Anode Material For Li-ion Batteries Research Articles

Design of Silicon-Based Anode Materials for High Energy Density Li-Ion Batteries

Compared to other types of batteries, lithium batteries have an extremely high energy density, which means they can store more energy while maintaining a smaller size and weight. The ideal electrode material must have a high lithium ion capacity to store many lithium ions. In addition, the electrode material must have good electronic conductivity to promote lithium ions' rapid entry and exit. However, traditional carbon materials have limited theoretical specific capacity, and the transmission of lithium-ion batteries in traditional materials is limited, resulting in a significant decrease in capacity. Silicon has a theoretical capacity of up to 4200mAh/g, more than ten times the capacity of commercial graphite negative electrodes. In addition, silicon and lithium can undergo alloying reactions to form Li Si alloys, which helps improve the material's specific capacity. This article first summarizes the advantages of electric vehicles and lithium-ion batteries. Then, the benefits and challenges of using silicon-based materials as negative electrodes for lithium-ion batteries were elaborated in detail, and finally, the prospects of silicon-based materials in lithium-ion battery applications were summarized. This article has reference significance in improving the energy density of lithium-ion batteries.

Unveiling BaTiO3-SrTiO3 as Anodes for Highly Efficient and Stable Lithium-Ion Batteries.

Amidst the swift expansion of the electric vehicle industry, the imperative for alternative battery technologies that balance economic feasibility with sustainability has reached unprecedented importance. Herein, we utilized Perovskite-based oxide compounds barium titanate (BaTiO3) and strontium titanate (SrTiO3) nanoparticles as anode materials for lithium-ion batteries from straightforward and standard carbonate-based electrolyte with 10% fluoroethylene carbonate (FEC) additive [1M LiPF6 (1:1 EC: DEC) + 10% FEC]. SrTiO3 and BaTiO3 electrodes can deliver a high specific capacity of 80 mA h g-1 at a safe and low average working potential of ≈0.6 V vs. Li/Li+ with excellent high-rate performance with specific capacity of ~90 mA h g-1 at low current density of 20 mA g-1 and specific capacity of ~80 mA h g-1 for over 500 cycles at high current density of 100 mA g-1. Our findings pave the way for the direct utilization of perovskite-type materials as anode materials in Li-ion batteries due to their promising potential for Li+ ion storage. This investigation addresses the escalating market demands in a sustainable manner and opens avenues for the investigation of diverse perovskite oxides as advanced anodes for next-generation metal-ion batteries.

Fly-ash derived crystalline Si (cSi) Improves the capacity and energy density of LiNi0.8Co0.1Mn0.1O2 battery: Synthesis and performance

For decades, graphite has been the key ingredient in the anode of Li-ion batteries (LIBs). The search for high-capacity anode materials for Li-ion batteries (LIBs) has led to increasing interest in silicon (Si) as a potential replacement for graphite. This study presents an innovative approach to synthesizing crystalline Si (cSi) from type C fly ash, addressing both the need for improved LIB anodes and the challenge of industrial waste management. Our novel process involves a stepwise method of extraction, gelation using various mineral acids (HCl, H2SO4, and HNO3), magnesiothermic reduction, and purification. X-ray diffraction and energy-dispersive X-ray spectroscopy confirmed the production of high-purity SiO2 and cSi. Notably, a cSi-doped graphite anode (5 % Si) paired with LiNi0.8Mn0.1Co0.1O2 (NMC811) in a cylindrical cell achieved a minimum specific discharge capacity of 388 mAh/ganode after formation, surpassing the theoretical capacity of graphite (372 mAh/g). This demonstrates that even a small amount of cSi can significantly enhance anode performance. Our scalable, simple, and economical process offers a dual benefit: improving battery characteristics while providing an efficient method for fly ash waste utilization. This approach paves the way for sustainable production of high-performance LIB anodes while addressing critical waste management challenges.

