamental in determining the overall electrochemical performance. This study suggests that enhancing the mixing entropy of the system by adding multiple lithium salts to a commercial electrolyte is an effective and cost-efficient strategy for improving graphite-electrolyte compatibility.

Interfacial modulation of hollow ZnS-SnS2 microboxs by Ti3C2Tx MXene to construct three-dimensional hybrid anodes for lithium-ion batteries with ultra high stability at low temperature

Metal sulfides exhibit obvious volume expansion due to the inherent poor conductivity and large temperature fluctuations, leading to reduced storage capacity. Herein, an electrostatic self-assembly strategy was proposed to fabricate a three-dimensional (3D) polyaniline (PANI) encapsulated hollow ZnS-SnS2 (H-ZSS) heterojunction confined on Ti3C2Tx MXene nanosheets (H-ZnS-SnS2@MXene@PANI, denoted as H-ZSSMP), which exhibits remarkable reversible capacity and cyclic stability (520.3 mAh/g at 2 A/g after 1000 cycles) at room temperature. Additionally, specific capacity can stabilized at 362.5 mAh/g for 250 cycles at −20 °C. A full cell with the configuration of H-ZSSMP//lithium iron phosphate (LiFePO4) can retain a satisfactory reversible capacity of 424.7 mAh/g after 100 cycles at 0.1 C. Theory calculations confirm heterogeneous interface can accelerate the transfer of ions through the interfacial regulation effect of MXene on H-ZSS. Our work provides a simple strategy to improve the capacity and stability of lithium-ion batteries (LIBs), as well as the new applications of MXene and bimetallic sulfides as anode materials, which will facilitate the development of MXene based composites for energy storage.

Stable surface lattice for prolonged cycle life of single-crystal lithium-rich layered oxide cathodes

Lithium-rich layered oxides (LLOs) have garnered significant attention due to their outstanding capacity. However, the severe capacity fading resulting from lattice deterioration initiated at the surface constrains the further advancement of LLOs. Here, we present a method to stabilize the surface lattice to enhance the capacity stability of LLOs. Specifically, we have engineered a nanometer-thin Gd-doped NiO rock-salt epitaxial layer on the surface of single-crystal LLOs, along with an atomic-level thickness LiGdO2coating layer. The dual-nanolayer protection strategy has successfully stabilized the surface structure of LLOs and suppressed electrode–electrolyte interface side reactions. As a result, the modified sample achieves a capacity retention rate of 93.4% after 500 cycles at 1C and 94.2% after 200 cycles at 0.2C. Our study underscores the importance of surface structure in achieving high cyclic stability in LLOs and provides an important approach for designing stable lithium-ion battery cathode materials.

A graded structure of silicon/carbon composite powder for highly stable lithium ion battery anode

Silicon has much higher theoretical specific capacity than traditional graphite materials (3579 mAh g−1vs. Graphite: 372mAh g−1). However huge volumetric expansion (∼300%) of silicon seriously reduces its cyclic stability as anode in lithium-ion batteries. Though reduce the size of silicon based composites to nanoscale and tuning their porosity have been extensively studied, above strategies reduce the vibration density of the anode material unsurprisingly, which is not conducive to the advantage of high volumetric capacity anode. In this work, we design a unique graded silicon/carbon powder to maintain excellent energy storage performance at high vibration density. The composite of graded structure is constructed by first particles and second particles. The construction strategy is proved to be adoptable to achieve cost effective production of high performance silicon/carbon composite anode for development of advanced lithium-ion battery. Under the premise of industrial powder materials’ production technologies, a graded structure silicon/carbon composite with optimized synthetic condition shows high-reversible capacity of 827.4 mAh g−1 at 200 mAh g−1 (equal to 1464.5 Ah L−1) and it capacity remains at 715.0 mAh g−1 after 800 cycles, with a capacity retention rate of 86.37%, which shows high cycle life.

