LiCoO2 Cathode Materials Research Articles

A review of solid-state halide electrolyte matched LiCoO2 and Ni-rich NCM

The energy issue is an important issue affecting the development of countries worldwide. To solve the problem of resource depletion faced by fossil energy, to cope with global warming, and to achieve sustainable development, the development, utilization, and promotion of new energy sources have received universal attention. Halide solid electrolytes have a stable oxidation potential above 4 V, matching the LiCoO2 cathode material with considerable electrochemical performance. This review addresses the electrochemical performance and possible problems matching solid-state halide electrolytes with LiCoO2 and Ni-rich NCM. This paper concludes that halides have electrochemical stability and high ionic conductivity at high potentials matching LiCoO2 and Ni-rich NCM and good electrochemical properties. However, whether surface reactions exist when it is matched to a high nickel ternary material with a high surface base content, the evolution of the interface between the high nickel ternary material and the halide electrolyte during cycling and the factors affecting the performance of Ni-rich NCM in halide solid-state batteries need to be further investigated.

Innovative green approach for recovering Co2O3 nanoparticles and Li2CO3 from spent lithium-ion batteries

Although previous studies have obtained promising results for recovering valuable metals from spent LIBs at low temperatures using organic acids combined with reducing agents, additional chemicals such as H2O2, huge amounts of organic acids, and environmental protection remain challenges. In this study, a subcritical water (SCW) assisted diluted formic acid process was proposed as a green approach for recovering Co2O3 nanoparticles and Li2CO3 from spent LiCoO2 cathode materials without using any reducing agents. The effects of leaching parameters such as (H2O: HCOOH) ratio (v/v), temperature, reaction time, and liquid-solid ratio on the extraction of Li and Co have been carefully evaluated. The findings revealed that SCW-assisted (DFA) successfully leaches Li and Co from the spent LiCoO2 cathode materials of Li-ion batteries without using any assistance from reducing reagents. The solid materials were characterized by XRD, XPS, FT-IR, and SEM-EDS analyses. Meanwhile, the leaching liquor was analyzed by ICP-OES. More than 99% of Li and Co were effectively recovered from the spent LiCoO2 powder at 220 °C for 25 min, H2O: HCOOH ratio (v/v,) of 78:12 and a liquid-solid ratio of 25 mL/g. Further, the activation energy for Li was 24.15 KJ/mol, while that for Co was 31 KJ/mol. Finally, Co2O3 and Li2CO3 were successfully recovered from the leaching liquor by the precipitation and calcination methods after the separation steps. The overall findings suggested that SCW-assisted (DFA) could be an alternative method due to its low energy consumption, dual function properties at mild temperatures, low chemical input, and environmentally friendly.

Increasing the Performance of {[(1-x-y) LiCo0.3Cu0.7] (Al and Mg doped)] O2}, xLi2MnO3, yLiCoO2 Composites as Cathode Material in Lithium-Ion Battery: Synthesis and Characterization

Twenty-eight samples of {[(1-x-y) LiCo0.3Cu0.7](Al and Mg doped)]O2}, xLi2MnO3, and yLiCoO2 composites were synthesized using the sol-gel method. Stoichiometric weights of LiNO3, Mn(Ac)2⋅4H2O, Co(Ac)2⋅4H2O, Al(NO3)3.H2o, Mg(NO3)2⋅6H2O, and Cu(NO3)2.H2O for the preparation of these samples were applied. From this work, we confirmed the high performance of two samples, namely, Sample 18, including Al doped with structure "Li1.5Cu0.117Co0.366Al0.017Mn0.5O2" and Sample 17, including Mg doped with structure "Li1.667Cu0.1Mg0.017Co0.217Mn0.667O2", compared with other compositions. Evidently, the used weight of cobalt in these two samples were lower compared with LiCoO2, resulting in advantages in the viewpoint of cost and toxicity problems. Charge and discharge characteristics of the mentioned cathode materials were investigated by performing cycle tests in the range of 2.2-4.5 V. These types of systems can help to reduce the disadvantages of cobalt arising from its high cost and toxic properties. Our results confirmed that the performance of such systems is similar to that of pure LiCoO2 cathode material, or greater in some cases. The biggest disadvantages of LiCoO2 are its cost and toxic properties, typically making it cost around five times more to manufacture than when using copper.