Enhanced structural stability of Si electrode employing TiNi/Si pillars with oriented Li diffusion pathway

As the anode materials of Li-ion batteries, pillar-shaped TiNi/Si particles fabricated by employing electrochemical etching of (100) Si wafers and TiNi alloy coating, were investigated for their structural and electrochemical properties. The most suitable porous wafer for producing Si pillars was obtained at a current density of 2.5 mA/cm2 during etching. The deposited TiNi alloy film consisted of a crystallized austenitic (B2) phase capable of inducing phase transformation through annealing at 500°C. Particularly, by coating with the inactive materials, only the (100) plane of single crystalline Si was exposed during the initial charging process to restrict Li ion movement exclusively along the <100>Si direction. The TiNi/Si electrode exhibited a lower capacity compared to the Si electrode but demonstrated improved cycling performance. It showed a charge capacity of 1110 mAh/g at 0.1 C with an initial efficiency of 77 % and maintained a capacity retention of 49 % (543 mAh/g) up to 100 cycles. After the initial cycle, Si electrodes exposed to various lithium insertion directions exhibited severe structural damage such as cracking and particle pulverization, whereas TiNi/Si electrodes demonstrated enhanced structural stability due to surface coating and restricted reaction pathway.

Facile fabrication of Fe3O4@C composites from cellulose of Nypa fruticants shell toward advanced anode materials in Li-ion batteries

Facile fabrication of Fe3O4@C composites from cellulose of Nypa fruticants shell toward advanced anode materials in Li-ion batteries

Exploring the potential of carbon and boron nitride integrated biphenyl frameworks as promising anode materials for high-performance Li-ion and Na-ion batteries: A comprehensive first-principles investigation

A protocol of evaluating 2D anode materials that was applied in our previous study has been refined. With the updated Li/Na potential profiles, the two-dimensional biphenyl network (BPN_C) and its isoelectronic structure, boron nitride (BPN_BN), were comprehensively investigated as potential anode materials. The electronic properties, the mechanic strength and the storage capacities were computed accordingly. The band structure results show that the BPN_C and BPN_BN exhibit the nature of conductor and wide-band semi-conductor, respectively. The calculated mechanic strengths of BPN_BN and BPN_C are competent for anode materials. The storage capacities of BPN_C and BPN_BN were addressed by means of the stepwise binding energies (Ead2) and ab initio molecular dynamic simulations. Higher storage capacities were identified as compared with those of the graphene structure. Furthermore, the calculated open-circuit voltages (OCVs) for both BPN_C and BPN_BN can meet the requirements of adequate anode materials. Finally, the diffusivities of Li/Na atoms on the surface of BPN_C and BPN_BN were investigated and found to be suitable for the application as anodes. Our results suggest that the BPN structures can be used as potential anode materials for both LIBs and SIBs.

Two-dimensional AsP3 monolayer as an efficient anode material for Li-Ion batteries: a theoretical perspective

Two-dimensional AsP3 monolayer as an efficient anode material for Li-Ion batteries: a theoretical perspective

Tubular-like Nanocomposites with Embedded Cu9S5-MoSx Crystalline-Amorphous Heterostructure in N-Doped Carbon as Li-Ion Batteries Anode toward Ultralong Cycling Stability.

Transition metal sulfides (TMSs) show the potential to be competitive candidates as next-generation anode materials for Li-ion batteries (LIBs) due to their high theoretical specific capacity. However, sluggish ionic/electronic transportation and huge volume change upon lithiation/delithiation remain major challenges in developing practical TMS anodes. We rationally combine structural design and interface engineering to fabricate a tubular-like nanocomposite with embedded crystalline Cu9S5 nanoparticles and amorphous MoSx in a carbon matrix (C/Cu9S5-MoSx NTs). On the one hand, the hybrid integrated the advantages of 1D hollow nanostructures and carbonaceous materials, whose high surface-to-volume ratios, inner void, flexibility, and high electronic conductivity not only enhance ion/electron transfer kinetics but also effectively buffer the volume changes of metal sulfides during charge/discharge. On the other hand, the formation of crystalline-amorphous heterostructures between Cu9S5 and MoSx could further boost charge transfer due to an induced built-in electric field at the interface and the presence of a long-range disorder phase. In addition, amorphous MoSx offers an extra elastic buffer layer to release the fracture risk of Cu9S5 crystalline nanoparticles during repetitive electrochemical reactions. Benefiting from the above synergistic effect, the C/Cu9S5-MoSx electrode as an LIB anode in an ether-based electrolyte achieves a high-rate capability (445 mAh g-1 at 6 A g-1) and superior ultralong-term cycling stability, which delivers an initial discharge capacity of 561 mAh g-1 at 2 A g-1 and its retention capacity after 3600 cycles (376 mAh g-1) remains higher than that of commercial graphite (372 mAh g-1).

C60 Fullerene-Reinforced Silicon Oxycarbide Composite Fiber Mats: Performance as Li-Ion Battery Electrodes.

