Nickel-rich Cathode Materials Research Articles

Dynamically constructing robust cathode-electrolyte-interphase on nickel-rich cathode by organic boron additive for high-performance lithium-ion batteries

Nickel-rich ternary cathode materials LiNi0.8Co0.1Mn0.1O2 (NCM811) have attracted broad attention due to their high voltage and high energy density for lithium-ion batteries. However, rapid capacity decay due to unstable particle surface inhibit the application. Artificial cathode electrolyte interface (CEI) is undoubtedly a more effective and simpler way to solve this issue. Here, stable and highly conductive in situ CEI is designed using a low-cost organic boron additive isopropoxy-4,4,5,5-tetramethyl-1,3,2-dioxaborolane (ITD). Higher occupied molecular orbital energy endows ITD ability to participate in forming CEI. ITD-contained CEI can reduce nickel dissolving, resulting in a lower self-discharge rate, which is benefit from the uniform and stable CEI on the NCM811 surface. As expected, ITD-based CEI can restrain NCM811crystal cracking in Li||NCM811 half batteries, improving capacity retention from 29.4 % to 93.0 % after 200 cycles at 1C (1C = 200 mA g−1). It is worth mentioning that ITD–derived CEI is conducive to ion migration, which improve the rate capacity retention from 91.5 % to 95.5 %.

The Role of Zinc Triflate Additive for Improved Electrochemical Performance of Nickel-Rich Layered Oxide Lithium Battery Cathode via Suppression of Interfacial Parasitic Reactions

Nickel-rich layered oxide cathode materials with low cobalt content, such as LiNi0.90Mn0.05Co0.05O2 (NMC90), have the potential to enable cost-effective, high-energy-density lithium-metal batteries. However, NMC90 cathode materials are prone to severe parasitic reactions at higher voltages during prolonged cycling. The addition of small percentages of electrolyte additives to the neat commercial electrolyte can significantly enhance the overall electrochemical performance of lithium-metal batteries. This study investigates the effects of zinc triflate (Zn(Otf)2) as an electrolyte additive on the enhancement of the electrochemical performances of lithium-metal batteries comprising nickel-rich layered oxide cathode materials. X-ray photoelectron spectroscopy analysis revealed that Zn(Otf)2 decomposition leads to enhanced fluorination at the interfacial layers, which contributes to improved chemical stability. Utilizing operando electrochemical mass spectroscopy, we demonstrate that Zn(Otf)2 additives effectively suppress the electrolyte degradation, which is otherwise detrimental to electrochemical performance. Electrochemical studies show that the inclusion of only ∼1% Zn(Otf)2 as additive in neat commercial electrolyte enhances the electrochemical performance indicated by a 10% improvement in discharge capacity after 150 cycles. This study paves the way for researchers to develop novel fluorinated triflate based electrolyte additives aimed at enhancing the stabilization of interfaces for lithium ion, and potentially also Li-metal batteries.

Surface modification of rare earth elements to enhance the electrochemical stability of Ni-rich Co-free cathodes

The Ni-rich Co-free cathode materials are considered the most optimistic choice for the long-term economic development of lithium-ion batteries (LIBs) due to the limited supply and high prices of cobalt. In this study, a uniform samarium oxide (Sm2O3) layer was coated on the surface of LiNi0.8Mn0.17Fe0.03O2 (NMF) cathode materials through wet subsequent heat treatment. Compared with the unmodified cathode materials, the modified cathode materials exhibit better electrochemical performance at high voltage. The specific discharge capacity of the modified cathode materials increased from 37.5 mAh g−1 (NMF) to 118.2 mAh g−1 after 200 cycles at 1 C and the retention rate increased from 21.18% to 69.77%. The samarium oxide coating effectively inhibits the reaction between the cathode materials and the electrolyte. Therefore, our study proposes a simple and scalable method for modifying nickel-rich cobalt-free cathode materials.

