Cathode Materials For Lithium-ion Batteries Research Articles

Stabilizing high temperature operation and calendar life of LiNi0.5Mn1.5O4

Severe capacity degradation at high operating voltages and poor interphase stability at elevated temperature have thus far precluded the practical application of LiNi0.5Mn1.5O4 (LNMO) as a cathode material for lithium-ion batteries. Addressing these challenges through a combination of experimental and theoretical methods in this work, we demonstrate how a fluorinated carbonate electrolyte enables both high-voltage and high temperature operation by mitigating the traditional interfacial reactions observed in electrolytes with conventional carbonate solvents. Computational studies confirm the exceptional oxidation stability of fluorinated carbonate electrolyte which reduces deprotonation at high voltage. The mitigated deprotonation will then minimize the formation of HF acid which corrodes the LNMO surface and leads to phase transformation and poor interphases. With fluorinated carbonate electrolyte at elevated temperature, it was found on LNMO’s subsurface a reduced amount of Mn3O4 phase which can block Li+ transfer and result in drastic cell failure. Leveraging this approach, LNMO/graphite full cells with a high loading of 3.0 mAh/cm2 achieve excellent cycling stability, retaining ∼84 % of their initial capacity at room temperature (25 °C) after 200 cycles and ∼68 % after 100 cycles at 55 °C. This advanced electrolyte also shows promise for improving calendar life, retaining >30 % more capacity than the carbonate baseline after high temperature storage. These results indicate that electrolytes based on fluorinated carbonates are a promising strategy for overcoming the remaining challenges toward practical commercial application of LNMO.

A Comprehensive Review on Reductive Recycling of Cathode Materials of Spent Lithium-Ion Batteries.

The prosperity of the lithium-ion battery market is inevitably accompanied by the depletion of corresponding resources and the accumulation of spent batteries in a dialectical manner. Spent lithium-ion batteries are harboring the characteristics of hazardous waste and high-value resources, so efficient recycling is of great significance. The cathode material is considered as an interesting target for repurposing. Despite some important reviews give commendable emphasis to recycling technologies, there is still a dearth of exploration of recycling mechanisms. This deficiency of awareness highlights the need for further research and development in this area. This review aims to systematically review and thoroughly discuss the reduction reaction mechanism of each method regarding different cathode materials. And systematically digest the selection of reducing agent and the effect of reduction reaction on material regeneration are systematically digested, as well as the impact of the reduction reaction on the regeneration of materials. This review emphasizes the importance of balancing efficiency, economic and environmental benefits in reuse technologies. Finally, the review proposes an outlook on the opportunities and challenges facing the reuse of key materials for next-generation spent batteries aimed at promoting the green and sustainable development of lithium-ion batteries, circular economy and ecological balance.

New Insight into Bulk Structural Degradation of High-Voltage LiCoO2 at 4.55 V.

The aggravated mechanical and structural degradation of layered oxide cathode materials upon high-voltage charging invariably causes fast capacity fading, but the underlying degradation mechanisms remain elusive. Here we report a new type of mechanical degradation through the formation of a kink band in a Mg and Ti co-doped LiCoO2 cathode charged to 4.55 V (vs Li/Li+). The local stress accommodated by the kink band can impede crack propagation, improving the structural integrity in a highly delithiated state. Additionally, machine-learning-aided atomic-resolution imaging reveals that the formation of kink bands is often accompanied by the transformation from the O3 to O1 phase, which is energetically favorable as demonstrated by first-principles calculations. Our results provide new insights into the mechanical degradation mechanism of high-voltage LiCoO2 and the coupling between electrochemically triggered mechanical failures and structural transition, which may provide valuable guidance for enhancing the electrochemical performance of high-voltage layered oxide cathode materials for lithium-ion batteries.

Boosting the Electrochemical Performance of Primary and Secondary Lithium Batteries with Mn-Doped All-Fluoride Cathodes.

