Positive Electrode Materials Research Articles

Is Aluminium Useful in NiMn Cathode Systems?: A Study of the Effectiveness of Al in Co-Free, Ni-Rich Positive Electrode Materials for Li-Ion Batteries

Aluminium has become a dopant of interest in many positive electrode materials, particularly the widely used LiNi1−x−yMnxCoyO2 (NMC). Despite the shift of the positive electrode active material space towards Co-free alternatives, the benefits of Al-doping in Co-free LiNixMn1−xO2 (NM) systems have yet to be extensively studied. In this work a series of polycrystalline NM and NMA pairs are compared head-to-head to better understand the effect of Al in Ni-rich, Co-free systems in terms of electrochemical, mechanical, surficial, and thermal stability. The materials tested vary in Ni-content, Al-doping amount as well as secondary particle size, as these parameters influence the effect of Al-presence on certain aspects of material performance. Although Al can bring certain advantages to NM materials, Al-substitution does not universally lead to improved performance in these systems.

Impact of Mechanical Degradation in Polycrystalline NMC Particle on the Electrochemical Performance of Lithium-Ion Batteries

Lithium-ion batteries (LIBs) are widely chosen for energy storage owing to their high coulombic efficiency and energy density. Within the positive electrode materials of LIBs, the structural integrity of secondary particles, composed of randomly oriented single-crystal primary particles, is crucial for sustained performance. These particles can fracture as a result of both mechanical stress and chemical interactions within the solid. Modelling LIBs is a complex task involving electro-chemo-mechanical phenomena and their interactions on different length scales. This study proposes a numerical modeling framework to investigate the active particle degradation and its impact on electrochemical performance. The model integrates mechanical and electrochemical processes, tracking crack evolution and mechanical failure through phase field damage. The coupled time-dependent non-linear partial differential equations are solved in a finite element framework using COMSOL Multiphysics. The model offers numerical insights into intergranular and transgranular fracture within secondary particles. The electrolyte infiltration into cracks reduces the electrochemical overpotential due to the increase in electrochemically active surface area, positively affecting performance. However, prolonged cycling with particle cracking poses severe threat to the battery performance and capacity. This comprehensive numerical modeling approach provides valuable insights into the intricate interplay of mechanical and electrochemical factors governing LIB performance and degradation.

Collision Oxidation Behavior of Silver Nanoparticles in Alkaline Solution.

In recent years, silver nanoparticles (Ag NPs) have been used as positive electrode material for zinc/silver batteries, and the silver oxides formed during the charging process determine the discharge performance of batteries. Therefore, it is important to study the oxidation behavior of Ag NPs in alkaline solution. Single-nanoparticle collision is an important tool for analyzing oxidation behavior of individual nanoparticles. Based on thermodynamic information from collision events, it is known that oxidation products are potential-dependent and size-dependent. Based on dynamic information, including collisional peak shapes and duration time, it was observed that the Ag NP collision oxidation process changed from stepwise oxidation to direct oxidation as the potential increased or size decreased. This work provides guidance for application of Ag NPs in zinc/silver batteries and proposed a strategy for oxidation behavior of individual NP that could be tracked in situ through an all-encompassing view of thermodynamic and dynamic information.

“Acid + Oxidant” Treatment Enables Selective Extraction of Lithium from Spent NCM523 Positive Electrode

With the rapid development of new energy vehicles and energy storage industries, the demand for lithium-ion batteries has surged, and the number of spent LIBs has also increased. Therefore, a new method for lithium selective extraction from spent lithium-ion battery cathode materials is proposed, aiming at more efficient recovery of valuable metals. The acid + oxidant leaching system was proposed for spent ternary positive electrode materials, which can achieve the selective and efficient extraction of lithium. In this study, 0.1 mol L−1 H2SO4 and 0.2 mol L−1 (NH4)2S2O8 were used as leaching acid and oxidant. The leaching efficiencies of Li, Ni, Co, and Mn were 98.7, 30, 3.5, and 0.1%, respectively. The lithium solution was obtained by adjusting the pH of the solution. Thermodynamic and kinetic studies of the lithium leaching process revealed that the apparent activation energy of the lithium leaching process is 46 kJ mol−1 and the rate step is the chemical reaction process. The leaching residue can be used as a ternary precursor to prepare regenerated positive electrode materials by solid-phase sintering. Electrochemical tests of the regenerated material proved that the material has good electrochemical properties. The highest discharge capacity exceeds 150 mAh g−1 at 0.2 C, and the capacity retention rate after 100 cycles exceeds 90%. The proposed new method can extract lithium from the ternary material with high selectivity and high efficiency, reducing its loss in the lengthy process. Lithium replenishment of the delithiation material can also restore its activity and realize the comprehensive utilization of elements such as nickel, cobalt, and manganese. The method combines the lithium recovery process and the material preparation process, simplifying the process and saving costs, thus providing new ideas for future method development.