Nickel-rich ternary cathode material as a novel capping layer to improve lithium iron phosphate electrochemical performance

Nickel-rich ternary cathode material as a novel capping layer to improve lithium iron phosphate electrochemical performance

Quenching-Induced Ultrathin LiF-Rich Interphases on LiNi0.8Co0.1Mn0.1O2 Cathode

Nickel-rich layered oxides (NCM) are a promising contender material for the cathode electrode of high-energy lithium-ion batteries (LIBs) due to their large reversible capacity and high operating voltage. However, the poor surface/interfacial stability and the dissolution of transition metal ions hinder the commercial application of NCM. To create an artificial cathode electrolyte interphase (CEI) with LiF-rich inorganic phase on the NCM surface, a practical and efficient way of quenching the NCM powder from high temperature in 1,1,2,2-Tetrafluoroethyl 2,2,2-trifluoroethyl ether (HFE) was devised. With this artificial CEI film, the side reactions between NCM and electrolytes are inhibited, and the dissolution of TM ions is retarded. The quenched-NCM achieved fantastic cycling performance and suppressed voltage decay. Our research offers an efficient and worthy approach for improving the surface/interfacial stabilization of nickel-rich cathode materials for high-energy-density LIBs.

Rest in phase transition: Should charging habits in next generation EVs be adapted?

Nickel-rich cathode materials are a popular cathode for high energy lithium ion batteries in the current and next generation of electric vehicles. While nickel-rich cathodes offer high energy density, their cycle-life is compromised due to several factors directly related to their (de)lithiation behavior. At high state of charge the nickel-rich cathode experiences a hexagonal-hexagonal transition which is accompanied by drastic changes in the unit cell parameters. This phenomenon is detrimental for cycle-life of a battery cell. This work elucidates on the effect of storing LiNi0.8Mn0.1Co0.1O2‖Graphite cells at 95 % state of charge corresponding to the above-mentioned transition for 10 h every six cycles. The results are compared to cells cycled without a rest at high state of charge and cells cycled to 100 % state of charge. Analysis of the obtained cycling data shows that resting lithium ion cells based nickel-rich cathode based cells is detrimental leading to higher impedance growth and capacity decay than cycling to 100 % state of charge.

Development and understanding of the lithiation/de-lithiation mechanism of a low cobalt and nickel-rich cathode material for lithium‐ion batteries

Nickel-rich LiNixMnyCo1−x−yO2 (NMC, with x ≥ 0.6) layered oxides are regarded as cathode candidates for high-energy density lithium-ion batteries (LIBs). However, this technology faces several challenges due to the scarcity of crucial raw materials such as cobalt precursors and the negative environmental impact of their extraction process. It is therefore, it becomes imperative to develop low cobalt content cathode compositions that offer alternative options with comparable electrochemical performance. Herein, we have used a systematic approach to modify the composition while keeping all other properties (particle size and morphology) constant to synthesise low-Co-cathode materials, namely LiNi0·8Mn0·1Co0·1O2 (NMC-10 %) and LiNi0·8Mn0·15Co0·05O2 (NMC-5%). A co-precipitation route using a continuous stirred thank reactor was used for synthesis. The physico-chemical properties, electrochemical performances, cycling stability, and rate capabilities of NMC-5% materials are comparable to those of NCM-10 % materials. NMC-10 % and NMC-5% half cells show initial specific discharge capacities of 191 mAh.g−1, and 185 mAh.g−1, respectively, in a voltage range of 2.8–4.3 V (vs. Li+/Li). The NMC-5% exhibits excellent thermal stability, characterized by a predominant exothermic peak at 432 °C and significantly lower total heat energy when compared to NMC-10 % counterpart, which displayed its main exothermic peak at 339 °C. The structural and electronic changes of both materials were evaluated through in operando synchrotron-based X-ray techniques. Regardless of the cobalt content, both materials show comparable structural and electronic evolution upon the de-intercalation/intercalation of Li+ ions. An irreversible phase transition at the first delithiation was observed as emphasized by diffraction of synchrotron radiations.