In-situ surface growth strategy to synthesize MXene@graphdiyne heterostructure for achieving high capacity and desirable stability in lithium-ion batteries

Two-dimensional (2D) heterostructured electrodes, combining graphdiyne (GDY) and MXenes, have exhibited substantial promise in augmenting the mobility of both ionic and electron movement. However, the widespread advancement and industrial utilization have been impeded by intricate manufacturing procedures and insufficient stability. This study introduces a more streamlined, in-situ growth approach for preparing MXene@GDY electrodes, presenting a novel heterostructure. The method simplifies the manufacturing process while enhancing the specific capacity of the electrode and the more stable cycle life of lithium-ion batteries (LIBs). The resulting electrode exhibited an impressive initial specific capacity of 464.4 mA h g−1, maintaining a high capacity of 492.9 mA h g−1 after 100 cycles at 100 mA current density. More importantly, after 1200 cycles, MXene@GDY showed a capacity of 340.7 mA h g−1, significantly outperforming pure MXene, which only reached 122.3 mA h g−1 at a current density of 1.0 A g−1. The proposed in-situ construction of heterojunction on the MXene surface has demonstrated immense potential for designing high-performance electrode materials which are applicable to LIBs.

Improving LiFePO4 cathode stability in lithium-ion batteries by hybridizing activated tannic with PEDOT:PSS binders

The conventional binder polyvinylidene fluoride (PVDF) exhibits substantial polarization resistance at high magnification because of its inertness to Li+ and electrons. In addition, 1-methyl-2-pyrrolidinone (NMP) solvents are toxic, expensive, and environmentally harmful. In this study, we enhanced the poly(3,4-ethylenedioxythiophene)/poly(styrenesulfonate) (PEDOT:PSS) binder by incorporating varying ratios of tannic acid (TA) to develop a water-soluble TA-PEDOT:PSS (TAPE) binder. TAPE1,1 with a TA to PEDOT:PSS ratio of 1:1, designated as TAPE1,1, exhibited high tensile strength (7.55 N/m), low impedance (61 Ω), remarkable cycling stability of 121 mAh g−1 (retaining 83.6 % capacity over 1000 cycles), and excellent rate performance (95 mAh g−1 at a 10C rate). Consequently, this study provides valuable insights into the design of high-performance lithium batteries.

Bacterial cellulose-derived carbon as a self-supported and flexible anode for stable-performance lithium-ion batteries

Lithium-ion batteries (LIBs) have been a breakthrough in the arena of energy storage devices since their inception. Earlier the slurry-coated electrodes are used for the development of LIBs. However, the slurry-coated electrode includes electrochemically inactive species (such as current collector, binder, and carbon additive) which decreases the energy density of the device. Therefore, the research community extensively explores self-supported and flexible electrodes for various electrochemical devices because of their lower electrochemical inactive species. This work reports the usage of sustainable bacterial cellulose as a precursor to derive a self-supported anode for stable lithium-ion batteries. Detailed electrochemical and physicochemical properties were evaluated to understand the efficacy of the self-supported anode. Benefitting from the porous morphology, interconnected nanofibrous assembly, and efficient graphitic domain in carbonized bacterial cellulose the lithium-ion battery delivers an impressive electrochemical performance. Notably, lithium-ion cells with the anode delivered a capacity of 548 mAh/g at 0.05 A/g with shallow irreversible capacity loss (coulombic efficiency of the first cycle is 90%). The cell maintains a capacity of 198 mAh/g at an extremely high current of 2 A/g and retains 82 % of capacity after 1000 cycles at 0.5 A/g. This work paves the way to create a self-supported and flexible electrode with a simple and scalable approach.

Film Thickness Effect in Restructuring NiO into LiNiO2 Anode for Highly Stable Lithium-Ion Batteries

The long-term stability of energy-storage devices for green energy has received significant attention. Lithium-ion batteries (LIBs) based on materials such as metal oxides, Si, Sb, and Sn have shown superior energy density and stability owing to their intrinsic properties and the support of conductive carbon, graphene, or graphene oxides. Abnormal capacities have been recorded for some transition metal oxides, such as NiO, Fe2O3, and MnO/Mn3O4. Recently, the restructuring of NiO into LiNiO2 anode materials has yielded an ultrastable anode for LIBs. Herein, the effect of the thin film thickness on the restructuring of the NiO anode was investigated. Different electrode thicknesses required different numbers of cycles for restructuring, resulting in significant changes in the reconstituted cells. NiO thicknesses greater than 39 μm reduced the capacity to 570 mAh g−1. The results revealed the limitation of the layered thickness owing to the low diffusion efficiency of Li ions in the thick layers, resulting in non-uniformity of the restructured LiNiO2. The NiO anode with a thickness of approximately 20 μm required only 220 cycles to be restructured at 0.5 A g−1, while maintaining a high-rate performance for over 500 cycles at 1.0 A g−1, and a high capacity of 1000 mAh g−1.

