Lithium-ion Battery Cathode Research Articles

Insulating behaviour in room temperature rhombohedral LiNiO2 cathodes is driven by dynamic correlation

Abstract Inspired by the experimental finding of a paramagnetic insulating state in rhombohedral LiNiO2, a lithium-ion battery cathode of great interest, we calculate the electronic, magnetic, and optical properties of LiNiO2 employing a range of single-particle and many-body methods. Within density-functional theory (DFT) using the generalized-gradient approximation (GGA), meta-GGA, and hybrid functionals, we obtain a ferromagnetic half-metallic ground state for rhombohedral LiNiO2, as has been seen previously. Self-consistent GW calculations including self-interaction corrections beyond DFT for various flavours show an electronic band gap albeit with a small quasiparticle peak at the Fermi energy. Moving beyond this, room temperature state-of-the-art dynamical mean-field theory (DMFT) calculations on rhombohedral LiNiO2 show for the first time a gap of combined Mott and charge-transfer character. The paramagnetic insulating state has a band gap of ~0.6 eV, in excellent agreement with experiments and is in sharp contrast to DFT calculations that require the presence of an extra structural symmetry breaking in the form of Jahn–Teller distortions to open a gap. We observe Ni to be in a +2 state in a d 8L configuration, with a charge-transfer ligand hole in O p, and identify the ligand hole state from the DMFT DOS. We further show that whereas DFT shows the presence of an unphysical metallic Drude peak in the optical absorption spectra, DMFT calculations capture the correct form of the optical absorption spectra, and have an excellent match with the calculated band gap as well. Our results clarify that at room temperature, it is the charge transfer gap with a Mott character that causes rhombohedral LiNiO2’s insulating nature; a structural distortion is not required.

Carbon-decorated hydrated V10O24 nanorods for high-performance lithium-ion battery cathodes

This study reports the successful synthesis of carbon-decorated hydrated V10O24 (HVO@C) nanorods using a facile hydrothermal method. The synthesized material was comprehensively characterized using XRD, FTIR, Raman, TGA/DSC, BET, SEM, and HRTEM to reveal its structure and morphology, and the resulting electrode's electrochemical performance as a lithium-ion battery (LIB) cathode was evaluated for the first time. The HVO@C nanorods exhibited a remarkable initial capacity of 292.5 mAh g−1 at 75 mA g−1 current rate, exceeding most of the reported V2O5-based LIB cathodes. Notably, the HVO@C electrode retained a good capacity retention of 67.1 % and a slower capacity loss rate of 0.26 % after 125 cycles compared to most V2O5-based counterparts with shorter lifespans. This outstanding performance could be due to a synergistic interplay of structural characteristics. The large interlayer spacing within the nanorods facilitated unimpeded Li-ion diffusion, while the short diffusion path minimized transport limitations. Furthermore, the strategic incorporation of carbon coating enhanced electrical conductivity and structural stability, leading to enduring LIB battery performance. These results indicate that in-situ carbon-decorated hydrated V10O24 nanoparticles have great potential as a promising cathode electrode for LIBs with exceptional performance.

Revealing Gliding-Induced Structural Distortion in High-Nickel Layered Oxide Cathodes for Lithium-Ion Batteries.

After charging to a high state-of-charge (SoC), layered oxide cathodes exhibit high capacities but suffer from gliding-induced structural distortions caused by deep Li depletion within alkali metal (AM) layers, especially for high-nickel candidates. In this study, we identify the essential structure of the detrimental H3 phase formed at high SoC to be an intergrowth structure characterized by random sequences of the O3 and O1 slabs, where the O3 slabs represent Li-rich layers and the O1 slabs denote Li-depleted (or empty) layers that glide from the O3 slabs. Moreover, we adopt two doping strategies targeting different doping sites to eliminate the formation of Li-vacant O1 slabs. First, we introduce direct transition metal (TM) pillars between TMO2 slabs achieved through dopants (e.g., Nb) positioned within AM layers, significantly improving the cycling stability. Second, we introduce indirect Li pillars achieved through dopants located at TM layers to adjust the Li-O bond strength. While this strategy can regulate the uniformity of Li at the slab level, it results in an uneven Li distribution at the particle scale, ultimately failing to enhance the electrochemical performance. Our established research strategy facilitates the realization of diverse pillars between TMO2 slabs through doping, thereby offering guidance for stabilizing high-capacity layered oxide cathodes at high SoC.

