Stability of graphene nanoparticles for lithium-ion battery electrodes: ReaxFF simulations

In nanofluid minimum quantity lubrication (NMQL) grinding of titanium (Ti) alloy, existing nanoparticles cannot solve the technical bottleneck of high surface integrity. Therefore, graphene (GR) nanoparticles, which have excellent lubrication performance, were applied in NMQL. The tribological properties of GR nanofluid on wheel–workpiece interface were studied by friction and wear test. In the experiment, 0.5–3 nm thick GR nanoparticles were used to prepare 3% vol. palm oil-based nanofluid. Ball-disc experiment under grinding conditions was carried out on the friction and wear tester. Grinding balls with SiC abrasive grains (to simulate the grinding wheel) and Ti-6Al-4V disc (to simulate the workpiece) were used. Load force was set for simulation of pressure boundary condition of the grinding wheel–workpiece interface. Stratiform nanoparticles (MoS2, MoO3, and HBN) were used as the comparison group. Results demonstrated that GR nanofluid achieved smaller friction coefficient (0.295), error bars (0.0029), and area of scratches (182,940 μm2). GR nanoparticles with small gravity and large specific surface area improved the viscosity of nanofluid and consequently the lubrication performance. The plane hexagonal honeycomb structure determines the strong lubrication stability and abrasive resistance of the GR nanoparticles. The scanning electron microscope (SEM) and energy dispersive spectrometer (EDS) images of the scratch surface also verified the above conclusions.

The slow and high energy consumption of drying process of the coated web of positive electrode for automotive lithium ion battery have become the bottleneck in the manufacturing process of cathode coating. However, high drying rate of solvent (commonly N-Methyl-2-pyrrolidone (NMP)) result in higher concentration of binder (commonly polyvinylidene fluoride (PVDF)) at the evaporating surface than at the bottom. The uneven distribution of binder between coating layers will lead to the decrease of adhesion between active layer and substrate, and even an increase in internal resistance and the associated deteriorated rate capability, thus seriously damaging the mechanical and electrochemical properties of the electrode. In order to improve the drying efficiency of the coated web, and regulate the concentration distribution of binder, this study mainly calculate the evaporation rate under different drying parameters. and determine the binder distribution at the different evaporation rates.

Ordered mesoporous tungsten oxide–carbon nanocomposite for use as a highly reversible negative electrode in lithium-ion batteries

The reaction mechanism of a “SiO”-carbon composite-negative electrode for high-capacity lithium-ion batteries is examined by Si K-edge X-ray absorption near edge structure (XANES), 7Li and 29Si nuclear magnetic resonance (NMR), and scanning transmission electron microscopy (STEM) with Si L-edge electron energy loss spectroscopy (EELS) and energy dispersive X-ray spectroscopy (EDX). According to the analytical results, “SiO” consisting of nano-size Si particles dispersed in amorphous SiO2 is converted to lithium-silicon alloys and lithium silicon oxides during the first charge in lithium-ion batteries, and the nano-size silicon particles surrounded by lithium silicon oxides are rechargeable for subsequent cycles. Molecular dynamics (MD) simulation of “SiO” is also carried out and shown that silicon particles grow during the first cycle and are surrounded by a good lithium-ion conductor of lithium silicon oxides. From these results, the reaction mechanism of “SiO” is discussed in terms of high-capacity negative electrodes for lithium-ion batteries.

Utilization of V 6O 13 as the positive electrode in lithium batteries

The possibility of usage of petroleum coke as active materials of negative electrodes in lithium batteries was studied in presented work. Studies show that crude petroleum coke has high specific resistance (1.4·107 Ohm·cm), that is in 7 times greater than the resistance of graphite (0.5-1.0 Ohm·cm), used as the active material of negative electrodes in lithium-ion batteries. Thermal treatment of crude petroleum coke at 800 °C in the atmosphere of air or nitrogen during 5 hours decreases the specific resistance to 1.3 and 1.5 Ohm·cm, correspondingly, and increases their specific surface area from <0.1 m2/g to 5.3 m2/g (nitrogen) and 0.7 m2/g (air). Specific surface area was estimated by sorption of dyes (methyl orange).Crude petroleum coke is not electrochemical active and can not be DC cycled (Figure). Heat treatment of petroleum coke, both in the atmosphere of air and in the atmosphere of nitrogen, leads to the appearance of electrochemical activity and the ability to reversibly intercalate lithium ions. At DC cycling of electrodes based on heat-treated petroleum coke in the range of voltage of 0 - 1.0 V vs Li/Li+ the reversible capacity is 300-350 mA·h/g.The shapes of charge and discharge curves (Figure) of semi-cells with electrodes based on petroleum coke are similar to the charge-discharge curves of semi-cells with electrodes based on structurally disordered carbons. This work was performed as part of the Government Order to Ufa Institute of Chemistry of the Russian Academy of Sciences by the Ministry of Science and Higher Education of the Russian Federation (Theme No. AAAA-A17-117011910031-7). Figure 1

