Lithium-ion Research Articles

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.

Constructing stable solid electrolyte interphases to enhance the calendar life of anode-free lithium metal batteries

Advancement of anode-free lithium metal batteries (AFLMBs) has been appreciated due to their exceptional volumetric energy density and manufacturing simplicity. However, AFLMBs suffer from poor cycle performance due to the absence of excess lithium and current research lacks an understanding of lithium corrosion and calendar aging in AFLMBs. Here, we investigate the practical effects of chemical and galvanic corrosion on battery performance (calendar life) through a modified full-cell cycling experiment. The impact of galvanic corrosion is negligible, whereas chemical corrosion during a rest period reduces the capacity retention (CR) from 47% to 32% over 100 cycles. Consequently, a corrosion control strategy is implemented, substituting 1,2-dimethoxyethane with 1,2-dimethoxypropane (DMP), which has weaker lithium ion solvation properties due to its inductive effect. This approach results in the formation of a Li2O-rich solid-electrolyte interphase (SEI) layer, which effectively prevents direct contact of lithium with the electrolyte and the formation of additional SEI layers. Consequently, the decrease in CR due to chemical corrosion is considerably mitigated in DMP-based electrolyte, with only a slight decrease from 51% to 49%. This study provides insights into lithium corrosion in practical AFLMBs and offers guidelines for designing less-corrosive electrolytes to improve AFLMB performance for diverse industrial applications as energy-storage devices.

Microcrystalline-Fe2P4O12 as eco-friendly and efficient anode for high-performance dual-ion battery

Dual-ion batteries (DIBs) have garnered significant interest because of their cost-effectiveness and high level of safety. However, the anode typically utilized tends to show low cyclic stability in complete batteries when the only sources of lithium are primarily consumed in the electrolyte following the development of a solid electrolyte interphase (SEI) during the initial electrochemical process. Here, a simple approach is used to produce microcrystalline carbon-coated Fe2P4O12 at a mild temperature. This material has the ability to store lithium ions, resulting in a specific capacity of 215 mAh/g at a potential range of 1 to 2.5 V vs Li+/Li0. Furthermore, it demonstrates a remarkable coulombic efficiency of 99 % in the initial cycles, even in the absence of a solid electrolyte interphase (SEI) formation. On the other hand, the issue of the high voltage plateau of the graphite cathode is addressed by selecting a total of 4.2 V as the optimal voltage range in DIBs. Simultaneously, the composite Fe2P4O12 also demonstrates exceptional ion diffusion kinetics and reduced interfacial impedance due to its microcrystalline structure. The utilization of the proposed Fe2P4O12 anode addresses a crucial deficiency in the complete range of deep in-situ bioremediation techniques, hence expediting the industrialization process.

Enhancing the performance of ionic conductivity for solid-state electrolytes: an effective strategy of injecting lithium ions within anionic metal-organic frameworks.

Metal-organic frameworks (MOFs) are considered as potential solid-state electrolyte (SSE) materials due to their structural diversity and porosity. Adding lithium ions into the anionic frameworks of MOFs and then realizing single-ion transport is an efficient way to enhance the performance of ionic conductivity of SSE materials. Herein, an ionotropic MOF (Li+[Cu-BTC]-) with lithium ions in the pores of the lattice was synthesized through an ion exchange strategy, which exhibits outstanding lithium ionic conducting properties over a wide temperature range (ionic conductivity: 0.11-2.96 × 10-3 S cm-1 in the temperature range of -40 to 100 °C). The strategy of injecting Li+ within anionic metal-organic frameworks provides a new opportunity for exploring advanced SSEs.

Advances in the Application of Graphene in Lithium-ion Batteries

The search for effective energy storage options has escalated due to the rising global energy demands and environmental concerns. Lithium-ion batteries (LIBs) emerge as a key technology. However, the performance of traditional LIBs still needs to be improved. Therefore, choosing new nanomaterials for the modification of LIBs has become an effective solution. Graphene, as a nanomaterial, is an excellent candidate material for modification. This paper delves into the application of graphene in enhancing the performance of LIBs. Graphene, with its superior electrical conductivity and substantial specific surface area, offers the potential to enhance the performance of both anode and cathode materials in LIBs. This can lead to significant improvements in the overall cycle life, energy density, and power density of these batteries. This work emphasizes the application of graphene in cathode and anode materials. In cathode materials, the layered structure of graphene enables lithium-ion with high theoretical capacity. Meanwhile, graphene helps improve the electron and lithium ion mobility of anode materials. Despite the promising developments, challenges such as lithium loading capacity and coulombic efficiency still remain. The continued exploration of graphene applications is expected to drive LIBs to unprecedented performance metrics. This is in line with the global quest for sustainable and efficient energy storage technologies.