Embedding silicon nanoparticle in porous carbon fiber for highly stable lithium-ion battery anode

Silicon is considered as one of the best anode material candidates for future lithium-ion battery. The composite engineering of silicon/carbon matrix is of great importance to prevent the silicon volume change. Traditional method of carbon coating although provide mechanical support but the ion transport is blocked by carbons. Herein, we developed a novel nanoporous carbon matrix synthesized by polymer template. The silicon/carbon nanoporous fiber anode shows high stability and high-rate performance thanks to the strong binding and robust porous structure between silicon nanoparticles and carbon matrix. The silicon/carbon nanoporous fiber anode provides high capacity of 992 mAh/g after 200 cycles at 1C rate and stable cycle retention of 84.4% after 200 cycles at 2C rate, and also shows impressive rate capacity retention of 68.2% at 2C compared with 34.5% retention of bare silicon anode.

Fine-Tuning Intrinsic and Doped Hydrogenated Amorphous Silicon Thin-Film Anodes Deposited by PECVD to Enhance Capacity and Stability in Lithium-Ion Batteries.

Silicon is a promising alternative to graphite as an anode material in lithium-ion batteries, thanks to its high theoretical lithium storage capacity. Despite these high expectations, silicon anodes still face significant challenges, such as premature battery failure caused by huge volume changes during charge-discharge processes. To solve this drawback, using amorphous silicon as a thin film offers several advantages: its amorphous nature allows for better stress mitigation and it can be directly grown on current collectors for material savings and improved Li-ion diffusion. Furthermore, its conductivity is easily increased through doping during its growth. In this work, we focused on a comprehensive study of the influence of both electrical and structural properties of intrinsic and doped hydrogenated amorphous silicon (aSi:H) thin-film anodes on the specific capacity and stability of lithium-ion batteries. This study allows us to establish that hydrogen distribution in the aSi:H material plays a pivotal role in enhancing battery capacity and longevity, possibly masking the significance of the conductivity in the case of doped electrodes. Our findings show that we were able to achieve high initial specific capacities (3070 mAhg-1 at the 10th cycle), which can be retained at values higher than those of graphite for a significant number of cycles (>120 cycles), depending on the structural properties of the aSi:H films. To our knowledge, this is the first comprehensive study of the influence of these properties of thin films with different doping levels and hydrogen distributions on their optimization and use as anodes in lithium-ion batteries.

Boosting LiMn2O4 Diffusion Coefficients and Stability via Fe/Mg Doping and MWCNT Synergistically Modulating Microstructure

The dissolution of manganese and its deposition on the anode surface cause poor cycling stability in lithium-ion batteries. To alleviate these issues, this study probes the electrochemical activity of highly crystalline and cation-adjusted lithium manganese oxide (LMO) carbon spinel composite obtained via a modified sol-gel synthesis procedure. The pristine LMO cathode was functionalized with a Fe and Mg alloy and fused with purified multiwalled carbon nanotubes (MWCNTs) to form a catalytically stabilized LiMn1.98Fe0.01Mg0.01O4/MWCNT (LMO-FeMg/MWCNT) framework. High-resolution SEM analysis showed well-dispersed particles in the nanometer size range. The electrochemical characteristics of the novel composite materials yielded favourable electrochemical results with diffusion coefficients of 1.91 × 10−9 cm2·s−1 and 5.83 × 10−10 cm2·s−1 for LMO-FeMg and LMO-FeMg/MWCNT, respectively. This improvement was supported by impedance studies which showed a considerable Rct reduction of 0.27 Ω and 0.71 Ω. The cation stabilized system outperformed the pristine LMO material with specific capacities around 145 mAh·g−1, due to an enhancement in electrochemical activity and structural stability.

