Li-ion Battery Cathode Research Articles

Enhanced performance of lithium-ion battery cathodes using a composite conductive network of CNTs, GQDs, and GNRs embedded in Li₁.₂Mn₀.₅₄Ni₀.₁₃Co₀.₁₃O₂ (LMNCO)

Lithium-rich Li-ion battery cathode materials are known for their high specific capacities and working potential. However, their practical application is limited by the significant decline in discharge potential and capacity during repeated cycling. In this study, we introduce a highly conductive electrode architecture, encapsulating within carbon nanotubes (CNTs), graphene nano-ribbons (GNRs) and graphene quantum dots (GQDs) to mitigate rapid capacity fading and suppress voltage decay. Three Li1.2Mn0.54Ni0.13Co0.13O2 cathode materials were synthesized. The first sample, pristine Li-rich L1.2Mn0.54Ni0.13Co0.13O2, was synthesized using a nitrate co-precipitation method. The second cathode, GNRs-CNTs@Li1.2Mn0.54Ni0.13Co0.13O2, incorporates a mixture of carbon nanotubes and graphene nanoribbons. The third cathode, GQDs:GNRs-CNTs@Li1.2Mn0.54Ni0.13Co0.13O2), further integrates graphene quantum dots within the graphene nanoribbons and carbon nanotubes matrix. The inclusion of highly conductive GNRs-CNTs and GQDs effectively enhances the electrical conductivity of L1.2Mn0.54Ni0.13Co0.13O2, increasing the specific capacity from 246.95 to 316.94 mAhg−1. Additionally, GQDs prevent side reactions and surface phase transitions, thereby improving thermal stability.

Sb-anchoring single-crystal engineering enables ultra-high-Ni layered oxides with high-voltage tolerance and long-cycle stability

Ni-rich layered oxides are promising cathodes for Li-ion batteries, but the inherent structural defects result in severe surface/bulk degradation during long cycling, especially at high cutoff voltage. Herein we propose a Sb-anchoring single-crystalline engineering to enhance the microstructural and electrochemical stability of ultra-high-Ni layered oxides, where the surface-enriched Sb doping inhibits Li-Ni mixing, suppressing the undesired layered to mixed/rock-salt phase transformation; the bulk-doped Sb rivets into Ni sites, reinforcing the bulk phase stability; the single-crystal endows enhanced crack resistance and reduced surface area, preventing surface parasitic reactions and the subsequent proliferation of cathode electrolyte interfaces. In-situ XRD reveals an essential correlation between cycle stability and phase reversibility, whereas Sb doping into both surface and bulk structures showcases a continuous anchoring effect, largely enhancing the phase transformation reversibility. DFT calculations prove a high oxidation tolerance, as Ni2+ diffusion barrier is higher than the pure cathode. A representative Li(Ni0.9Co0.05Mn0.05)0.99Sb0.01O2 cathode exhibits a high-voltage up to 4.6V, and a Li(Ni0.9Co0.05Mn0.05)0.99Sb0.01O2//graphite full-cell demonstrates an ultra-high capacity retention of 93.4% after 1000 cycles at 1C in 3.0−4.2V. This simple and efficient cathode engineering will promote the promising application of Ni-rich layered oxides in high-energy Li-ion batteries.

Structural analysis of deeply charged Li(Ni0.95Co0.04Al0.01)O2 cathode for Li-ion battery.

LiNi0.95Co0.04Al0.01O2 (NCA95) is charged up to 4.6 V to study its structural stability at a highly delithiated state using transmission electron microscopy (TEM). The TEM analysis shows that the localized depletion of Li ions near the surface triggers the transition from the H3 phase to the H4 phase with the H4 phase with the O1 stacking appearing as a series of stacking faults even at 4.4 V. The H3 → H4 transition appears to be irreversible and leads to the initial capacity loss. In addition, intraparticle cracks are observed when charged above 4.3 V. These intraparticle microcracks, unlike interparticle cracks that become sealed upon Li-uptake, likely remain during deintercalation, compromising the mechanical stability of the cathode and lead to fast deterioration of the cycling stability. The TEM analysis of the overcharged NCA95 cathode suggests a clear limit above which the cathode can be cycled without significant capacity loss. The introduction of doping elements that promote the migration of Ni2+ ions into the Li layer would hinder the H3 → H4 transition and help suppress the intraparticle cracks.