Transition metal fluorides are potentially high specific energy cathode materials of next-generation lithium batteries, and strategies to address their low conductivity typically involve a large amount of carbon coating, which reduces the specific energy of the electrode. In this study, MnyFe1-yF3@CFx was generated by the all-fluoride strategy, converting most of the carbon in MnyFe1-yF3@C into electrochemical active CFx through a controllable NF3 gas phase fluorination method, while still retaining a tightly bound graphite layer to provide initial conductivity, which greatly improved the energy density of the composite. This synergistic effect of nonfluorinated residual carbon (∼11%) and Mn doping ensures the electrochemical kinetics of the composite. The loading mass of the active substance had been increased to 86%. The theoretical and actual discharge capacity of MnyFe1-yF3@CFx composite was up to 765 mAh g-1 (pure FeF3 is 712 mAh g-1) and 728 mAh g-1, respectively. The discharge capacity at the high-voltage (3.0 V) platform was more than three times higher than that of the non-Mn-doped composite (FeF3@CFx).

Facile synthesis of LiFePO4/Cu composite as enhanced cathode material for lithium-ion battery by a solid-state grinding method

Lithium iron phosphate (LiFePO4, LFP) is a frequently utilized cathode material for lithium-ion batteries. However, its practical applications are constrained by its relatively low ionic and electronic conductivities. To address this issue, it is possible to utilize highly conductive metallic coatings to enhance the material's electronic conductivity. Herein, LiFePO4 with Cu composites (LFP/Cu) as cathode was synthesized by a simple solid-state process via one-step grinding in the presence of CuNO3 and ascorbic acid. The discharge capacity of the LFP/Cu cathode with 0.75 wt% Cu was found to be 160.9 mA h g−1 at 0.1 C, representing a close approximation of its theoretical capacity and a notable enhancement compared to pure LFP (145.9 mA h g−1). Furthermore, it demonstrates excellent stability with a capacity retention of 136.5 mA h g−1 after 100 cycles at 2 C, as well as good rate performance. The electrochemical impedance spectra demonstrate that the incorporation of copper results in a further reduction in the resistance of LFP/Cu compared to pure LFP. The incorporation of copper particles into lithium iron phosphate has been shown to enhance its electronic conductivity, thereby further enhancing its electrochemical performance. In this study, we present a facile and cost-effective room-temperature synthesis method for the preparation of LiFePO4/Cu composites with improved electrochemical properties. This work provides a promising avenue for the design of cathode materials in lithium-ion batteries.

Boosting interface compatibility of high-voltage LiNi0.5Mn1.5O4 cathode materials with an ionic-conductive Li0.33La0.56TiO3 coating

High voltage LiNi0.5Mn1.5O4 (LNMO) is a crucial cathode material for lithium-ion batteries (LIBs) aiming at high energy densities. However, its performance is hindered by the dissolution of transition metal ions and the instability of the cathode electrolyte interface (CEI) film at elevated voltages. To address these issues, we report a solvothermal method to prepare LNMO coated with Li+-conductor Li0.33La0.56TiO3 (LNMO@LLTO). Our study reveals that the LLTO coating not only enhances ion diffusion at the interface, minimizing the Li+ concentration gradient, and acts as a barrier against Mn-ion dissolution. This coating minimizes side reactions, mitigates structural degradation, and promotes the formation of a stable and balanced CEI film that incorporates LLTO, thus ensuring the long-term cycle stability. When compared to bulk LNMO, the LNMO@LLTO cathode demonstrates superior performance, maintaining reversible capacities of 111.4 and 102.2 mAh·g−1 after 500 cycles at 2 and 5C at 25 °C, respectively. Even at 60 °C, the LNMO@LLTO maintains a high capacity of 94.3 mAh·g−1 with minimal electrochemical polarization after 200 cycles at 2C. This simple preparation technique, together with its performance promotion, offers new insights into the development of high voltage cathode materials for high energy density LIBs.

Recent advances of cobalt-free and nickel-rich cathode materials for lithium-ion batteries

Recent advances of cobalt-free and nickel-rich cathode materials for lithium-ion batteries

Fast lithium-ion conductor LiTi2(PO4)3 coating modified LiNi0.8Co0.15Al0.05O2 as cathode material for lithium-ion batteries

Fast lithium-ion conductor LiTi2(PO4)3 coating modified LiNi0.8Co0.15Al0.05O2 as cathode material for lithium-ion batteries

The dual modification of La and Zr of Ni-rich cathodes for improved cycling stability at elevated voltage and temperature