Constructing and Evaluating Machine-Learned Interatomic Potentials for Li-Based Disordered Rocksalts.

Lithium-based disordered rocksalts (LDRs), which are an important class of positive electrode materials that can increase the energy density of current Li-ion batteries, represent a significantly complex chemical and configurational space for conventional density functional theory (DFT)-based high-throughput screening approaches. Notably, atom-centered machine-learned interatomic potentials (MLIPs) are a promising pathway to accurately model the potential energy surface of highly disordered chemical spaces, such as LDRs, where the performance of such MLIPs has not been rigorously explored yet. Here, we represent a comprehensive evaluation of the accuracy, transferability, and ease of training of five atom-centered MLIPs, including the artificial neural network potentials developed by the atomic energy network (AENET), the Gaussian approximation potential (GAP), the spectral neighbor analysis potential (SNAP) and its quadratic extension (qSNAP), and the moment tensor potential (MTP), in modeling a 11-component LDR chemical space. Specifically, we generate a DFT-calculated data set of 10,842 configurations of disordered LiTMO2 and TMO2 compositions, where TM = Sc, Ti, V, Cr, Mn, Fe, Co, Ni, and/or Cu. To provide a point-of-comparison on the performance of atom-centered MLIPs, we also trained the neural equivariant interatomic potential (NequIP) on a subset of our data. Importantly, we find AENET to be the best potential in terms of accuracy and transferability for energy predictions, while MTP is the best for atomic forces. While AENET is the fastest to train among the MLIPs considered at low number of epochs (300), the training time increases significantly as epochs increase (3300), with a corresponding reduction in training errors (∼60%). Note that AENET and GAP tend to overfit in small data sets, with the extent of overfitting reducing with larger data sets. Finally, we observe AENET to provide reasonable predictions of average Li-intercalation voltages in layered, single-TM LiTMO2 frameworks, compared to DFT (∼10% error on average). Our study should pave the way both for discovering novel disordered rocksalt electrodes and for modeling other configurationally complex systems, such as high-entropy ceramics and alloys.

Elucidating Consequences of Selenium Crystallinity on Its Electrochemical Reduction in Aluminum-Selenium Batteries.

Selenium (Se) is an attractive positive electrode material for rechargeable aluminum (Al) batteries due to its high theoretical capacity of 2037 mA h g-1 and its higher electronic conductivity compared to sulfur. Selenium can undergo a series of electrochemical reactions between Se(-II) and Se(IV), resulting in a six-electron capacity per Se atom. However, existing Al-Se battery literature is inconsistent regarding the different electrochemical reactions possible, while the conditions enabling the electrochemical reduction of Se to Al2Se3 are not well understood. Here, we demonstrate that this electrochemical reduction is achievable using amorphous selenium but is suppressed for crystalline selenium. We further show that the electrochemical oxidation of Se to SeCl4, which occurs at higher potentials, reduces the long-range order of crystalline Se and enables its discharge to Al2Se3. Solid-state 77Se nuclear magnetic resonance (NMR) measurements further establish that the local Se helical structures are maintained upon the loss of crystallinity.

Exploring the Limits of Fe-Rich Chemistries in Na-Based CaFe2O4-Type Postspinel Oxides.

