Anode For Lithium-ion Batteries Research Articles

Monolithic Layered Silicon Composed of a Crystalline-Amorphous Network for Sustainable Lithium-Ion Battery Anodes.

While nanostructural engineering holds promise for improving the stability of high-capacity silicon (Si) anodes in lithium-ion batteries (LIBs), challenges like complex synthesis and the high cost of nano-Si impede its commercial application. In this study, we present a local reduction technique to synthesize micron-scale monolithic layered Si (10-20 μm) with a high tap density of 0.9-1.0 g cm-3 from cost-effective montmorillonite, a natural layered silicate mineral. The created mesoporous structure within each layer, combined with the void spaces between interlayers, effectively mitigates both lateral and vertical expansion throughout repeated lithiation/delithiation cycles. Furthermore, the remaining SiO2 network fortifies the layered structure, preventing it from collapsing during cycling. Half-cell tests reveal a capacity retention of 92% with a reversible capacity of 1130 mAh g-1 over 500 cycles. Moreover, the pouch cell integrated with this Si anode (with a mass loading of 3.0 mg cm-2) and a commercial NCM811 cathode delivers a high energy density of 655 Wh kg-1 (based on the total mass of the cathode and anode) and maintains 82% capacity after 200 cycles. This work demonstrates a cost-efficient and scalable strategy to manufacture high-performance micron Si anodes for the ever-growing demand for high-energy LIBs.

Facile synthesis of SiOx/C as high-performance anodes for lithium-ion batteries

Despite its high capacity (∼2615 mAh·g−1), silicon oxide (SiOx) suffers from low electrical conductivity and volume expansion during cycling, leading to capacity fading. In this work, a SiOx/C composite was synthesized by magnesium thermal reduction using co-assembled mesoporous SiO2 and graphitic carbon nitride (g-C3N4) as precursors. The SiOx/C composite displays a sheet-like nanostructure with highly dispersed SiOx. The presence of carbon enhances the conductivity and structural stability of the composite, leading to a low charge resistance (94.0 Ω), fast lithium diffusion (DLi+ = 5.15 × 10−14 cm2·s−1), and excellent cycling capability (863 mAh·g−1 after 160 cycles).

Construction of sub micro-nano-structured silicon based anode for lithium-ion batteries

The significant volume change experienced by silicon (Si) anodes during lithiation/delithiation cycles often triggers mechanical-electrochemical failures, undermining their utility in high-energy-density lithium-ion batteries (LIBs). Herein, we propose a sub micro-nano-structured Si based material to address the persistent challenge of mechanic-electrochemical coupling issue during cycling. The mesoporous Si-based composite submicrospheres (M-Si/SiO2/CS) with a high Si/SiO2 content of 84.6 wt.% is prepared by magnesiothermic reduction of mesoporous SiO2 submicrospheres followed by carbon coating process. M-Si/SiO2/CS anode can maintain a high specific capacity of 740 mAh g−1 at 0.5 A g−1 after 100 cycles with a lower electrode thickness swelling rate of 63%, and exhibits a good long-term cycling stability of 570 mAh g−1 at 1 A g−1 after 250 cycles. This remarkable Li-storage performance can be attributed to the synergistic effects of the hierarchical structure and SiO2 frameworks. The spherical structure mitigates stress/strain caused by the lithiation/delithiation, while the internal mesopores provide buffer space for Si expansion and obviously shorten the diffusion path for electrolyte/ions. Additionally, the amorphous SiO2 matrix not only servers as support for structure stability, but also facilitates the rapid formation of a stable solid electrolyte interphase layer. This unique architecture offers a potential model for designing high-performance Si-based anode for LIBs.