Nickel-rich layered oxides are regarded as a promising cathode material for next-generation lithium-ion batteries (LIBs) with advanced power capabilities. However, their poor cycling performance, especially under high voltage and temperature conditions, has seriously limited their large-scale application. In this work, a simple and effective strategy is proposed to enhance the structural and interface stability of Ni-rich materials by La4NiLiO8 coating and Zr doping. The interfacial side reactions and intergranular microcracks of the modified material are inhibited, which is helpful in improving the electrochemical performance. Therefore, the initial capacity of dual modification of La and Zr of Ni-rich cathode is 196.4 mA h g−1 at 4.5 V and exhibits excellent cycling performance with a capacity retention of 82.1 % after 200 cycles. Moreover, at 50 °C, the initial capacity of the modified material is 239.0 mA h g−1, and the capacity retention is 63.1 % after 100 cycles, representing a significant improvement of 94.8 % over the unmodified sample.

Effects of transition metal ions migration at the cathode|electrolyte interface on the performance of thin-film Lithium-ion batteries with NCM cathodes

The advent of all-solid-state thin-film lithium-ion batteries (LIBs) has revolutionized the powering of microsystems due to their miniaturization ease and seamless integration capabilities. Despite the pressing demand for LIBs with higher energy density and enhanced safety, the performance of these devices has been consistently hindered by the complex interfacial dynamics at the cathode|electrolyte boundary. This study delves into the nuanced characterization of transition metal (TM) ions at the cathode|electrolyte interface, utilizing LiNi0.5Co0.2Mn0.3O2 (NCM523) thin films as the cathode material for LIBs. We meticulously explored the profound impact of NCM523|LiPON interfacial properties on the LIBs' overall performance, uncovering that the migration of TM ions and the emergence of TM–O spinel phases, induced by targeted annealing treatments of the cathodes, play pivotal roles in dictating the battery's capacity density and cycling stability. Heat treatments at 600 and 800 °C led to the formation of inhomogeneous spinel-phase nanolayers on the surfaces of NCM523 thin films, which hindered Li+ transport and affected the LIBs. In stark contrast, the 700 °C treatment yielded a pristine layered structure with clear boundary against LiPON, culminating in a battery with outstanding capacity density and remarkable cycle stability. Our theoretical calculations have unraveled that the temperature-dependent migration of TM ions is intricately linked to the varying strengths of TM–O bonds and the associated Jahn-Teller effects, providing a novel perspective on the design of high-performance LIBs.

Borate modified Co-free LiNi0.5Mn1.5O4 cathode material: A pathway to superior interface and cycling stability in LNMO/graphite full-cells

Cobalt-free LiNi0.5Mn1.5O4 (LNMO) holds great promise as a next-generation cathode material for high-energy and high-power density lithium-ion batteries (LIBs), making it a key contender for large-scale energy storage systems (ESS) and transportation applications. Despite its potential, the commercial utilization of LNMO has been impeded by its rapid capacity deterioration attributed to an unstable LNMO/electrolyte interface caused by the intrinsically high operating voltage of LNMO. Here, we present a pragmatic and scalable strategy to improve the LNMO/electrolyte interface through borate-based surface coating of the LNMO. Optimizing the coating process yielded high-rate capability and stable LNMO/electrolyte interface analyzed by extended float tests. Borate-LNMO materials show superior cycling stability at 25 °C and 45 °C, attributed to a robust cathode electrolyte interphase (CEI) formation. The bare LNMO and 0.25-B2O3-LNMO demostrated a cycling stability of around 41.20 % and 62.50 % respectively after 1000 cycles in LNMO/graphite full-cells. Post-mortem X-ray photoelectron spectroscopy (XPS) analysis revealed fewer side reaction products on borate-LNMO cathodes compared to bare LNMO. Additionally, scanning electron microscopy (SEM) revealed a thicker and denser solid-electrolyte interphase (SEI) on cycled graphite anodes from bare LNMO cells, while a thin and robust SEI was observed on graphite from borate-LNMO cells. Finally, we have conclusively demonstrated that the primary aging mechanism in LNMO/graphite full cells stems from the instability at the LNMO/electrolyte or/and graphite/electrolyte interface, rather than material-related degradation phenomenon. These compelling outcomes underscore the potential of cathode material surface coating in general and especially of borate coating on LNMO as a promising and cost-effective enabler for the use of LNMO in next-generation LIBs.

