Performance Of Lithium-ion Batteries Research Articles

Poly(Acrylic Acid)-Based Polymer Binders for High-Performance Lithium-Ion Batteries: From Structure to Properties.

Poly(acrylic acid) (PAA) and its derivatives have emerged as promising candidates for enhancing the electrochemical performance of lithium-ion batteries (LIBs) as binder materials. Recent research has focused on evaluating their ability to improve adhesion with silicon (Si) particles and facilitate ion transport while maintaining electrode integrity. Various strategies, including mixing modifications and copolymerization methods, are highlighted and the structural and physicochemical properties of these binders are examined. Additionally, the interaction mechanisms between PAA-based binders and active materials and their impact on key electrochemical properties such as initial Coulombic efficiency (ICE) and cycle stability are discussed. The findings underscore the efficacy of tailored PAA-based binders in enhancing the electrochemical properties of LIBs, offering insights into the design principles and practical implications for advanced battery materials. These advancements hold promise for developing high-performance lithium batteries capable of meeting future energy storage demands.

Laser-formed nanoporous graphite anodes for enhanced lithium-ion battery performance

Lithium-ion batteries are pivotal in modern energy storage, commonly utilizing graphite anodes for their high theoretical capacity and long cycle life. However, graphite anodes face inherent limitations, such as restricted lithium-ion storage capacity and slow diffusion rates. Enhancing the porosity of graphite and increasing d-spacing in expanded graphite anodes have been explored to improve lithium-ion diffusion and intercalation. Recent advancements suggest that nanoscale modifications, such as utilizing nano-graphite and graphene, can further enhance performance. Laser processing has emerged as a promising technique for synthesizing and modifying graphite and graphene-related materials, offering control over surface defects and microstructure. Here, we demonstrate an industrially compatible one-step laser processing method to transform a nano-graphite and graphene mixture into a nanoporous matrix, significantly improving lithium-ion battery performance. The laser-processed anodes demonstrated significantly enhanced specific capacities at all charge rates, with improved relative performance at higher charge rates. Additionally, long-term cycling at 1 C showed that laser-processed cells outperformed their non-processed counterparts, with specific capacities of 323 and 241 mAh/g, respectively.

Synthesis Methods of Si/C Composite Materials for Lithium-Ion Batteries

Silicon anodes present a high theoretical capacity of 4200 mAh/g, positioning them as strong contenders for improving the performance of lithium-ion batteries. Despite their potential, the practical application of Si anodes is constrained by their significant volumetric expansion (up to 400%) during lithiation/delithiation, which leads to mechanical degradation and loss of electrical contact. This issue contributes to poor cycling stability and hinders their commercial viability, and various silicon–carbon composite fabrication methods have been explored to mitigate these challenges. This review covers key techniques, including ball milling, spray drying, pyrolysis, chemical vapor deposition (CVD), and mechanofusion. Each method has unique benefits; ball milling and spray drying are effective for creating homogeneous composites, whereas pyrolysis and CVD offer high-quality coatings that enhance the mechanical stability of silicon anodes. Mechanofusion has been highlighted for its ability to integrate silicon with carbon materials, showing the potential for further optimization. In light of these advancements, future research should focus on refining these techniques to enhance the stability and performance of Si-based anodes. The optimization of the compounding process has the potential to enhance the performance of silicon anodes by addressing the significant volume change and low conductivity, while simultaneously addressing cost-related concerns.

A Computational Review on Localized High‐Concentration Electrolytes in Lithium Batteries

AbstractElectrolyte engineering plays a vital role in improving the battery performance of lithium batteries. The idea of localized high‐concentration electrolytes that are derived by adding “diluent” in high‐concentration electrolytes has been proposed to retain the merits and alleviate the disadvantages of high‐concentration electrolytes, and it has become the focus of attention in high‐voltage lithium batteries, flame‐retardant lithium batteries, and low‐temperature lithium batteries. Extensive efforts have been made to elucidate the fundamentals of localized high‐concentration electrolytes. This review provides an overview of state‐of‐the‐art computational progress in the studies of localized high‐concentration electrolytes, focusing on the application of computational techniques to analyze the redox stability, solvation structures, and interface characteristics of lithium batteries with localized high‐concentration electrolytes. Integrated with experimental approaches, complementing each other, computational methods are believed to be conducive to understanding the working mechanism and designing localized high‐concentration electrolytes for better lithium batteries in the future.