In-situ electrochemical passivation for constructing high-voltage PEO-based solid-state lithium battery

Polyethylene oxide (PEO) is one of the promising substrates for polymer solid electrolyte. However, when coupled with high energy density nickel-rich layered cathode materials, PEO faces the risk of catalytic decomposition by delithium nickel-rich materials. In this work, the in-situ electrochemical passivation strategy is employed to obtain high voltage PEO-based solid-state lithium battery. Trace commercial liquid electrolyte was added on the surface of LiNi0.8Co0.1Mn0.1O2 (NCM811) electrode, and liquid electrolyte is prior to PEO electrolyte to react with the cathode during charge/discharge process, leading to the formation of cathode-electrolyte interface (CEI) layer. The CEI layer avoids the direct contact between PEO and NCM811, thus effectively prevents PEO from being decomposed by NCM811 under high voltage. As a result, the optimized NCM811||PEO||Li battery displays enhanced electrochemical performance, especially cycling performance. This simple but effective strategy not only simplifies the manufacturing process, but also has instructional guidance for high-voltage PEO-based battery.

Enhancing performance and stability of LiNi0.8Co0.1Mn0.1O2 cathode via Na/Y dual doping for Lithium-Ion batteries

Nickel-rich layered oxide cathode materials face limitations in practical applications due to trade-offs between capacity and structural stability. As more Li+ is extracted during charging, the layered structure of nickel-rich materials becomes increasingly fragile. To address this, a double doping strategy with Na and Y is proposed in this study to enhance the strength of the layered structure. The research findings demonstrate that Na doping enlarges the spacing between Li layers in the crystal structure, while Y doping improves the reversibility of the H2-H3 phase transition but narrows the Li layer spacing in nickel-rich materials. Na and Y double doping, the advantages of Na in enlarging the Li layer, and Y in improving the H2-H3 phase transition can be harnessed simultaneously. This double doping strategy ensures that the laminar structure of the cathode material remains stable even when it is highly detached, effectively solving the trade-off between the capacity and structural stability of nickel-rich laminar cathode materials. The application in LiNi0.8Co0.1Mn0.1O2 shows that the capacity and cycle life of cathode materials can be significantly improved after Na/Y double doping. These findings open up opportunities for practical applications of nickel-rich cathode materials in lithium-ion batteries.

Highly stable nickel-rich cathode materials LiNi0.90Co0.05Mn0.05O2 with Mn concentration gradient for lithium-ion batteries

Ni-rich layered cathode materials (LiNixCoyMn1-x-yO2) have attracted much attention due to their high energy density and environmentally friendly advantages. However, the capacity fading and structural instability with the increase of Ni content are still the main problems restricting the commercialization of high nickel cathodes. In this paper, the method of co-precipitation and calcination is used to prepare LiNi0.90Co0.05Mn0.05O2 (CG-NCM5) with Mn concentration gradient, which the Ni content is decreasing from the core to the outer of CG-NCM5, while the Mn content is increasing. The CG-NCM5 has less Li/Ni mixing and a good layered structure. More importantly, the Mn-rich outer plays a key role in preventing the appearance of microcracks and enhancing the structure stability, because it can effectively suppress the volume change stemming from the phase transition during charge/discharge process. Meanwhile, the low Ni on the surface reduces the highly reactive Ni4+ that easily reacts with electrolyte, mitigates material surface degradation and accelerates lithium-ion transport. Therefore, it exhibits a superior reversible capacity of 191.4 mAh/gat 1C and a capacity retention of 83.7 % after 200 cycles in 2.7–4.3 V. These results indicate that Mn concentration gradient materials may provide a practical approach to highly stable nickel-rich cathode materials for lithium-ion batteries.

