Intercalation Reaction Research Articles

Unraveling the Factors of Host Materials Affecting the Kinetics of Electrochemical Anion Intercalation Reaction

Unraveling the Factors of Host Materials Affecting the Kinetics of Electrochemical Anion Intercalation Reaction

Microenvironment Control over Electrocatalytic Activity of g-C3N4/2H-MoS2 Superlattice-like Heterostructures for Hydrogen Evolution.

Microenvironments in heterogeneous catalysis have been recognized as equally important as the types and amounts of active sites for regulating catalytic activity. Two-dimensional (2D) nanospaces between van der Waals (vdW) gaps of layered materials provide an ideal microenvironment to create novel functionalities. Here, we explore a facile method for fabricating g-C3N4/2H-MoS2 superlattice-like heterostructures based on thermochemical intercalation and polymerization reactions of formamide within enlarged vdW gaps of 2H-MoS2 nanosheets without any transfer process. DFT calculations demonstrate that the interlayer electron-electron correlations due to the intercalation effect of g-C3N4, rather than high-κ dielectric environments, lead to the improvement of intrinsic conductivity of 2H-MoS2 nanosheets. As the proof of concept in applications for the electrocatalysis field, the heterostructure for hydrogen electrochemical reaction (HER) exhibits high stability and catalytic activity in both acid and alkaline media, such as a quite low onset overpotential of 98 mV, a high exchange current density of 77.6 μA cm-2, and a small Tafel slope (52.9 mV dec-1) in an acid medium. The enhanced HER activity is attributed to the improved conductivity and nanoconfinement effect of 2D nanospaces that decrease the reaction activation energy and activate the inert basal planes.

Exploring the potential of MXene nanohybrids as high-performance anode materials for lithium-ion batteries

Lithium-ion batteries (LIBs) are an integral part of modern life, powering diverse applications from transportable devices to electric vehicles. Efficacy of LIBs depends on the performance of their components with anode material playing the pivotal role. Traditional graphite anodes have limitations in capacity and rate capability. This review comprehensively discusses utilization of MXene-based composites as anode materials in LIBs. MXene composites exhibit versatile lithium storage mechanisms, involving intercalation and/or conversion reactions. Pure MXenes offer advantages of high capacity and cycling stability having challenges due to limited conductivity and mechanical fragility, restricting their practical utility, thereby affecting their performance in solid-state polymer electrolytes (SPEs). MXene composites overcome unsystematic dispersal and accumulation issues of pure MXene. MXenes in composite form could increase LIBs performance by overcoming limitations of pure MXenes, enabling breakthroughs in energy storage. The review covers different MXene composites viz., MXene/graphene, MXene/silicon, MXene/tin, MXene/carbon, MXene/metal oxide, and MXene/conducting polymer providing a holistic overview. Their performance, cycling stability, and rate capability are discussed to cover challenges and future prospects.

Analysis of Battery-like and Pseudocapacitive Ion Intercalation Kinetics via Distribution of Relaxation Times

Abstract Improving the kinetics of electrochemical ion intercalation processes is of interest for realizing high-power electrochemical energy storage. This includes classical battery-like intercalation and pseudocapacitive intercalation processes with a capacitor-like electrochemical signature. Electrochemical methods are needed to probe the kinetics of such complex multistep processes in detail. Here, we present the use of the distribution of relaxation times (DRT) analysis of electrochemical impedance data to identify the kinetic limits of intercalation reactions. We study the lithium intercalation reaction in TiS2 from organic and aqueous electrolytes as a model system. The material can exhibit both battery-like and pseudocapacitive intercalation regimes depending on the potential range, variable diffusion lengths by adjusting its particle size, and a tunable degree of solvent cointercalation by choosing the electrolyte solvent. Using DRT, we can distinguish between the kinetic limitations imposed by solid-state ion diffusion, interfacial ion adsorption and transport, and ion desolvation processes. Thus, DRT analysis can complement existing methods, such as voltammetry or 3D-Bode analysis, to better understand the kinetics of intercalation reactions.