Realizing the single-crystalline LiNi0.90Mn0.05Co0.05O2 cathode with long-life and high-safety property driven by polysiloxane covering and PO43− doping

As a promising cathode for lithium-ion batteries, the ultra-high nickel content layered oxide LiNi0.90Co0.05Mn0.05O2 demonstrates the great attention for the high discharging capacity. However, the serious capacity attenuation resulted from the instable interface, crystal structure degeneration and strong side-reactions on cathode-electrolyte interphase with charging-discharging drastically restricts its extensive application. To alleviate the intrinsic drawbacks, the combination improvement strategy for polysiloxane covering and PO43− doping is adopted to lower the surface residual alkali amounts, defend the HF/F− attacking and enhance the cation location order of LiNi0.90Co0.05Mn0.05O2. X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS) are used to evaluate the synthesized samples. The cathodes after the polysiloxane covering and PO43− doping deliver the improved crystal structure, larger lattice parameters and superior electrochemical properties. The polysiloxane coated and PO43− doped sample exhibits a high discharging capacity of 147.5 mAh g−1 at 10.0C rate and 155.4 mAh g−1 at −30 °C, remains a capacity of 193.2 mAh g−1 at 1.0C after 300 cycles with a retention of 91.2 %. Besides, when applied in pouch full batteries, it could pass the rigorous safety tests of Bar impact, Overcharging test and Nail penetration successfully, and still maintain the superior cycling stability in practice application.

Electrophoresis study on carbon cloth loaded with LiFePO4 for integrated flexible cathodes in lithium-ion batteries

Electrophoresis study on carbon cloth loaded with LiFePO4 for integrated flexible cathodes in lithium-ion batteries

Free-Standing Poly(vinyl benzoquinone)/Reduced Graphene Oxide Composite Films as a Cathode for Lithium-Ion Batteries.

Quinones with a rapid reduction-oxidation rate are promising high-capacity cathodes for lithium-ion batteries. However, the high solubility of quinone molecules in polar organic electrolytes results in low cycle stability, while their low electric conductivity causes low utilization of electrode materials. In this article, a new p-benzoquinone derivative, poly(vinyl benzoquinone) (PVBQ), is designed and synthesized, and a solution-based method of preparing free-standing PVBQ/reduced graphene oxide (RGO) composite films is developed. PVBQ has a high theoretical specific capacity (400 mA h g-1) because of its low dead moiety mass. In the produced composite films, PVBQ nanoparticles are uniformly dispersed on RGO sheets, which endows the composite films with high electric conductivity and inhibits the dissolution of PVBQ through strong adsorption. As a result, the composite films show a high active material utilization, high practical specific capacity, and excellent cycling stability. PVBQ in the composite membrane containing 60.2 wt % RGO deliver 244 mA h g-1 capacity after 200 charge-discharge cycles at a current density of 300 mA g-1. At a current density of 1500 mA g-1, the reversible specific capacity is still 170 mA h g-1. This work provides a high-performance cathode material for lithium-ion batteries, and the molecular structure and electrode structure design ideas are also instructive for developing other organic electrode materials.

Boosting cationic and anionic redox activity of Li-rich layered oxide cathodes via Li/Ni disordered regulation

