Anode For LIBs Research Articles

Mo–O–Sn Bond Boosting Kinetics of MoO2−xSnO2/Sn Anode for High‐Performance Li‐ion Batteries

Obtaining a robust electrode composed of Sn‐based metal oxides and carbonaceous matrix through nanoscale structure engineering is essential for effectively improving Li‐ion batteries' electrochemical performance and stability. Herein, we report a bimetallic MoO2‐xSnO2/Sn nanoparticles uniformly anchored on N, S co‐doped graphene nanosheets (MoO2‐xSnO2/Sn@NSG) as an anode electrode for Li‐ion battery via a one‐step hydrothermal and thermal treatment approach. In the MoO2‐xSnO2/Sn nanocomposite, the generated Sn‐O‐Mo bond can modulate the electronic and composition structures to improve the intrinsic conductivity of SnO2 and reinforce the structural stability during cycles. Moreover, featuring excellent electronic conductivity via coupling of MoO2‐xSnO2/Sn and hierarchical NBG matrix, the MoO2‐xSnO2/Sn@NSG electrode possesses ultrafast electrochemical kinetics and superior long‐term cycling stability and rate capability. Additionally, the hierarchical MoO2‐2SnO2/Sn@NSG can suppress the aggregation and accommodate the volume variations of active substances, thereby providing more lithium storage sites. Consequently, the optimized MoO2‐2SnO2/Sn@NSG anode exhibits a high reversible capacity of 904 mA h g‐1 at 0.2 A g‐1 and excellent cycling performance with the reversible capacity of 456 mAh g‐1 at 1 A g‐1 over 600 cycles. The universal synthesis technology of bimetallic oxide anodes for advanced LIBs may provide vital guidance in designing high‐performance energy‐storage materials.

Electrochemical Properties of MIL‐100(Fe) Derived Double‐Shell Coating Anode Materials for Lithium‐Ion Battery

AbstractFe‐based anode materials with a high specific capacity, non‐toxic and abundant resources are among the ideal anode candidates for the new generation of LIBs. But their significant bulk effect causes the problems of the broken electrode structure and short cycle life that seriously hinder their practical applications. Herein, we prepared the core‐shell structure Fe3O4@C@SiO2 for the anode of LIBs by MIL‐101(Fe) derivatization using the solvent thermal method combined with the hydrolytic coating method. The porous carbon layer generated in situ by MOF pyrolysis, together with the coating of the SiO2 shell, can mitigate the volume expansion of ferric tetroxide during the cycling process. With these structural advantages, the Fe3O4@C@SiO2 anode preserves excellent performance with a specific capacity of 716 mAh/g for the 300 cycles at 1 A/g and 428 mAh/g after 2000 cycles as the density is up to 5 A/g. This work presents a promising approach for preparing SiO2‐coated core‐shell structured TMOs composite anodes.

Aluminum particles as anode material for lithium ion batteries: effect of particle sizes on the electrochemical behaviours

This study presents a preliminary investigation on using pristine aluminum particles as anodes for lithium-ion battery. The microstructural characteristics of aluminum particle samples with sizes from 100 nm (0.1 μm) to 70 µm were analyzed by the SEM and XRD methods. The electrochemical behaviors of the aluminum particles were examined by the cyclic voltammetry (CV) and galvanostatic charge/discharge (GCD) measurements. The obtained results demonstrated the distinct lithiation/delithiation features of the aluminum electrodes at the potential couple of around 0.25 V/0.50 V vs. Li/Li+. Moreover, the GCD results also revealed the strong impact of the particle size on the initial capacity and galvanostatic discharge/charge potential profiles of electrode samples. However, aluminum electrodes with the large-sized particles showed dramatical capacity decay after certain cycles, and stabilized at around the specific capacity of 50 mAh g-1 and exhibited capacitive charge/discharge behavior. In contrast, the nano-sized particles aluminum electrodes possessed stable electrochemical performance upon cycling, but with low initial capacities. The results in this work will enrich the knowledge of the aluminum-based anode for LIBs in future works.