Enhancing Li4Ti5O12 Anodes for High‐Performance Batteries: Ti3+ Induction via Plasma‐Enhanced Chemical Vapor Deposition and Dual Carbon/LLZO Coatings

AbstractLithium titanium oxide (LTO) is a promising anode material due to its ability to store lithium through intercalation reactions. However, its electrochemical performance is limited by poor electron conductivity and side reactions with the electrolyte. In this study, plasma‐enhanced chemical vapor deposition (PECVD) is employed to introduce oxygen vacancies and self‐doped Ti3+ into LTO to improve the internal conductivity. Subsequent carbon coating and aluminum‐doped lithium lanthanum zirconate garnet (LLZO) layers resulted in a multi‐layered composite denoted as LTO−L‐x. Morphological analyses using SEM and TEM demonstrated the successful growth of Al‐doped LLZO on carbon‐coated LTO. Aluminum ions in LLZO cubic structure are crucial for stabilizing the high ionic conductive phase during cooling, as confirmed by X‐ray diffraction. The dual coating layers have a significant impact on the rate capability, reducing polarization gaps and enabling higher capacities at various current rates. Long‐term cycling tests reveal the robustness of the composite, with LTO−L‐1.0 retaining 90.8 % capacity after 4000 cycles at 1.0 A g−1. This underscores the sustained high electronic and ionic conductivity facilitated by the dual coating layers. The study contributes to the design of advanced anode materials for lithium‐ion batteries, emphasizing the importance of tailored coating strategies to address conductivity and stability challenges.

Triggering Reversible Intercalation-Conversion Combined Chemistry for High-Energy-Density Lithium Battery Cathodes.

Combining intercalation and conversion reactions maximizes the utilization of redox-active elements in electrodes, providing a means for overcoming the current capacity ceiling. However, integrating both mechanisms within a single electrode material presents significant challenges owing to their contrasting structural requirements. Intercalation requires a well-defined host structure for efficient lithium-ion diffusion, whereas conversion reactions entail structural reorganization, which can undermine intercalation capabilities. Based on the previous study that successfully demonstrated reversible intercalation-conversion chemistry in amorphous LiFeSO4F, this study aims to provide an in-depth understanding on how this can be enabled. Experimental and theoretical investigations of a model system based on tavorite-structured LiFeSO4F revealed that amorphization governs the activation and reversibility of the combined reactions. Enhanced reversibility is achieved through the facile migration of transition metals within the amorphous matrix. Unexpectedly, it is found that amorphization also narrowed the voltage gap between the intercalation and conversion reactions. This voltage-gap reduction is explained by the thermodynamic metastability of the amorphous phase. The applicability of the approach to other intercalation hosts is further demonstrated, showing that amorphization enables reversible intercalation and conversion. These findings suggest a new strategy that leverages the full potential of intercalation and conversion reactions, introducing new avenues for cathode design.

Long-term corrosion protection of reinforcing bars via a self-responsive coating incorporating ZrP functional fillers

The conventional coating of reinforcing bars exhibits inadequate anti-corrosion efficacy stemming from a non-specific, blind protection mechanism, poses a threat to the durability of concrete. We devised a novel self-responsive functional filler, L-arginine (LA) intercalated zirconium phosphate (LCZrP), synthesized via an intercalation reaction. This innovative filler was seamlessly integrated into an epoxy (EP) resin matrix, yielding a smart anticorrosive coating that harmoniously combines active and passive corrosion protection strategies. The integration of LCZrP within the coating matrix serves a trifecta of purposes: it extends the corrosion propagation path, effectively disperses nanofiller agglomeration, and enhances interfacial adhesion with the epoxy coating. Critically, the controlled release of corrosion inhibitors from the interlayer further fortifies the coating's resistance to corrosion, imparting a multi-layered protective shield. After enduring a 60-day immersion in a simulated concrete pore solution, the LCZrP/EP coating demonstrated exceptional durability, maintaining a low-frequency impedance modulus value consistently within the range of 4.27×1010 to 5.12×1010 Ω·cm2, marking a remarkable 34-fold enhancement over the performance of the epoxy coating alone. This breakthrough underscores the LCZrP/EP coating's potential as a groundbreaking solution for reinforcing bar protection in concrete, harnessing the complementary strengths of epoxy resin's physical barrier, the impermeability of two-dimensional lamellar structures, and the proactive release of corrosion inhibitors to forge a robust, multi-faceted passivation layer.