Structural trends, physical properties, and electrochemical performances of the NaFexRu2-xO4 system have been investigated. Synthesis attempts using both conventional solid-state routes and high-pressure methods were explored for the compositional range 1.0 ≤ x ≤ 1.67. Based on Rietveld refinements against powder X-ray diffraction data, analyses of 57Fe Mössbauer spectroscopy data, and elemental analysis by electron microprobe, the existence of a confined compositional solid solution (1 ≤ x ≤ 1.3) adopting the CaFe2O4-type postspinel structure is demonstrated. This is contrasted with the NaFexTi2-xO4 system, for which no evidence of a solid solution is observed. However, for all explored synthetic routes of NaFexRu2-xO4 compositions, a trivalent iron oxidation state is maintained. Structural analysis and qualitative bond valence energy landscape models reveal that the progressive integration of iron into the postspinel framework results in narrowed sodium ion diffusion channels, restricting electrochemical deintercalation of sodium. Consequently, the CaFe2O4-type iron-rich compounds explored in this study demonstrate limited potential as positive electrode materials for sodium batteries. It is expected that this fundamental insight will help guide the exploration of alternative NaM2O4-based positive electrode materials with similar structure types.

Inherent Behavior of Electrode Materials of Lithium-Ion Batteries.

For independency from the fossil fuels and to save environment, we need to move toward the green energies, which requires better energy storage devices, especially for usage in electric vehicles. Li-ion and beyond-lithium insertion batteries are promising to this aim. However, they suffer from some inherent limitations which must be understood to allow their development and pave the way to find suitable energy storage alternatives. It is found that each positive or negative electrode material (cathode or anode) of the intercalation batteries has its own behavioral (charge-discharge) properties. The modification of preparation parameters (composition, loading density, porosity, particle size, etc.) may improve some aspects of the electrode performance, but cannot change the intrinsic property of the electrode itself. Accordingly, these properties are called as the "inherent behavior characteristics" of the active material. It is concluded that the behavior of a specific electrode substance, even following different preparation routes, depends only on diffusion mechanisms. This work shows that the inherent electrode properties can be visualized by representation of current density vs. capacity.

Beam Effects in Synchrotron Radiation Operando Characterization of Battery Materials: X-Ray Diffraction and Absorption Study of LiNi0.33Mn0.33Co0.33O2 and LiFePO4 Electrodes.

Operando synchrotron radiation-based techniques are a precious tool in battery research, as they enable the detection of metastable intermediates and ensure characterization under realistic cycling conditions. However, they do not come exempt of risks. The interaction between synchrotron radiation and samples, particularly within an active electrochemical cell, can induce relevant effects at the irradiated spot, potentially jeopardizing the experiment's reliability and biasing data interpretation. With the aim of contributing to this ongoing debate, a systematic investigation into these phenomena was carried out by conducting a root cause analysis of beam-induced effects during the operando characterization of two of the most commonly employed positive electrode materials in commercial Li-ion batteries: LiNi0.33Mn0.33Co0.33O2 and LiFePO4. The study spans across diverse experimental conditions involving different cell types and absorption and scattering techniques and seeks to correlate beam effects with factors such as radiation energy, photon flux, exposure time, and other parameters associated with radiation dosage. Finally, it provides a comprehensive set of guidelines and recommendations for assessing and mitigating beam-induced effects that may affect the outcome of battery operando experiments.

High-performance lithium batteries achieved by electrospun MXene-Enhanced cation-selective membranes

Conventional separators applied in lithium batteries face limitations like low porosity, poor electrolyte wettability, lower cation selectivity, and thermal instability, which impact battery performance and safety characteristics. Besides the challenge in separator design, transition metal ion migration from positive electrodes during cycling greatly accelerates capacity fading because of unrestricted diffusion of transition metal cation across the separator. This study explores an innovative strategy for the separator design by incorporating MXene (spraying MXene solution on both sides of the separator), a two-dimensional material, into electrospun Polyacrylonitrile/Polyetherimide membranes with the function of cation selection. Li+ can be accelerated, and its transference number increases along with the anion limitation in the MXene layer. Ni, Co, and Mn ion dissolution from the positive electrode is inhibited due to the cation selectivity of the MXene layer. Leveraging electrospinning advantages, the resultant membranes exhibit high porosity, excellent liquid absorption, mechanical strength, and superior thermal properties. Benefiting from MXene's layered structure and excellent adsorption ability, the membrane significantly inhibits the dissolution of transition metal ions while enabling smooth lithium deposition due to its cation selectivity. Eventually, the Li||NMC811 batteries deliver outstanding cyclic performance (91.3 % capacity retention after 200 cycles) and robust lithium dendrite suppression (800 h of stable cycling). Moreover, the MXene-modified membrane demonstrates exceptional electrolyte wettability, significantly improving ionic transference number (0.67) and conductivity (1.6 mS/cm). Modification of membrane surfaces with MXene offers insights into addressing transition metal ion migration from the positive electrode material perspective, providing a promising avenue for high-performance LIBs.