A new universal aqueous conductive binder via esterification reinforced electrostatic/H-bonded self-assembly for high areal capacity and stable lithium-ion batteries

A new universal aqueous conductive binder composed of carboxylic CNTs interwoven in flexible membranes of the neutralizing product of 6-amino-1-hexanol and commercial PAA is constructed, enabling high areal capacity and high stability for LIBs.

Morphology Control of Ball Milled Si-Ti Alloys and a Comparison of Their Surface Reactivity with SiOx

Si-based anode materials have been widely studied due to their higher volumetric capacity compared to graphite.1 However, they can suffer from poor cycling due to severe volume changes, crystallization effects (formation of Li15Si4), an unstable solid electrolyte interphase (SEI) and surface erosion. Alloying Si with an electrochemically inactive material can decrease the volume expansion and lead to better cycling performance. If nanostructured or amorphous Si-based alloys are used, the phase transition due to the crystallization effect is suppressed.1,2 Considering all improvements, Si-based anode materials still experience large surface erosion that continuously increases the surface area of active material particles during cycling. Different studies show that the main causes of surface erosion are the volume changes during cycling and the reaction between the active material and electrolyte.3,4 It is known that higher active material surface area leads to a higher reaction rate with electrolyte. This leads to a larger lithium inventory loss and a decrease in coulombic efficiency (CE), which is undesirable.5 Mechanical milling has long been used to create metal alloys. Cao et al showed that preparing Si-based alloys with a two-step milling method, in which Si is first milled alone with the metal added in the second step, produces Si-M alloys having an amorphous active Si-phase and a reduced surface area compared to conventional one-step milling.5 SiOx has also been extensively studied as an anode material because of reduced volume expansion, less side reactions with electrolyte, and high capacity retention during cycling.6 Despite decades of research to our knowledge, it has yet to be determined how the surface erosion or reactivity of SiOx compares with Si-based alloys with a similar surface area. This fundamental question needs to be answered if Si-based alloys are to be considered as candidates for practical application as negative electrode materials. A barrier to answering this question has been the very different surface areas of Si-based alloys (typically high surface area materials prepared by ball milling) and SiOx, which has a low surface area. Increasing the surface area of SiOx and reducing the surface area of the Si-based alloys using the two-step milling method can provide the opportunity to compare their surface reactivity.In this study, SixTi100-x (x= 85,70, 60) alloys were prepared by ball milling using the one-step and two-step methods, allowing low and high surface area alloys to be synthesized. The results show that reducing alloy surface area results in an increased CE, however, the difference is not pronounced. The surface erosion or reactivity of low surface area Si0.85Ti0.15 was compared with SiOx with a similar surface area. Cycling results show that Si0.85Ti0.15 has a higher CE than SiOx in initial cycles, but SiOx has a markedly higher CE after longer term cycling. These results are verified by direct observations of reduced surface erosion on cycled SiOx alloy particles compared to Si0.85Ti0.15 particles. Figure 1(a) and (b) shows the cross-section SEM images of low surface area Si0.85Ti0.15 and SiOx with a similar surface area after 50 cycles, respectively. The SiOx particles are almost pristine, while the Si0.85Ti0.15 particles are severely eroded. These results imply that the chemistry of SiOx plays a more important role in its good cycling performance than does its low surface area. References. Obrovac, M. N. & Chevrier, V. L. Alloy Negative Electrodes for Li-Ion Batteries. Chem Rev 114, 11444–11502 (2014).Iaboni, D. S. M. & Obrovac, M. N. Li15Si4 Formation in Silicon Thin Film Negative Electrodes. J Electrochem Soc 163, A255 (2016).Chevrier, V. L., Aiken, C. & Krause, L. J. Impact of Electrolyte on the Cycling of Si-Based Materials. in 228th ECS Meeting – Phoenix (2015).4.Krause, L. J., Brandt, T., Chevrier, V. L. & Jensen, L. D. Surface Area Increase of Silicon Alloys in Li-Ion Full Cells Measured by Isothermal Heat Flow Calorimetry. J Electrochem Soc 164, A2277 (2017).Cao, S., Tahmasebi, M. H., Gracious, S., Bennett, J. C. & Obrovac, M. N. Preparation of Low Surface Area Si-Alloy Anodes for Li-Ion Cells by Ball Milling. J Electrochem Soc 169, 060540 (2022).Liu, Y., Charlton, M., Wang, J., Bennett, J. C. & Obrovac, M. N. Si85Fe15Ox Alloy Anode Materials with High Thermal Stability for Lithium Ion Batteries. J Electrochem Soc 168, 110521 (2021). Figure 1