VBO3/V2O3@C heterogeneous anode material with high-specific-capacity and high-stability for lithium-ion batteries

The design and synthesis of high-performance anode materials is the key to further improve the performance of lithium-ion batteries. In this study, VBO3/V2O3 heterogeneous material with high crystallinity was prepared in vacuum quartz tubes by a facile high-temperature solid-phase method, and the electron transport capacity of VBO3/V2O3 was further improved by ball-milling with conductive carbon. As a result, the obtained VBO3/V2O3@C heterogeneous anode material delivers an initial discharge specific capacity of 927 mAh·g−1 and good cycling stability. Even at −20 °C, VBO3/V2O3@C still presents a discharge specific capacity of 432 mAh·g−1. In addition, ex-situ XRD and ex-situ XPS measurements reveal the conversion reaction and (de)intercalation reaction mechanism during charge/discharge. This work deepens the understanding of the structure-activity relationship of borate/oxide heterogeneous anode materials.

Discharging of Ramsdellite MnO2 Cathode in a Lithium-Ion Battery.

We report an application of our unbiased Monte Carlo approach to investigate thermodynamic and electrochemical properties of lithiated manganese oxide in the ramsdellite phase (R-MnO2) to uncover the mechanism of lithium intercalation and understand charging/discharging of R-MnO2 as a cathode material in lithium-ion batteries. The lithium intercalation reaction was computationally explored by modeling thermodynamically significant distributions of lithium and reduced manganese in the R-MnO2 framework for a realistic range of lithium molar fractions 0 < x < 1 in Li x MnO2. We employed interatomic potentials and analyzed the thermodynamics of the resultant grand canonical ensemble. We found ordered or semiordered phases at x = 0.5 and 1.0 in Li x MnO2, verified by configurational entropy changes and simulated X-ray diffraction patterns of partially lithiated R-MnO2. The radial distribution functions show the preference of lithium for homogeneous distributions across the one-dimensional 2 × 1 ramsdellite channels accompanied by alternating reduced/oxidized manganese ions. The occupation of the interstitial sites in the channels is correlated with the calculated voltage profile, showing a sharp voltage drop at x = 0.5, which is explained by the energy penalty of shifting lithium ions from stable tetrahedral to unstable octahedral sites. To facilitate this work, our in-house software, Knowledge Led Master Code (KLMC) was extended to support massive parallelism on high-performance computers.

A High-Rate and Ultrastable Re2Te5/MXene Anode for Potassium Storage Enabled by Amorphous/Crystalline Heterointerface Engineering.