“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.

The oxidation reaction mechanism and its kinetics for a carbonaceous precursor prepared from ethylene tar for use as a cathode material for lithium-ion batteries

The oxidation reaction mechanism and its kinetics for a carbonaceous precursor prepared from ethylene tar for use as a cathode material for lithium-ion batteries

Rational design of V2O5 nanorod anchored carbon microsphere cathode materials for improved-performance lithium-ion batteries

Rational design of V2O5 nanorod anchored carbon microsphere cathode materials for improved-performance lithium-ion batteries

Comprehensive Study of Zr-Doped Ni-Rich Cathode Materials Upon Lithiation and Co-Precipitation Synthesis Steps.

Ni-rich layered oxides LiNi1-x-yMnxCoyO2 (NMC811, x = 0.1 and y = 0.1) are considered promising cathode materials in lithium-ion batteries (LiBs) due to their high energy density. However, those suffer a severe capacity loss upon cycling at high delithiated states. The loss of performance over time can be retarded by Zr doping. Herein, a small amount of Zr is added to NMC811 material via two alternative pathways: during the formation of the transition metal (TM) hydroxide precursor at the co-precipitation step (0.1%-Zr-cp) and during the lithiation at the solid-state synthesis step (0.1%-Zr-ss). In this work, the crystallographic Zr uptake in both 0.1%-Zr-ss and 0.1%-Zr-cp is determined and quantified through synchrotron X-ray diffraction and X-ray absorption spectroscopy. We prove that the inclusion of Zr in the TM site for 0.1%-Zr-cp leads to an improvement of both specific capacity (156 vs 149 mAh/g) and capacity retention (85 vs 82%) upon 100 cycles compared to 0.1%-Zr-ss where the Zr does not diffuse into the active material and forms only an extra phase separated from the NMC811 particles.

LaCoO3@Fe3O4 as peroxymonosulfate activator derived from spent lithium battery cathode materials for degradation of sulfamethoxazole in water

To reduce the various hazards of SMX to aquatic ecosystems, in this study, magnetically separable LaCoO3@Fe3O4 catalysts for the degradation of sulfamethoxazole (SMX) in water by activated peroxymonosulfate (PMS) were successfully prepared by using cobalt oxalate recovered from spent batteries using sol–gel, hydrothermal, and high-temperature calcination methods. The main factors influencing the reaction and the effect of coexisting ions on the degradation efficiency of SMX were investigated. The results showed that under optimal conditions ([SMX] = 30 mg, [LaCoO3@Fe3O4] = 10 mg/L, [PMS] = 30 mg/L, pH (initial) = 7.02), the LaCoO3@Fe3O4/PMS system degraded SMX up to 93 % in 15 min. The degradation of SMX in the LaCoO3@Fe3O4/PMS system was shown to be achieved by a combination of radical (SO4•-/•OH/•O2–) and non-radical (1O2) pathways by quenching experiments and electron paramagnetic resonance spectroscopy (EPR) analysis. Then, three possible degradation pathways were proposed using LC-MS, and Ecological Constitutive Relationship (ECOSAR) analysis showed that the toxicity of the intermediate products was all lower than that of SMX, indicating that the system is feasible for SMX degradation. This study provides a new idea for activating PMS for the degradation of antibiotics in water by preparing catalysts using precious metals from recycled batteries.

Surface Pinning of Mn by Oxidation State Control for the Synthesis of Cobalt-Free, Ni-Rich, Core/Shell Structured Cathode Materials.

Motivated by the increasing cost, environmental concerns, and limited availability of Co, researchers are actively seeking alternative cathode materials for lithium-ion batteries. A promising strategy involves structure-modified materials, such as a NiMn core/shell system. This design leverages the high energy density of a Ni-rich core while employing an Mn-rich shell to enhance interfacial stability by suppressing unwanted reactions with the electrolyte. This approach offers improved cycling stability and reduced reliance on Co. However, the interdiffusion of Mn ions between the core and shell remains a significant challenge during synthesis. This work presents a facile approach to address the issue of Mn interdiffusion in core/shell cathode materials. The study demonstrates that partial oxidation of the precursor during the drying stage effectively enhances the Mn oxidation state. This strategy successfully suppresses Mn interdiffusion during subsequent calcination, leading to the preservation of the core/shell architecture in the final cathode material. This optimized structure mitigates interfacial reactions, enhances chemomechanical properties, and reduces crosstalk, a major contributor to rollover failure. This work presents a novel approach for synthesizing high-performance core/shell cathode materials for next-generation lithium-ion batteries.