Biomass carbon micro/nano-structures derived from ramie fibers and corncobs as anode materials for lithium-ion and sodium-ion batteries

Lithium ion batteries are among the most used rechargeable batteries in the world. Carbon nanostructures including carbon nanotubes (CNTs) are considered as important electrode materials for this kind of batteries. Therefore improving the performance of these carbon based electrodes in Lithium ion batteries is an important issue and attracts much attention in the battery community. In this manuscript, a new method for high content Nitrogen doping on CNTs is reported as an efficient approach for enhancing the battery performance. Direct current-plasma enhanced chemical vapor deposition (DC-PECVD) system was used for nitrogen doping. Annealing with Nitrogen during CNT growth and plasma exposure after the growth has been used for Nitrogen doping of the CNTs. The growth was performed on an Indium Tin oxide (ITO) covered Silicon substrate. Implementation of Silicon substrate enables the possibility of future integration of other electronic circuits with the fabricated Lithium ion battery. Vertically aligned CNTs with an average diameter of around 150 nm and 4 um height has been obtained on this substrate. The synthesized CNTs was subsequently used as the electrode of Lithium ion battery in a half cell configuration. The results show a significant improvement of about 400% in the specific capacity of the battery as a result of Nitrogen doping. For Nitrogen doped CNT based battery, specific capacity of around 0.4 mAh/cm2 and coulombic efficiency of 97% were achieved after 28 cycles of charge/discharge with C rate of 2.5. This Nitrogen doping method is propped as an efficient technique for enhancing the performance of Lithium ion batteries with carbon based electrodes.