Waste polyethylene terephthalate-derived organic-inorganic hybrid materials as sustainable dual electrodes for Li-ion batteries

The hybrid Fe-Li2TP structure is constructed from waste polyethylene terephthalate (w-PET) derived dilithium terephthalate (Li2TP) and conventional Fe2O3 by hydrothermal reaction. It is being studied for both anode and cathode for LIBs. As an anode, it exhibits a reversible capacity of 505 mAh/g after 100th cycle at 1 C-rate with ∼100 % coulombic efficiency (CE). In addition, as a cathode, it shows highly reversible charge/discharge capacities of 107.50/107.52 mAh/g after the 100th cycle at 0.1 C-rate with 100 % CE. Further, in the cathodic studies via galvanostatic intermittent titration technique (GITT), the average lithium diffusion (DLi+) coefficients are calculated to be 2.96 × 10-10, 3.89 × 10−10 cm2 s−1 and the electrical (µ) mobilities to be 5.86 × 1011 m2 V−1 s−1, 1.12 × 1011 m2 V−1 s−1 for charge and discharge pulses, respectively. The combined nano-rod and nano-spherical morphologies reduce the diffusion length, and adding 10 % SWCNTs during electrode fabrication enhances the electronic conductivity. This organic–inorganic hybrid strategy of Fe-Li2TP strongly mitigates the electrode dissolution, reducing the structural strain and preventing electrolyte decomposition at higher voltage. Computational studies show an optimized Fe-Li2TP structure with a 2.7-fold lower band gap value (1.9040 eV) than the pristine Li2TP.

Constructing MXene-/coconut-derived carbon composite as a robust anode material for enhanced lithium storage

MXene is one kind of a promising anode material due to its graphene-like structure, excellent electrochemical characteristics and low lithium ion diffusion barrier. But the lower specific capacity couldn’t meet the demands in practical application. Here, we have constructed coconut-derived carbon anchored within the MXene layers, which improves the conductivity to prompt the kinetics upon redox reactions, in the meantime, shorts the transfer distance and buffers volume changes, synergistically improving the electrochemical reversibility during charge and discharge processes. Naturally, the MXene/C hybrid anode delivers a high initial discharge specific capacity of 1951.7 mAh g[Formula: see text] at 0.1 A g[Formula: see text]. Additionally, it maintains a stable cycle with a reversible capacity of 511.7 mAh g[Formula: see text] after 500 cycles at 0.5 A g[Formula: see text]. This work paves a straightforward avenue to developing a versatile MXene-based anode for high performance LIBs.

Co-precipitation derived MnCO3 particles as LIB anode and effect of Zn substitution on its lithium storage

In the present work, Zn-doped MnCO3 i.e., Mn1−xZnxCO3 (x=0to0.3) have been successfully synthesized by easy and commercial co-precipitation method at atmospheric pressure and temperature. The structural, morphological, chemical, and thermal properties of as-synthesized samples were examined by XRD, FESEM, EDX, XPS, FTIR and TGA techniques. Rietveld refinements of XRD patterns reveal the successful incorporation of Zn in the crystal lattice of MC (MnCO3). Further, the Li-storage performance of all the samples have been examined from 0.005 to 3.0 V vs. Li/Li+ by GCD at a constant current rate of 60 mA·g−1 and CV measurement techniques. The result shows that MZC-2 (Mn0.8Zn0.2CO3) exhibits a better Li-storage performance with the reversible capacity of 667 (±10) mA·h·g−1 and better cyclic stability at least for 100 cycles and superior rate performance. A plausible charge storage mechanism is proposed based on ex-situ XRD and TEM analysis. The results indicate the contribution of both the alloying-de-alloying and conversion reaction of Zn. Incorporation of Zn into MnCO3 have been found beneficial to stabilize the cyclability of MnCO3.