Constructing High-performance Cobalt-based Environmental Catalysts from Spent Lithium-Ion Batteries: Unveiling Overlooked Roles of Copper and Aluminum from Current Collectors.

Converting spent lithium-ion batteries (LIBs) cathode materials into environmental catalysts has drawn more and more attention. Herein, we fabricated a Co3O4-based catalyst from spent LiCoO2 LIBs (Co3O4-LIBs) and found that the role of Al and Cu from current collectors on its performance is nonnegligible. The density functional theory calculations confirmed that the doping of Al and/or Cu upshifts the d-band center of Co. A Fenton-like reaction based on peroxymonosulfate (PMS) activation was adopted to evaluate its activity. Interestingly, Al doping strengthened chemisorption for PMS (from -2.615 eV to -2.623 eV) and shortened Co-O bond length (from 2.540 Å to 2.344 Å) between them, whereas Cu doping reduced interfacial charge-transfer resistance (from 28.347 kΩ to 6.689 kΩ) excepting for the enhancement of the above characteristics. As expected, the degradation activity toward bisphenol A of Co3O4-LIBs (0.523 min-1) was superior to that of Co3O4 prepared from commercial CoC2O4 (0.287 min-1). Simultaneously, the reasons for improved activity were further verified by comparing activity with catalysts doped Al and/or Cu into Co3O4. This work reveals the role of elements from current collectors on the performance of functional materials from spent LIBs, which is beneficial to the sustainable utilization of spent LIBs.

Double gradient coupling heterostructure design accurately regulates the anion process of the Li-rich cathode

Lithium-rich layered oxides are regarded as the next generation of cathode materials for lithium-ion batteries due to their high capacity and high operating voltage. However, the release of oxygen at high voltage has caused serious failure problems, severely limiting the commercial application of lithium-rich cathode materials. As the irreversible release of oxygen occurs first at the surface of the particles, the change in structure at the surface is also more drastic. In response to the variability of anion redox processes from surface to interior in the particles, a coupling strategy of Al, oxygen vacancies double gradient and spinel heterostructure was designed. The high concentration of oxygen vacancies and Al on the surface inhibits excessive oxidation of lattice oxygen and oxygen release. The surface heterostructure improves the reaction kinetics and increases the activity and reversibility of the electrode process. The concentration of oxygen vacancies and Al in the interior ensures highly active anionic redox and further enhances structural stability. The specific capacity (0.13 mAh/g/cycle) and voltage (1.34 mV/cycle) decay of the modified material is greatly reduced. In-situ and ex-situ characterisations were used to analyse the modification mechanism, which can effectively guide the improvement of lithium-rich cathode material performance.

Balancing Ionic and Electronic Conduction at the LiFePO4 Cathode–Electrolyte Interface and Regulating Solid Electrolyte Interphase in Lithium‐Ion Batteries

AbstractRecently, in electric mobilities and stationary energy storage device applications, the development of long‐lasting, low‐cost, and high‐safety lithium‐ion batteries (LIBs) is widely studied. LiFePO4 (LFP) is a core cathode material for LIBs owing to its cost‐effectiveness and high safety. However, it exhibits low electronic conductivity and sluggish Li+ diffusion, hindering the application of LFP cathodes in high‐power battery industries. Herein, a triazole‐motivated electrolyte additive, 1‐(trimethylsilyl)−1H‐benzotriazole (TMSBTA) is presented, for mitigating iron dissolution via HF scavenging, reinforcing the robustness of the solid electrolyte interphase and constructing a cathode–electrolyte interface (CEI) to balance the ion and electron conduction of the CEI on the LFP cathode. Scanning probe microscopy performed in the conductive atomic force microscopy mode indicates that the electronically conductive CEI created by the oxidative decomposition of TMSBTA enables rapid and homogeneous lithiation and delithiation during cycling without morphological changes in the LFP particles. This study elucidates the design principles of the CEI on the LFP cathode and is expected to guide integrated electrolyte additive engineering for LFP‐containing LIBs.