Atomistic Interpretation of the Oxygen K-Edge X-ray Absorption Spectra of Layered Li-Ion Battery Cathode Materials.

Core loss spectroscopies can provide powerful element-specific insight into the redox processes occurring in Li-ion battery cathodes, but this requires an accurate interpretation of the spectral features. Here, we systematically interpret oxygen K-edge core loss spectra of layered lithium transition-metal (TM) oxides (LiMO2, where M = Co, Ni, Mn) from first principles using density-functional theory (DFT). Spectra are simulated using three exchange-correlation functionals, comprising the generalized gradient approximation (GGA) functional PBE, the DFT-PBE + Hubbard U method, and the meta-GGA functional rSCAN. In general, rSCAN provides a better match to experimentally observed excitation energies of spectral features compared to both PBE and PBE + U, especially at energies close to the main edge. Projected density of states of core-hole calculations show that the O orbitals are better described by rSCAN. Hybridization, structural distortions, chemical composition, and magnetism significantly influence the spectra. The O K-edge spectrum of LiNiO2 obtained using rSCAN shows a closer match to the experimental X-ray absorption spectroscopy (XAS) when derived from a simulation cell which includes a Jahn-Teller distortion, showing that the DFT-calculated pre-edge feature contains information about not only chemical species but also geometric distortion. Core loss spectra derived from DFT can also differentiate between materials with the same structure and magnetic configuration but comprising different TMs; these differences are comparable to those observed in experimental XAS from the same materials. This foundational work helps establish the extent to which DFT can be used to bridge the interpretation gap between experimental spectroscopic signatures and ab initio methods describing complex battery materials, such as lithium nickel manganese cobalt oxides.

A Case Study of an Energy Barrier in Li-Ion Battery Cathode Material Using DFT and Post-HF Approaches.

With the ever-increasing interest toward energy storage materials, an accurate understanding of the underlying physicochemical processes becomes mandatory for enabling accurate and predictive simulations. In this study, we apply multilevel quantum chemical calculations on a benchmark material commonly adopted as a cathode in Lithium batteries, Li0.5Co0.5+3Ni0.5+4O2. We estimate the Lithium hopping barrier, a key quantity for the estimate of Li diffusion coefficient, at different levels: Hartree-Fock (HF), density functional theory (DFT), periodic local Møller-Plesset perturbation theory of second order, complemented with a coupled cluster correction evaluated using an embedded-fragment approach. The post-HF methods were used here not only for benchmarking the key quantities themselves but also for assessing the accuracy of different functionals and probing the influence of the long-range and static correlation. For the given system and quantity in question, we observe that obtained results do not significantly vary across different DFT functionals or post-HF methods, which is rather uncommon. Such an agreement between the employed methods suggests that static correlation, even if prominent in this system, cancels out in the studied energy differences. In fact, the values of the T1 diagnostics, which test the reliability of the single-reference description, do vary from one fragment to another. But for certain fragments they are fairly small and of similar magnitude, indicating the applicability of such fragments for the correction. Our best estimate of the reaction barrier is about 0.85 eV.

Utilization of manganese ore waste in development of mesoporous Mn3O4 and spinel LiMn2O4 octahedrons as a cathode for Li-ion battery

Nowadays, research on extracting gainful materials from waste precursors is highly fascinating and possesses excellent economic importance. This contribution validates the utilization of waste manganese sulphate (MnSO4) solution produced during the Mn mining processes for value-added battery materials. Specifically, the nano-sized spherical Mn3O4 particles were prepared using the MnSO4 solution by a controlled crystallization process in high purity, which was subsequently employed to develop efficacious cathode material i.e. LiMn2O4 (LMO) by a scalable solid-state method. The structural and morphological properties of as-prepared Mn3O4 and LiMn2O4 are studied by various characterization techniques like XRD, FTIR, Raman spectroscopy, FE-SEM, FE-TEM, XPS, and BET. The investigation reveals the formation of highly crystalline and phase-pure materials. The well-defined truncated octahedral LMO was successfully demonstrated as cathode electrode materials in the assembly li-ion battery coin cell. The as-prepared pristine, highly crystalline LiMn2O4 exhibited specific charge and discharge capacities of 122 mAhg-1 and 116 mAhg-1, respectively at 0.1C and prolonged stability with 71.4% capacity retention after 900 cycles at the current density of 1C within the potential window of 3.6 to 4.5V. The superior cycling performance of LMO suggests the significance of surface orientation in achieving enhanced electrochemical performance.