Recovery of Cobalt and Lithium by Carbothermic Reduction of LiCoO2 Cathode Material: A Kinetic Study

Recycling of Li-ion battery cathode materials using carbon from the anode materials via carbothermic reduction would provide a reduction process option that could be carried out without introducing any external reactants. From this basis, this study investigated and examined the kinetics of carbothermic reduction of LiCoO2 at 700 °C to 1100 °C under inert atmosphere up to 240 minutes reaction time using an isothermal mass change analysis combined with detailed microstructure evolution observation. The overall reduction mechanism appeared to involve diffusion of oxygen in LiCoO2 during its thermal decomposition in the first stage, followed by the nucleation of cobalt in the second stage. The activation energy of the diffusion and nucleation stages were calculated to be 121 and 95 kJ/mol, respectively. The microstructure analyses showed a complex evolution of phases. At 700 °C to 900 °C, Li2CO3 and Co phases were observed as the product of the reductions; while at 1000 °C to 1100 °C, Li2O and Co phases were observed. The information and data obtained are useful when comparing different recycling methods and optimizing the carbothermic reduction parameters for recycling cathode materials from spent Li-ion batteries.

Waste to Treasure: Regeneration of Porous Co-Based Catalysts from Spent LiCoO2 Cathode Materials for an Efficient Oxygen Evolution Reaction

The increasing demand for portable electronic devices and electric vehicles (EVs) has triggered the rapid growth of the rechargeable Li-ion battery (LIB) market. However, in the near future, it is predicted that a large amount of spent LIBs will be scrapped, imposing huge pressure on environmental protection and resource reclaiming. The effective recycling or regeneration of the spent LIBs not only relieves the environmental burdens but also avoids the waste of valuable metal resources. Herein, a porous Co9S8/Co3O4 heterostructure is successfully synthesized from the spent LiCoO2 (LCO) cathode materials via a conventional hydrometallurgy and sulfidation process. The fabricated Co9S8/Co3O4 catalyst exhibits high catalytic activity toward oxygen evolution reaction (OER) in an alkaline solution, with an overpotential of 274 mV to achieve the current density of 10 mA cm–2 and a Tafel slope of 48.7 mV dec–1. This work demonstrates a facile regeneration process of Co-based electrocatalysts from the spent LiCoO2 cathode materials for efficient oxygen evolution reaction.

A Novel Cathode Material Synthesis and Thermal Characterization of (1-x-y) LiCo1/3Ti1/3Fe1/3PO4, xLi2MnPO4, yLiFePO4 Composites for Lithium-Ion Batteries (LIBs)

Lithium-ion batteries are known for their high efficiency for storing electrical energy, especially for hybrid vehicles. In this research, the development of mixture composites in the cathode electrode of LIBs has been discussed and designed based on ternary solid solutions. We have given a novel synthesis and method preparation of cathode electrode materials to reduce costs while increasing the efficiency and simultaneity for the future of these technologies. The major problem in the LIBs is related to LiCoO2 as a popular cathode material that, although it has a high efficiency, is expensive and very toxic. Therefore, the usage of a lower weight of cobalt compared to the LiCoO2 cathode material is economically advantageous for this research. Several samples of the (1-x-y) LiCo1/3Ti1/3Fe1/3PO4 xLi2MnPO4 and yLiFePO4 system were synthesized via sol-gel experiments. Various stoichiometric amounts of the LiNO3, Li2MnPO4, Mn (Ac)2. 4H2O, Co (Ac)2.4H2O, Ti(NO3)2.6H2O and LiFePO4 have been used for several compositions of chrome, manganese, cobalt and titanium in 28 samples of (1-x-y) LiCo1/3Ti1/3Fe1/3PO4. By using thermal characterization, five samples have been selected due to their conditions in viewpoints of capacity and cyclability as well as activation energy, which is one of the major factors. These composites exhibited fairly consistent charge/discharge curves during the electrochemical testing. From the viewpoint of the physical and chemical properties, among these samples, the Li1.501Co0.389Ti0.055Fe0.055Mn0.501PO4 structure has a high efficiency compared to other compositions.