Lithium-rich layered oxides (LLOs) are increasingly recognized as promising cathode materials for next-generation high-energy-density lithium-ion batteries (LIBs). However, they suffer from voltage decay and low initial Coulombic efficiency (ICE) due to severe structural degradation caused by irreversible O release. Herein, we introduce a three-in-one strategy of increasing Ni and Mn content, along with Li/Ni disordering and TM–O covalency regulation to boost cationic and anionic redox activity simultaneously and thus enhance the electrochemical activity of LLOs. The target material, Li1.2Ni0.168Mn0.558Co0.074O2 (L1), exhibits an improved ICE of 87.2% and specific capacity of 293.2 mA h g−1 and minimal voltage decay of less than 0.53 mV cycle−1 over 300 cycles at 1C, compared to Li1.2Ni0.13Mn0.54Co0.13O2 (Ls) (274.4 mA h g−1 for initial capacity, 73.8% for ICE and voltage decay of 0.84 mV/cycle over 300 cycles at 1C). Theoretical calculations reveal that the density of states (DOS) area near the Fermi energy level for L1 is larger than that of Ls, indicating higher anionic and cationic redox reactivity than Ls. Moreover, L1 exhibits increased O-vacancy formation energy due to higher Li/Ni disordering of 4.76% (quantified by X-ray diffraction Rietveld refinement) and enhanced TM–O covalency, making lattice O release more difficult and thus improving electrochemical stability. The increased Li/Ni disordering also leads to more Ni2+ presence in the Li layer, which acts as a pillar during Li+ de-embedding, improving structural stability. This research not only presents a viable approach to designing low-Co LLOs with enhanced capacity and ICE but also contributes significantly to the fundamental understanding of structural regulation in high-performance LIB cathodes.

Boosting the intrinsic kinetics of lithium vanadium phosphate via an electrochemically active cross-link framework

The monoclinic lithium vanadium phosphate Li3V2(PO4)3 (LVP) is considered a promising cathode for lithium-ion batteries (LIBs) due to its high working voltage (>4.0 V, vs. Li+/Li) and high theoretical specific capacity (197 mAh g−1). However, the electrochemical procedure accompanied by three-electron reactions in LVP has proven challenging due to the complexity or asymmetry of the reaction pathways, thus limiting its wide application. Herein, an electrochemically active cross-link framework of LVP, LiFe0.3Mn0.7PO4 (LFMP) and graphene are successfully synthesized by an in situ catalytic process, which enables stable cycling and high-rate capabilities up to 4.8 V (vs. Li+/Li). Graphene-like carbon can be formed in situ with VOx as the catalyst and polyvinyl alcohol as the carbon source, and LFMP also inhibits the growth of LVP particles, allowing rapid Li+ and electron transport in the cathodes. Both in situ and ex situ X-ray diffraction prove that the cross-link framework efficiently smooths the lattice mismatch and achieves highly reversible structural phase transitions. The prepared 0.9LVP·0.1LFMP is able to provide a superior rate capability of 123 mAh g−1 at 20 C. After 150 cycles, the 0.9LVP·0.1LFMP shows 97.4 % capacity retention even under a voltage of 4.8 V (vs. Li+/Li). This work develops a new strategy for the future design of high-voltage and high-power cathode materials for LIBs.

Electrochemical Relithiation in Spent LiFePO4 Slurry for Regeneration of Lithium-Ion Battery Cathode.

Recycling spent lithium-ion batteries (LIBs) in a green and economical way is vital for maintaining the sustainability of the LIB industry. However, given the low content of high-value components in olivine-type lithium iron phosphate (LFP), traditional metallurgical processes are economically unfeasible for recycling due to high chemical/energy consumption and labor-intensive procedures. This study proposes a facile electrochemistry strategy to directly regenerate the spent LFP material by an electrically driven lithiation process as a spent LFP slurry (200 g/L) rather than as electrodes. Minimal energy and chemical consumption are achieved by enabling the healing of spent LFP without destroying the original olivine-type crystal structure. The proposed method utilizes mild healing conditions (25 °C for 2 h) and LiCl solution as the only reagent in the regeneration process, significantly lowering the expenses associated with producing cathode electrodes. The electrochemical performance of the regenerated LFP have been dramatically recovered after regeneration, exhibiting a capacity of 151.5 mA h g-1 at 0.1 C and 96.6% capacity retention over 400 cycles at 1 C. This approach demonstrates a high processing capability and offers considerable economic and environmental benefits, making it an eco-friendly option and supporting the sustainable development of the LFP industry.

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.