Silicon Oxycarbide-Coated Bismuth for Enhanced Anode Stability in Lithium-Ion Batteries

The current state-of-the-art lithium-ion batteries (LIBs) with graphite as an anode foresees shortcomings to demands in energy storage and supplies with high energy and power densities for large-scale applications such as electric vehicles. Metallic Bi alloy is among the promising alternative alloy candidates to replace the graphitic anode owing to its high volumetric capacity (3765 mAh cm−3), relatively small volume expansion (~215%), and unique layered crystalline structure with large interlayer spacing along the c-axis (d 003 = 3.95 Å). Nevertheless, inevitable volume expansion during repetitive Li+-ion insertion/extraction build-ups localized mechanical strain, causing particle pulverization, cracking, and isolations, eventually leading to cell failure. Herein, to achieve decent reversibility of alloys, we introduce a polymer-derived ceramic silicon oxycarbide (SiOC) coating onto Bi nanoparticles (NPs) via facile dispersion of bismuth hydroxide in silicone oil and consecutive heat treatment. The SiOC coating layer alone is an active conversion material with a higher specific capacity but lower volumetric capacity than Bi. To promote the fabrication of high volumetric capacity Bi-based composites using higher tap density materials with a well-balanced specific capacity, the content of the metal precursor and silicone oil were varied. The sturdy SiOC matrix embedded with the Bi NPs cushions the stress cultivated upon (de)lithiation reactions, achieving stable capacity (507 mAh g−1 at 0.05 A g−1 after 150 cycles), high volumetric capacity (872 mAh cm−3), superb cyclic stability (380 mAh g−1 at 0.5 A g−1 after 500 cycles), and adequate cell integrity when tested as an anode in a half cell. In a full cell configuration coupled with a LiNi0.5Co0.2Mn0.3O2 cathode, high gravimetric and volumetric energy densities of 343 Wh kg−1 and 607 Wh L−1 can be estimated, respectively. The conducted kinetic and postmortem analyses provide additional insights into the effectiveness of amorphous SiOC as a protective layer in preventing excess solid electrolyte interface passivation and preserving the electrically conductive network for continuous transport of ions and electrons. Figure 1

Designing electrolytesand interphases for high-energy lithium batteries.

High-energy and stable lithium-ion batteries are desired for next-generation electric devices and vehicles. To achieve their development, the formation of stable interfaces on high-capacity anodes and high-voltage cathodes is crucial. However, such interphases in certain commercialized Li-ion batteries are not stable. Due to internal stresses during operation, cracks are formed in the interphase and electrodes; the presence of such cracks allows for the formation of Li dendrites and new interphases, resulting in a decay of the energy capacity. In this Review, we highlight electrolyte design strategies to form LiF-rich interphases in different battery systems. In aqueous electrolytes, the hydrophobic LiF can extend the electrochemical stability window of aqueous electrolytes. In organic liquid electrolytes, the highly lithiophobic LiF can suppress Li dendrite formation and growth. Electrolyte design aimed at forming LiF-rich interphases has substantially advanced high-energy aqueous and non-aqueous Li-ion batteries. The electrolyte and interphase design principles discussed here are also applicable to solid-state batteries, as a strategy to achieve long cycle life under low stack pressure, as well as to construct other metal batteries.

Long Cycle Life for Rechargeable Lithium Battery using Organic Small Molecule Dihydrodibenzo[c,h][2,6]naphthyridine-5,11-dione as a Cathode after Isoindigo Pigment Isomerization.