Lithium modulated spinel high entropy oxide anode of LIBs through microwave solvothermal method

Spinel structured high entropy oxides (HEO) with three-dimensional Li+ transport channel and two different Wyckoff sites show high theoretical capacities due to multiple hypervalent ions and abundant oxygen vacancies. However, the intrinsic poor electrical conductivity of oxides and the lack of low-energy-consumption synthesis methods remain problems. Herein, Li+ with low-electronegativity is introduced into (FeCoNiCrMn)3O4 through high-efficiency microwave-assisted solvothermal method. The nano-scale high entropy oxide particles with homogeneous distribution of elements are successfully obtained in a short time. The addition of Li+ in HEO not only increases the valence states of transition metal cations to increase the number of electron transfers, but also induces more oxygen vacancies, which facilitates Li ion storage and increases ionic conductivity. The Li induced lattice distortion together with the entropy stabilization mechanism alleviate the lattice stress, featuring the anode superior electrochemical stability. The anode HEO-15 with the optimal Li content shows the specific capacity of 452.8 mAh g-1 at a current density of 500 mA g-1 after 300 cycles for LIBs, much higher than that of HEO-0 (248.9 mAh g-1). This research provides an effective method to improve the lithium storage performance of HEO.

Nonequilibrium fast-lithiation of Li4Ti5O12 thin film anode for LIBs

Li4Ti5O12 (LTO) is known for its zero-strain characteristic in electrochemical applications, making it a suitable material for fast-charging applications. Here, we systematically studied the quasi-equilibrium and non-equilibrium lithium-ion transportation kinetics in LTO thin-film electrodes, across a range of scales from the crystal lattice to the microstructured electrodes. At the crystal lattice scale, during the non-equilibrium lithiation process, lithium ions are dispersedly embedded into the 16c position, resulting in more 8a → 16c migration compared with the quasi-equilibrium lithiation, and forming numerous fast lithium diffusion channels inside the LTO lattice. At the microstructural electrode scale, optical spectrum characterizations supported the “nano-filaments” lithiation model in polycrystalline LTO thin-film electrodes during the lithiation process. Our results reveal the patterns of lithium migration and distribution within the LTO thin film electrode under the non-equilibrium and quasi-equilibrium lithiation process, offering profound insights into the potential optimization strategies for enhancing the performance of fast-charging thin film batteries.

Enhancing Methylated Amorphous Silicon Anode Performances in Li-Ion Batteries By Boron Doping

Methylated amorphous silicon has already demonstrated some advantages as compared to silicon in terms of mechanical properties and cyclability for Li-ion batteries (LIB) [1]. However, the conductivity of methylated amorphous silicon drops by several orders of magnitude when increasing the methyl content in the material, which prevents investigating methyl contents higher than 10%. It is well known that doping significantly improves the conductivity of crystalline or amorphous silicon, and has sometimes been reported to improve the material cyclability when used as a LiB anode [2].Here, boron-doped methylated amorphous silicon electrodes with different methyl contents were investigated as anodes for LiB in half-cell configuration. Boron doped methylated silicon thin films (100nm thick) with various methyl content were cycled in the range 0.025V – 1V at C/2 rate (electrolyte: LP30 with 5%FEC). 10% methylated amorphous silicon with 2% boron doping performs a capacity retention of 77% after 1000 cycles (exhibiting a capacity around 1800 mAh.g-1) of full lithiation/delithiation. Figure 1a shows a clearly improved performance as compared to the undoped material. The stability upon cycling of higher methyl contents (15% and 20%) electrodes is further increased, with a capacity retention exceeding 80% over 1000 cycles of full lithiation/delithiation.The evolution of the SEI thickness can be quantitatively determined from IR spectra during cycling. The thickness in the delithiated state is found to increase from cycle to cycle, but with a lower rate for the doped 10% methylated electrodes (thickness lower than 25 nm after 40 cycles and 30 nm after 80 cycles) than for the undoped ones (thickness larger than 35 nm after 40 cycles), see Figure 1b. The SEI evolution upon cycling for higher methyl content is currently under investigation. Reference [1] L. Touahir, A. Cheriet, D. A. D. Corte, J.-N. Chazalviel, C. H. Villeneuve, F. Ozanam, I. Solomon, A. Keffous, N. Gabouze et M. Rosso, «Methylated silicon: A longer cycle-life material for Li-ion batteries,» Journal of Power Sources, vol. 240, pp. 551-557, 10 2013. [2] M. Salah, C. Hall, P. Murphy, C. Francis, R. Kerr, B. Stoehr, S. Rudd et M. Fabretto, «Doped and reactive silicon thin film anodes for lithium ion batteries: A review,» Journal of Power Sources, vol. 506, p. 230194, 9 2021. Figure 1