The pursuit of anode materials capable of rapid and reversible potassium storage performance is a challenging yet fascinating target. Herein, a heterointerface engineering strategy is proposed to prepare a novel superstructure composed of amorphous/crystalline Re2Te5 anchored on MXene substrate (A/C-Re2Te5/MXene) as an advanced anode for potassium-ion batteries (KIBs). The A/C-Re2Te5/MXene anode exhibits outstanding reversible capacity (350.4 mAh g-1 after 200 cycles at 0.2 A g-1), excellent rate capability (162.5 mAh g-1 at 20 A g-1), remarkable long-term cycling capability (186.1 mAh g-1 at 5 A g-1 over 5000 cycles), and reliable operation in flexible full KIBs, outperforming state-of-the-art metal chalcogenides-based devices. Experimental and theoretical investigations attribute this high performance to the synergistic effect of the A/C-Re2Te5 with a built-in electric field and the elastic MXene, enabling improved pseudocapacitive contribution, accelerated charge transfer behavior, and high K+ ion adsorption/diffusion ability. Meanwhile, a combination of intercalation and conversion reactions mechanism is observed within A/C-Re2Te5/MXene. This work offers a new approach for developing metal tellurides- and MXene-based anodes for achieving stable cyclability and fast-charging KIBs.

When and Where Lithium Plating Occurs, Its Correlation with Microstructure Heterogeneity, and the Mechanisms That Initiate and Self-Regulate Electrochemical Heterogeneity

A microstructure scale electrochemical LIB model was used to investigate lithium plating onset, material non-uniform utilization, and in-plane heterogeneities for an NMC-graphite full cell [1]. Model predicts active material particle surface roughness and size distribution (respectively, non-uniform curvature within and between particles) initiate in-plane heterogeneity, and that particle size heterogeneity at the separator interface controls the lithium plating preferential deposition (“Where”). These in-plane heterogeneities are then exacerbated by through-plane heterogeneities induced at fast charge as electrolyte depletion occurs and concentrates intercalation reaction near the anode-separator interface. Also, overall magnitude and occurrence of lithium plating is controlled by effective, or macroscale, microstructure parameters (“When”).As local states of charge start to diverge between nearby active material regions, overpotential differences induced by OCP difference kick in and contribute to reduce these SOC local heterogeneities. However, for staged materials such as graphite, with OCP profile alternating between plateaus and varying regions, this balancing mechanism is, respectively, inactive and active. This leads to a dynamic, non-monotonic, in-plane heterogeneity time evolution for state of charge and Faraday current density, for which their respective in-plane heterogeneity magnitude alternates. Such behavior has been modeled both for the whole electrode at the microstructure scale and at the particle scale. In-plane heterogeneities are usually considered to be detrimental, as they result in material non-uniform utilization (i.e., under and over stressed regions) and earlier degradations. However, this work provides a more granular approach as it discriminates between a harmful in-plane heterogeneity (non-uniform curvature) that triggers SOC in-plane heterogeneity, and a beneficial in-plane heterogeneity (Faraday current density) that contributes to reduce SOC in-plane heterogeneity.This work comprehensively explains the mechanisms that initiate, exacerbate, and regulate heterogeneity at the microstructure scale, while providing some design suggestions to reduce both in-plane and through-plane heterogeneities, as summarized in the graphical abstract.[1] F. L. E. Usseglio-Viretta, A. M. Colclasure, J. Allen, D. P. Finegan, P. Graf, and K. Smith, Microstructure Scale Lithium-ion Battery Modeling, Part I: on lithium plating prediction and heterogeneity, in preparation. Figure 1

(Invited) Using a Chemo-Mechanical Model to Investigate Electrolyte Infiltration and Surface Reconstruction within Cracked Cathode Material

One of the main goals in modeling lithium-ion batteries is to improve/predict longevity and resilience of new chemistries. To that end, this talk investigates the formation of stress-induced fracture within polycrystalline cathode particles and the impact on capacity loss. The model captures anisotropic Li diffusion within a single polycrystalline particle comprised of hundreds to thousands of randomly oriented grains. Fracture is primarily due to non-ideal grain interactions with slight dependence on high-rate charge demands. Essentially, when neighboring grains are misaligned, they expand a different rates relative to one another leading to high stresses and ultimately the formation of intraparticle cracks. A previous study showed that small particle with large or single grain geometry tend to crack less and retain the most capacity.Cracks within the cathode particle that have access to the surface can potentially fill with electrolyte. When this happens, the cracks can be considered new active surface area where the lithium intercalation reaction can occur. Under sufficient conditions, this could lead to better performance because the grains of the cracked particle start to operate more like a network of single-grain particles. However, the newly open surface area is also subject to side reactions and surface reconstruction resulting in diminished transport properties and potentially trapped lithium. The goal of this talk is to investigate this balance between improved lithium transport pathways caused by lithium infiltration and the reduced diffusion due to surface reconstruction.

