Low Open-circuit Voltage Research Articles

Metallic bilayer Kagome borophene as a promising anode material for Li and post-Li ion batteries

For future breakthroughs in alkali metal ion batteries, it is essential to explore new anode materials with high storage capacity. Recently, a novel two-dimensional material, bilayer Kagome borophene (BK-borophene), consisting of lightweight elemental boron and having excellent metal conductivity, has been proposed. Thus, the structure, stability, electronic and electrochemical properties of BK-borophene are investigated using first-principles calculations to examine its feasibility as an anode material. Our results show that a single Li/Na/K can stably adsorb on the BK-borophene surface with adsorption energy values of −0.46/-0.25/-0.69 eV. Besides, the low diffusion barrier values (0.55/0.30/0.15 eV) ensure that Li/Na/K can migrate rapidly on its surface, and the low open circuit voltage values are favorable for increasing the operating voltage of the assembled battery. Most importantly, BK-borophene shows high theoretical storage capacities of 826 mA h g−1 for Li, 1377 mA h g−1 for Na, and 275 mA h g−1 for K, which is much more favorable than other reported anode materials. Not only that, BK-borophene also exhibits good cycling stability. The above-mentioned findings suggest that BK-borophene can be a promising and convincing anode material for alkali metal ion batteries.

Influence of Ti Layers on the Efficiency of Solar Cells and the Reduction of Heat Transfer in Building-Integrated Photovoltaics

This study examined the potential application of metallic coatings to mitigate the adverse effects of ultraviolet (UV) and infrared (IR) light on photovoltaic modules. Titanium coatings were applied on low-iron glass surfaces using magnetron sputtering at powers of 1000, 1250, 1500, 1750, 2000, and 2500 W. The module with uncoated glass served as a reference. The Ti layer thickness varied from 7 nm to 20 nm. Transmittance and reflectance spectra were used to calculate visible light transmittance Lt, UV light transmittance Ltuv, solar transmittance g, and visible light reflectance Lr. The obtained parameters indicated that the thinnest Ti layer (1000 W) coating did not significantly affect light transmittance, but thicker layers did, altering the Lt, g, and Lr factors. However, every sample noticeably changed Ltuv, probably due to the natural formation of a UV-reflective thin TiO2 layer. The differences in fill factor (FF) were minimal, but thicker coatings resulted in lower open-circuit voltages (Uoc) and short-circuit currents (Isc), leading to a reduction in power conversion efficiency (PCE). Notably, a Ti coating deposited at 2500 W reduced the power of the photovoltaic module by 78% compared to the uncoated sample but may protect modules against the unwanted effects of overheating.

Photoinduced Zn-Air Battery-Assisted Self-Powered Sensor Utilizing Cobalt and Sulfur Co-Doped Carbon Nitride for Portable Detection Device.

Most self-powered electrochemical sensors (SPESs) are limited by low open circuit voltage and power density, leading to a narrow detection range and low sensitivity. Herein, a photoinduced Zn-air battery-assisted SPES (ZAB-SPES) is proposed based on cobalt and sulfur co-doped carbon nitride with the cyano group (Co, S-CN). The cyano functionalization remarkably enhances visible light utilization, and the cyano moiety acts as an electron-withdrawing group to promote electron enrichment. Co and S co-doping can create a p-n homojunction within carbon nitride, enabling the efficient migration and separation of carriers, thereby significantly improving the performance of the oxygen reduction reaction. The synergistic effects endow Co, S-CN photocathode with an open circuit voltage of 1.85V and the maximum power density of 43.5µW cm-2 in the photoinduced ZAB. Employing heavy metal copper ions as the target model, the photoinduced ZAB-SPES exhibited dual-mode and sensitive detection. Furthermore, a portable detection device based on the photoinduced ZAB-SPES is designed and exhibits high linearity in the range of 5 ~ 600nM with a detection limit of 1.7nM. This work offers a portable detection method based on the photoinduced ZAB-SPES in the aquatic environment.

Dimerized Non-Fullerene Acceptor-based organic photovoltaics for Round-the-Clock functioning

Organic photovoltaics (OPVs) have emerged as a key sustainable energy technology capable of efficiently generating electricity from both direct sunlight and low-intensity indoor lighting. Despite ongoing research to improve their performance, limited efforts have been undertaken to develop OPVs that can operate consistently (24/7/365) under versatile lighting conditions. For effective utilization, OPVs must demonstrate efficient operation under both outdoor and indoor illumination conditions, generating sufficient electrical power to drive microelectronic devices. Low-bandgap non-fullerene acceptors (NFAs) in OPVs are limited by low open-circuit voltage (VOC) under indoor lighting, restricting their performance. While high-bandgap NFAs can improve indoor power-conversion efficiency (PCE) by elevating VOC, they may often reduce outdoor performance owing to reduced light harvesting. Thus, we developed OPVs using the oligomeric dimerized NFA DYBO, which simultaneously achieved an excellent PCE of 16.7 % under simulated solar illumination and a remarkable maximum power output density (Pmax) of 0.079 and 0.396 mW/cm2 under a 5,200 K LED and halogen lamp (1000 lx), respectively, attributed to elevated VOC and reduced short-circuit current density (JSC) losses. The optimized OPVs demonstrated PCEs nearly equivalent to those of the current state-of-the-art under indoor illumination, with a remarkable Pmax capable of autonomously powering a variety of microelectronic devices.