Insight into the Role of Fluoroethylene Carbonate in Solid Electrolyte Interphase Construction for Graphite Anodes of Lithium-Ion Batteries

Insight into the Role of Fluoroethylene Carbonate in Solid Electrolyte Interphase Construction for Graphite Anodes of Lithium-Ion Batteries

A Facile Chemical Reduction Approach of Li–Sn Modified Li Anode for Dendrite Suppression

Lithium dendrites are among the most significant threats associated with the practical application of lithium metal anode in lithium batteries. Lithium dendrites are caused by the slow Li‐ion diffusivity in the bulk lithium, which results in a non‐uniform electric field‐cum‐uneven Li plating/stripping at the electrode/electrolyte interface over prolonged cycling. Herein, a facile chemical reduction method is utilized to construct a Li‐ion diffusive Li–Sn protective layer on the electrolyte‐exposed surface of lithium metal to overcome the aforementioned challenge. A systematic study on the SnCl4 precursor concentration variation demonstrated that 25 mM SnCl4 concentration is the most effective and displays a cumulative areal capacity beyond 700 mAh cm−2 at 1 mA cm−2 for 1 h. Moreover, it exhibits superior cumulative capacities than bare Li metal at higher current densities of 2 and 3 mA cm−2. In situ optical microscopy reveals more uniform lithium deposition on the Li–Sn‐modified electrode, while mossy and dendritic lithium growth is observed on the bare lithium electrode. Full cells fabricated with Li–Sn modified anode and NMC532 cathode exhibited 83% capacity retention after 150 cycles, outperforming bare Li‐containing cells, which shows a catastrophic decay post 100 cycles, illustrating the propensity for safer Li metal batteries with Li–Sn modified anode.

Core-shell NiCo2S4@C with three dimensional carbon frameworks for enhanced asymmetrical supercapacitor and lithium storage performance

Transition-metal sulfides have been considered as promising candidates for electrochemical supercapacitor and lithium ion batteries. Unfortunately, the shortcomings including large volume change, low conductivity as well as severe structural exfoliation from conductive substrate or current collector inhibit their practical application. Herein, the hydrothermal and solvothermal approach are developed for the controllable synthesis of core-shell NiCo2S4@C with three dimensional carbon frameworks. As an asymmetric supercapacitor, the NiCo2S4@C/YP-50 F displays a high energy density of 46.7 Wh kg−1 at a power density of 0.8 kW kg−1 and the good cycling stability (∼110 % of the initial capacitance retention at 16 kW kg−1 over 2000 cycles). Furthermore, the NiCo2S4@C exhibits the specific capacity of 414 mAh g−1 after 500 cycles at 2000 mA g−1 when evaluated as anode for lithium ion batteries. The excellent performance can be ascribed to the core-shell structure and the three dimensional carbon frameworks. The synthetic approach can be extended to fabricate other high performance metal sulfides for energy storage.

Lithium insertion/extraction mechanism in Mg2Sn anode for lithium-ion batteries

Due to its high capacity and excellent voltage properties, the Mg2Sn intermetallic phase is considered a promising anode material for next-generation lithium-ion batteries. However, the rapid capacity loss with cycling presently limits the application of Mg2Sn-based anodes. In this work, the Mg2Sn intermetallic phase was synthesized via a conventional casting method, and mechanisms of lithium ions intercalation into Mg2Sn alloy anodes were systematically studied. Density functional theory (DFT) calculations and electrochemical analyses identified two pathways involving four electrochemical reactions for Li+ intercalation/extraction in the Mg2Sn phase. The first pathway involves the insertion reaction of lithium ions into the octahedral sites of the Mg2Sn face center cubic (FCC) matrix, whilst the second involves the substitution of Mg by Li ions (releasing Mg metal). Furthermore, ex-situ EIS analysis and DFT calculations verified that adjusting the cut-off voltage range could control the reaction pathways. Excessively high or low cut-off voltages adversely impact the stability of the Mg2Sn anode. At cut-off voltages between 0.1 and 1 V, Mg2Sn anodes show very good capacity retention (78 % after 50 cycles), benefiting from the minimized formation of metallic Mg and Sn phases.

Nanoflake Ni-MOF anchored octahedral nickel-porphyrins as a high-performance anode for lithium-ion batteries

Metal-organic framework materials (MOFs) have great potential as organic electrode materials for lithium-ion batteries due to their amiable porous structure and property tunability. However, the structure instability and poor electrochemical durability of MOFs hinders their application. An interesting metal–organic composite composed of Ni-MOF and Nickel (II)meso-Tetraphenylporphyin (NiTPP) is strategically proposed and configured in this study. The synergic integration of Ni-MOF and NiTPP presents a stable electrochemical cycling performance with a high retention capacity up to 840 mAh/g after 200 cycles, ascribed to the facilitation of the charge transfer capability and the diffusion kinetics. The configured metal–organic composites provide an explorative approach for organic alternatives for nonaqueous metal-ion batteries.