Chemical modification of nickel-rich layered cathode materials to improve battery life

Mechanical integrity issues of Ni-rich cathode materials are major bottlenecks for their commercial application, stemming from the abrupt anisotropic lattice contraction during H2 ↔ H3 phase transitions. Herein, zirconium is used to modify LiNi0.9Co0.05Mn0.05O2 to solve the mechanical integrity issues. The relationship between the mechanical integrity issues and electrochemical performance is systematically examined to gain insights into the Zr activity-governing mechanisms. Results find that the addition of zirconium not only improves the diffusion ability of lithium ions by providing a rapid channel for diffusion of lithium ions, but also enhances mechanical properties by inhibiting cation mixing. As a result, the optimal LiNi0.9Co0.05Mn0.05O2 achieves superiority capacity retention of 84.12 % after 200 cycles at 5C, higher than that of unmodified LiNi0.9Co0.05Mn0.05O2 74.32 %. This work deeply investigates the information on the bulk structure and interaction mechanism between substitution cations and Ni-rich layered oxides, which provides a new insight to design and construct of advanced high-capacity cathode materials.

Review on Oxygen Release Mechanism and Modification Strategy of Nickel-Rich NCM Cathode Materials for Lithium-Ion Batteries: Recent Advances and Future Directions

Review on Oxygen Release Mechanism and Modification Strategy of Nickel-Rich NCM Cathode Materials for Lithium-Ion Batteries: Recent Advances and Future Directions

Mg/Al Double-Pillared LiNiO2 as a Co-Free Ternary Cathode Material Ensuring Stable Cycling at 4.6 V.

Cobalt-free (Co-free) and nickel-rich (Ni-rich) cathode materials have attracted significant attention and undergone extensive studies due to their affordability and superior energy density. However, the commercialization of these Co-free materials is hindered by challenges such as cation disorder, irreversible phase changes, and inadequate high-voltage performance. To overcome these challenges, a Co-free ternary cathode material of Mg/Al double-pillared LiNiO2 (NMA) synthesized via a wet-coating and lithiation-sintering technique is proposed. Fundamental studies reveal that Mg and Al have the potential to form a distinctive double-pillar structure within the layered cathode, enhancing its structural stability. To be specific, the strategic placement of Mg and Al in Li and Ni layers, respectively, effectively reduces Li+/Ni2+ disorder and prevents irreversible phase transitions. Additionally, the inclusion of Mg and Al refines the primary grains and compacts the secondary grains in the cathode material, reducing stress from cyclic usage and preventing material cracking, thereby mitigating electrolyte erosion. As a result, NMA demonstrates exceptional electrochemical performance under a high charge cutoff voltage of 4.6 V. It maintains 70% of initial specific capacity after 500 cycles at 1 C and exhibits excellent rate performance, with a capacity of 162 mAh g-1 at 5 C and 149 mAh g-1 at 10 C. As a whole, the produced NMA achieves a high structural stability in cases of excessive delithiation, providing a groundbreaking solution for the development of cost-effective and high-energy-density cathode materials for lithium-ion batteries.

Investigation of Zinc and Chromium Substitution Nickel-rich LiNi1-x-yZnyCrxO2 Cathode Materials to Improve the Redox Reaction of Lithium-ion battery: A First-principles Study

Abstract First-principles calculations are employed to investigate the structural, electronic, magnetic, thermoelectric, and electrochemical characteristics of Nickel-rich layered cathodes by substitution of Zn and Cr such as LiNi1-x-yZnyCrxO2 (with x= 0.00, 0.16 and 0.32, y = 0.00 and 0.16). The structure of pure LiNiO2 and substituted are organized in a trigonal arrangement inside the P3m1 space group. Using PBE-GGA approximation, the spin-polarized calculation of pure LiNiO2 in a spin-down channel exhibits a band gap of 0.48 eV. Whereas Zn and Cr substitution results in the band gap reduction to zero, and metallic behavior is observed. Electronic charge density calculation Ni(Zn, Cr)-O reveals covalent bonding. In electrochemical investigation, by the increasing substitution concentration of Zn and Cr in LiNi1-x-yZnyCrxO2 significant improvements are observed at 4.65-3.89 V potential with a good theoretical discharge capacity of 48-246 mAhg-1. The exchange constants N∘α and N∘β demonstrate negative values that validate the ferromagnetic nature of substituted material. The thermoelectric parameters have been determined using the BoltzTraP code and the highest ZT value of 0.35 is obtained for LiNi0.52Zn0.16Cr0.32O2. These results offer a new perspective of doping techniques for nickel-rich cathode materials, providing helpful insight for the development of high-performance cathodes for lithium-ion battery applications

Mechanism Behind the Loss of Fast Charging Capability in Nickel-Rich Cathode Materials.