Sustainability and adaptability in structural design of the organic cathodes present promises for applications in alkali metal ion batteries. Nevertheless, a formidable challenge lies in their high solubility in organic electrolytes, particularly for small molecular materials, impeding cycling stability and high capacity. This study focuses on the design and synthesis of organic small molecules, the isomers of (E)-5,5'-difluoro-[3,3'-biindolinylidene]-2,2'-dione (EFID) and 3,9-difluoro-6,12-dihydrodibenzo [c, h][2,6]naphthyridine-5,11-dione (FBND). While EFID, characterized by a less π-conjugated structure, exhibits subpar cycling stability in lithium-ion batteries (LIBs), intriguingly, another isomer, FBND, demonstrates exceptional capacity and cycling stability in LIBs. FBND delivers a remarkable capacity of 175mAhg-1 at a current density of 0.05Ag-1 and maintains excellent cycling stability over 2000 cycles, retaining 90% of its initial capacity. Furthermore, an in-depth examination of redox reactions and storage mechanisms of FBND are conducted. The potential of FBND is also explored as an anode in lithium-ion batteries (LIBs) and as a cathode in sodium-ion batteries (SIBs). The FBND framework, featuring extended π-conjugated molecules with an imide structure compared to EFID, proves to be an excellent material template to develop advanced organic small molecular cathode materials for sustainable batteries.

Polymeric Electrolytes for Solid-state Lithium Ion Batteries: Structure Design, Electrochemical Properties and Cell Performances.

The solid-state electrolytes are keys to achieve high energy, safety and stability for lithium ion batteries. In this review, core indicators of solid polymer electrolytes are discussed in detail including ionic conductivity, interface compatibility, mechanical integrity and cycling stability. Besides, we have also summarized how above properties can be improved by the design strategy of functional monomers, groups and assembly of batteries. Structures and properties of polymers are investigated here to provide a basis for all-solid-state electrolyte design strategies of multi-component polymers. Meanwhile, adjustment strategies of quasi-solid-state polymer electrolytes such as adding functional additives and carrying out structural design have also been investigated, aiming at solving problems caused by simply adding liquids or small molecular plasticizer. We hope that fresh and established researchers can achieve a general perspective of solid polymer electrolytes via this review, and spur more extensive interests for exploration of high-performance lithium ion batteries.

Effect of crystal morphology of ultrahigh-nickel cathode materials on high temperature electrochemical stability of lithium ion batteries

Higher nickel content endows Ni-rich cathode materials LiNixCoyMn1−x−yO2 (x > 0.6) with higher specific capacity and high energy density, which is regarded as the most promising cathode materials for Li-ion batteries. However, the deterioration of structural stability hinders its practical application, especially under harsh working conditions such as high-temperature cycling. Given these circumstances, it becomes particularly critical to clarify the impact of the crystal morphology on the structure and high-temperature performance as for the ultrahigh-nickel cathodes. Herein, we conducted a comprehensive comparison in terms of microstructure, high-temperature long-cycle phase evolution, and high-temperature electrochemical stability, revealing the differences and the working mechanisms among polycrystalline (PC), single-crystalline (SC) and Al doped SC ultrahigh-nickel materials. The results show that the PC sample suffers a severe irreversible phase transition along with the appearance of microcracks, resulting a serious decay of both average voltage and the energy density. While the Al doped SC sample exhibits superior cycling stability with intact layered structure. In-situ XRD and intraparticle structural evolution characterization reveal that Al doping can significantly alleviate the irreversible phase transition, thus inhibiting microcracks generation and enabling enhanced structure. Specifically, it exhibits excellent cycling performance in pouch-type full-cell with a high capacity retention of 91.8% after 500 cycles at 55 °C. This work promotes the fundamental understanding on the correlation between the crystalline morphology and high-temperature electrochemical stability and provides a guide for optimization the Ni-rich cathode materials.

Controlled solution combustion synthesis of Ni incorporated rice-shape V2O5 cathode material for stable lithium ion battery

V2O5 has been considered as ideal alternatives of cathode materials for lithium ion battery due to its high specific capacity. However, the poor ionic and electronic conductivity has limited the practical application. Herein, Ni incorporated V2O5 with rice shape was successfully prepared by a synergistic strategy of solution combustion synthesis and low temperature calcine. The specific structure can rapidly transfer Li+ and shorten the transmission distance of electrolyte, which improves the kinetics of the chemical reaction and the electrochemical performance of V2O5. The sample delivers a high discharge capacity of 225.1 mA h/g with 92.3% capacity retention after 100 cycles and good rate capability. This work puts forward a new Vision to optimize the vanadium-based cathode material for lithium ion battery.