Improving electrochemical performance of silicon anode through building “soft-hard” double-layer coating

Silicon is believed to be a critical anode material for approaching the roadmap of lithium-ion batteries due to its high specific capacity. But this aim has been hindered by the quick capacity fading of its electrodes during repeated charge–discharge cycles. In this work, a “soft-hard” double-layer coating has been proposed and carried out on ball-milled silicon particles. It is composed of inside conductive pathway and outside elastic coating, which is achieved by decomposing a conductive graphite layer on the silicon surface and further coating it with a polymer layer. The incorporation of the second elastic coating on the inside carbon coating enables silicon particles strongly interacted with binders, thereby making the electrodes displaying an obviously improved cycling stability. As-obtained double-coated silicon anodes deliver a reversible capacity of 2280 mAh g−1 at the voltage of 0.05–2 V, and maintains over 1763 mAh g−1 after 50 cycles. The double-layer coating does not crack after the repeated cycling, critical for the robust performance of the electrodes. In addition, as-obtained silicon particles are mixed with commercial graphite to make actual anodes for lithium-ion batteries. A capacity of 714 mAh g−1 has been achieved based on the total mass of the electrodes containing 10 wt.% double-coated silicon particles. Compared with traditional carbon coating or polymeric coating, the double-coating electrodes display a much better performance. Therefore, the double-coating strategy can give inspiration for better design and synthesis of silicon anodes, as well as other battery materials.

The chemo-mechanics of initiation of crack advance in Niobium Tungsten Oxide single crystals due to delithiation

Niobium tungsten oxide (NWO) micron-sized single crystals show promise as the active particles in the anodes of lithium ion batteries due to their fast charge/discharge and high storage capabilities. Within the “block” phases such as Nb16W5O55, Nb14W3O44 and the HNb2O5 polymorph, Li ion diffusion occurs in a unidirectional manner along a single axis of the crystal and lithiation/delithiation results in significant length changes in this direction. A chemo-mechanics analysis is developed for delithiation of an NWO “block” phase single crystal that contains a pre-existing flaw in the form of a through-thickness edge crack. Galvanostatic delithiation occurs by the flux of Li ions through the free ends of the crystal and also through the faces of the crack, with concomitant shrinkage of the surface layer over a depth equal to that of the crack. The induced tensile stress in the surface layer can be of sufficient magnitude to advance the crack in the NWO crystal, consistent with recent experimental observations for Nb14W3O44. A 2D full-field finite element version of the chemo-mechanics model is used to explore the sensitivity of cracking to crack length, delithiation rate of the anode, diffusivity of Li ions within the NWO single crystal storage particle and to the kinetics of Li ion transfer across the particle surface-electrolyte interface. Additionally, a simplified, lumped parameter model is developed by assuming that the Li ion occupancy is spatially uniform in a surface layer that extends to a depth of the pre-existing crack, and has a spatially uniform but different value than that of the underlying core of the particle. This simplified model can be expressed as a set of first order differential equations in time and gives the main features of delithiation and the associated transient stress state in the single crystal. Both the full model and the lumped parameter version predict that crack advance from a pre-existing defect is triggered by a high delithiation rate, consistent with the experimental literature.

Rapid preparation of Mo2CTx MXene by hydrothermal etching in ammonium hydrogen fluoride solution

In this paper, we report a novel method to rapidly prepare two-dimensional Mo2CTx MXene in a low-concentration etching solution. By this method, highly pure Mo2CTx MXene was synthesized from Mo2Ga2C by hydrothermal etching at 180 ℃ in the solution of ammonium hydrogen fluoride (NH4HF2). The whole process requires only 2 h and the etching solution concentration is only 1 M. Compared with the acid solutions used in other methods, NH4HF2 used in this method is in solid state and its water solution is mild for handling. Compared with other methods, this method requires a lower concentration of etching solution and a much shorter etching time. The Mo2CTx MXene made this method have comparable microstructure and properties with those made by other methods. The initial discharge capacity as an anode of lithium-ion batteries (LIB) was 139.35 mAh g-1 at 0.1 A g-1. After 150th cycles, the final discharge capacity was 62.42 mAh g-1 at 0.1 A g-1. The electrochemical performance is slightly higher than the sample made by general HF etching. This is the first report to make Mo2CTx MXene from the etching of bifluoride salt. Due to the short etching time and low concentration of the etching solution, this method can rapidly make Mo2CTx MXene at in low cost, which provides a route to explore the large-scale production of Mo2CTx MXene.