Qualitative analysis of the coupling effect of fluid velocity distribution in microchannels on the performance of water-cooling lithium-ion batteries system

ABSTRACT Lithium-ion batteries are the direct power sources of electric vehicles, but their high heat flux density restricts their development. Microchannel heat sinks (MCHS) can assist in heat dissipation to overcome this. The distribution of fluid velocity among microchannels has a considerable effect on the performance of MCHS for a water-cooling lithium-ion batteries system. In this paper, a new microchannel heat sink with high depth to width aspect ratio is proposed and the influence of four different aspect ratios on the distribution of fluid velocity among microchannels and heat transfer performance of MCHS was numerically studied by computational fluid dynamics (CFD). The results showed that at the same inlet flow rate, the larger the aspect ratio of the microchannels, the better the uniformity of the internal fluid velocity. The heat performance of microchannel structures with four different aspect ratios for a water-cooling lithium-ion batteries is further investigated experimentally. Compared with the simulation results of the fluid velocity distribution, the coupling effect between the fluid velocity distribution in the microchannels and the heat dissipation performance of a water-cooling lithium-ion batteries is analyzed. The results fully demonstrated that a larger aspect ratio of the microchannels results in a better heat dissipation performance on the surface of the lithium-ion batteries. Optimizing the aspect ratio of the microchannels to facilitate a relatively uniform velocity distribution to improve heat dissipation performance of the water-cooling system may be a key factor to be considered, which provides a new idea for passive thermal management of batteries.

Recent research progress on Li29Zr9Nb3O40-based solid electrolytes for lithium batteries

All-solid-state batteries have become a research hotspot because of their high specific capacity and safety. Solid-state electrolytes are the key material of all-solid-state lithium-ion batteries, and their properties directly affect the overall performance of lithium-ion batteries. So far, many inorganic solid electrolytes have been reported, such as NASICON, LISICON, perovskite, and garnet-type solid electrolyte. However, some lithium-rich rock salt-structured electrolytes, such as Li2ZrO3, LiNbO4, and Li6Zr2O7, have been underappreciated in the field of solid-state electrolytes due to their lower ionic conductivity at room temperature. While investigating solid solution formation, Li6Zr[Formula: see text][Formula: see text]Nb[Formula: see text]O[Formula: see text][Formula: see text][Formula: see text], a new phase known as Li[Formula: see text]Zr9Nb3O[Formula: see text] with a rock-salt structure was discovered. After decades, it was not until a team prepared Li[Formula: see text]Zr9Nb3O[Formula: see text] ceramics by sol-gel method, which exhibited high ionic conductivity (10[Formula: see text]–10[Formula: see text]S cm[Formula: see text]) at room temperature, that the substance showed great potential as a solid electrolyte in all-solid-state lithium-ion batteries. In this paper, the crystal structure, lithium-ion transport mechanism, preparation method, and element doping of Li[Formula: see text]Zr9Nb3O[Formula: see text] are described comprehensively based on research progress in recent years. Then, development prospects and challenges of the concrete application of Li[Formula: see text]Zr9Nb3O[Formula: see text]in all-solid-state lithium-ion batteries are also discussed.

Dual Function of Hydrogen Bond and CEI to Enhanced Lithium-Ion Battery Performance.

The stability of the commercial electrolyte is linked to the internal solvent molecule, particularly in enhancing the stability of these molecules. Hereby, we introduce a dual function strategy involving hydrogen bond induced solvent molecules and the in situ fabrication cathode-electrolyte interphase (CEI) to address this issue. The additive N-(4-(2,5-dioxo-4-oxazolidinyl)butyl)-2,2,2-trifluoroacetamide (DOTFA), with its oxazolidinyl and trifluoroacetamide functional units, establishes hydrogen bonds with the solvent, forming CEI films on the cathode surface that enhance the antioxidation ability of the electrolyte. These hydrogen bonds contribute to enhancing the high-pressure structural stability of the solvent molecule. Additionally, the uniform and robust in situ constructed CEI films act as a shield, protecting the cathode from various side reactions and enhancing interface compatibility. By incorporation of the DOTFA additive in the electrolyte, lithium-ion batteries with NCM811 cathodes exhibit excellent cycling performance. The work highlights the significance of dual function in solvent molecules and provides an effective method for enhancing the antioxidation ability of the electrolyte.