A biodegradable multifunctional pectin–montmorillonite fertilizer coating: Controlled-release, water-retention and soil-cementation

Coated fertilizers have been widely used to improve fertility in barren land. However, improving soil structure and water-retention capacity is also essential for arid and semi-arid areas with sandy soils to promote crop growth. Most currently available coated fertilizers rarely meet these requirements, limiting their application scope. Therefore, this study “tailored” pectin–montmorillonite (PM) multifunctional coatings for arid areas, featuring intercalation reactions and nanoscale entanglement between pectin and montmorillonite via hydrogen bonding and electrostatic and van der Waals forces. Notably, PM coatings have demonstrated an effective “relay” model of action. First, the PM-50 coating could act as a “shield” to protect urea pills, increasing the mechanical strength (82.12 %). Second, this coating prolonged the release longevity of urea (<0.5 h to 15 days). Further, the remaining coating performed a water-retention function. Subsequently, the degraded coating improved the soil properties. Thus, this coating facilitated the growth of wheat seedlings in a simulated arid environment. Moreover, the cytotoxicity test, life cycle assessment, and soil biodegradation experiment showed that the PM coating exhibited minimal environmental impact. Overall, the “relay” model of PM coating overcomes the application limitations of traditional coated fertilizers and provides a sustainable strategy for developing coating materials in soil degradation areas.

Development of V2O3 Nanostructures for Alkali Metal Ion Batteries: A Novel Approach through Mild Metal Vapor Reduction and Interface Engineering.

V2O3 has been extensively researched as a battery electrode material due to its ample reserves and high theoretical capacity. However, the synthesis of valence-sensitive V2O3 presents technical challenges as it requires a strict combination of high-temperature treatment and a narrow range of oxygen partial pressures. This study proposes a gentle Li vapor-assisted thermal reduction method to synthesize pure-phase V2O3 at a relatively low temperature of 480 °C without any hazardous gases. It has been discovered that reducing the temperature also improves the specific surface area of the nanoto-mesoscale hierarchical structures and enhances the reactive sites between their secondary grains. These advantages enable the V2O3 micronano particles to store higher levels of Li+, Na+, and K+, increase ionic transport, and tolerate volume expansion. It demonstrates a significant capacity of 767 mA h g-1 in lithium-ion batteries, 393 mA h g-1 in sodium-ion batteries, and 209 mA h g-1 in potassium-ion batteries. It has also been discovered that the crystal structure of V2O3 is easily adjustable by varying the synthesis temperature, which significantly affects the electrochemical storage mechanism. The V2O3 synthesized at 480 °C with low crystallinity exhibits a notable intercalation reaction, facilitating the electrochemical kinetics of reversible insertion/extraction of Li+, Na+, and K+. In contrast, the highly crystalline sample synthesized at 580 °C displays pseudocapacitance behavior instead of an intercalation reaction. The highly crystalline sample synthesized at 680 °C exhibits a thorough pseudocapacitance reaction possessing the capacitive functionality for the electrochemical storage of Na+ or K+ with larger ion radii. This study describes a new synthesis strategy and rational modification of vanadium-based electrodes for alkali metal ion batteries, leading to the development of reasonably priced rechargeable battery systems with applications extending beyond lithium-ion batteries.