Electrochemically induced interface by LiBOB to enhance cycling performance of LiFe0.4Mn0.6PO4 cathode for lithium-ion batteries

Olivine-type lithium iron manganese phosphate (LFMP) combines the high energy density of LiMnPO4 with the high safety of LiFePO4, is considered to be one of the most promising cathode materials for the next generation. However, the Mn dissolution behavior due to the Jahn-Teller effect of Mn3+ irreversibly causes loss of active material during electrochemical cycling, accompanied by severe capacity decay and structural degradation, which is more severe at elevated temperature. Herein, in order to enhance the cycling performance of LFMP cathode material, the cathode-electrolyte interface is stabilized by inducing bis(oxalate)borate (LiBOB) decomposition electrochemically to form a CEI layer. Specifically, the capacity retention of the battery in the electrolyte containing 0.75 wt% LiBOB is 95.37 % after 200 cycles at 25 °C and 1C. (1C = 170 mA g−1) The capacity retention is 89.17 % after 200 cycles at 55 °C and 1C, compared to only 72 % in the electrolyte without LiBOB. The superior cycling performance is attributed to the formation of a uniform CEI layer induced by LiBOB electrochemically, which inhibits the parasitic reaction between the cathode and electrolyte, reduces the dissolution of Mn in the active substance, enabling superior and safer cycling performance even at elevated temperature.

2D Covalent Organic Framework Covalently Anchored with Carbon Nanotube as High-Performance Cathodes for Lithium and Sodium-Ion Batteries.

Covalent organic frameworks (COFs), featuring structural diversity, permanent porosity, and functional versatility, have emerged as promising electrode materials for rechargeable batteries. To date, amorphous polymer, COF, or their composites are mostly explored in lithium-ion batteries (LIBs), while their research in other alkali metal ion batteries is still in infancy. This can be due to the challenges that arise from large volume changes, slow diffusion kinetics, and inefficient active site utilization by the large Na+ or K+ ion. Herein, microwave-assisted imide-based 2D COF, TAPB-NDA covalently connected with amine-functionalized carbon nanotubes (TAPB-NDA@CNT) targeting the application in both Li-/Na-ion batteries, is synthesized. As-synthesized, TAPB-NDA@CNT50 displays the good performance as LIB cathode with a specific capacity of ≈138mAhg-1 at 25mAg-1, long cycling stability (81.2% retention after 2000 cycles at 300mAg-1), with excellent reversible capacity retention of ≈79.6%. Similarly, TAPB-NDA@CNT50, when employed in sodium-ion battery (SIB), exhibited 136.7mAhg-1 specific capacity at 25mAg-1, retained ≈80% of the reversible capacity after 1000 cycles at 300mAg-1 and showing excellent rate performance. The structural advantage of TAPB-NDA@CNT will encourage researchers to design COF-based cathodes for the alkali ion batteries.

Application of a simple organic acid as a green alternative for the recovery of cathode metals from lithium-ion battery cathode materials

Industrialization, technology, and population growth have on one hand resulted in the rapid rise for energy demand and on the other hand led to the pursuit for alternative carbon neutral energy sources to satisfy demand, address climate change and promote sustainable development. The transition to renewable energy sources has resulted in the rapid rise in energy storage options with battery technologies at the forefront. Lithium-ion batteries (LIBs) have emerged as a leading battery energy storage option. The rise in LIB technology demand has resulted in a proportional increase in the demand for the various materials used in their manufacture. Primary sources of several of the LIB component materials largely consist of mining activities, however, recycling has emerged as a promising secondary material source. In this work, we evaluate the application of a green, organic acid treatment approach utilizing propionic acid in the recovery of key metals from LIB cathode materials. The study delved into exploring the application of both commercially sourced virgin LIB cathode powder (VCP) and recovered spent LIB cathode powder (SCP) and investigating the system leaching characteristics. The highest metal recoveries were obtained on leaching the SCP, with metal recoveries determined as 92.9%, 87.4%, 92.7% and 94.0% for Co, Li, Mn and Ni respectively. The difference in the recoveries on leaching metals from the VCP and SCP was under 5% for each metal. Further, the leaching model was determined as chemical reaction-controlled on using the SCP, and the activation energies were evaluated as 60.37 kJ/mol, 53.38 kJ/mol, 63.98 kJ/mol and 60.20 kJ/mol for Co, Li, Mn and Ni respectively, agreeing with the deduced chemical reaction-controlled leaching mechanism. By application of a simple organic acid, propionic acid, for organic acid leaching operations we contribute to the diversification of the lixiviant options for LIB waste treatment.