Fulgide Derivatives as Photo-Switchable Coatings for Cathodes of Lithium Ion Batteries - A DFT Study.

Photo-switchable coatings for lithium ion batteries (LIB) can offer the possibility to control the diffusion processes from the electrode materials to the electrolyte and thus, for example, reducing the energy loss in the fully charged state. Fulgide derivatives, as known photo-switches, are investigated concerning their use as coating for vanadium pentoxide, a potential cathode material for LIB. With the help of Density Functional Theory calculations, two fulgide derivatives are characterized with respect to their photophysics, their aggregation behaviour on the cathode material and the ability to form self-assembled monolayers (SAM). Furthermore, the two states of the photo-switchable coating are tested with respect to lithium diffusion from the cathode material, passing the SAM and entering the electrolyte. We found a difference for the energy barriers depending on the state of the photo-switch, preferring its closed form. This behaviour can be used to prevent the loss of charge in batteries of portable devices.

Construction of Ordered and Fast Lithium Ion Channels in Gel Electrolytes for Li-SPAN Batteries.

As one of the most promising battery systems, the lithium sulfur battery is expected to be widely used in fields of high energy density demands. Owing to the unique solid-solid conversion mechanism, there is no shuttle effect for the Li-SPAN (sulfurized polyacrylonitrile) battery. However, the compatibility between Li anode and carbonate electrolyte has not been resolved, which prevents the SPAN from practical applications. Herein, an organic-inorganic gel carbonate electrolyte is proposed to stabilize interphases and structures of both the anode and cathode, where polyimide (PI) is used for electrolyte gelation, which can assist in the uniform distribution of inorganic components at the electrolyte interface. Furthermore, ZnS nanodots loaded on two-dimensional MoS2 flakes provide abundant Li-ion diffusion paths, improve the transfer kinetic of Li ions, and induce uniform nucleation and deposition of Li. This gel electrolyte ensures Li symmetric cells a long-term cycle life of more than 900 h under the condition of deep lithium plating/stripping at 5 mAh cm-1. Li∥Cu cells exhibit a prolonged lifespan of 800 h with a CE of 98.3%. Furthermore, the Li-SPAN battery shows stability of more than 850 cycles, with the capacity retention of 85.1%. This work provides an approach for high-energy Li-SPAN batteries with carbonate-based electrolytes.

First-principles study on the lithiation process of amorphous SiO anode for Li-ion batteries with Bayesian optimization.

Amorphous silicon monoxide (a-SiO), which contains Si atoms with various valence states, has attracted much attention as a high-performance anode material for lithium (Li) ion batteries (LIBs). Although current experiments have provided some information during charge/discharge cycles, further investigation of structural changes at the atomic scale is needed. To investigate the lithiation process of a-SiO using first-principles simulations and machine learning techniques, we developed a computational code employing Bayesian optimization to efficiently identify stable sites for Li insertion in the large search-space of amorphous models to reproduce the actual lithiation process and compared this approach to the conventional random scheme by applying it to an a-SiO model previously generated with neural network potentials. The lithiation process based on Bayesian optimization resulted in lower formation energies compared to the conventional random scheme, indicating a more stable structure. During lithiation, Li atoms tended to enter the silicon (Si) phase after the SiO2 phase, in agreement with experimental results. We analyzed the structural changes and observed significant differences in the structural evolution between the conventional and new schemes. Our study highlights the significant influence of the lithiation process on the structural transformation of a-SiO materials, which in turn affects the reversible capacity of the material. These findings will provide a framework for improving the performance and lifetime of a-SiO materials.

Na ions doped Fe2VO4 cathode for high performance aqueous zinc‐ion batteries

Aqueous zinc ion batteries are thought to be a new generation of secondary batteries that will replace lithium ion batteries due to their great safety and inexpensive cost. In the cathode materials of aqueous zinc ion batteries with long life and high capacity, abundant active sites and crystal structure stability play an important role. In the present work, the strategy of Na+ intercalation of Fe2VO4 (FVO) is proposed, aiming at the insertion of Na+, which not only enriches the active sites, but also sodium and iron ions act as guest species with the negatively charged VOx lattice to provide strong electrostatic attraction to stabilize the lamellar structure. In terms of electrochemical performance, the discharge specific capacity is 370 mAh g‐1 at a current density of 0.1 A g‐1, and when the current density is arising 5 A g‐1, the specific capacity also reaches 200 mAh g‐1 after cycling 2000 with a capacity retention of 99%, which is better than the electrochemical performance of Fe2VO4 (FVO) alone at 50 mAh g‐1. The superior electrochemical performance proves that FVO‐Na is an ideal cathode material for zinc ion batteries.