Precursor-derived silicon oxycarbide (SiOC) has emerged as a potential high-capacity anode material for rechargeable Li-ion batteries. The polymer processing and pyrolysis route, a hallmark of polymer-derived ceramics, allows chemical interfacing with a variety of nanoprecursors and nanofiller phases to produce composites with low-dimensional structures such as fibers and coatings not readily attained in traditional sintered ceramics. Here, buckminsterfullerene or C60 was introduced as a filler phase in a hybrid precursor of 1,3,5,7-tetramethyl-1,3,5,7-tetravinyl-cyclotetrasiloxane (TTCS) along with polyvinylpyrrolidone or PVP as a spinning agent to fabricate electrospun fiber mats, which upon a high-heat treatment transformed to a C60-reinforced SiOC ceramic composite. Tested as the self-supporting working electrode in a Li-ion half-cell, C60-reinforced fiber mats show a much-improved reversible capacity (825 mA h g-1), nearly 100% Coulombic efficiency, and superior rate capability with low-capacity decay at high currents (only 25.5% decay at 800 mA g-1) compared to neat C60 and neat carbonized fiber electrodes.

One-Dimensional Van Der Waals V2Se9 As a Conversion-Type Anode Material for Advanced Li Rechargeable Batteries

Volume expansion of active materials during lithium storage is one of the main issues in Li-ion batteries (LIBs) that should be addressed. In particular, large volume changes and particle cracking are problematic for electrode materials based on conversion reaction, which are considered attractive anode materials with high energy densities. In this study, a one-dimensional van der Waals (1D vdW) material, V2Se9, is proposed as a conversion-type anode material for LIBs. The V2Se9 electrode material has a 1D chain molecular structure with vdW interactions between chains to form a bulk crystal structure. The spaces between the 1D chains act as structural buffers and provide short Li+ diffusion paths that can improve the electrochemical performance of the electrode materials. The V2Se9 electrode exhibits a high reversible capacity of 563.3 mAh g-1 at 100 mA g-1 and a high rate capability of 109.1 mAh g-1 at 3200 mA g-1. The capacity retention of V2Se9 electrodes is 83.72 % after 100 cycles. Synchrotron X-ray diffraction and X-ray absorption spectroscopy reveal the formation of Li2Se and V metal, indicating that Li ion storage occurs via the conversion reaction. The structural stability of V2Se9 is demonstrated using SEM measurements of the discharged and charged V2Se9 electrodes during cycling. These results demonstrate the reaction mechanism of V2Se9 and highlight the potential of 1D vdW materials as high-performance anode materials in LIBs.

Silicon Nitride Anodes for Li-Ion Batteries: Understanding the Origin of Enhanced Cycle Stability over Silicon with Operando AFM

Silicon is highly coveted as the potential anode for next generation batteries, owing to its high specific capacity (3579 mAh g-1, Li3.75Si), high abundance and low cost. However, the large volume expansion of silicon during lithiation (up to 300 %) poses inherent challenges, namely cracking/fracturing of the anode which constitutes to drastic capacity fade, thereby greatly limiting the long-term cyclability and ultimately leads to terminal cell failure mechanisms such as delamination [1]. A promising alternative is the use of conversion alloying materials such as silicon nitride (SiNx). During the initial lithiation (first cycle), these materials irreversibly convert into a mixture of matrix (LixSiyNz) and the redox active electrode (LixSi). In subsequent cycles, the improved cycle performance and lifetime is attributed to the matrix helping buffer the volume expansion of the Si particles, thus mitigating against the aforementioned degradation pathways and ultimately extending the cycle performance lifetime. Currently, insights into the silicon nitride alloying conversion reaction are limited. There remains debate in the literature around whether the matrix is redox active, and uncertainty over the topographical distribution of the anode, specifically whether discrete domains of silicon and matrix are generated in situ, or the silicon nitride remains as amorphous solid solution of silicon and lithiated nitridosilicates, where only the short-range chemical environment resembles a given phase [2-4].At time of writing there have been no operando observations of the reaction. In this presentation, we address this by studying pulse laser deposited (PLD) SiNx thin films with operando electrochemical atomic force microscopy (EC-AFM). This technique (performed in a glovebox under inert Ar conditions) enables insights into the morphological, mechanical, chemical, and physical properties of battery materials when they evolve under electrochemical control. Crucially, operando measurements enable real time detection of the morphological changes of the SiNx anode during the formation cycle, in conjunction with Young’s Modulus mapping enabling phase-identification of the matrix and silicon components. First, we report thorough electrochemical characterisation of SiNx films with varying composition (x), demonstrating performance equivalent to the best-in-class. Then, EC-AFM studies are communicated; comparisons are made between SiNx and Si films to elucidate the alloying conversion reaction, how it impacts the morphological evolution of the anode, and consequently, establish the origins of the improved SiNx cyclability. References Shi, F., Song, Z., Ross, P.N., Somorjai, G.A., Ritchie, R.O. and Komvopoulos, K., 2016. Failure mechanisms of single-crystal silicon electrodes in lithium-ion batteries. Nature communications, 7(1), p.11886.Ulvestad, A., Mæhlen, J.P. and Kirkengen, M., 2018. Silicon nitride as anode material for Li-ion batteries: Understanding the SiNx conversion reaction. Journal of Power Sources, 399, pp.414-421.Ulvestad, A., Skare, M.O., Foss, C.E., Krogsæter, H., Reichstein, J.F., Preston, T.J., Mæhlen, J.P., Andersen, H.F. and Koposov, A.Y., 2021. Stoichiometry-controlled reversible lithiation capacity in nanostructured silicon nitrides enabled by in situ conversion reaction. ACS nano, 15(10), pp.16777-16787.Kilian, S.O., Wankmiller, B., Sybrecht, A.M., Twellmann, J., Hansen, M.R. and Wiggers, H., 2022. Active Buffer Matrix in Nanoparticle‐Based Silicon‐Rich Silicon Nitride Anodes Enables High Stability and Fast Charging of Lithium‐Ion Batteries. Advanced Materials Interfaces, 9(26), p.2201389.