Advanced parameter estimation for lithium-ion battery model using the information sharing group teaching optimization algorithm

Accurate battery modeling is crucial for optimizing the performance and safety of Lithium-ion batteries (LiBs), particularly in applications such as electric vehicles and smart grids. This paper introduces the Information Sharing Group Teaching Optimization Algorithm (ISGTOA), a novel human-based metaheuristic algorithm designed to estimate the 21 parameters of third-order Equivalent Circuit Model (ECM) for LiBs. Unlike existing methods, ISGTOA effectively manages the increased complexity of a model through advanced group teaching strategies and sophisticated information-sharing mechanisms inspired by classroom dynamics. We validated the effectiveness of ISGTOA using two distinct datasets—High Dynamic Profile (HDP) and Urban Dynamometer Driving Schedule (UDDS)—across various LiB chemistries (NCA and NMC) and temperature conditions (−5 °C, 25 °C and 45 °C). The results demonstrate that ISGTOA achieves superior parameter estimation accuracy and convergence speed compared to established and recent optimization methods such as TLBO, TLSBO, AISA, MTBO, and DTBO. Specifically, ISGTOA attained a minimum RMSE of 8.357 mV with rapid convergence and high stability in the HDP dataset and minimized RMSE to 10 mV within ten iterations at both 25 °C and 45 °C in the UDDS dataset. Additionally, ISGTOA exhibited high efficiency (up to 97.75 %) under varying thermal environments. This work not only introduces a novel algorithm for complex battery modeling but also sets the stage for future advancements in real-time battery management systems, emphasizing the importance of robust, versatile, and efficient parameter estimation techniques.

A Review on Advanced Battery Thermal Management Systems for Fast Charging in Electric Vehicles

To protect the environment and reduce dependence on fossil fuels, the world is shifting towards electric vehicles (EVs) as a sustainable solution. The development of fast charging technologies for EVs to reduce charging time and increase operating range is essential to replace traditional internal combustion engine (ICE) vehicles. Lithium-ion batteries (LIBs) are efficient energy storage systems in EVs. However, the efficiency of LIBs depends significantly on their working temperature range. However, the huge amount of heat generated during fast charging increases battery temperature uncontrollably and may lead to thermal runaway, which poses serious hazards during the operation of EVs. In addition, fast charging with high current accelerates battery aging and seriously reduces battery capacity. Therefore, an effective and advanced battery thermal management system (BTMS) is essential to ensure the performance, lifetime, and safety of LIBs, particularly under extreme charging conditions. In this perspective, the current review presents the state-of-the-art thermal management strategies for LIBs during fast charging. The serious thermal problems owing to heat generated during fast charging and its impacts on LIBs are discussed. The core part of this review presents advanced cooling strategies such as indirect liquid cooling, immersion cooling, and hybrid cooling for the thermal management of batteries during fast charging based on recently published research studies in the period of 2019–2024 (5 years). Finally, the key findings and potential directions for next-generation BTMSs toward fast charging are proposed. This review offers an in-depth analysis by providing recommendations and potential solutions to develop reliable and efficient BTMSs for LIBs during fast charging.

Cu2SnS3/rGO nanocomposites with optimized pore structure for high-performance lithium-ion batteries