Thirty years after the release of the first commercial lithium-ion battery, capacity fading due to complex ageing mechanisms remains one of the major concerns in lithium-ion battery research. Lithium-ion battery cathodes age due to phenomena as transition metal dissolution, electrolyte oxidation and volume expansions.[1] To suppress these effects, a protective coating can be applied to the cathode’s surface to avoid direct contact with the liquid electrolyte. Many studies exist in literature, showing the protective effect of conformal and pinhole-free Atomical Layer Deposited (ALD) coatings. However, the inorganic coatings deposited by ALD are rigid and will crack upon volume expansion of the cathode.[2]Molecular Layer Deposition (MLD) offers the same benefits as ALD but can be used to deposit hybrid inorganic/organic flexible films that can accommodate potential volume expansions of the cathode. To our knowledge, apart from ‘metalcones’ i.e. MLD films grown using a metal containing precursor and an alcohol, MLD films remain to be explored as protective and flexible coatings for lithium-ion batteries.[3] In this work, hybrid MLD titanium carboxylate thin films are deposited using tetrakis(dimethylamido)titanium (TDMAT) and various dicarboxylic acid precursors: oxalic acid, malonic acid, succinic acid, glutaric acid and 3,6-dioxaoctanedioic acid. The latter containing two ethylene oxide units per molecule, potentially increasing the lithium-ion conductivity.[4]The growth of the titanium carboxylate MLD processes is studied using in situ ellipsometry at a substrate temperature of 100 °C and 160 °C. Only the TDMAT/oxalic acid process is found to display good saturation behavior, while a parasitic CVD component is present during the TDMAT pulse for the other processes. The structure of the as-deposited films is physically characterized using Fourier Transform IR spectroscopy (FTIR) and X-Ray Photoelectron Spectroscopy (XPS), confirming the successful deposition of titanium carboxylate films. The films are found to be stable in air up to 50 days as shown by FTIR. This is in contrast to many metalcone MLD films which are considered to be air sensitive as the organic backbone degrades upon air exposure. In addition, FTIR, X-Ray Reflectivity (XRR) and X-Ray Fluorescence (XRF) measurements show that the titanium carboxylate films remain intact upon immersion into a solution of 1 M LiClO4 in propylene carbonate, the liquid electrolyte used for electrochemical characterization.The electrochemical properties of a 5 nm TDMAT/oxalic acid, TDMAT/3,6-dioxaoctanedioic acid and TDMAT/glycerol film (conventional titanicone film [5]) are tested on top of three ideal electrode systems: anatase TiO2, TiN and LiMnO2 (LMO). The titanium carboxylate films are observed to have little to no effect on the lithium-ion kinetics of the TiO2 electrode system compared to the uncoated electrode. This is in contrast to the titanicone film displaying a detrimental effect on the kinetics. All films are observed to effectively suppress electrolyte oxidation when exposing the TiN electrode system to elevated potentials. On the LMO electrode an activation step is necessary for all films, after which a good lithium-ion mobility through the titanium carboxylate films is observed without the severe irreversible reactions detected in the potential profile for the titanicone films. Overall, the explorative tests on thin film electrodes in this work indicate that the electrochemical properties of the titanium carboxylate films seem promising candidates as protective and flexible coating of lithium-ion battery cathodes.[1] Vetter, J., Novák, P., Wagner, M. R., Veit, C., Möller, K. C., Besenhard, J. O., ... & Hammouche, A. (2005). Ageing mechanisms in lithium-ion batteries. Journal of power sources, 147(1-2), 269-281.[2] Ban, C., & George, S. M. (2016). Molecular layer deposition for surface modification of lithium‐ion battery electrodes. Advanced Materials Interfaces, 3(21), 1600762.[3] Zhao, Y., Zhang, L., Liu, J., Adair, K., Zhao, F., Sun, Y., ... & Sun, X. (2021). Atomic/molecular layer deposition for energy storage and conversion. Chemical Society Reviews, 50(6), 3889-3956.[4] Xue, Z., He, D., & Xie, X. (2015). Poly (ethylene oxide)-based electrolytes for lithium-ion batteries. Journal of Materials Chemistry A, 3(38), 19218-19253.[5] Van de Kerckhove, K., Mattelaer, F., Deduytsche, D., Vereecken, P. M., Dendooven, J., & Detavernier, C. (2016). Molecular layer deposition of “titanicone”, a titanium-based hybrid material, as an electrode for lithium-ion batteries. Dalton Transactions, 45(3), 1176-1184.

Nowadays, Lithium ion batteries (LIBs) can be found in every corner of our daily life. However, safety and cost of lithium ion batteries are the two major issues. Aqueous rechargeable lithium ion batteries are believed to be the promising candidates for LIBs due to nonflammable，low cost higher ionic conductivity of aqueous electrolyte [1]. To reduce the cost of aqueous lithium-ion cells, researchers focus on developing methods to synthesize electrode material in an energy efficient way. It has been reported that TiP2O7 has a low intercalation /de-intercalation potential (2.6 V versus Li/Li+) [2], which makes it a promising anode material for aqueous lithium-ion batteries [3,4]. One report demonstrated a solid-state synthesis method annealing at 300◦C for 2 hours, annealing at 800◦C for 3 hours and cooling to room temperature for 4 hours [5]. The solid-state synthesis route is very common in industrial applications due to its simplicity. However, the long calcining duration and high temperature requirement increases the processing cost for the electrode materials. One report applied microwave to synthesize C-NaTi2(PO4)2, the negative electrode for aqueous sodium ion batteries [6]. Functional electrode materials can be synthesized in less than 20 minutes. In this work, a very fast microwave synthesis method was developed to produce C-TiP2O7 (Carbon and TiP2O7 Composite material). The precursor consists of (NH4)2HPO4 and anatase TiO2 in a molar ratio of 2:1, with 10wt%, 15wt% and 20wt%(the weight percent is relative to the precursor mixture) graphite added. After being ball milled together for 1 hour, the mixture was heated in a microwave oven (CEM Discover Proteomics System) for 10 minutes at 150W. The SEM figure shows the surface of Graphite-TiP2O7 composite, and the particle size of Graphite-TiP2O7 composite is around 40nm (Figure 1a). In XRD test (Figure 1b), the pattern of product matches with the reference pattern (JCPDS #38-1468) at major peaks (511), (600), (630), (721), (660), (933). The products we get from this method are tested in cyclic voltammetry tests, which shows promising electrochemical performance (Figure 2a); after ten cycles, the specific capacity of 10% Graphite-TiP2O7 composite maintains 107.4 mAh/g. (Figure 2b). Figure 1 a) SEM of Graphite-TiP2O7 composite. B) XRD patterns of Graphite-TiP2O7 composite and reference peaks. Figure 2 a) Second cycles of cyclic voltammetry curves of 10% Graphite-TiP2O7 composite, 15% Graphite-TiP2O7 composite and 20% Graphite-TiP2O7 composite in 1 M Li2SO4 at scan rate 0.5 mV/s in range of −0.5 V and −1.6 V versus MSE. b) Discharge cycling performance of Graphite-TiP2O7 composite. The total synthesis time is only 10 minutes for heating and 30 minutes for cooling, which is much less than for traditional solid state synthetic methods. Reference: Kim H, Hong J, Park K Y, et al. Aqueous Rechargeable Li and Na Ion Batteries[J]. Chemical Reviews, 2014, 114(23):11788.Aravindan V, Reddy M V, Madhavi S, et al. Hybrid supercapacitor with nano-TiP2O7, as intercalation electrode[J]. Journal of Power Sources, 2011, 196(20):8850-8854.Wang H, Huang K, Zeng Y, et al. Electrochemical properties of TiP2O7, and LiTi2(PO4)3, as anode material for lithium ion battery with aqueous solution electrolyte[J]. Electrochemical Acta, 2007, 52(9):3280-3285.Rai A K, Gim J, Song J, et al. Electrochemical and safety characteristics of TiP2O7 –graphene nanocomposite anode for rechargeable lithium-ion batteries[J]. Electrochemical Acta, 2012, 75(4):247-253.Wu W, Shanbhag S, Wise A, et al. High Performance TiP2O7 Based Intercalation Negative Electrode for Aqueous Lithium-Ion Batteries via a Facile Synthetic Route[J]. Journal of the Electrochemical Society, 2015, 162(9): A1921-A1926.Wu W, Mohamed A, Whitacre J F. Microwave Synthesized NaTi2(PO4)3 as an Aqueous Sodium-Ion Negative Electrode[J]. Journal of the Electrochemical Society, 2013, 160(3): A497-A504. Figure 1