Phase compatible surface engineering to boost the cycling stability of single-crystalline Ni-rich cathode for high energy density lithium-ion batteries

Nickel-rich layered oxide is a promising cathode material for the next generation lithium-ion batteries (LIBs) because of its high energy density and cost efficiency. Unfortunately, it suffers from unsatisfying electrochemical performance owing to intrinsic interfacial and structural instability, which limits its application at scale. In this work, a phase compatible TiBO3 coating layer on single crystalline LiNi0.83Co0.11Mn0.06O2 (TBO-SC-NCM) is constructed via modified solid-state chemical reaction. The coating layer serves as a protective screen to mitigate the erosion of organic electrolyte towards TBO-SC-NCM. Furthermore, both titanium ions and boron ions successfully diffuse into the TBO-SC-NCM bulk phase during the annealing process, with titanium ions being uniformly distributed while boron ions accumulating close to the surface. The formation of strong Ti-O bond effectively inhibits the bulk phase structure degradation of TBO-SC-NCM. The near-surface enriched B-O bond greatly stabilizes the surface lattice oxygen at the deeply delithiated state. Additionally, the spread of layer spacing due to the doping of heterogeneous ions ensures the rapid diffusion of Li+, thus improving the rate performance of TBO-SC-NCM. As a h cathode materials.

Effect of organic solvent additives on the enhancement of ultrasonic cavitation effects in water for lithium-ion battery electrode delamination

Ultrasonic delamination is a low energy approach for direct recycling of spent lithium-ion batteries. The efficiency of the ultrasonic delamination relies both on the thermophysical properties (such as viscosity, surface tension, and vapour pressure) of the solvent in which the delamination process is carried out, and the properties of the ultrasound source as well as the geometry of the containment vessel. However, the effect of tailoring solutions to optimise cavitation and delamination of battery cathode coatings has not yet been sufficiently investigated. Acoustic detection, high-speed imaging, and sonochemiluminescence (SCL) are employed to study the cavitation processes in water-glycol systems and identify the effect of tailoring solvent composition on cavitation strength. The addition of small volume fractions of organic solvent (ca. 10–30 vol%), including ethylene glycol or glycerol, to the aqueous delamination solution were found to significantly improve the delamination efficiency of lithium-ion battery cathode coatings due to the alteration of these thermophysical properties. However, greater volume fractions of glycol decrease delamination efficiency due to the signal-dampening effect of viscosity on the ultrasonic waves. The findings of this study offer valuable insights for optimising ultrasonic bath solution composition to enhance film delamination processes.

Recommended Practices for the Electrochemical Recovery of Cobalt from Lithium Cobalt Oxide: A Case Study of the Choline Chloride:Ethylene Glycol Deep Eutectic Solvent.

We recommend best practices for the recovery of cobalt from LiCoO2 (LCO) lithium-ion battery (LIB) cathodes by (i) leaching using green deep eutectic solvents (DES) and (ii) subsequent electrodeposition, through a case study of the choline chloride (ChCl):ethylene glycol (EG) DES. DES physical properties (conductivity, viscosity, and surface tension) were tailored by varying the composition between mole ratios of 1:2 and 1:5 (ChCl:EG). Examined along with leaching process parameters (temperature, duration), increasing the fraction of hydrogen bond donors (HBDs) decreased DES surface tension and enhanced leaching. Complete Co recovery was achieved using1:5 ChCl:EG DES at 160oC and 48 hours. Leaching temperatures >160oC are discouraged due to DES thermal degradation. The electrodeposition process was optimized for selective Co recovery with high faradaic efficiency. The leaching ability of the DES was antithetical to the stability of electrodeposition cell components and required operational parameter adjustment to minimize degradation. The optimized system (copper cathode and stainless-steel anode) employing 1:5 DES leachate exhibited a faradaic efficiency of ~80 %, specific Co recovery of ~0.8 mg hr-1 cm-1 at 50 oC and evidence of uniform deposition. DES surface tension is a key descriptor of metal recovery, and guidelines are presented to maximize selective Co recovery.