Developing advanced anode materials is essential for enhancing the rate performance and stability of lithium-ion batteries (LIBs), which is critical for meeting the demands for next-generation energy storage solutions. In this research, Cu2SnS3/rGO nanocomposites were synthesized via a rapid microwave-assisted one-step method, followed by post-synthetic annealing. The incorporation of reduced graphene oxide (rGO) not only significantly improves its electrical conductivity, but also effectively inhibits the agglomeration of CTS nanoparticles. The nanocrystal size in the CTS/rGO nanocomposites has been dramatically downsized, transitioning from the pristine CTS dimensions of 0.9–1.5 μm to a mere 100 nm. This downsizing is a critical advancement in the electrode, as it enhances the surface area and reactivity of the composite. The subsequent high-temperature annealing process shrinks the pore size in the CTS/rGO nanocomposite, decreasing from an average of 42.13 nm to a more confined range of 7.81 to 8.77 nm, depending on the annealing temperatures. Electrochemical testing reveals that the CTS/rGO-A nanocomposite annealed at 300 °C exhibits superior electrochemical performance to the unmodified CTS and non-annealed CTS/rGO composite. The performance is evidenced by an initial capacity of 1856.97 mAh g−1 at a current density of 1 A g−1 and retains a capacity of 1250.32 mAh g−1 after 500 cycles. To elucidate the underlying mechanisms governing the lithium ion diffusion kinetics, capacitance and diffusion behavior of the CTS/rGO-A electrode, advanced techniques such as galvanostatic intermittent titration technique (GITT) and rate cyclic voltammetry (CV) were utilized. These analyses revealed that the synergistic effect of an increased Li+ diffusion coefficient (DLi+), coupled with a notable capacitive contribution, is demonstrated to the enhanced electrochemical performance observed. Furthermore, the COMSOL Multiphysics simulation also indicates improved structural stability of CTS/rGO-A, attributed to minimized stress from volume expansion during discharge. The CTS/rGO-A nanocomposites, featuring enhanced electrochemical performance, coupled with a straightforward and efficient fabrication method, emerge as a promising material for scalable and practical energy storage solutions.

Enhancing the Capacity and Cycling Performance of Lithium Ion Batteries Through Perforated Current Collectors

Enhancing the Capacity and Cycling Performance of Lithium Ion Batteries Through Perforated Current Collectors

Cooling lithium-ion batteries with silicon dioxide -water nanofluid: CFD analysis

Temperature is recognized to have a major impact on the safety, performance, and cycle life of lithium-ion batteries (LiBs). Since LiB cells are sensitive to temperature variations, even little variations can result in a reduction in performance or even cell failure. This work introduces a novel cooling system utilizing SiO2-Water Nanofluid and CFD analysis to enhance the thermal management of lithium-ion battery packs with varying silicon dioxide nanoparticle diameters. The results showed that SiO2 nanofluids with smaller nanoparticle diameters had higher average Nusselt numbers at all Reynolds numbers. This is because smaller nanoparticles have a larger surface area, which increases the collision rate of the nanoparticles with the fluid and thus enhances heat transfer. The increase in Nusselt number was found to be 2.8 %, 5.5 %, 11.6 %, and 22.6 % for nanoparticle sizes of 50, 40, 30, and 20 nm, respectively. The results also showed that for all particle sizes, the temperature of cell 4 equalled the inlet temperature at Re = 30,000. This is because cell 4 is located at the first column of the system and is oriented towards the entrance section, which results in a large temperature difference between the cell and the coolant. Cell 4, therefore, experiences a higher heat discharge to the coolant than the other cells. Overall, this study has shown that smaller nanoparticles and higher Reynolds numbers significantly improve the heat exchange capacity of LiB cells. This can lead to improved electrical properties and extended battery cell lifespan.

Multi-channeled halloysite nanotube-blended polybenzimidazole separators for enhancing lithium-ion battery performance

The microscopic transport mode of lithium ions in the separator is crucial for solving the problem of irregular lithium dendrite growth, thereby enhancing the safety of battery operation, and it also has a positive impact on the electrochemical performance of the battery. Furthermore, the heat resistance of the separator is an important indicator for measuring the performance of the separator and the safety of battery usage. In this work, we have introduced sulfonated and lithiated halloysite nanotubes into a high-temperature-resistant OPBI matrix through an easily implementable NIPS, resulting in a high-temperature-resistant separator with multiple lithium-ion micro-transport morphologies. Lithium ions can shuttle through the halloysite nanotube pores, negatively charged sulfonate groups on the surface, and larger finger-like pores formed by NIPS within the separator, creating a high and uniform lithium-ion flux that prevents excessive localized ion flow leading to the aggressive growth of lithium dendrites. According to the characterization data, this separator exhibits relatively satisfactory performance, such as an ionic conductivity of 1.82 mS cm−1, a porosity of 82 %, an electrolyte uptake of 397 %, and no significant physical shrinkage at 200 °C. Additionally, the cells assembled using the OPBI@sHNT-Li20 separator delivers higher discharge capacity (164.92 mAh·g−1), more stable cycle, superior rate performance. So the OPBI@sHNT-Li separator is expected to play an active role in improving the safety and electrochemical performance of lithium-ion batteries.