Failure mechanism of LiCoO2-based pouch-type full cells during 1C/10 V overcharge and the countermeasure

Overcharge is one of the most common causes that triggers thermal runaway of lithium-ion batteries, which leads to personal injury and property loss. Therefore, it is momentous to penetrate into the mechanism of overcharge and enhance the overcharge safety from the essence of battery materials. Herein, the combined Al doping and Al2O3 coating strategies are applied to the LiCoO2 cathode materials, which are employed to enhance the overcharge performance of 950 mAh LiCoO2-based pouch-type full cells. The results show that only the pouch-type full cells using LiCoO2 with both Al doping and Al2O3 coating as cathode pass the 1C/10 V overcharge test successfully. In-situ X-ray diffraction (XRD) and differential electrochemical mass spectrometry (DEMS) results illustrate that the critical factors leading to thermal runaway lie in the structural instability of LiCoO2 and the violent interfacial reaction rooted in electrolyte decomposition. Further post analysis of pouch-type full cells demonstrate that the enhanced overcharge safety depends on the synergetic effect of Al doping and Al2O3 coating of LiCoO2. That is the Al doping can enhance the structural robustness of LiCoO2 significantly, while the coated Al2O3 works as a passive film to cut off the further reaction between the cathode and the electrolyte during overcharge.

Carbothermic reduction of LiCoO2 cathode material: Thermodynamic analysis, microstructure and mechanisms

Carbothermic reduction using secondary carbon materials such as graphite anode provides an option for recycling critical elements in the spent Li-ion batteries. In this study, carbothermic reduction of battery cathode material LiCoO2 using graphite as reductant was systematically investigated. The study included thermodynamic evaluation using the FactSage™ thermochemical modelling, isothermal high-temperature experimentation at 700–1100 °C under argon atmosphere, and detailed microstructure evolution analysis to establish the mechanisms of the reduction. The products from the reduction experiments were found to be Li2CO3, Li2O, and Co, and these corresponded well with the thermodynamic assessments. The overall reduction mechanism was evaluated to start with LiCoO2 decomposition followed by the reduction of cobalt oxide to form metallic cobalt. The results also suggest that reduction occurs indirectly through reduction by CO(g). The information generated in the study are useful for improvement and parameter optimization for high temperature recycling of Li-ion batteries.

Synergy effects of Tb/Y/Zn for structural stability of high-voltage LiCoO2 cathode material

As a popular cathode material in rechargeable lithium-ion batteries, lithium cobalt oxide (LiCoO2) is required to achieve high-level safety with high energy density to meet the ever-increasing energy demand for energy storage devices. The method of lifting the operating voltage of LiCoO2 to release more capacity for higher energy density usually causes severe structural instability at the deeply delithiated state, resulting in capacity fade and limited lifespan. Herein, we present a series of zinc, yttrium and terbium modified LiCoO2 through solid-state reaction to tackle this long-term issue of structure destruction cycling at high voltages. Compared with the mediocre electrochemical performance of LiCoO2 doped with single elements of Zn, Y and Tb, respectively, the dual-doped LiCoO2 exhibits better structural stability and capacity retention at high voltages. Furthermore, the prepared Zn–Y–Tb ternary-doped LiCoO2 exhibits excellent electrochemical capability with a discharge capacity of 185mAh/g after 100 cycles and capacity retention of 98% at 4.55 V. These multiple dopants synergistically maintain structural integrity after 300 cycles and effectively promote the cycle stability of lithium cobalt oxide cathode material at high voltages.