Fast charging technology for electric vehicles (EVs), offering rapid charging times similar to conventional vehicle refueling, holds promise but faces obstacles owing to kinetic issues within lithium-ion batteries (LIBs). Specifically, the significance of cathode materials in fast charging has grown because Ni-rich cathodes are employed to enhance the energy density of LIBs. Herein, the mechanism behind the loss of fast charging capability of Ni-rich cathodes during extended cycling is investigated through a comparative analysis of Ni-rich cathodes with different microstructures. The results revealed that microcracks and the resultant cathode deterioration significantly compromised the fast charging capability over extended cycling. When thick rocksalt impurity phases form throughout the particles owing to electrolyte infiltration via microcracks, the limited kinetics of Li+ ions create electrochemically unreactive areas under high-current conditions, resulting in the loss of fast charging capability. Hence, preventing microcrack formation by tailoring microstructures is essential to ensure stability in fast charging capability. Understanding the relationship between microcracks and the loss of fast charging capability is essential for developing Ni-rich cathodes that facilitate stable fast charging upon extended cycling, thereby promoting widespread EV adoption.

Investigating the Path Dependent Aging Behavior of Nickel Cobalt Aluminum Oxide Cathode Batteries During High C-rate Cycling Conditions

Nickel-rich cathode material batteries such as the nickel cobalt aluminum oxide with graphite anode are common in the automotive sector due to their high energy density and power performance capabilities, however, they are limited in lifetime performance. Accelerated degradation in specific operation conditions, such as high C-rates are known to significantly contribute to this issue. To better understand a chronological dependence of these high-stress conditions occurring during battery lifetime, a path dependent aging study is performed using profiles inspired by high-performance race operation. The focus on C-rates >1C during charging and discharging using real-world inspired profiles- known to induce particle cracking or lithium plating- addresses the need to understand aging behavior in less studied, but highly relevant high-performance automotive context. The aging conditions were tailored to induce specific degradation modes to better identify potential degradation mode coupling. Using differential voltage and capacity analysis techniques, degradation modes were identified which likely contributed to path dependent aging behavior, including loss of lithium inventory and loss of active material in the positive electrode. Two critical paths were identified in this study where later high C-rate conditions in the form of fast-charging at temperatures of 25 °C resulted in accelerated aging and where loss of lithium inventory induced stresses in the positive electrode, accelerating loss of active material.

State of Charge-Dependent Impedance Spectroscopy as a Helpful Tool to Identify Reasons for Fast Capacity Fading in All-Solid-State Batteries.

Thiophosphate-based all-solid-state batteries (ASSBs) are considered the most promising candidate for the next generation of energy storage systems. However, thiophosphate-based ASSBs suffer from fast capacity fading with nickel-rich cathode materials. In many reports, this capacity fading is attributed to an increase of the charge transfer resistance of the composite cathode caused by interface degradation and/or chemo-mechanical failure. The change in the charge transfer resistance is typically determined using impedance spectroscopy after charging the cells. In this work, we demonstrate that large differences in the long-term cycling performance also arise in cells, which exhibit a comparable charge transfer resistance at the cathode side. Our results confirm that the charge transfer resistance of the cathode is not necessarily responsible for capacity fading. Other processes, such as resistive processes on the anode side, can also play a major role. Since these processes usually depend on the state of charge, they may not appear in the impedance spectra of fully charged cells; i.e., analyzing the impedance spectra of charged cells alone is insufficient for the identification of major resistive processes. Thus, we recommend measuring the impedance at different potentials to get a complete understanding of the reasons for capacity fading in ASSBs.