Recent Advancements of Graphene and Some Selected Graphene-Based Electrode Materials for Lithium-Ion Battery

Graphene is a two-dimensional monolayer of carbon atoms arranged in a hexagonal lattice consisting of sp2 hybridized conjugated carbon atoms and serves as a promising electrode material for lithium-ion batteries (LIBs) owing to its superior properties, including a high specific surface area (2630 m2g-1), a high theoretical capacity (744 mAhg-1), excellent electrical conductivity, and a wide electrochemical potential window. Despite having these superior properties, the restacking as well as the van der Waals forces of attraction among the graphene layers and the long path for Li-ion diffusion are factors that reduce the specific surface area and active site for Li-ion storage, which in turn influence the electrochemical performance of LIBs. The functionalization of graphene to porous graphene, graphene quantum dots, and graphene oxides, as well as the integration of graphene with other foreign materials such as transitional metal oxides, various heteroatoms (boron, nitrogen, sulfur, etc.), and covalent organic frameworks (COF), are the two main strategies that have been widely applied to improve the properties of graphene for Li-ion battery applications. In this review, recent works regarding the performance of graphene and graphenebased electrode materials for LIBs applications were reviewed and presented in detail. Moreover, various graphene fabrication techniques in terms of quality and quantity of graphene produced as well as the future overview of graphene and some selected graphene-based materials for LIBs applications have been assessed and summarized.

Facile One-Pot Synthesis of Fe3O4 Nanoparticles Composited with Reduced Graphene Oxide as Fast-Chargeable Anode Material for Lithium-Ion Batteries.

To address the rapidly growing demand for high performance of lithium-ion batteries (LIBs), the development of high-capacity anode materials should focus on the practical perspective of a facile synthetic process. In this work, iron oxide nanoparticles (Fe3O4 NPs) in situ grown on the surface of reduced graphene oxide (rGO), denoted as Fe3O4 NPs@rGO, were prepared through a facile one-pot synthesis under the wet-colloidal conditions. The synthesized Fe3O4 NPs showed that uniform Fe3O4 NPs, with a size of around 9 nm, were distributed on the rGO surfaces. When applied as an anode material for LIBs, the Fe3O4 NPs@rGO anode revealed a high reversible capacity of 1191 mAh g-1 at 1.0 A g-1 after 200 cycles. It also exhibited excellent rate performance, achieving 608 mAh g-1 at a current density of 5.0 A g-1 over 500 cycles, with improved electronic and ionic conductivities due to the rGO template. This suggested that practically available anode materials can be developed through our one-pot synthesis by in situ growing the Fe3O4 NPs.

Bio-Inspired Self-Healing Silicon Anodes: Harnessing Tea Polyphenols to Enhance Lithium-Ion Battery Performance.

This study introduces an anode material for lithium-ion batteries, achieved by integrating tea polyphenols (TP) with the widely utilized polyacrylic acid (PAA) binder. The composite material capitalizes on the intrinsic self-healing properties of TP, enhancing the anode's durability and adhesiveness without the need for additional organic synthesis. The incorporation of TP has been demonstrated to significantly elevate ionic conductivity and expedite lithium ion diffusion, thereby reducing interfacial resistance and decelerating the rate of capacity fade due to electrolyte decomposition and silicon particle expansion. Employing a comprehensive analytical toolkit, including Fourier transform infrared spectroscopy, thermogravimetric analysis, peel strength measurements, and density functional theory calculations, we elucidated the physicochemical properties of the Si@PAA-TP anode. The anode's electrochemical performance was systematically assessed through galvanostatic charge-discharge, cyclic voltammetry, and electrochemical impedance spectroscopy, with scanning electron microscopy providing insights into postcycling mechanical property alterations. This research advances a cost-effective, high-performance adhesive strategy for silicon anodes and contributes to the development.

Elucidating Heterogeneous Li Insertion Using Single-Crystalline and Freestanding Layered Oxide Thin Film.