Isolation and Crystallographic Characterization of an Octavalent Co2O2 Diamond Core.

High-valent cobalt oxides play a pivotal role in alternative energy technology as catalysts for water splitting and as cathodes in lithium-ion batteries. Despite this importance, the properties governing the stability of high-valent cobalt oxides and specifically possible oxygen evolution pathways are not clear. One root of this limited understanding is the scarcity of high-valent Co(IV)-containing model complexes; there are no reports of stable, well-defined complexes with multiple Co(IV) centers. Here, an oxidatively robust fluorinated ligand scaffold enables the isolation and crystallographic characterization of a Co(IV)2-bis-μ-oxo complex. This complex is remarkably stable, in stark contrast with previously reported Co(IV)2 species that are highly reactive, which demonstrates that oxy-Co(IV)2 species are not necessarily unstable with respect to oxygen evolution. This example underscores a new design strategy for highly oxidizing transition-metal fragments and provides detailed data on a previously inaccessible chemical unit of relevance to O-O bond formation and oxygen evolution.

Correction to “Regenerating Spent Lithium-Ion Battery Cathodes as Dual-Functional Biocatalysts for Highly-Efficient Oxygen and Hydrogen Evolution Using Aspergillus niger Soluble Extracellular Polymers”

Correction to “Regenerating Spent Lithium-Ion Battery Cathodes as Dual-Functional Biocatalysts for Highly-Efficient Oxygen and Hydrogen Evolution Using <i>Aspergillus niger</i> Soluble Extracellular Polymers”

Mo-doped LiNi0.8Co0.1Mn0.1O2 cathode materials with improved performance for lithium ion batteries

The high nickel ternary LiNi[Formula: see text]Co[Formula: see text]Mn[Formula: see text]O2 (NCM811) cathode material has attracted much attention owing to its advantages of high capacity and low price. However, NCM811 suffers from surface side reactions and cation mixing, which results in an unstable crystal structure and lower Coulomb efficiency and capacity in lithium ion batteries. In this work, Mo-doped cathode material NCM811 is effectively synthesized by high-temperature solidification approach. The characterization results show that the doped NCM811 can form a coating layer on the surface, preventing electrolyte side reactions with the electrode. As the cathode for lithium ion batteries, the Mo-doped NCM811 electrode shows an initial discharge capacity of 185.21[Formula: see text]mAh/g and obtains 156.33[Formula: see text]mAh/g with a capacity retention of 84.5% after 100 cycles at 1C. This study provides a simple and reliable method of fabricating high-performance NCM811 cathode materials.

Unveiling the Stability Mechanism of Oriented Ni-Rich Layered Oxides.

Single-crystal and polycrystalline structures are the two main structural forms of the Ni-rich layered cathode for lithium-ion batteries. The structural difference is closely related to the electrochemical performance and thermal stability, but its internal mechanism is unclear and is worthy of further exploration. In this study, both polycrystalline and single-crystal LiNi0.83Co0.12Mn0.05O2 cathodes were prepared by adjusting the calcination temperature and mechanical post-treatment, respectively. Systematic comparisons were made to assess the effects of different grain structures on the electrochemical performance and thermal stability. The study revealed the superior thermal stability of monocrystalline cathodes, attributing it to oxygen vacancies and phase transitions. From the perspective of grain boundaries, it was demonstrated that the diffusion of oxygen vacancies and the reduction of Ni in polycrystalline cathodes exhibit anisotropy. This research elucidates the origins of the superior thermal stability of monocrystalline cathodes in lithium-ion batteries, providing valuable insights into battery material design.