Reevaluating the Stability of the PEO-Based Solid-State Electrolytes for High Voltage Solid-State Batteries

Poly(ethylene oxide) (PEO) is a very popular polymer-based solid electrolyte material with relatively high ionic conductivity and dielectric constant1. However, many previous works mentioned that it could not be used in high voltage cells for its low oxidation potential (~3.9V vs. Li/Li+)2. However, only a handful of prior investigations evaluated the stability of the PEO-based solid-state electrolyte considering the contribution of the cathode surface chemistry to electrolyte oxidation and decomposition. Since most of the previous research exploring high voltage cathodes with PEO used LiCoO2, it could be possible the other cathode compositions will erode the PEO-based solid electrolyte in different and less extreme ways.Our work revisits the high voltage electrochemical stability of PEO-based solid state-electrolyte materials. Potentiodynamic and galvanostatic tests were performed in test cells using PEO electrolyte layers with either LiNixMnyCozO2 or LiCoO2 cathode materials. We found that the high voltage instability of PEO-based solid-state cells is profoundly affected by the instability of the cathode material used. Specifically, the LiCoO2 electrodes were observed to undergo an irreversible oxidation process where they shattered into small pieces, which then led to a rapid irreversible loss in capacity. In contrast, we found that the PEO-based solid-state electrolytes could be stably cycled with high-nickel content cathodes stably at a voltage up to 4.5V vs. Li/Li+ over many cycles with minimal capacity deterioration. K. Chrissopoulou, K. S. Andrikopoulos, S. Fotiadou, S. Bollas, C. Karageorgaki, D. Christofilos, G. A. Voyiatzis, and S. H. Anastasiadis, 44, 9710–9722 (2011).J. Qiu, X. Liu, R. Chen, Q. Li, Y. Wang, P. Chen, L. Gan, S.-J. Lee, D. Nordlund, Y. Liu, X. Yu, X. Bai, H. Li, and L. Chen, Adv. Funct. Mater., 30, 1909392 (2020).

Real-space measurement of orbital electron populations for Li1-xCoO2

The operation of lithium-ion batteries involves electron removal from and filling into the redox orbitals of cathode materials, experimentally probing the orbital electron population thus is highly desirable to resolve the redox processes and charge compensation mechanism. Here, we combine quantitative convergent-beam electron diffraction with high-energy synchrotron powder X-ray diffraction to quantify the orbital populations of Co and O in the archetypal cathode material LiCoO2. The results indicate that removing Li ions from LiCoO2 decreases Co t2g orbital population, and the intensified covalency of Co–O bond upon delithiation enables charge transfer from O 2p orbital to Co eg orbital, leading to increased Co eg orbital population and oxygen oxidation. Theoretical calculations verify these experimental findings, which not only provide an intuitive picture of the redox reaction process in real space, but also offer a guidance for designing high-capacity electrodes by mediating the covalency of the TM–O interactions.

Stable 4.5 V LiCoO2 cathode material enabled by surface manganese oxides nanoshell

Stable 4.5 V LiCoO2 cathode material enabled by surface manganese oxides nanoshell

A novel ternary deep eutectic solvent for efficient recovery of critical metals from spent lithium-ion batteries under mild conditions

In terms of environmental pollution and the shortage of resources, an efficient recovery of valuable metals in spent lithium-ion batteries (LIBs) is currently the most promising measure to achieve green sustainability of cathode materials. In this study, an choline chloride (ChCl)/ benzenesulfonic acid (BSA)/ ethanol ternary deep eutectic solvent (e.g., ChCl:BSA:Ethanol = 1:1:2 in molar ratio) was designed and applied to efficiently leach lithium (Li) and cobalt (Co) from spent LIBs under mild conditions. The experimental results show that the leaching efficiencies of Li and Co can reach 99% and 98%, respectively, under the optimal conditions: (i) a reaction temperature of 90 °C, (ii) a Solid/Liquid ratio of 20 g L−1, (iii) ChCl:BSA:Ethanol with a molar ratio of 1:1:2 and (iv) a reaction time of 2 h. The kinetics of the leaching process shows that the leaching is controlled by a surface chemical reaction. Furthermore, the Co2+ in the leachate can be directly converted into Co3O4 via precipitation of H2C2O4 and NaOH and calcination. The recovered high-value product Co3O4 can regenerate the LiCoO2 cathode material. This study provides a new method for the green recovery of spent LIB cathode materials with high efficiency and low energy consumption.