Synthesis, intercalation reactions, and electrochemical studies for VO2/PEO/Chitosan

VO2 obtained by hydrothermal synthesis from V2O5 was used as a matrix to obtain hybrid compounds containing different proportions of polyethylene oxide and chitosan. The XRD results demonstrate that monoclinic VO2 was obtained, and hybrid compounds showed variation in the displacement of the lamella peak, indicating an intercalation of polymers into the matrix. The stretching and vibration bands show a variation towards higher wavelength values of the hybrid compounds, which indicates that the intercalation of the polymers occurred into the matrix. The UV–Vis spectra show the absorptions that can be attributed to the transitions of each material. Absorption in the visible region decreases for hybrid compounds in relation to VO2. The hybrid compounds presented lower bandgap values compared to VO2. From cyclic voltammetry, it was possible to observe anodic and cathodic peaks linked to the redox process of the VIV/VIII pair for both VO2 and VO2/polymers, which is derived from the insertion/disinsertion process of lithium ions, where the hybrid compound presented a different voltammetric profile compared to VO2. The total charge curves as a function of the number of cycles demonstrate better cycling stability and a greater total charge of the hybrid compounds compared to VO2. These results demonstrate that hybrid compounds have potential as cathode materials for lithium-ion batteries.

Berberine-doped montmorillonite nanosheet for photoenhanced antibacterial therapy and wound healing

Bacterial infections pose a substantial threat to human health, particularly with the emergence of antibiotic-resistant strains. Therefore, it is essential to develop novel approaches for the efficient treatment of bacterial diseases. This study presents a therapeutic approach involving BBR@MMT nanosheets (NSs), wherein montmorillonite (MMT) was loaded with berberine (BBR) through an ion intercalation reaction to sterilize and promote wound healing. BBR@MMT exhibits nano-enzymatic-like catalytic activity, is easy to synthesize, and requires low reaction conditions. This nanocomplex showed photodynamic properties and superoxide dismutase (SOD) activity. The in vitro experiments indicated that BBR@MMT was able to effectively inhibit the growth of Gram-positive bacteria (S. aureus) and Gram-negative bacteria (E. coli) through the production of ROS when exposed to white light. Meanwhile, BBR@MMT inhibited the secretion of pro-inflammatory factors and scavenged free radicals via its SOD-like activity. In vivo results showed that BBR@MMT NSs were capable of effectively promoting the wound-healing process in infected mice under white light irradiation. Hence, it can be concluded that photodynamic therapy based on BBR@MMT NSs with nano-enzymatic activity has the potential to be used in treating infections and tissue repair associated with drug-resistant microorganisms.

Optimized Phase and Crystallinity of Cr2(NCN)3 Dominating Electrochemical Lithium Storage Performance.

Cr2(NCN)3 is a potentially high-capacity and fast-charge Li-ion anode owing to its abundant and broad tunnels. However, high intrinsic chemical instability severely restricts its capacity output and electrochemical reversibility. Herein we report an effective crystalline engineering method for optimizing its phase and crystallinity. Systematic studies reveal the relevancy between electrochemical performance and crystalline structure; an optimal Cr2(NCN)3 with high phase purity and uniform crystallinity exhibits a high reversible capacity of 590 mAh g-1 and a stable cycling performance of 478 mAh g-1 after 500 cycles. In-operando heating XRD reveals its high thermodynamical stability over 600 °C, and in-operando electrochemical XRD proves its electrochemical Li storage mechanism, consisting of the primary Li-ion intercalation and subsequent conversion reactions. This study introduces a facile and low-cost method for fabricating high-purity Cr2(NCN)3, and it also confirms that the Li storage of Cr2(NCN)3 can be further improved by tuning its phase and crystallinity.