Li2FeCl4 as a Cost-Effective and Durable Cathode for Solid-State Li-Ion Batteries.

Low-cost cathode materials with high energy density and good rate performance are critical for the development of next-generation solid-state Li-ion batteries (SSLIBs). Here, we report Li2FeCl4 as a cathode material for SSLIBs with highly reversible Li intercalation and deintercalation, a high operation voltage of 3.7 V vs Li+/Li, good rate capability, and good cycling stability with an 86% capacity retention after 6000 cycles. Operando synchrotron XRD reveals that the phase evolution of Li2FeCl4 during charge-discharge cycling involves both solid-solution and two-phase reactions, which maintains a very stable framework during Li insertion and extraction.

Supplying active lithium to single-crystal Li(Ni0.90Co0.05Mn0.05)0.98Ta0.02O2 with Li2MnO3 coating served as cathode for Li-ion batteries

Ni-rich layered oxide with Ni molar content larger than 90% was regarded as an extremely promising candidate for cathode material applied in lithium-ion batteries owing to the significant discharging capacity and low cost. Nevertheless, rigorous cycling attenuation resulted from the crystal structure collapse and unstable particles interface deeply restrained the commercial application. In the work, LiNi0.90Co0.05Mn0.05O2 was modified by Ta5+ doping and Li2MnO3 covering, which was aimed to enhance the structure stability, defend the electrolyte attacking and promote Li+ migration during cycling. The material characterization demonstrated the cathodes after Ta5+ doping delivered the larger cell lattice parameters and higher cation ordering, which was helpful to improve the rate property and discharge capacity at low temperature. The Li2MnO3 layer was tightly adhered on the outside of LiNi0.90Co0.05Mn0.05O2, which could effectively relieve the electrolyte attacking and sustain the particle morphology integrity. As a result, 2 wt% Li2MnO3 coated Li(Ni0.90Co0.05Mn0.05)0.98Ta0.02O2 exhibited the outstanding discharge capacity of 150.2 mAh g−1 at 10.0 large current density and 140.6 mAh g−1 at −30 °C as well as the remarkable capacity retention of 93.1% after 300 cycles. Meanwhile, the pouch full batteries obtained by 2 wt% Li2MnO3 coated Li(Ni0.90Co0.05Mn0.05)0.98Ta0.02O2 also showed the more stable storage capability, cyclic property in comparison with bare LiNi0.90Co0.05Mn0.05O2.

Publisher Correction: Theoretical approaches to study degradation in Li-ion battery cathodes: Crucial role of exchange and correlation

Publisher Correction: Theoretical approaches to study degradation in Li-ion battery cathodes: Crucial role of exchange and correlation

Metal-ligand redox in layered oxide cathodes for Li-ion batteries

Metal-ligand redox in layered oxide cathodes for Li-ion batteries

Comparative environmental and economic assessment of emerging hydrometallurgical recycling technologies for Li-ion battery cathodes

The growing demand for electric vehicles has led to a growing concern for battery recycling, particularly for critical raw materials. However, there is insufficient investigation into the environmental and economic impacts of hydrometallurgical recycling methods. In this study we explored emerging hydrometallurgical technologies in economic and environmental perspective to establish conceptual routes to recover Co, Ni and Mn oxides from waste LiNi0.33Mn0.33Co0.33O2 cathode materials from spent Li-ion batteries. After, life cycle assessment and costing techniques were utilized to compare the environmental and economical performances of each conceptual route. Recovery efficiency of metal oxides through each route was also considered as a key factor. Results suggested that deep eutectic solvent-based leaching produces the highest impact under many impact categories while electrolysis-based leaching showed the least. Under purification technologies assessed, ion-exchange based purification showed significantly lower impact under many categories except stratospheric ozone depletion. Solvent based purification has been identified as the worst technology for purification. Hydroxide based calcination has been identified as the most environmentally sustainable calcination method compared to oxalate calcination. The route consists with inorganic leaching, ion-exchange based purification and hydroxide calcination showed the lowest environmental impact (emission effect at 33.8 kg CO2 eq), with lower economic impact ($ 119) and the highest recovery efficiency (78 %) per 1 kg of cathode active materials. However, using electrolysis-based leaching can slightly increase the impacts with lower recovery efficiency (75 %) and better economic performance ($104/kg of cathode active materials). Terrestrial ecotoxicity was identified to be the most affected impact category for the recovery processes. It is recommended that technologies like deep eutectic solvent-based leaching, solvent extraction and environmentally sustainable technologies like supercritical fluid extraction need further studies prior to industrial applications.