Lithium-ion batteries have attracted great deal of attention recently. Silicon is one of the most promising anode materials for high-performance lithium-ion batteries, due to its highest theoretical specific capacity. However, the short lifetime confined by mechanical failure in the silicon anode is now considered to be the biggest challenge in desired applications. High stress induced by the huge volume change due to lithium insertion/extraction is the main reason underlying this problem. Some theoretical models have been developed to address this issue. In order to properly implement these models, we develop a finite element based numerical method using a commercial software package, ABAQUS, as a platform at the continuum level to study fully coupled large deformation and mass diffusion problem. Using this method, large deformation, elasticity–plasticity of the electrodes, various spatial and temporal conditions, arbitrary geometry and dimension could be fulfilled. The interaction between anode and other components of the lithium ion batteries can also be studied as an integrated system. Several specific examples are presented to demonstrate the capability of this numerical platform.

Two-dimensional distribution of potential and current density in planar electrodes of pouch-type lithium-ion batteries are investigated numerically and analytically. A concentration-independent polarization expression, obtained experimentally, is used to mimic the electrochemical performance of the battery. By numerically solving the charge balance equation on each electrode in conjugation with the polarization expression, the battery behavior during constant-current discharge processes is simulated. The numerical analysis shows that reaction current density between the electrodes remains approximately uniform during most of the discharge process, i.e., when depth-of-discharge varies from 5% to 85%. This observation suggested simplifying the electrochemical performance of the battery such that the charge balance equation on each electrode can be solved analytically to obtain closed-form solutions for potential and current density distributions. The analytical model shows fair agreement with experimental and numerical data at modest computational cost. The model is applicable for both charge and discharge processes, and its application is demonstrated for 20 Ah and 75 Ah prismatic lithium-ion batteries. The analytical model is used to describe electrical conduction in the electrodes, and to investigate the effects of tab design on voltage drop. It is demonstrated that constriction/spreading resistance in current collectors of the considered battery is fairly small; about 10% of the total cell resistance but it is larger than the contribution of bulk resistance which is about 3%. The model confirms that constriction/spreading increase with: decrease in the aspect ratio of the current collector, decrease in the tab width, and increase in the tab eccentricity.