Anion‐repulsive polyoxometalate@MOF‐modified separators for dendrite‐free and high‐rate lithium batteries

AbstractCommercial polyolefin separators in lithium batteries encounter issues of uncontrolled lithium‐dendrite growth and safety incidents due to their low Li+ transference numbers () and low melting points. To address these challenges, this study proposes an innovative approach by upgrading conventional separators through the incorporation of metal‐organic framework (MOF)‐confined polyoxometalate (POM). The presence of POM restricts anion diffusion through electrostatic repulsion while facilitating Li+ transport within MOF nanochannels through their affinity for lithium ions. Moreover, MOF confinement effectively mitigates the acidification of electrolytes induced by POM. As a proof‐of‐concept, the polypropylene separators decorated with phosphotungstic acid@UIO66 (denoted as PW12@UIO66‐PP) exhibit remarkable lithium‐ion conductivity of 0.78 mS cm−1 with a high of 0.75 at room temperature. The modified separators also display excellent thermal stability, preventing significant shrinkage even at 150°C. Furthermore, Li symmetric cells employing PW12@UIO66‐PP separators exhibit stable cycling for 1000 h, benefiting from rapid Li‐ion transport and uniform deposition. Additionally, the modified separator shows promising adaptability to industrial manufacturing of lithium‐ion batteries, as evidenced by the assembly of a 4 Ah NCM811/graphite pouch cell that retains 97% capacity after 350 cycles at C/3, thus highlighting its potential for practical applications.

LiTFSI salt concentration effect for well‐balanced ion transport and physical properties in nanocellulose‐reinforced PEO#600 solid electrolytes

AbstractPoly(ethylene oxide) (PEO) with an oxygen group serves as a reactive site for the pathway of lithium‐ion transport. Reducing the PEO crystal domain in solid electrolytes is an extremely efficient approach for enhancing the mobility of ions. The present study applied various EO/Li molar ratios to modify the physical and electrochemical properties of PEO nanocomposite reinforced by nanocellulose. An elevated lithium salt concentration causes a gradual decline in crystallinity and mechanical strength. The electrochemical performance of the 13 EO/Li molar ratio voltammogram and charge–discharge shows efficient Li‐ion transport with 5.6 × 10−4 S/cm conductivity at room temperature and 131 mA h g−1 initial discharge capacity. The shifting glass transition and melting point at lower temperatures (−40.5 to −44.5°C and 45.3–43.8°C) suggest greater ion mobility throughout the large non‐crystalline structure. Lithium ions are limited by membrane weakening and re‐crystallization caused by high lithium salt (EM_11) concentrations. EM_13 has the highest specific capacity, operating voltage, and lithium transfer number depends on balanced electrochemical performance and physical features. XPS surface chemistry analysis explains LiF, Li2CO3, and Li2O solid electrolyte interfaces (SEI) in EM samples. A lower Li2O (11.62 at.%) than LiF (38.4 at.%) after cycling enhances Li‐ion diffusion and cell reversibility.

Imaging in-operando LiCoO2 nanocrystallites with Bragg coherent X-ray diffraction

Although the LiCoO2 (LCO) cathode material has been widely used in commercial lithium ion batteries (LIB) and shows high stability, LIB’s improvements have several challenges that still need to be overcome. In this paper, we have studied the in-operando structural properties of LCO within battery cells using Bragg Coherent X-ray Diffraction Imaging to identify ways to optimise the LCO batteries’ cycling. We have successfully reconstructed the X-ray scattering phase variation (a fingerprint of atomic displacement) within a ≈ (1.6 × 1.4 × 1.3) μm3 LCO nanocrystal across a charge/discharge cycle. Reconstructions indicate strained domains forming, expanding, and fragmenting near the surface of the nanocrystal during charging, with a determined maximum relative lattice displacements of 0.467 Å. While discharging, all domains replicate in reverse the effects observed from the charging states, but with a lower maximum relative lattice displacements of 0.226 Å. These findings show the inefficiency-increasing domain dynamics within LCO lattices during cycling.

Improving the Cycle Stability of LiNiO2 through Al3+ Doping and LiAlO2 Coating.