One-step surface-to-bulk modification of single-crystalline Ni-rich Co-poor cathodes for high-rate and long-life Li-ion batteries at high-voltage operations

Single-crystalline Ni-rich Co-poor cathodes operating at high-voltage are attractive owing to their higher energy density for meeting the requirements of next-generation Li-ion batteries, yet they usually suffer from sluggish Li-ion diffusion kinetics and serious Li/Ni disordering. Herein, an in-situ co-precipitation strategy is implemented to achieve the novel In-doped and Li3InO3 coated single-crystalline LiNi0.90Co0.05Mn0.05O2 cathodes with a highly ordered layered structure. The In-doping facilitates grain growth by decreasing the surface energy of crystal faces, reducing the synthesis temperature by about 20 °C, which thus drastically suppresses Li/Ni disordering and lattice oxygen loss. Furthermore, the pillar effect of In-ion doping and the in-situ formation of the ultrafast Li-ion conductive Li3InO3 coating synergistically enhance the Li-ion diffusion kinetics. These merits enable the as-obtained Ni-rich Co-poor cathodes with a high reversible capacity of 229.4 mAh g−1 at 0.1C and 124.6 mAh g−1 at 7C. In a pouch-type full cell, 93.9 % of the initial capacity is still maintained after 500 cycles at 1C within 2.7–4.5 V. This finding opens up a new path for improving the rate performance and cycle life of single-crystalline Ni-rich cathodes for high-voltage Li-ion batteries.

Multiple enhancement effects of dipoles within polyimide cathode promoting highly efficient energy storage of lithium-ion batteries

Polyimide (PI) has been recognized as a potential organic cathode for Li-ion batteries (LIBs) due to its programmable structural design, high theoretical capacity, and resource availability. However, the poor intrinsic electrical conductivity of PI means that PI-based cathodes of LIBs have inefficient energy storage performance, especially at high current densities. In this work, the molecular structure of PI is optimized to obtain a layer-stacked crystalline PI with significantly enhanced dipoles, denoted NT-B for the first time. The dipoles in this PI are induced by the electronegative carbonyl groups from the monomer biuret and further enhanced via a π-π layer stacking effect. This work is the first to verify that the co-directional dipole enhancement effect of biuret is surprisingly different from that of monomer urea. A series of ex-situ/in-situ and theoretical DFT simulations are carried out to understand the functional mechanism of such effects. The multiple enhancement effects of the dipoles synergistically promoting the generation of a strong built-in electric field (BIEF) within NT-B are proposed based on the results obtained. It is confirmed that this BIEF plays a significant role in accelerating electron transport, which enhances the electrochemical activity of LIB cathodes. This work provides a new idea for the structural design of high-performance PI cathodes for LIBs.

Review on the Polymeric and Chelate Gel Precursor for Li-Ion Battery Cathode Material Synthesis.

The rapid design of advanced materials depends on synthesis parameters and design. A wide range of materials can be synthesized using precursor reactions based on chelated gel and organic polymeric gel pathways. The desire to develop high-performance lithium-ion rechargeable batteries has motivated decades of research on the synthesis of battery active material particles with precise control of composition, phase-purity, and morphology. Among the most common methods reported in the literature to prepare precursors for lithium-ion battery active materials, sol-gel is characterized by simplicity, homogeneous mixing, and tuning of the particle shape. The chelate gel and organic polymeric gel precursor-based sol-gel method is efficient to promote desirable reaction conditions. Both precursor routes are commonly used to synthesize lithium-ion battery cathode active materials from raw materials such as inorganic salts in aqueous solutions or organic solvents. The purpose of this review is to discuss synthesis procedure and summarize the progress that has been made in producing crystalline particles of tunable and complex morphologies by sol-gel synthesis that can be used as active materials for lithium-ion batteries.