Physics-Based State of Health Prediction of Lithium-Ion Battery during Fast Charging

Electrification of the transportation sector and increased use in consumer electronics have driven the increasing demand for lithium-ion batteries (LiBs) (1). Despite their high energy density and long service life, LiBs suffer from capacity degradation due to continuous growth of solid electrolyte interface (SEI) layer and plating of lithium on the anode surface. Graphite, the anode in most LiBs, has a high tendency to catalyze the degradation of the electrolyte consisting of LiPF6 and ethylene carbonate to form an SEI of Li-rich carbonate, phosphate, and fluoride compounds (2, 3). The SEI film grows during service due to the deposition of reaction products and repeated cycles of damage and reformation due to the contraction and expansion associated with volume changes during Li-ion intercalation and deintercalation. Additionally, fast or low-temperature charging of batteries results in lithium plating on the anode surface because the elevated concentration of Li+ on the anode surface results in graphite potential falling below 0V vs. Li+/Li and increased likelihood of Li deposition compared to intercalation (4). Lithium loss due to the side reactions of SEI growth and plating contributes to capacity loss and may increase the likelihood of battery failure. Hence, accurate modeling of the side reactions is required to determine the state of health (SOH) and predict the remaining capacity of LiBs during operation (5).We report an experimentally validated single particle model (SPM) to estimate the influence of SEI growth and Li plating on the capacity changes in Lithium Cobalt Oxide (LCO)/Carbon cells during repeated cycling (6-8). The SPM model idealizes each electrode as a single particle to approximate the cell response. A. Sarkar et al. (5) included the influence of SEI growth, plating, SEI fracture, and temperature in the SPM model to determine the influence of the side reactions on battery performance. The parameters corresponding to side reactions, such as the SEI film growth rate, conductivity of the SEI film, and reversibility of the plating reaction, were determined through comparison of numerical predictions of cell voltage and capacity change with experimental response measured at charging rates of 0.1C and fast charging rate of 2C on PowerStream 35 mAh LCO/C coin cells (Lir2032) as shown in Figure 1. In addition, the coin cells were subjected to charge/discharge experiments at charging rates varying from 0.1C – 5C for 100 cycles. Experimental measurements of the cell capacity changes were compared to model predictions for the different charging rates to validate the modeling assumptions and determine the efficacy of the estimated parameters in describing the cell degradation. The agreement between the model prediction and measured experimental response showed that the single particle model augmented with side reaction mechanisms can describe the cell degradation and is suitable for predicting the remaining capacity and safety of LiBs subjected to a range of charging rates. The model can also predict the accumulation of irreversibly plated lithium on the anode surface during repeated fast charging. The amount of plated lithium determines the severity of dendritic growth, and thus, model predictions of lithium accumulation may be used to estimate the likelihood of battery failure under fast charging conditions. Acknowledgment:This work was supported by the National Science Foundation, Iowa State University, and University of Connecticut.

Understanding the structural relation and electrochemical evolution between ZnGeP2 and ZnSiP2 twin phosphides for advanced Li-ion batteries

Ternary ZnGeP2 with large capacity and suitable plateau is considered to be alternative anode for LIBs, while it suffers heavy-use of Ge raw-material inducing high cost-price thus failure of commercialization. Herein, a unique atomic substitution strategy is proposed by using Si-atom to totally replace Ge site in ZnGeP2. Interestingly, novel ZnSiP2 as twin-analogue is achieved, keeping the great advantages of high ICE (90 %), low plateau (∼0.35 V) and comparable rate performance (4000 mA/g, 629 mAh/g) for LIBs. More specially, such ZnSiP2 twin even exhibits higher thermo-stability (1046 vs 891 °C), larger capacity (1554 vs 1387 mAh/g) and lower voltage-hysteresis (0.28 vs 0.44 V) than ZnGeP2, which are unexpected and attractive for battery-safety and energy improvement. The above unusual phenomena are investigated in-detail, and the results show that owing to the similar radius and electronegativity between Si&Ge, the ZnSiP2 enables the same structural phase with ZnGeP2 matrix thus keeping its electrochemical advantages. Meanwhile, the ZnSiP2 exhibits larger formation energy (−1.24 eV) toward better structural-stability, lighter Si-component to higher capacity, lower Si-lithiated potential oriented smaller voltage-hysteresis, thus showing high performances in LiCoO2//ZnSiP2 full-cell. The above atomic substitution strategy can be easily extended to other good performance yet high cost electrode materials toward application.