Layer‑by‑layer assembled binder-free hydrated vanadium oxide-acetylene black electrode for flexible aqueous zinc ion battery

Vanadium oxides are potential positive electrode materials for aqueous zinc ion batteries (ZIBs) owing to their advantages of high theoretical capacity, low cost, and so on. Developments of methods for preparing binder-free vanadium oxide electrodes on a large scale and further investigation of their Zn2+ storage mechanisms are essential for expanding their uses in large-scale energy storage systems and wearable electronics. In this work, binder-free electrodes with hydrated vanadium oxide (V2O5·nH2O, denoted as VOH)-acetylene black (AB) on carbon cloth (VOH-AB/CC) are fabricated by a simple and scalable method which combined low-temperature hydrothermal treatment with layer-by-layer drop/spray-coating process. The AB can greatly improve the electrical conductivity of VOH, thereby enhancing the electrochemical performance. The as-prepared electrode with 20 wt% of AB (VOH-AB2/CC) delivers a high capacity of 280 mA h g−1 at 1 A/g and a good rate capability of 205 mA h g−1 at 4 A/g, which is better than many of the reported binder-free vanadium base electrodes. Besides, excellent cycling performance with 89 % retention rate after 3000 cycles at 4 A/g is achieved on the VOH-AB2/CC electrode. Furthermore, a storage mechanism of Zn2+/H+/H2O insertion accompanied by the formation of basic zinc salt precipitate during the discharging process is proposed by the aid of ex-situ XRD and XPS techniques. Additionally, the flexible Quasi-Solid-State ZIB constructed using VOH-AB/CC as positive electrode can work well at different bending states and two ZIBs connected in series can lighten a light-emitting diode even under bending state. This work provides a low-cost, time-saving, environmental-friendly and scalable method to fabricate binder-free hydrated vanadium oxide electrodes for flexible aqueous ZIBs.

Preparation of Positive and Negative Composite Electrode Materials for High-Performance Aqueous Asymmetric Supercapacitor by a Sequential Two-Step Reaction

Preparation of Positive and Negative Composite Electrode Materials for High-Performance Aqueous Asymmetric Supercapacitor by a Sequential Two-Step Reaction

Synergetic supercapattery: Stitching of cobalt zinc manganese oxide and polyaniline matrix for efficient energy storage applications

Optimizing energy storage performance requires the integration of both battery and supercapacitor advantages into a hybrid device. This study focuses on the strategic combination of positive (battery-like) and negative (electrical double layer, EDL) electrode materials in a single device, known as a supercapattery. Cobalt zinc manganese oxide (CZMO) ternary composite and polyaniline (PANI) are synthesized via hydrothermal and polymerization methods, respectively. The CZMO/PANI composite is prepared using a physical blending method. XRD and FTIR analyses confirmed the composition of CZMO/PANI, while surface morphological analysis (FESEM and HRTEM) demonstrated successful intercalation between CZMO nanorods and the PANI matrix. XPS and BET analyses are employed to examine the chemical composition and surface area of the composite. Electrochemical performance of CZMO, PANI, and CZMO/PANI is individually analyzed using a three-electrode system. It is evident that the CZMO/PANI composite exhibits a better specific capacity (340 C g−1) than CZMO and PANI. The two-electrode system (device), embodying CZMO/PANI as the positive electrode and activated carbon as the negative electrode, exhibits promising Specific energy 30.75 Wh kg−1 and specific power 820 W kg−1. Based on these results, it is evident that the CZMO/PANI composite will be a viable option for supercapattery applications.

PEDOT-coated rice husk-based activated carbon: Boosting lead-acid battery performance