First principles study of the electronic structure and Li-ion diffusion properties of co-doped LIFex-1MxPyNy-1O4 (M=Co/Mn, N[dbnd]S/Si) Li-ion battery cathode materials

In this work, a first-principles method based on density functional theory was systematically employed to investigate the stability, electronic properties, lithium-ion migration rates, and capacity-voltage curves of the LiFex-1MxPyNy-1O4 (M = Co/Mn, NS/Si) system. The results indicate that the lattice constants of the LiFex-1MxPyNy-1O4 (M = Co/Mn, NS/Si) system show little variation, and the system exhibits low formation and binding energies. Among the investigated systems, LFP-Mn/S demonstrates the best structural and thermodynamic stability. The bandgap of the doped systems decreases, leading to enhanced electronic conductivity. The LiFe0.875Co0.125P0.875Si0.125O4 and LiFe0.875Mn0.125P0.875Si0.125O4 systems remain semiconductors, while the LiFe0.875Co0.125P0.875S0.125O4 and LiFe0.875Mn0.125P0.875S0.125O4 systems exhibit semi-metallic properties due to the introduction of sulfur. Differential charge density calculations reveal changes in the covalent bond strength of the doped systems, with the introduction of Si and S respectively increasing and decreasing the covalency of their bonds with surrounding oxygen atoms. Additionally, doping reduces the Li-ion diffusion energy barriers, with the LiFe0.875Co0.125P0.875Si0.125O4 system exhibiting the lowest migration energy barrier. The Li-ion diffusion rate is four orders of magnitude faster than that of the intrinsic system. This is attributed to changes in the average lengths of Li–O, Co–O, and Fe–O bonds. Finally, doping also alters the de-lithiation voltage, with values ranging from 2.69 V to 3.65 V for the doped systems, and the LiFe0.875Co0.125P0.875Si0.125O4 system shows the highest complete de-lithiation voltage of 3.65 V. The overall performance improvements of the doped system have significant implications for enhancing the performance of Li-ion batteries.

Dual-active sites and reversible-structural covalent organic framework for highly stable alkali metal-ion batteries

Organic materials are promising candidates for energy storage due to their sustainability, environmental friendliness, and structural designability. However, their application is severely limited due to short lifespan and sluggish kinetics caused by low redox stability, solubility, and low electronic conductivity. Here, we designed a polyimide-conjugated covalent organic framework (NAA-COF). Its highly covalent framework cannot only endow the organic material with strong π–π interactions and robust network ensuring its structure stability, but also offer open channels for rapid ions/electrons transfer inside. Additionally, the introduction of multiple redox-active sites can significantly enhance ion-storage capacity. Consequently, when evaluated as a cathode for Li-ion batteries, NAA-COF exhibits large capacity of 220mAh/g, superb initial coulombic efficiency (90 %), good voltage platform, long lifespan (10000 cycles), and high-rate performance (110 mAh/g at 10 A/g). More importantly, even for Na-/K-ion batteries, the exceptional electrochemical performances can still be maintained. In situ transmission electron microscopy (TEM) and in/ex situ spectroscopy further elucidate the low volume expansion (12.2 %) during the lithiation process and 8-electron reaction mechanism for the NAA-COF cathode. This work provides a high-performance universal COF cathode material that can simultaneously satisfy the requirements of alkali metal-ion batteries.

Theoretical approaches to study degradation in Li-ion battery cathodes: Crucial role of exchange and correlation

Abstract Li-ion batteries have become essential in energy storage, with demand rising steadily. Cathodes, crucial for determining capacity and voltage, face challenges like degradation in the form of thermal runaway and battery failure. Understanding these degradation phenomena is vital for developing mitigation strategies. Experimental techniques such as XAS, XPS, PES, UV–Vis, RIXS, NMR, and OEMS are commonly used, but theoretical modelling, particularly atomistic modelling with density-functional theory (DFT), provides key insights into the microscopic electronic behaviours causing degradation. While DFT offers a precise formulation, its approximations in the exchange-correlation functional and its ground-state, 0K limitations necessitate additional methods like ab initio molecular dynamics. Recently, many-body electronic structure methods have been used alongside DFT to better explain electron–electron interactions and temperature effects. This review emphasizes material-specific methods and the importance of electron–electron interactions, highlighting the role of many-body methods in addressing key issues in cathode degradation and future development in electron–phonon coupling methods. Graphical abstract