Selective lithium extraction and regeneration of LiCoO2 cathode materials from the spent lithium-ion battery

Due to the mounting pressure to mitigate environmental pollution and guarantee the sustainability of the battery metals, the recycling of spent lithium-ion batteries (LIBs) has become a crucial issue in recent years. Numerous studies have focused on utilizing high temperatures or strong acid/alkali to reduce the spent active cathode material to a low valence state, which exacerbates recycling and post-treatment costs. Herein, a low-temperature roasting process followed by a water leaching strategy is developed to recycle and regenerate LiCoO2 cathode material from spent LiCoO2 batteries. The spent LiCoO2 is roasted with glucose (C6H12O6) as a reagent to attain reduction of the cathode material into water-soluble Li salt (Li2O and Li2CO3) and water-insoluble (Co and CoO). The proposed method utilizes moderate roasting temperature and water as the only leaching reagent, which effectively reduces energy and chemical consumption. Li and Co recovery rates are 97 % and 99 %, respectively, under the optimal conditions of 1 h roasting at 550 °C followed by 30 min water leaching using a solid–liquid ratio of 50 g/L. The recovered Li-rich solution and Co-rich residue can be easily converted to Li2CO3 and Co3O4, respectively, which are the precursors for regenerating the LiCoO2 cathode material. The regenerated LiCoO2 exhibits superior cycling stability with 87 % capacity retention after 800 cycles at 4.4 V. This developed closed-loop recycling process has lower recycling costs, is eco-friendly and efficient, and thus could potentially promote the sustainable long-run development of the LIBs industry.

A new surface phase of Al2Ti7O15 to enhance the electronic conductivity and interfacial stability of LiCoO2 cathode materials

LiCoO2 (LCO) is one of the most commonly used cathodes for lithium ion batteries applied in consumer electronics products. However, higher upper cutoff voltage (greater than4.2 V vs Li/Li+) is necessary for LCO in pursuit of higher energy density, which comes along with structural and interfacial instability of LCO. Herein, the combined modification of Al-Mg-Ti co-doping and Al2O3 coating of LCO is employed to improve the stability of LCO under 4.5 V (vs Li/Li+). As a result, the electrochemical performance, kinetic performance and the storage performance evaluated at both coin cell and pouch cell levels are promoted after the modification. Further analysis proves that the suppression of phase transition from order to disorder, and the retarded side reaction between LCO and the electrolyte are the main reasons for the enhanced performances of modified LCO. Interestingly, a new phase, Al2Ti7O15 (ATO), is discovered near the surface of the modified LCO, which is beneficial to elevating the electron conductivity and transmission property of lithium ions as demonstrated by the DFT calculation and conductivity measurement. This work provides new insights into the effect of Al-Mg-Ti co-doping on LCO materials.

Anion doping in LiCoO2 cathode materials for Li-ion batteries: a first-principles study

Anion doping in LiCoO2 cathode materials for Li-ion batteries: a first-principles study

An effective dysprosium modification to enhance the structural stability and diffusion kinetics of LiCoO2 at high-voltage

As the most attractive cathode for digital devices, LiCoO2 can acquire a more specific capacity by raising the cut-off voltage. However, the unstable layered structure is considered a critical obstacle to the practical application of LiCoO2 at high-voltage. Herein, the dysprosium modification strategy to reinforce the structural stability of LiCoO2 at 4.5 V by the sloid-state method is proposed. Dysprosium doping enhances the stability of the Co-O chemical bonds, thus suppressing the lattice oxygen release during cycling at high-voltage. Meanwhile, the doping of dysprosium enlarges the c-axis spacing and restrains the formation of the Li-insulator Co3O4 phase, further providing a stable and expanded channel for the rapid intercalation/extraction of Li+. The dysprosium-modified LiCoO2 cathode material exhibits a discharge capacity of 162.1 mAh·g−1 with a retention rate of 81.1% after 400 cycles over 3.0–4.5 V at 1 C. Despite a higher current density of 8 C, the modified sample displays a discharge capacity of 154.4 mAh·g−1, with a retention rate of 93.3% after 300 cycles. Hence, it is believed that the study can provide some insights into enhancing the structural stability of cathode materials under high-voltage.