Recent progress in the recycling of spent graphite anodes: Failure mechanisms, repair techniques, and prospects

Recycling spent lithium-ion batteries (S-LIBs) is an effective strategy for addressing environmental concerns and the increasing demand for critical energy minerals. This process involves the recyclization of spent graphite (S-Gr), a key component of LIB anodes, which has been less studied compared to the recovery of high-value elements from the cathode. Despite its lower market value, graphite possesses unique properties and plays a vital role in LIBs, emphasizing the need for innovative recycling solutions due to the economic and environmental impacts of graphite extraction and processing. This review presents a comprehensive analysis of the failure mechanisms and structural characteristics of S-Gr, offering valuable insights into the complexities of graphite anode recyclization. Existing methodologies and advancements in S-Gr recyclization are thoroughly summarized. Additionally, surface modification strategies for S-Gr recovery are analyzed, aiming to repair the damaged surface structure and restore its electrochemical performance. Finally, the prospects and challenges associated with S-Gr recyclization are presented, contributing to the sustainable development of LIB technologies and promoting the global transition toward renewable energy sources.

Synergistic effect of carbon nanotube and encapsulated carbon layer enabling high-performance SnS2-based anode for lithium storage

Tin disulfide (SnS2), due to large interlayer spacing and high theoretical capacity, is regarded as a prospective anode material for lithium-ion batteries. Nevertheless, the poor electron conductivity of SnS2 and huge volumetric change during the lithiation/delithiation process lead to a rapid capacity decay of the battery, hindering its commercialization. To address these issues, herein, SnS2 is in-situ grown on the surface of carbon nanotubes (CNT) and then encapsulated with a layer of porous amorphous carbon (CNT/SnS2@C) by simple solvothermal and further carbonization treatment. The synergistic effect of CNT and porous carbon layer not only enhances the electrical conductivity of SnS2 but also limits the huge volumetric change to avoid the pulverization and detachment of SnS2. Density functional theory calculations show that CNT/SnS2@C has high Li+ adsorption and lithium storage capacity achieving high reaction kinetics. Consequently, cells with the CNT/SnS2@C anode exhibit a high lithium storage capacity of 837 mAh/g after 100 cycles at 0.1 A/g and retaining a capacity of 529.8 mAh/g under 1.0 A/g after 1000 cycles. This study provides a fundamental understanding of the electrochemical processes and beneficial guidance to design high-performance SnS2-based anodes for LIBs.

Rational Design of Electrolyte Additives for Improved Solid Electrolyte Interphase Formation on Graphite Anodes: A Study of 1,3,6-Hexanetrinitrile

The construction of a thin, uniform, and robust solid electrolyte interphase (SEI) film on the surface of active materials is pivotal for enhancing the overall performance of lithium-ion batteries (LiBs). However, conventional electrolytes often fail to achieve the desired SEI characteristics. In this work, we introduced 1,3,6-hexanetrinitrile (HTCN) in the baseline electrolyte (BE) of 1.0 M LiPF6 in Ethylene Carbonate/Dimethyl Carbonate (EC/DMC) (3:7 by volume) with 5 wt.% fluoroethylene carbonate (FEC), denoted as BE-FH. By systematically investigating the influence of FEC: HTCN weight ratios on the electrochemical performance of graphite anodes, we identified an optimal composition (FEC:HTCN = 5:4 by weight, denoted as BE-FH54) that demonstrated greatly improved initial Coulombic efficiency, rate capability, and cycling stability compared with the baseline electrolyte. Deviations from the optimal FEC:HTCN ratio resulted in the formation of either small cracks or excessively thick SEI layers. The enhanced performance of BE-FH54-based LiB is mainly ascribed to the synergistic effect of FEC and HTCN in forming a robust, thin, homogeneous, and ion-conducting SEI. This research highlights the importance of rational electrolyte design in enhancing the electrochemical performance of graphite anodes in LiBs and provides insights into the role of nitrile-based additives in modulating the SEI properties.