Despite the surge in novel energy storage systems, lead-acid batteries remain entrenched in the market, chiefly attributed to their well-established technology, affordability, and dependable safety profile. Yet, they are not without shortcomings, notably their limited energy density and abbreviated cycle life. The profound impact of positive electrode materials on lead-acid batteries is undeniable, as these materials directly dictate the batteries' charging and discharging efficiency, energy density, cycle longevity, and overall stability. Here we report on an innovative positive active material additive, wherein the conductive polymer poly(3,4-ethylenedioxythiophene) (PEDOT) is coated onto rice husk-based activated carbon (RHAC) surfaces via in-situ polymerization in solution to form a composite material (PEDOT@RHAC). Astonishingly, lead-acid batteries fortified with PEDOT@RHAC within their positive plates showcased remarkable electrochemical prowess. Incorporating PEDOT@RHAC into the positive plates of lead-acid batteries has demonstrated exceptional electrochemical performance. The enhanced deep cycling capability of these batteries is evident, with a substantial increase in cycle life by 2.08 times and an augmentation in discharge capacity by 1.3 times compared to the control batteries. This positive electrode additive plays a pivotal role in augmenting the overall performance and extending the lifespan of lead-acid batteries, potentially paving the way for their broader commercial application.

Effect of process conditions on the performance of LiNi0.815Co0.15Al0.035O2 positive electrode material powder synthesized by hydrothermal approach

LiNi0.815Co0.15Al0.035O2 (NCA) lithium-ion battery cathode material was prepared using a hydrothermal approach. XRD and SEM analyzed the crystal parameters and powder morphology of the cathode material. The results show that the nickel cobalt precursor exhibits a petal-like morphology, and the nanoneedle primary particles are randomly distributed. Accompanied by the increase in calcination temperature and time, the peak intensity ratio of I003/I104 tends to decrease and then increase. The peak intensity ratio reached a maximum when the NCA sample calcined at 750°C for 8 h, indicating the lowest extent of Li/Ni mixing and the best electrochemical performance of the positive electrode material.

Residual NMP and Its Impacts on Performance of Lithium-Ion Cells

N-methyl-2-pyrrolidone (NMP) is the most common solvent used in coating positive electrode materials on aluminum foil during the manufacturing of lithium-ion batteries. NMP is a strongly polar aprotic solvent that effectively dissolves the polyvinylidene difluoride binder. While the majority of NMP typically evaporates during the electrode baking process, trace amounts may persist, particularly in positive electrodes containing nano-sized and highly-porous active materials. We noted residual NMP in the positive electrodes of Li-ion pouch cells containing LiMn0.8Fe0.2PO4 due to the extremely high surface area of the material and we wanted to determine the impact of this residual NMP. Therefore, a control electrolyte was purposely spiked with varying amounts of NMP and used in NMC532/graphite pouch cells to investigate the impact of residual NMP on lithium-ion battery performance. Experimental results indicate that NMP has the potential not only to neutralize the electrolyte additive ethylene sulfate but also to independently increase cathode impedance, leading to a higher rate of capacity loss during charge-discharge cycling. It is crucial to establish the appropriate procedure for baking electrodes containing NMP, both in laboratory and industrial settings, to mitigate these effects.

Enhancing Electrochemical Performance of Aluminum-Ion Batteries with Fluorinated Graphene Cathode.

In pursuit of high-performance aluminum-ion batteries, the selection of a suitable positive electrode material assumes paramount importance, and fluorinated graphene (FG) nanostructures have emerged as an exceptional candidate. In the scope of this study, a flexible tantalum foil is coated with FG to serve as the positive electrode for aluminum-ion batteries. FG positive electrode demonstrates a remarkable discharge capacity of 109 mA h g-1 at a current density of 200 mA g-1, underscoring its tremendous potential for energy storage applications. Concurrently, the FG positive electrode exhibits a discharge capacity of 101 mA h g-1 while maintaining an impressive coulombic efficiency of 95 % over 300 cycles at a current density of 200 mA g-1, which benefiting from the significant structure of FG. The results of the in-situ Raman spectroscopy signified the presence of intercalation/de-intercalation processes of AlCl4 - behavior within the FG layers.

Experimental study on the internal short circuit and failure mechanism of lithium-ion batteries under mechanical abuse conditions