Developing thick electrodes is a promising strategy to increase the energy density of lithium-ion batteries (LIBs), but severe polarization and ion transport limitations hinder their electrochemical performance [1–3]. Laser structuring has recently emerged as an attractive method to create ion-conducting pathways within the electrode, thereby alleviating transport restrictions and enhancing performance [4–6]. In this study, we systematically investigate the influence of laser structuring on the electrochemical behavior of thick electrodes by combining experiments with a physics-based electrochemical model. Pouch-type mono-cells (50 × 50 mm²) composed of NMC622 cathodes and graphite anodes were fabricated with unstructured and laser-structured electrodes at pitches of 100, 200, and 300 μm. The model was validated against discharge experiments, achieving voltage RMSE values of 61–79 mV across all cases, confirming its predictive reliability. [5,6].The results show that for thin electrodes (~50 μm), laser structuring provides negligible improvement, whereas for electrodes thicker than 100 μm, the benefits become significant. At 100 μm thickness, the liquid-phase ohmic overpotential was reduced by ~62 mV at 1C, and the total overpotential decreased by ~220 mV at 3C compared to unstructured electrodes [4,7]. During 1C charging, structured electrodes achieved nearly twice the usable capacity while maintaining the anode overpotential above 0 V, thereby fully suppressing lithium plating [7]. For thicker electrodes (e.g., 300 μm), unstructured cells suffered from concentration depletion and failed even at 0.1C, whereas structured electrodes alleviated polarization and sustained stable operation. Furthermore, when electrolytes with higher ionic conductivity and diffusivity were employed, overall transport limitations in thick electrodes were substantially alleviated, and the beneficial effects of laser structuring were reinforced under demanding conditions [8,9].These findings demonstrate that laser structuring effectively mitigates transport limitations in thick electrodes, improving charging efficiency, reducing polarization, and suppressing lithium plating. Importantly, the results clarify the thickness and porosity ranges in which structuring is most effective and highlight its synergy with advanced electrolytes. Overall, this work provides design guidelines for next-generation LIBs that balance energy density and rate capability through application-specific electrode structuring strategies References [1] M. Singh, J. Kaiser, H. Hahn, Thick Electrodes for High Energy Lithium Ion Batteries, J. Electrochem. Soc., 162 (2015) A1196–A1201.[2] H. Gao, Q. Wu, Y.X. Hu, J.P. Zheng, K. Amine, Z.H. Chen, Revealing the Rate-Limiting Li-Ion Diffusion Pathway in Ultrathick Electrodes for Li-Ion Batteries, J. Phys. Chem. Lett., 9 (2018) 5100–5104.[3] H.H. Zheng, J. Li, X.Y. Song, G. Liu, V.S. Battaglia, A comprehensive understanding of electrode thickness effects on the electrochemical performances of Li-ion battery cathodes, Electrochim. Acta, 71 (2012) 258–265.[4] J. Kriegler, L. Hille, S. Stock, et al., Enhanced performance and lifetime of lithium-ion batteries by laser structuring of graphite anodes, Appl. Energy, 303 (2021) 117611.[5] J. Park, S. Hyeon, S. Jeong, H.J. Kim, Performance enhancement of Li-ion battery by laser structuring of thick electrode with low porosity, J. Ind. Eng. Chem., 70 (2019) 178–185.[6] V. Goel, K.H. Chen, N.P. Dasgupta, K. Thornton, Optimization of laser-patterned electrode architectures for fast charging of Li-ion batteries using simulations parameterized by machine learning, Energy Storage Mater., 57 (2023) 44–58.[7] J.B. Habedank, J. Kriegler, M.F. Zaeh, Enhanced Fast Charging and Reduced Lithium-Plating by Laser-Structured Anodes for Lithium-Ion Batteries, J. Electrochem. Soc., 166 (2019) A3940–A3949.[8] K.M. Diederichsen, E.J. McShane, B.D. McCloskey, Promising Routes to a High Li+ Transference Number Electrolyte for Lithium Ion Batteries, ACS Energy Lett., 2 (2017) 2563–2575.[9] P. Zhou, X.K. Zhang, Y. Xiang, K. Liu, Strategies to enhance Li+ transference number in liquid electrolyte for better lithium batteries, Nano Res., 16 (2023) 8055–8071.

Heat-induced formation of porous and free-standing MoS2/GS hybrid electrodes for binder-free and ultralong-life lithium ion batteries

Electrospun SiOC ceramic fiber mats as freestanding electrodes for electrochemical energy storage applications