Stabilizing LiNi0.8Co0.1Mn0.1O2 cathodes with a mixed ionic-electronic conducting Li0.34La0.55MnO3-x multifunctional coating formed via in-situ conversion of surface Li residual

In this work, we for the first time utilize the harmful surface Li residual on NCM811 to in-situ form a mixed Li+/electron conducting Li0.34La0.55MnO3-x (LLMO) coating. The formation of the (electro)chemically stable LLMO coating not only achieves effective surface cleaning, but also stabilizes the cathode surface against electrolyte attack, alleviating structure degradation and intergranular cracking. Equally importantly, the mixed conducting LLMO layer affords considerably high Li+ and electronic conductivities (2.35 ×10−5 S/cm and 1.86 ×10−3 S/cm respectively), accelerating the charge-transfer process at the interface. The in-situ LLMO-coated NCM811 exhibits notable improvements in both rate and cycling performance, featuring a capacity retention rate of 82.51% over 100 cycles at 1 C in stark contrast to 48.26% of the pristine NCM811. When combined with a dendrite-suppressed Li@Pb@carbon cloth composite Li metal anode in a full battery, a high capacity retention rate of 86.96% over 200 cycles at 1 C and a N/P ratio of 37.7 is achieved, significantly outperforming that with NCM811 (42.24%, 40.2). This study provides a novel and comprehensive solution to stabilize nickel-rich layered cathode materials for high-energy-density Li-metal batteries.

Synthesis of Fe/Mg-doped NMC6 22 from Spent Nickel Catalyst as Lithium-Ion Battery Cathode

The co-precipitation approach, along with nickel-rich (NMC622) cathode materials, magnesium, and Fe doping, was used to produce nickel-rich NMC (NMC622) cathode materials from spent nickel catalysts. Both X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR) were utilized in order to carry out the characterization of the NMC622 materials. The structural study showed that the doped materials had a structure that was equal to that of Li[Ni0,6Mn0,2Co0,2Xy]O2, which has a layered hexagonal structure similar to that of α-NaFeO2. The electrochemical test found that Mg 1 mol% had the highest discharge capacity at 99.61 mAh/g. This was determined by the results of the test. The use of magnesium as a dopant in structurally stable, Ni-rich NMC materials led to an increase in the electrochemical capacity of the Mg-doped NMC. Magnesium exhibited a significant amount of potential as a dopant. It is necessary to do additional research into the functional testing of magnesium as a doping material in order to maximize its use for a longer cycle life and improved thermal stability lithium ion batteries.

Revealing Phase Transition in Ni-Rich Cathodes Via Nondestructive Entropymetry Method

With the expanding requirements of recent energy regulations and economic interest in high-performance batteries, the need to improve battery energy density and safety has gained prominence. High-energy-density lithium batteries, employed in next-generation energy storage devices, rely on nickel-rich cathode materials. Since these have extremely high charge/discharge capacity, high operating voltage, prolonged cycle life, and low cost, nickel-rich cathode materials such as Ni-rich NCM (LiNix>0.8CoyMnzO2) and Ni-rich NCA (LiNix>0.8CoyAlzO2) are of particular interest to researchers. Several in situ characterization methodologies are currently used to understand lithium-ion battery electrode response and deterioration better. Nevertheless, in many contexts, these measurement methodologies must be combined with specially designed cells and electrode materials with distinct forms, which is sometimes inconvenient. As an alternative, thermothermo-voltametric dynamic characterization may be utilized to describe the thermal internal characteristics of various electrode materials, such as the structural changes and electrode reactions that occur during charging and discharging. In this paper, a non-destructive entropy measurement method demonstrates that phase change occur for NCM (LiNi0.83Co0.12Mn0.05O2) and NCA (LiNi0.88Co0.09Al0.03O2) at 40-30% of SOC and 90-80% of SOC, respectively. This is confirmed by ex-situ X-ray diffraction measurements for these highly popular cathodes.