Catalytic decomposition of ethylene carbonate by pyrrolic-N to stabilize solid electrolyte interphase on graphite anode under extreme conditions

Despite the dominated anode materials of graphite for lithium-ion batteries (LIBs), the poor rate capability and inferior cyclability restain their applications under extreme conditions due to their deficient interfacial chemistry. Herein, an ultrathin but Li2CO3-rich solid electrolyte interphase (SEI) is manipulated by the decomposition of ethylene carbonate (EC) on graphite anode with nitrogenous amorphous carbon coating (denoted as GMIB-2P). Specifically, Li2CO3 can enable a decreased charge transfer resistance and faster Li+ diffusion capability. In addition, we demonstrate the catalytic effect of pyrrolic-N on graphite surface with prominent wettability induces the rapid decomposition of EC with low reaction energy barrier through density function theory (DFT) calculation. Consequently, GMIB-2P delivers an outstanding capacity retention ratio of 90.82% after 300 cycles at 1 C and an improved initial Coulombic efficiency (ICE, 90.77% vs. 85.35%). More importantly, GMIB-2P possesses durable-cycling capability even with lean electrolytes of 5 μL mg-1 and as well as 85.68% capacity retention for over 300 cycles at 60 ℃. Our work highlights the key role of EC in tailoring interfacial chemistry from structure regulations and provides new guidelines to design more reliable anodes for LIBs under extreme conditions.

Ion-crosslink alginate emulsion droplets toward synthesis of porous carbon microspheres as anodes for lithium-ion batteries

Porous carbon microsphere (PCM) is an important anode material for lithium-ion batteries; however, the preparation of PCM at large scale is still complex, sometimes even needing sophisticated instruments. Herein, we developed a water-in-oil (W/O) phase-separation strategy to prepare PCM in terms of simple and low-cost manner. As-prepared PCM has a large surface area of 182 m2/g, and abundant mesopores, which benefits the penetration of Li+-carrying electrolyte into the electrode. Therefore, the optimized PCM electrode shows a high-rate capability (408 mA h g−1 at 2 A/g). This work broadens a new vision in preparing PCM for energy-storage/-conversion applications.

Lithium-Ion Dynamic and Storage of Atomically Precise Halogenated Nanographene Assemblies via Bottom-Up Chemical Synthesis.

Graphene has received much scientific attention as an electrode material for lithium-ion batteries because of its extraordinary physical and electrical properties. However, the lack of structural control and restacking issues have hindered its application as carbon-based anode materials for next generation lithium-ion batteries. To improve its performance, several modification approaches such as edge-functionalization and electron-donating/withdrawing substitution have been considered as promising strategies. In addition, group 7A elements have been recognized as critical elements due to their electronegativity and electron-withdrawing character, which are able to further improve the electronic and structural properties of materials. Herein, we elucidated the chemistry of nanographenes with edge-substituted group 7A elements as lithium-ion battery anodes. The halogenated nanographenes were synthesized via bottom-up organic synthesis to ensure the structural control. Our study reveals that the presence of halogens on the edge of nanographenes not only tunes the structural and electronic properties but also impacts the material stability, reactivity, and Li+ storage capability. Further systematic spectroscopic studies indicate that the charge polarization caused by halogen atoms could regulate the Li+ transport, charge transfer energy, and charge storage behavior in nanographenes. Overall, this study provides a new molecular design for nanographene anodes aiming for next-generation lithium-ion batteries.