Preparing a binder-free cathode composed of NMC811/sulfonated reduced graphene oxide sheets/carbon black via in-situ electrophoretic deposition to enhance cyclability of Li-ion batteries

Disruption in the restacking of the graphene present in the electrodes could hamper the reduction in the conductivity and also the surface area, which may be a good reason why graphene has not yet performed as predicted. In this research, we employed the scalable electrophoretic deposition (EPD) procedure to make instantly a binder-free Li-ion battery cathode, consisting of LiNi0.8Mn0.1Co0.1O2 (NMC811), sulfonated reduced graphene oxide (SRGO) sheets, and carbon black (CB) particles. The EPD process caused a squeezing force, which not only wrapped the SRGO sheets around the NMC811 nanoparticles, but also inserted the CB particles into the composite in an electrostatically stabilized combination. As evidenced by the electrochemical measurements, the binder-free NMC/SRGO/CB electrode manifested better cycling performance at the current density of 0.2 C, where this electrode delivered discharge capacities of 170.3 and 143.7 mAh g−1, respectively, at the 1st and 200th cycle compared to discharge capacities of 162.3 and 122.6 mAh g−1 acquired for the NMC/SRGO electrode. The excellent cycle stability and rate capability of the optimized binder-free NMC/SRGO/CB cathode can be attributed to withstanding the volume expansion of the active particles during cycling due to wrapping graphene sheets, inhibition of the restacking of graphene sheets by sulfonated groups and CB spacers, electrostatic interaction between sulfonated groups and lithium ions, and efficient electrolyte infiltration by ion and electron conductive channels in the binder-free cathode structure.

Effect of strontium phosphate coating on NCM811 powders for high-performance Li-ion battery cathode

The NCM811 cathode material, characterized by a high nickel content, is known for its substantial energy capacity but is afflicted by challenges, including electrolyte degradation and inadequate cyclic stability. In this study, a chemical bath deposition technique is utilized to apply a layer of Sr3(PO4)2 material onto the surface of NCM811 particles to address these problems. This procedure yields a continuous protective coating that shields the NCM811 particles from detrimental interactions with the electrolyte, such as HF attack and the formation of surface cracks, while also promoting the diffusion of lithium ions during charge/discharge cycles. XRD analysis indicated that the application of Sr3(PO4)2 coating did not cause any changes in the structure of the NCM811 cathode material. SEM images of all coated samples demonstrated that all coated samples have spherical morphology. Additionally, both Raman and FTIR examinations provide evidences supporting the existence of strontium phosphate material on the surface of the NCM811 cathode material. The distinctive 5.9 nm-thick Sr3(PO4)2 coating enables the NCM811 material to maintain 96 % of its capacity after 100 charge/discharge cycles in a voltage range of 2.8–4.4 V vs. Li/Li+ at a current rate of 1C.

First-principles calculations to investigate the impact of fluorine doping on electrochemical properties of Li-rich Li2MnO3 layered cathode materials.

Li-rich layered oxides are promising candidates for high-capacity Li-ion battery cathode materials. In this study, we employ first-principles calculations to investigate the effect of F doping on Li-rich Li2MnO3 layered cathode materials. Our findings reveal that both Li2MnO3 and Li2MnO2.75F0.25 exhibit significant volume changes (greater than 10%) during deep delithiation, which could hinder the cycling of more Li ions from these two materials. For Li2MnO3, it is observed that oxygen ions lose electrons to compensate for charge during the delithiation process, leading to a relatively high voltage plateau. After F doping, oxidation occurs in both the cationic (Mn) and anionic (O) components, resulting in a lower voltage plateau at the beginning of the charge, which can be attributed to the oxidation of Mn3+ to Mn4+. Additionally, F doping can somewhat suppress the release of oxygen in Li2MnO3, improving the stability of anionic oxidation. However, the increase of the activation barriers for Li diffusion can be observed after F doping, due to stronger electrostatic interactions between F- and Li+, which adversely affects the cycling kinetics of Li2MnO2.75F0.25. This study enhances our understanding of the impact of F doping in Li2MnO3 based on theoretical calculations.