Coupling effect of defects and enriched adsorption sites in bimetal-MOF derived porous carbonaceous anode for high-performance lithium-ion capacitor

Lithium-ion capacitors (LICs) have attracted considerable attention for their ability to combine the high energy characteristics of lithium-ion batteries and the high power densities of supercapacitors. However, the development of LICs still faces critical challenges. Herein, a robust bimetal-MOF derived fluorine and nitrogen co-doped hierarchical porous carbon embedding with Co nanoparticles anode materials (Co@NFC-800) for LICs are developed, which combined with the advantages of amplified interlayer, enriched active sites and improved electrical conductivity. Both theoretically and experimentally results demonstrate that such advantaged structure via fluorine doping to introduce defects and regulate doped nitrogen atom configuration to enrich Li+ adsorption sites and enhance diffusion kinetics synergistically is attempted. Co@NFC-800 deliveres a high reversible capacity and excellent long cycling stability as anode in LIBs, By coupling the Co@NFC-800 anode with commercial activated carbon (AC) cathode, the assembled LICs deliver a high specific energy of 164 Wh kg−1 at 162.9 W kg−1 and maintained to 68.3 Wh kg−1 even at high specific power of 9.1 kW kg−1 as well as long cycling stability (80.2 % over 2000 cycles).The fluorine doping induced both enriched defects and regulable nitrogen atom configuration strategy opens up a new way of carboneous materials for lithium storage.

Soft-in-Rigid Strategy Promoting Rapid and High-Capacity Lithium Storage by Chemical Scissoring.

Large and rapid lithium storage is hugely demanded for high-energy/power lithium-ion batteries; however, it is difficult to achieve these two indicators simultaneously. Sn-based materials with a (de)alloying mechanism show low working potential and high theoretical capacity, but the huge volume expansion and particle agglomeration of Sn restrict cyclic stability and rate capability. Herein, a soft-in-rigid concept was proposed and achieved by chemical scissoring where a soft Sn-S bond was chosen as chemical tailor to break the Ti-S bond to obtain a loose stacking structure of 1D chain-like Sn1.2Ti0.8S3. The in situ and ex situ (micro)structural characterizations demonstrate that the Sn-S bonds are reduced into Sn domains and such Sn disperses in the rigid Ti-S framework, thus relieving the volume expansion and particle agglomeration by chemical and physical shielding. Benefiting from the merits of large-capacity Sn with an alloying mechanism and high-rate TiS2 with an intercalation mechanism, the Sn1.2Ti0.8S3 anode offers a high specific capacity of 963.2 mA h g-1 at 0.1 A g-1 after 100 cycles and a reversible capacity of 250 mA h g-1 at 10 A g-1 after 3900 cycles. Such a strategy realized by chemical tailoring at the structural unit level would broaden the prospects for constructing joint high-capacity and high-rate LIB anodes.

Heterostructure Engineering Enables MoSe2 with Superior Alkali-Ion Storage

Molybdenum diselenide (MoSe2) is a promising anode for alkali-ion storage due to its intrinsic advantages. However, MoSe2 still encounters the issues of structural instability and poor rate performance caused by drastic volume change and sluggish reaction kinetics. Reasonable design of electrode structure is crucial for achieving superior electrochemical performance. Herein, a novel hierarchical structure coupled with 1D/1D subunits is elaborately designed and constructed, in which the MoSe2/CoSe2 heterostructure is the “trunk” and the N-doped carbon nanotubes are the “branches” (MoSe2/CoSe2/NCNTs). Benefiting from the properties endowed by unique configurations, MoSe2/CoSe2/NCNTs electrodes manifest faster reaction kinetics and better structure durability. Evaluated as an anode for LIBs and SIBs, MoSe2/CoSe2/NCNTs deliver high reversible capacity, superior rate capability (452 at 10 A g−1 in LIBs and 296 at 10 A g−1 in SIBs), and prominent cycle life (553 after 2000 cycles at 5 A g−1 in LIBs and 310 after 2000 cycles at 5 A g−1 in SIBs). Such design conception can also provide guidance for the development of other high-performance electrodes.