(Invited) Carbon in Electrochemical Energy Storage

Carbon materials play a pivotal role in the realm of electrochemical energy storage. Their significance stems from the diverse applications they find based on surface chemistries and morphologies. In batteries, various carbons serve as electrochemical active materials, hosting structures and additives. For instance, fluorinated carbon emerges as an excellent cathode material for primary batteries. Fine-tuning the C/F ratio on cabron surfaces allows customization of the power/energy ratio, catering to specific applications. Graphene, with its ability to self-assemble into hierarchical structures, has proven to be an ideal oxygen electrode. Porous nanocarbon structures are commonly employed to host sulfur, although addressing challenges at the electrode level is imprative for further processing. Carbon additives become essential components in cathode or anode materials for Li-ion batteries. Establishing a continuous electronic conductive network using a minimal amount of carbon in electrodes is a constant pursuit, aiming to reduce parasitic weight at the cell level. This talk wil ldelve into the fundamental roles that carbon play in various systems, such as Li/CFx, Li/O2, Li-S and advanced Li-ion batteries to underscore the crucial role of carbon in advancing battery technologies.

A Microstructure Resolved Multi-Material Model for Silico-Graphite Composite Electrode

Silicon (Si) has been considered as the most promising anode material for next-generation high-capacity Li-ion batteries due to its very high theoretical specific capacity. However, the large deformation associated with (de)lithiation and its detrimental consequences like pulverization, loss of electrical contact, and subsequent capacity loss, have long been a roadblock in deploying high-capacity electrodes. Grafting small amounts of Si with graphite has been proven to utilize the higher capacity of silicon and the stability of graphite. The intricacies of interactions between the two active materials and their effect on the overall performance of the composite electrode are still not well known. Here, we present a novel fully coupled multiphysics electrochemical-mechanical model based on 3D microstructure extracted from X-ray tomography scans of Si-C composite electrode. The theoretical framework integrates the large deformation and viscoplastic response of Si, and the two-way coupling between diffusion and interfacial reactions with mechanical stress. The resolution of the pore phase from the silicon and graphite phases allows for the simulation of the Li+ ion kinetics in the composite electrode and influence of the microstructure. The model is employed to study the phenomena of preferential lithiation, crosstalk between active materials, partial utilization due to mechanical influences, and develop strategies to maximize the specific capacity. Lastly, we also explore the potential and avoidance of mechanical damage within active materials and interfacial delamination. The first-of-its-kind 3D microstructure resolved, multi-material model presents a novel tool to simulate the performance of Si-C composite electrode and decode the depth of interactions between the active materials.