In this study, we addressed the poor cycling and rate performance of LiNiO2, a material with ultrahigh nickel content considered a strong contender for high-energy-density lithium-ion battery cathodes. We introduced nano-Al2O3 during the lithiation process to achieve dual modified material through bulk phase element doping and in situ LiAlO2 coating. Comparison revealed notable improvements in the modified materials. In particular, LiNi0.99Al0.01O2 maintained a capacity retention rate of 73.1% after 300 cycles in a long-cycle test at 0.5C current density, outperforming the undoped material. In rate performance tests, the doped samples consistently exhibited higher discharge-specific capacities than that of the undoped counterpart. Notably, at a high current density of 5C, LiNi0.99Al0.01O2 exhibited a discharge-specific capacity of 101.75 mAh g-1. The results indicate that an appropriate amount of Al doping can effectively stabilize the layered structure of the cathode material and delay the irreversible phase transition from H2 to H3. Further, Al doping facilitates the formation of a LiAlO2 coating on the surface of the particles. This coating acts as a fast-ion conductor, enhancing the transport of lithium ions and reducing the erosion of the active material by the electrolyte.

On the Electrochemical Properties of Poly(Vinylidene Fluoride)/Polythiophene Blends Doped with Lithium‐Based Salt

AbstractIn this study, polymer blends of polythiophene (PTH) and poly(vinylidene fluoride) (PVDF) are investigated by focusing on their structural and electrochemical characteristics. These blends displayed immiscibility confirmed through field emission scanning electron microscopy (FE‐SEM) and interaction assessments. PTH's role as a plasticizer is evident, diminishing crystallinity. A rise in PTH level led to a lower glass transition temperature and a higher melting point, suggesting reduced intermolecular forces and increased polymer chain flexibility. Conversely, a dispersed phase presence elevated the melting point, restricting chain movement and crystallization. The thermal properties of blends are enhanced by increased PTH content. Applying the Vogel–Tammann–Fulcher model to ionic conductivity measurements, it observed a direct relationship between temperature and free volume, impacting conductivity and ion transport numbers. Certain materials exhibit increased activation energies, indicating substantial thermodynamic barriers to local motion. Higher PTH content within the PVDF matrix notably increased the lithium ion transfer number from 0.22 to 0.71, a change tied to the C–S–C structure of polythiophene. However, elevated PTH levels also led to diminished negative charge transfer and ionic conductivity in the PTH‐PVDF blend compared to pure PVDF, likely due to an ionic conduction hindrance.

A Polysaccharide Binder with Carbon Quantum Dots for Improved Flexibility of Si Anodes in Lithium–Ion Batteries

A Polysaccharide Binder with Carbon Quantum Dots for Improved Flexibility of Si Anodes in Lithium–Ion Batteries

Metal‐Organic Framework Hosted Silicon for Long‐Cycling, Low‐Cost, and Flexible Batteries

AbstractDeveloping biodegradable electrodes is a significant step toward environmental sustainability and cost reduction in battery technology. This paper presents a new approach that utilizes metal‐organic framework (MOF)‐encapsulated silicon nanoparticles (SiNPs) as the active anode material within a cellulose‐based electrode. The electrode is free‐standing, flexible, biodegradable, and significantly reduces the strain experienced by SiNPs during volume expansion, resulting in improved capacity and cycle life stability of SiNPs. The high porosity of the electrode creates efficient lithium (Li+) ion transport channels and enhances electrolyte absorption, thus promoting effective contact between the electrolyte and active material. The outcome is rapid electrode kinetics and a highly reversible discharge capacity of 1744.6 mAh g−1 at 0.5 A g−1 versus Li/Li+ over 1000 cycles. Further, full cell tests are conducted that demonstrate a stable cycle performance exceeding 3400 cycles, with an initial discharge capacity retention of 80.5% at 0.5 A g−1. By employing cellulose and avoiding toxic organic solvents and binders, the proposed approach is promising for a substantial reduction of the production costs of Li‐ion batteries. The scalability of the proposed method further enhances its practical viability, offering intriguing economic implications for the future of battery technology.

Li-ion solvation structure at electrified solid-liquid interface: Understanding solvation structure dynamics and its role in electrochemical energy storage through binary ethylene carbonate and dimethyl carbonate solvent.