A multi-kernel-shell indium selenide@carbon nanosphere enabling high-performance lithium-ion batteries

Indium selenide has garnered significant attention for high volumetric capacities, but is currently plagued by the sluggish charge transfer kinetics, severe volume effect, and rapid capacity degradation that hinder their practical applications. Herein, we design, synthesize, and characterize a multi-kernel-shell structure comprised of indium selenide encapsulated within carbon nanospheres (referred to as m-K-S In2Se3@C) through an integrated approach involving a hydrothermal method followed by a gaseous selenization process. Importantly, experimental measurements and density functional theory calculations confirm that the m-K-S In2Se3@C not only improve the adsorption capability for Li-ions but also lower the energy barrier for Li-ions diffusion. Profiting from numerous contact points, shorter diffusion distances and an improved volume buffering effect, the m-K-S In2Se3@C achieves an 800 mA h g−1 capacity over 1000 loops at 1000 mA g−1, a 520 mA h g−1 capacity at 5000 mA g−1 and an energy density of 270 Wh kg−1 when coupled with LiFePO4, surpassing most related anodes reported before. Broadly, the m-K-S structure with unique nano-micro structure offers a new approach to the design of advanced anodes for LIBs.

F, O co-doped porous hard carbon from conjugated microporous polymer for efficient lithium storage

Hard carbon is a promising alternative to conventional graphite due to its adjustable chemical composition and amorphous structure. Herein, F, O co-doped hard carbon (FOPHC) is constructed from F-containing conjugated microporous polymers, which is synthesized from 1,3,5-triethynylbenzene and 1,4-dibromotetrafluorobenzene. BET, XPS, and EDS analyses demonstrate that FOPHC is a nanoparticle with a hierarchical pore structure and F, O co-doping. When evaluated as an anode for LIBs, the FOPHC delivers an impressive 781 mA h g−1 at 0.1 A/g and 420 mA h g−1 at 0.6 A/g after 300 cycles. Kinetic calculation reveals that the dominated pseudocapacitance contribution of Li-storage in FOPHC (67.5 %, at 1.0 mV/s), attributed to the well-developed hierarchical pore structure and abundant defect sites. This work provides original insights for the microstructure regulation and design of hard carbon.

Unraveling the Interactions between Lithium and Twisted Graphene.

Graphene is undoubtedly the carbon allotrope that has attracted the attention of a myriad of researchers in the last decades more than any other. The interaction of external or intercalated Li and Li+ with graphene layers has been the subject of particular attention for its importance in the applications of graphene layers in Lithium Batteries (LiBs). It is well known that lithium atoms and Li+ can be found inside and/or outside the double layer of graphene, and the graphene layers are often twisted around its parallel plane to obtain twisted graphene with tuneable properties. Thus, in this research, the interactions between Li and Li+ with bilayer graphene and twisted bilayer graphene were investigated by a first-principles density functional theory method, considering the lithium atom and the cation at different symmetry positions and with two different adsorption configurations. Binding energies and equilibrium interlayer distances of filled graphene layers were obtained from the computed potential energy profiles. This work shows that the twisting can regulate the interaction of bilayer graphene with Li and Li+. The binding energies of Li+ systematically increase from bilayer graphene to twisted graphene regardless of twisted angles, while for lithium atoms, the binding energies decrease or remain substantially unchanged depending on the twist angles. This suggests a higher adsorption capacity of twisted graphene towards Li+, which is important for designing twisted graphene-based material for LiB anode coating. Furthermore, when the Li or Li+ is intercalated between two graphene layers, the equilibrium interlayer distances in the twisted layers increase compared to the unrotated bilayer, and the relaxation is more significant for Li+ with respect to Li. This suggests that the twisted graphene can better accommodate the cation in agreement with the above result. The outcomes of this research pave the way for the study of the selective properties of twisted graphene.