The kinetics of interfacial ion insertion govern the uniformity of electrochemical reactions, playing a crucial role in lithium-ion battery performance. In two-dimensional lithium-conducting layered-oxide battery particles, variation in insertion rates across insertion channels remains unclear due to poorly defined crystal orientation at the solid-liquid interface and solid-state-lithium-diffusion length. This ambiguity complicates understanding inhomogeneous lithium-insertion channels activation. A systematic study requires crystallographically predefined interfaces and in situ lithium-concentration mapping. Here, we fabricated a freestanding, (104)-oriented-LiNi1/3Mn1/3Co1/3O2 single-crystal thin film using dissolution-induced release and performed in situ scanning-transmission-X-ray-microscopy to spatially resolve lithium-insertion at well-defined-interfaces. We observed heterogeneous lithium-concentration evolution due to channel-by-channel insertion rate variation, despite the potential for homogeneous lithium distribution via a solid-solution-phase at equilibrium in NMC111. Increasing current density exacerbates this heterogeneity, highlighting channel-by-channel variation. Our findings provide critical insights into battery electrode utilization and lifetime management, potentially guiding the design of more efficient and durable lithium-ion batteries.

Defect Chemistry in High-Voltage Cathode Materials for Lithium-Ion Batteries.

High-voltage cathodes (HVCs) have emerged as a paramount role for the next-generation high-energy-density lithium-ion batteries (LIBs). However, the pursuit of HVCs comes with inherent challenges related to defective structures, which significantly impact the electrochemical performance of LIBs. The current obstacle lies in the lack of a comprehensive understanding of defects and their precise effects. This perspective aims to provide insights into defect chemistry for governing HVCs. The classifications, formation mechanisms, and evolution of defects are outlined to explore the intricate relationship between defects and electrochemical behavior. The pressing need for cutting-edge characterization techniques that comprehensively investigate defects across various temporal and spatial scales is emphasized. Building on these fundamental understandings, engineering strategies such as composition tailoring, morphology design, interface modification, and structural control to mitigate or utilize defects are thoroughly discussed for enhanced HVCs performance. These insights are expected to provide vital guidelines for developing high-performance HVCs for next-generation high-energy lithium-ion batteries.

Recyclability study for the next generation of cobalt-free lithium-ion battery systems with C-LNMO, Si/C- LRLO and TiNbO-LNMO active materials via hydrometallurgical route

The scarcity and uncertain supply of cobalt poses significant challenges for the lithium-ion battery industry. To address this issue, alternative chemistries excluding cobalt have been developed. Despite solving supply issues, these developments raise concerns about recyclability and their impact on current recycling trends.This study presents a recycling strategy and evaluates its performance for next-generation cobalt-free lithium-ion batteries. It focuses on three prototypes that use innovative cathode materials (titanium niobium oxide, carbon, and silicon/carbon) and electrolyte systems (ionic liquid and gelified). The proposed recycling process includes pyrolysis, mechanical separation, neutral and acid leaching, cementation, and neutralisation for selective metal separation.The results indicate that gelified electrolytes exhibit greater thermal stability than their liquid counterparts, indicating an effect on the degradation temperature and gas emissions, which are crucial for metal recovery. This study highlights the reduced toxicity of ionic liquid electrolytes and emphasises the need for strict pyrolysis gas handling due to hazardous emissions. High recovery rates (65–90 %) were achieved for nickel, manganese, lithium, and anode components.With potential for process optimisation to improve the quality of products, this study shows that cobalt-free battery systems can be integrated into existing recycling frameworks with adjustments, supporting progress towards sustainable battery practices.

The effect of low-temperature starting on the thermal safety of lithium-ion batteries

With the widespread application of lithium-ion batteries (LIBs) in the field of energy equipment, their probability of starting or operating in low-temperature environments is also increasing. However, there is currently a lack of research on the changes in thermal safety of batteries after use in corresponding environments. In this work, the thermal safety performance, degradation mechanisms and evaluation method of LIBs at low-temperature start-up conditions are studied. The results show that starting at low temperature leads to the decrease of cell capacity. Electrochemical characterization and cell disassembly analysis indicate that the loss of active lithium ions is mainly caused by the evolution of lithium and the growth of solid electrolyte interface films. In addition, the low-temperature startup results in the decrease of thermal runaway (TR) onset temperature and the advance of TR time. In order to quantitatively evaluate the safety state of the LIBs, an evaluation model based on Informer algorithm is established. The model extracts the discharge capacity, discharge energy and dV/dQ as aging characteristic parameters, and extracts TR temperature as thermal safety characteristic parameters. The data set is processed by cubic spline interpolation. After training and verification, the accuracy of the model reaches 80 %.