Carbon-Based Modification Materials for Lithium-ion Battery Cathodes: Advances and Perspectives.

Lithium-ion batteries (LIBs) have attracted great attention as an advanced power source and energy-storage device for years due to their high energy densities. With rapid growing demands for large reversible capacity, high safety, and long-period stability of LIBs, more explorations have been focused on the development of high-performance cathode materials in recent decades. Carbon-based materials are one of the most promising cathode modification materials for LIBs due to their high electrical conductivity, large surface area, and structural mechanical stability. This feature review systematically outlines the significant advances of carbon-based materials for LIBs. The commonly used synthetic methods and recent research advances of cathode materials with carbon coatings are first represented. Then, the recent achievements and challenges of carbon-based materials in LiCoO2, LiNixCoyAl1-x-yO2, and LiFePO4 cathode materials are summarized. In addition, the influence of different carbon-based nanostructures, including CNT-based networks and graphene-based architectures, on the performance of cathode materials is also discussed. Finally, we summarize the challenges and perspectives of carbon-based materials on the cathode material design for LIBs.

Computational Design to Suppress Thermal Runaway of Li-Ion Batteries via Atomic Substitutions to Cathode Materials.

The cathode material of a lithium-ion battery is a key component that affects durability, capacity, and safety. Compared to the LiCoO2 cathode material (the reference standard for these properties), LiNiO2 can extract more Li at the same voltage and has therefore attracted considerable attention as a material that can be used to obtain higher capacity. As a trade-off, it undergoes pyrolysis relatively easily, leading to ignition and explosion hazards, which is a challenge associated with the application of this compound. Pyrolysis has been identified as a structural phase transformation of the layered rocksalt structure → spinel → cubic rocksalt. Partial substitution of Ni with various elements can reportedly suppress the transformation and, hence, the pyrolysis. It remains unclear which elemental substitutions inhibit pyrolysis and by what mechanism, leading to costly material development that relies on empirical trial and error. In this study, we developed several possible reaction models based on existing reports, estimated the enthalpy change associated with the reaction by ab initio calculations, and identified promising elemental substitutions. The possible models were narrowed down by analyzing the correlations of the predicted dependence of the reaction enthalpies on elemental substitutions, compared between different reaction models. According to this model, substitution by P and Ta affords the highest enthalpy barrier between the initial (layered rocksalt) and the final (cubic rocksalt) structures but promotes the initial transformation to spinel as a degradation. Substitution by W instead generates the barrier to the final (preventing dangerous incidents) process, as well as for the initial degradation to spinel; therefore, it is a promising strategy to suppress the predicted pyrolysis.

Stabilizing the Anionic Redox in 4.6 V LiCoO2 Cathode through Adjusting Oxygen Magnetic Moment

AbstractThe irreversible oxygen redox and the resulting structure degradation of LiCoO2 at a high voltage cause very poor cycling performance. Herein, the anionic redox chemistry in 4.6 V LiCoO2 cathode material through manipulating the oxygen magnetic moment (OMM) with oxygen vacancy and V doping is proposed to stabilize, and the relationship between OMM and the oxidation degree of oxygen is revealed. Oxygen vacancy induces the generation of OMM, and the synergy of oxygen vacancy and V doping reduces the change of OMM during charge/discharge processes. This mitigates the oxidation degree of oxygen and improves the reversibility of oxygen redox, which greatly inhibits the irreversible oxygen escape. The oxygen vacancies can further reduce the overlap of the electron clouds and lower the O 2p band center thus decreasing the oxygen redox activity. Moreover, the introduced V also increases the energy barrier of the phase transition and suppresses the irreversible phase transition and Co migration. The irreversible O2 release is significantly inhibited and the cycling stability at 4.6 V is largely enhanced. This study presents the relationship between OMM and the oxidation degree of oxygen and provides some insights into improving the anion redox reversibility through adjusting the oxygen magnetic moment.