Binary solvent electrolytes can provide interpretations for designing advanced electrolytes of next generation batteries. This study investigates the adsorption mechanisms of solvated lithium ions in binary solvents near charged electrodes. Molecular dynamic simulations are performed for lithium hexafluorophosphate (LiPF6) in ethylene carbonate and dimethyl carbonate (EC:DMC) solvent sandwiched between two electrodes. Results show that lithium ions form a tetrahedral solvation structure with two EC and two DMC molecules. The solvated lithium ion shows anti-electrostatic interaction with electrodes. This can be attributed to the electrostatic attraction of the polar end of the DMC molecule, which keeps the cation anchored to the positive electrode. Meanwhile, the solvation structure adopts a fix orientation at the negative electrode, which leads to unchanged electrostatic interaction at high charge density. Finally, EC molecules are swapped by DMC molecules near the negative electrode at high charge density. This leads to a decrease in local relative permittivity and, therefore, a decrease in differential capacitance. The differential capacitance of the positive electrode continuously decreases with increasing charge density. This is caused by the partial anchoring of solvent molecules holding the cations, which cancels the adsorption of anions near the positive electrode. This study provides insights into designing better electrolytes for efficient battery performance.

Dendrite-Free Lithium Batteries Enabled by an Artificial High-Dielectric Biopolymer Interface Layer.

Lithium (Li) metal batteries face challenges, such as dendrite growth and electrolyte interface instability. Artificial interface layers alleviate these issues. Here, cellulose nanocrystal (CNC) nanomembranes, with excellent mechanical properties and high specific surface areas, combine with polyvinylidene-hexafluoropropylene (PVDF-HFP) porous membranes to form an artificial solid electrolyte interphase (SEI) layer. The porous structure of PVDF-HFP equalizes the electric field near metallic lithium surfaces. The high mechanical modulus of CNC (6.2 GPa) effectively inhibits dendrite growth, ensures the uniform flow of lithium ions to the lithium metal electrode, and inhibits the growth of lithium dendrites during cycling. The synergy of high polarity β-phase poly(vinylidene fluoride) (PVDF) and CNC provides over 1000 h of stability for Li//Li batteries. Moreover, Li//LiFePO4 (LFP) full cells with this artificial protective layer perform well at 5 C, showcasing the potential of this film in lithium metal batteries.

Developing a lithiophilic, solvent-phobic dual-functionality film for dendrite-free Li metal anodes

Li metal anodes (LMAs) are promising candidate for advanced batteries that encounters significant challenges, including electrolyte corrosion and uneven deposition. These issues not only reduce battery lifespan but also pose safety risks due to the uncontrolled growth of dendrites. Herein, we introduce a lithiophilic, solvent-phobic dual-functionality film (LSDF) designed to tackle these problems. The LSDF features an inner layer of polyethylene oxide directly applied to the LMAs and an outer layer of poly(vinylidene fluoride-co-hexafluoropropylene) facing the electrolyte. Both layers contain N-ethyl-N-methylpyrrolidinium bis(trifluoromethanesulfonyl)imide, which enhances the rapid transport of Li ions. The inner layer promotes high interfacial stability, while the outer layer offers solvent resistance and Li affinity, thereby inhibiting dendrite growth and reducing side reactions. Consequently, Li||Li symmetric cells achieve stable cycling for 1650 h with a minimal overpotential of 15 mV at 3 mAh cm−2 and 3 mA cm−2. Additionally, full cells paired with LiFePO4 cathodes maintain 85 % capacity retention over 500 cycles at 1 C and demonstrate excellent rate capability. This study presents a new approach to modulate the interface of LMAs, significantly enhancing its stability for high-energy–density battery applications.

Revealing Enhanced Optical Modulation and Coloration Efficiency in Nanogranular WO3 Thin Films Through Precursor Concentration Modifications

Electrochromic (EC) materials allow for dynamic tuning of optical properties via an applied electric field, presenting great potential in energy-efficient technologies, such as smart windows for effective light and temperature regulation. The precise control of precursor concentration has proven to be a powerful approach in tailoring the physicochemical properties of semiconducting metal oxides. In this study, we employed a one-step electrodeposition technique to fabricate tungsten oxide (WO3) thin films, systematically exploring how varying precursor concentrations influence the material’s characteristics. X-ray diffraction analysis revealed significant changes in diffraction patterns, reflecting subtle structural modifications due to concentration variations. Additionally, scanning electron microscopy revealed significant changes in the microstructure, showing a progression from small nanogranules to larger agglomerations within the film matrix. The W-25 mM thin film delivered exceptional EC performance, efficiently accommodating lithium ions while showcasing superior EC properties. The optimized electrode, denoted as W-25 mM, showcased exceptional EC metrics, featuring the highest optical modulation at 82.66%, outstanding reversibility at 99%, and a notably high coloring efficiency of 83.01 cm2/C. These findings emphasize the importance of precursor concentration optimization in enhancing the EC properties of WO3 thin films, contributing to the advancement of high-performance, energy-efficient materials.