Enhanced performance of H-C3N2 monolayer as anode material for Li-ion batteries by phosphorus doping

Graphitic carbon nitride sheets (CxNy), which possess a two-dimensional structure similar to N-doped graphene, have been extensively studied as potential anode materials for ion batteries due to their high nitrogen content and porous defect sites that can serve as atomic storage sites for alkali metals. compared with most carbon nitride sheets, monolayer H-C3N2 has the characteristics of higher pyridinic nitrogen content and porosity, and can provide more Li adsorption sites, resulting in a superior theoretical capacity of 2791 mAh/g. However, the high diffusion barrier of 1.75 eV implies the low charge/discharge rate, which limits its application in lithium-ion batteries. Here, this paper demonstrates that doping P atoms in H-C3N2 (PC18N11) has some advantages for application in batteries. Specifically, monolayer PC18N11 exhibits excellent stability and conductivity, much higher theoretical specific capacity (3542 mAh/g). Moreover, PC18N11 exhibits metallic properties when Li-ion is adsorbed, the conductivity is improved, and the interaction between Li-ions will greatly reduce the diffusion barrier. These favorable properties indicate that P-doped H-C3N2 monolayer is a promising anode material for Li-ion batteries.

Colloidal hot injection synthesis of Cu2FeSnS4 nanoparticles towards an enhanced capacity anode material for Li-ion batteries

The increasing demand for portable energy storage devices has prompted a considerable exploration into advanced anode material with higher Li-ion battery capacities. Quaternary chalcopyrite semiconductors have generated significant attention as promising materials in applications such as optoelectronic devices, energy conversion, and energy storage devices. In this paper, Cu2FeSnS4 (CFTS) nanoparticles were prepared through a colloidal hot injection method (HIM). The structural analysis indicates that the CFTS nanoparticles exhibit a pure tetragonal structure characterized by high crystallinity. The morphological and elemental analysis shows the stoichiometric synthesis of CFTS nanoparticles with significant agglomeration of crystallites, accompanied by variation in size. The CFTS nanoparticles, employed as an anode material for Li-ion batteries, demonstrated significant performance characterized by high reversible capacity and stability at ambient temperature. The initial discharge capacity is achieved at 1181 mAhg−1 and retains 528 mAhg−1 during charge-discharge cycles within the voltage range of 0.005 to 3.0 V (versus Li/Li+) after 5 cycles. The CFTS nanoparticle performance findings indicate its promising implementation as an anode electrode in Li-ion batteries.

In-Plane Mesoporous 3D Flower-Like Mo2Ti2C3Clx MXene Anodes for Li-Ion Batteries: From Structure to Performance.

MXenes are known for their exceptional electrical conductivity and surface functionality, gaining interest as promising anode materials for Li-ion batteries. However, conventional 2D multilayered MXenes often exhibit limited electrochemical applicability due to slow ion transport kinetics and low structural stability. Addressing these challenges, this study develops a 3D flower-type double transition metal MXene, Mo2Ti2C3Clx, with precisely engineered in-plane mesoporosity using HF-free Lewis acid-assisted molten salt method, coupled with intercalation and freeze-drying. The molar ratio of Lewis acid to eutectic salts is meticulously controlled to create the mesoporosity, which is preserved through freeze-drying. Molecular dynamics (MD) simulations assess the impact of in-plane pore size on the structure and transport dynamics of electrolyte components. Density functional theory (DFT) shows that chlorine surface functional groups significantly reduce Li-ion diffusion barriers, thereby enhancing ion transport and battery performance. Electrochemical evaluations reveal that small-sized (2-5nm) mesoporous Mo2Ti2C3Clx achieves a specific capacity of 324 mAh g-1 at 0.2 A g-1 and maintains 97% capacity after 500 cycles at 0.5 A g-1, outperforming larger-pored (10nm) and non-porous variants. This research highlights a scalable strategy for designing mesoporous materials that optimize ion transport and structural stability, essential for advancing next-generation high-performance energy storage solutions.

DFT study of lithium adsorption on silicon quantum dots for battery applications

Understanding lithium (Li) adsorption in silicon quantum dots (SiQDs) is crucial for optimizing Li-ion battery (LIB) anode materials. We systematically investigated Li adsorption in ten hydrogenated SiQDs (Si10H16, Si14H20, Si18H24, Si22H28, Si26H30, Si30H34, Si35H36, Si39H40, Si44H42, and Si48H46) across five adsorption sites (bridge(B), on-top(T), hollow-tetrahedral inner(Tdinner), hollow-tetrahedral surface(Tdsurface), and hollow-hexagonal(Hex)), utilizing density functional theory (DFT) with the M06–2X hybrid functional and 6-31G+(d) basis set. Findings identify Tdinner as the most favorable adsorption site, with a binding energy (Ebind) of 0.80–1.00 eV, dependent on SiQD size. The adsorption site exerts a more pronounced impact on Ebind than the cluster size. Multiple adsorptions in SiQDs show increased Ebind per Li atom with Li atom number. Molecular volume changes, independent of Li atom number but site-dependent, exhibit a maximum of 2.51 %. SiQD energy gap, influencing conductivity, varies with size, larger SiQDs being more conductive, especially with Li adsorption. Conclusively, our study recommends large-sized SiQDs as optimal LIB anode materials, offering high capacity, minimal volume expansion, and reasonable conductivity. This research addresses a theoretical gap, illuminating the impact of Li adsorption on SiQD molecular volumes and electronic structures, aiding in the design of enhanced capacity silicon anodes for LIB.