Boosting the intercalation reaction of FeOF-based cathode toward highly reversible lithium storage

FeOF as an intercalation-conversion cathode features a high theoretical capacity toward high energy density lithium-ion batteries (LIBs). However, the inadequate intercalation process and poor reversibility of redox reaction deteriorate its practical capacity and cycling stability. Herein, a S-substitution strategy in FeOF (FeOF-S) is proposed to boost the intercalation reaction and enhance the reaction kinetics, achieving a record-high capacity of 668 mAh g−1 at 0.05 A g−1 and a long cycling stability up to 1500 cycles at 0.5 A g−1. Under this strategy, the Li+ intercalation energy of FeOF-S is remarkably reduced in thermodynamics, promoting the intercalation capacity to 230 mAh g−1 which is 50% higher than that of FeOF. Furthermore, a nearly zero band gap with superior electronic conduction is achieved in FeOF-S, leading to excellent rate capability with much enhanced pseudo-capacitance contribution. This work presents new insights into the regulation of thermodynamics and kinetics toward the boosted electrochemical performance of conversion-type electrodes for high energy density LIBs.

Constructing surface protective film of V-Se-O to promote zinc ion storage by surface oxygen implantation strategy

Interfacial chemical modification is an effective strategy to adjust the strong Coulombic ion-lattice interactions with high valence cations experienced by electrode materials, facilitating the reaction kinetic. In this paper, a simple and fast surface oxygen implantation strategy was designed to adjust the electronic structure of stainless steel (SS) supported vanadium diselenide (VSe2) nanosheets and form a surface protective film, which effectively accelerates the reaction kinetics of Zn2+ and extends the cycle life of the battery. It is demonstrated that the conductivity, pseudocapacitance and specific capacity can be tuned by selectively introducing oxygen species to the surface, which provides an important reference for the design of electrodes with controlled surface chemistry. Density functional theory (DFT) calculations also confirm that the electronic structure can be adjusted by surface oxygen injection strategy, which not only improves the conductivity, but also adjusts the adsorption energy, thus providing favorable conditions for zinc ion storage. Benefiting from the selenium vacancies and pores generated by the removal of part of selenium, and the oxide film formed on the surfaces, the VSe2-xOx-SS-30 electrode showed higher specific capacity (188.4 mAh/g at 0.5 A g−1 after 50 cycles), better rate performance (107.1 mAh/g at 4 A g−1) and more satisfactory cycling stability (83.1 mAh/g at 5 A g−1 after 1800 cycles) than VSe2-SS electrode. Importantly, the flexible quasi-solid-state VSe2-xOx-SS-30//Zn battery also exhibits high specific capacity and excellent environmental adaptability. Furthermore, the zinc (de)intercalation and transformation reactions mechanism was revealed by some ex-situ/in-situ techniques.

Enhancing Rate Capability, Capacity, and Durability of Co‐Doped Germanium Phosphide Anodes for Li‐Ion Batteries

AbstractWhile germanium‐based anodes for Li‐ion batteries (LIBs) have potential to offer high energy density, their commercialization is impeded by low ionic and electronic conductivity and poor tolerance to volume change during cycling. Here a new quaternary CuGeSiP3 anode is reported to simultaneously overcome these limitations. Synthesized via ball milling process, CuGeSiP3 displays high ionic and electronic conductivity and excellent flexibility to accommodate volume change, attributed to increased structural entropy and reversible formation of favorable intermediates of both electronic and Li ion conductors, as confirmed by experimental measurements and theoretical calculations. When used as an LIB anode, CuGeSiP3 demonstrates large reversible capacity, high Coulombic efficiency, robust cycling stability, and high‐rate capability because it undergoes a reversible lithiation process that involves intercalation and conversion reaction. When composited with layered graphite, the electrode demonstrates exceptional cycling stability (1 261 mA h g−1 after 600 cycles at 400 mA g−1 and 861 mA h g−1 after 1 450 cycles at 20 00 mA g−1) and ultrahigh rate capability (448 mA h g−1 at 20 000 mA g−1). Further, the quaternary, pentanary, and hexanary cation‐disordered phosphides are also synthesized, all having similar Li‐storage superiority, implying the multiple co‐doping strategy is applicable to other material systems.