Self-consuming expansion stress construct piezoelectric field to accelerate anion for SiO/PbZr0.52Ti0.48O3 with persistent lithium storage performance

The high theoretical specific capacity and suitable working potential of silicon oxides (SiOx) making it one of the most promising candidates for the next generation of lithium-ion battery anode materials. However, the large-scale application of SiOx in lithium-ion battery anodes is hampered by the huge volume change (>200 %) during cycling process. This experiment adopts a method which is completely contrary to the traditional modification method——composite with piezoelectric materials to take advantage of this expansion. During the lithiation process, the significant volume expansion stress of SiO is transformed into a driving force by PbZr0.52Ti0.48O3 (PZT) particles that enhances the transport of Li+. The polarization of PZT particles occurs as a result of the consumption of mechanical stress caused by the expansion of SiO, leading to the generation of a piezoelectric potential. Since then, the volume expansion stress of SiO when deintercalating lithium is converted into a potential difference, which can promote the migration of Li+. This process not only reduces the volume expansion of SiO, but also promotes the mobility of Li+. The SiO/PZT anode shows an admirable cycle performance: The discharge capacity is 825.4 mA h g−1, and the capacity retention ratio is reach up to 92.5 % (200 mA g−1, 200 cycles). These findings illuminate the surface coupling approach employed to regulate the behavior of interfacial Li+ kinetics, while simultaneously enhancing the structural stability of alloy-based anodes. This research will undoubtedly capture the attention of researchers engaged in the study of multifunctional interface design for electrochemical systems.

N-doped C encapsulated Li2TiSiO5 nanoparticles for high-rate highly stable lithium storage

Achieving high charging rates (≤ 15 min) in lithium-ion batteries (LIBs) is imperative for their widespread implementation in all-electric vehicles. However, the pursuit of elevated charging rates often leads to compromises in capacity and cycling stability. In this manuscript, we present a groundbreaking approach utilizing a composite material composed of nitrogen-doped carbon-encapsulated Li2TiSiO5 nanoparticles (LTSO@C-N) as the anode material for LIBs, offering rapid and exceptionally stable lithium storage. The encapsulation of Li2TiSiO5 nanoparticles by nitrogen-doped carbon is realized via a facile liquid-phase polymerization and the following pyrolysis route. The uniformly deposited nitrogen-doped carbon layer on the surface of Li2TiSiO5 nanoparticles within LTSO@C-N serves a dual purpose: enhancing the conductive properties of Li2TiSiO5 to ensure efficient charge transfer and Li+ transport, while concurrently inhibiting grain pulverization over extended cycling periods. The deliberate incorporation of nitrogen-doped carbon optimizes Li2TiSiO5 anode electrochemical performance, simultaneously reducing structural degradation during prolonged cycling. This enhances the lithium-ion battery system's long-term stability and reliability. While exhibiting an average operational potential of approximately 0.28 V in comparison to Li+/Li, the LTSO@C-N electrode manifests a commendable specific capacity of 345 mAh g-1 at a current density of 0.1 A g-1. Notably, it attains a robust lithium storage capability even under high-rate conditions, exemplified by a sustained capacity of 205 mAh g-1 over 1000 cycles at 2 A g-1, devoid of any discernible decay. The electrode's impressive electrochemical performance highlights its potential as an advanced anode for high-performance lithium-ion batteries, ensuring stability.

Core-Double-Shell TiO2@Fe3O4@C Microspheres with Enhanced Cycling Performance as Anode Materials for Lithium-Ion Batteries.

Due to the volume expansion effect during charge and discharge processes, the application of transition metal oxide anode materials in lithium-ion batteries is limited. Composite materials and carbon coating are often considered feasible improvement methods. In this study, three types of TiO2@Fe3O4@C microspheres with a core-double-shell structure, namely TFCS (TiO2@Fe3O4@C with 0.0119 g PVP), TFCM (TiO2@Fe3O4@C with 0.0238 g PVP), and TFCL (TiO2@Fe3O4@C with 0.0476 g PVP), were prepared using PVP (polyvinylpyrrolidone) as the carbon source through homogeneous precipitation and high-temperature carbonization methods. After 500 cycles at a current density of 2 C, the specific capacities of these three microspheres are all higher than that of TiO2@Fe2O3 with significantly improved cycling stability. Among them, TFCM exhibits the highest specific capacity of 328.3 mAh·g-1, which was attributed to the amorphous carbon layer effectively mitigating the capacity decay caused by the volume expansion of iron oxide during charge and discharge processes. Additionally, the carbon coating layer enhances the electrical conductivity of the TiO2@Fe3O4@C materials, thereby improving their rate performance. Within the range of 100 to 1600 mA·g-1, the capacity retention rates for TiO2@Fe2O3, TFCS, TFCM, and TFCL are 27.2%, 35.2%, 35.9%, and 36.9%, respectively. This study provides insights into the development of new lithium-ion battery anode materials based on Ti and Fe oxides with the abundance and environmental friendliness of iron, titanium, and carbon resources in TiO2@Fe3O4@C microsphere anode materials, making this strategy potentially applicable.