Lithiophilic Multichannel Layer to Simultaneously Control the Li-Ion Flux and Li Nucleation for Stable Lithium Metal Batteries.

Although the Li metal has been gaining attention as a promising anode material for the next-generation high-energy-density rechargeable batteries owing to its high theoretical specific capacity (3860 mAh g-1), its practical use remains challenging owing to inherent issues related to Li nucleation and growth. This paper reports the fabrication of a lithiophilic multichannel layer (LML) that enables the simultaneous control of Li nucleation and growth in Li-metal batteries. The LML, composed of lithiophilic ceramic composite nanoparticles (Ag-plated Al2O3 particles), is fabricated using the electroless plating method. This LML provides numerous channels for a uniform Li-ion diffusion on a nonwoven separator. Furthermore, the lithiophilic Ag on the Li metal anode surface facing the LML induces a low overpotential during Li nucleation, resulting in a dense Li deposition. The LML enables the LiNi0.8Co0.1Mn0.1O2|| Li cells to maintain a capacity higher than 75% after 100 cycles, even at high charge/discharge rates of 5.0 C at a cutoff voltage of 4.4 V, and achieve an ultrahigh energy density of 1164 Wh kg-1. These results demonstrate that the LML is a promising solution enabling the application of Li metal as an anode material in the next-generation Li-ion batteries.

Unveiling Electrochemical Properties of Silicon for Stable Cycling Performance of Silicon Anode Materials

Research on silicon (Si) as an anode material for Li-ion batteries has spanned two decades; however, certain electrochemical properties of Si remain unclear. Specifically, the cyclic voltammogram (CV) pattern of Li/Si cells varies from case to case, influenced not only by the material but also by the experimental conditions. In this work, slow cyclic voltammetry is employed to investigate Li/Si cells, resulting in three distinct CV patterns. It is further observed that the CV pattern, particularly during the delithiation, is contingent on the state-of-lithiation (SOL) during lithiation and correlates with the capacity fade of Li/Si cells in subsequent cycles. Additionally, it is revealed that the primary mechanism for capacity fade differs between nano-sized silicon (Si-NP) and micro-sized silicon (Si-MP). In brief, capacity fade in Li/Si-NP cells predominantly arises from parasitic reactions between the highly lithiated Li-Si alloy and electrolyte solvents, exacerbated by the large specific surface area of Si-NP materials, whereas capacity fade in Li/Si-MP cells is primarily attributed to the Li electrode rather than the Si-MP electrode due to the restricted lithiation of Si-MP materials. Finally, this work concludes that limiting the SOL of Li/Si cells offers a straightforward and effective pathway to achieving stable cycling performance.

3D porous SnO2/MXene as a superior anode material for Li-ion and Na-ion battery

In this paper, we synthesized the SnO2/MXene composite with unique three-dimensional(3D) porous framework by removing of polystyrene (PS) nanospheres as sacrificial templates. The SnO2 nanopaticles are evenly anchored in MXene nanosheets by electrostatic self-assembly. The composite demonstrates plenty of hierarchical pores and a greatly enlarged interfacial area, which can facilitate the permeation of electrolyte and provide more active sites for Li+/Na+ intercalation. The conductive porous structure can also promote the fast transport of electrons and ions, and maintain the structural stability of eletrode in the cycling. The SnO2/MXene composite shows increased reversible capacities and excellent cycling stability for dual storage of both Li+ and Na+. As anode material for lithium ion storage, it has long-life cycling performance of 373.7 mAh/g after 1400 cycles at 5 A/g, superior than most reported SnO2/carbide composites. For sodium ion storage, the conposite also shows a increased capacity of 236.8 mAh/g at 0.4 A/g after 100 cycles. This study provides a design strategy for preparing anode materials of advanced battery system with promising electrochemical performance.