The safety issues of lithium-ion batteries under mechanical abuse conditions have attracted widespread attention due to their high uncertainty and risk. This research takes cylindrical lithium-ion batteries as the research object and conducts three-point bending tests on cylindrical lithium-ion batteries with different states of charge (SOC), electrode thicknesses and electrode materials. The mechanical response, voltage changes, temperature changes during the loading process of the battery, and the microstructural changes of the battery's electrodes and separator after the bending test were examined. The results show that the maximum load-bearing capacity of the battery and the displacement corresponding to the short circuit decreases with the SOC of battery; the higher the battery SOC means a faster average temperature rise rate of the battery. When the SOC is higher than 60 %, the battery will experience violent thermal runaway phenomena such as explosions and spouting fire after bending tests. The mass loss rate of the battery is also greatly affected by the battery SOC and the electrode thickness, however, electrode material have almost no effect on the mass loss rate of the battery. According to the SEM images of the electrodes, it is found that short circuits cause graphite particles to break, separators to close and electrolytes oxidize on the surface of positive electrode particles. After triggering the internal short circuit, more broken particles are observed in the positive electrode material of the battery with thicker electrodes and the surface roughness of the broken particles is higher. By comparing the electrode changes of LFP and NCM, it is found that the intensity of the internal electrochemical reactions in NCM is far greater than that in LFP. The research results provide theoretical insights for understanding the electrothermal characteristics and mechanical integrity of lithium-ion batteries under mechanical abuse, which can shed light on the design and optimization of high-performance and safe lithium-ion batteries.

A highly-sensitive wearable capacitance pressure sensor based on calcium copper titanate/polydimethysiloxane/graphene oxide and polydimethysiloxane/silver nanowires sanwich strustures combination for human body monitoring

In recent years, flexible pressure sensors, with their high sensitivity, low detection limit, wide working pressure range and fast response speed, have been playing an important role in the development of wearable artificial devices, human-computer interaction and healthcare systems, and have attracted wide attention. However, the pressure sensors face challenges related to the weak tightness of bipolar materials, low charge density, and limitation in dielectric layers. In this paper, we present a novel configuration of flexible capacitive pressure sensors, utilizing a polydimethysiloxane (PDMS) thin film covered by silver nanowires (PDMS/SN, PSN) as the electrode materials and a porous material composed of calcium copper titanate (@CCTO), PDMS and graphene oxide (GO)(@CCTO/PDMS/GO, @CPG) as the positive electrode material. The sacrificial material, sugar, is employed to create dense internal pores within the substrate material, @CPG, leading to the formation of a profoundly porous substrate. The integration of the flexible capacitive pressure sensor using @CPG/PSN results in enhanced output performance. The modified sensors achieves a sensitivity of 0.22 kPa−1, which is 7 times higher than that of a pure PDMS dielectric layer sensor. Moreover, the sensors has a response time of 87 ms, a low detection pressure of 5 Pa with an extensive detection range from 0 to 150 kPa, and are capable of enduring 7200 cycles without sustaining damage. To validate the practical performance of the @CPG/PSN sensor, various human body activities are detected, including swallowing, coughing, neck bending, wrist bending, elbow bending, finger flexing, and holding objects like cups using a digitally designed glove capable of accommodating different materials. The pressure sensor based on @CPG/PSN demonstrates significant promise in detecting both low and high pressures, thus expanding the potential applications of capacitive pressure sensors.

Disentangling the ligand and electronic structure in KVPO4F1-xOx positive electrode materials by valence-to-core X-ray emission spectroscopy

Understanding the intricate crystal structure of polyanionic positive electrode materials is essential for elucidating the mechanisms involved during cycling and predicting the working potential of the electrode. To achieve this goal, a clear comprehension of how the coordination environment of the transition metal ion influences the ionicity/covalency of the metal-ligand bonds is necessary. Yet, discriminating these ligands poses challenges due to the limited sensitivity to light elements of common characterization techniques such as X-ray diffraction (XRD) and extended X-ray absorption fine structure (EXAFS) analysis. To address this issue, we employed valence-to-core Kβ X-ray emission spectroscopy combined with ab initio modelling and conducted a systematic investigation using potassium vanadium oxyfluoride phosphate compounds with the general formula KVPO4F1-xOx (x = 0, 0.25, 0.5, 0.75, 1). Our approach allows distinguishing the contributions of VF, VO, and VO bonds at the Kβ" region, with intensities highly correlated to the F− and O2− anion composition. Additionally, the evolution of the features at the Kβ2,5 region is highly correlated to the presence of short VO bonds, strongly influencing the electrode potential of the material. Density of state (DOS) analysis based on ab initio modelling of the end member compounds KVPO4F and KVOPO4 further supports the existence of VF and VO bonding through the mixing of F/O p-DOS with V d-DOS. Overall, we present a detailed and reliable approach for understanding the occupied electronic states of the bulk material, proving valuable for a thorough comprehension of the structure of positive electrode materials in batteries.