A Naphthalenetetracarboxdiimide‐Containing Covalent Organic Polymer: Preparation, Single Crystal Structure and Battery Application

AbstractInspired by dative boron‐nitrogen (B←N) bonds proven to be the promising dynamic linkage for the construction of crystalline covalent organic polymers/frameworks (COPs/COFs), we employed 1,4‐bis(benzodioxaborole) benzene (BACT) and N,N′‐Di(4‐pyridyl)‐1,4,5,8‐naphthalenetetracarboxdiimide (DPNTCDI) as the corresponding building blocks to construct a functional COP (named as CityU‐25), which had been employed as an anode in rechargeable lithium ion batteries. CityU‐25 displayed an excellent reversible lithium storage capability of 455 mAh/g after 170 cycles at 0.1 A/g, and an impressive one of 673 mAh/g after 720 cycles at 0.5 A/g. These findings suggest that CityU‐25 is a standout candidate for advanced battery technologies, highlighting the potential application of this type of materials.

A Naphthalenetetracarboxdiimide-Containing Covalent Organic Polymer: Preparation, Single Crystal Structure and Battery Application.

Inspired by dative boron-nitrogen (B←N) bonds proven to be the promising dynamic linkage for the construction of crystalline covalent organic polymers/frameworks (COPs/COFs), we employed 1,4-bis(benzodioxaborole) benzene (BACT) and N,N'-Di(4-pyridyl)-1,4,5,8-naphthalenetetracarboxdiimide (DPNTCDI) as the corresponding building blocks to construct a functional COP (named as CityU-25), which had been employed as an anode in rechargeable lithium ion batteries. CityU-25 displayed an excellent reversible lithium storage capability of 455 mAh/g after 170 cycles at 0.1 A/g, and an impressive one of 673 mAh/g after 720 cycles at 0.5 A/g. These findings suggest that CityU-25 is a standout candidate for advanced battery technologies, highlighting the potential application of this type of materials.

Additive-Free Anode with High Stability: Nb2CTx MXene Prepared by HCl-LiF Hydrothermal Etching for Lithium-Ion Batteries.

MXenes, represented by Ti3C2Tx, have been widely studied in the electrochemical energy storage fields, including lithium-ion batteries, for their unique two-dimensional structure, tunable surface chemistry, and excellent electrical conductivity. Recently, Nb2CTx, as a new type of MXene, has attracted more and more attention due to its high theoretical specific capacity of 542 mAh g-1. However, the preparation of few-layer Nb2CTx nanosheets with high-quality remains a challenge, which limits their research and application. In this work, high-quality few-layer Nb2CTx nanosheets with a large lateral size and a high conductivity of up to 500 S cm-1 were prepared by a simple HCl-LiF hydrothermal etching method, which is 2 orders of magnitude higher than that of previously reported Nb2CTx. Furthermore, from its aqueous ink, the viscosity-tunable organic few-layer Nb2CTx ink was prepared by HCl-induced flocculation and N-methyl-2-pyrrolidone treatment. When using the organic few-layer Nb2CTx ink as an additive-free anode of lithium-ion batteries, it showed excellent cycling performance with a reversible specific capacity of 524.0 mAh g-1 after 500 cycles at 0.5 A g-1 and 444.0 mAh g-1 after 5000 cycles at 1 A g-1. For rate performance, a specific capacity of 159.8 mAh g-1 was obtained at a high current density of 5 A g-1, and an excellent capacity retention rate of about 95.65% was achieved when the current density returned to 0.5 A g-1. This work presents a simple and scalable process for the preparation of high-quality Nb2CTx and its aqueous/organic ink, which demonstrates important application potential as electrodes for electrochemical energy storage devices.