Exploring the potential of two-dimensional MB4 (M=Cr, Mo, and W) monolayer as a high-capacity negative electrode material for Al-ion batteries

Rechargeable metal-ion batteries can employ two-dimensional transition metal tetraboride monolayers because of their numerous accommodating sites, high specific surface area, and layered structure. Li-ion batteries (LIBs) can be efficiently replaced by aluminum ion batteries (AIBs) because aluminum is a cheap and abundant resource. In this work, the density functional theory approach has been used for Al-ion batteries to predict MB4(M= Cr, Mo, W) monolayers performance as anode material. We analyze these monolayers' structures, which are mechanically, thermally, and dynamically stable. Utilizing the energy-efficient adsorption of six Al-atom layers and their lightweight properties, with large storage capacities of 5066 mA h g−1, 3466 mA h g−1, and 2124 mA h g−1, with relatively low average open circuit voltages of 0.18 V, 0.15 V, and 0.11 V for CrB4, MoB4, and WB4, respectively, these monolayers show significant superiority over other 2D anode materials. Likewise, MB4 monolayer showed faster Al ion mobility as seen by the low activation barriers of 0.95 eV, 0.83 eV, and 0.49 eV for CrB4, MoB4, and WB4, respectively. Additionally, even after the full content of Al ions was adsorbed, the metallic characteristics of the materials were mostly retained. These traits suggest that monolayer CrB4, MoB4, and WB4 are promising anode materials for AIBs, with impressive rate capacities.

Strain Engineering of ScYCCl2 MXene Monolayer and Intercalation of Metal-ions on MXene Surface: A DFT Study

The present work theoretically examines the influence of bi-axial strain on functionalized ScYCCl2 monolayer. The indirect to direct band gap transition on tensile conditions and the phase transition from semiconductor to metal on compressive strain have been studied. The analysis of extreme conditions of 10% compressive and 10% tensile strain through phonon and AIMD simulations underscore the kinetic and thermal stability, respectively of the monolayer under strain. These findings assure the possibility of experimental synthesis of the ScYCCl2 monolayer. After metallization, ScYCCl2 MXene is used as an anode of metal-ion (−Na, −K, −Li, −Mg) batteries as it has high theoretical storage capacity and low open circuit voltage. Work function engineering and the strain-dependent optical behavior of the ScYCCl2 monolayer have been examined. The work function of the ScYCCl2 monolayer has been raised under compressive strain and decreased under tensile strain. The Crystal Orbital Hamiltonian Population has been simulated under tensile and compressive strain to check the bond- strengths. Hence, the ScYCCl2 monolayer has the capability to alter its characteristics under strain. The improved optical characteristics recommend its applications in low-dimensional photonic devices and metallization after compressive strain recommends its energy storage applications in metal-ion batteries.

Harnessing MBene termination for superior anode interfaces in Li/Ca-ion batteries

The elevation of two-dimensional (2D) transition metal borides, specifically MBenes, as anode materials for lithium-ion batteries (LIBs) and calcium-ion batteries (CIBs) can be achieved through strategic functionalization with appropriate groups. Utilizing a first-principles approach, we conducted an in-depth investigation into the electrochemical properties of chlorine-terminated V2B (V2BCl2) as a candidate anode material for LIBs and CIBs. V2BCl2 exhibits metallic behavior, as demonstrated by band structure analysis, which endows it with exceptional conductivity due to the free electron surface of the system, thereby embodying ideal anode characteristics. The dynamic and thermal stability of the system was assessed through comprehensive phonon dispersion analyses and ab-initio molecular dynamics (AIMD) calculations. High net charge transfer rates of Li/Ca ions towards the monolayer, augmented electron localization function (ELF) near system atoms, and the presence of ionic bonds between Ca/Li and the V2BCl2 monolayer contribute to the enhanced conductivity observed in these anode systems. This is corroborated by metrics such as the projected crystal orbital Hamiltonian population (-pCOHP), low diffusion energy barriers (< 0.35 eV) facilitating rapid charging mechanisms, and low open circuit voltages (< 0.32 V) ensuring robust battery performance stability. Furthermore, V2BCl2 exhibits notable specific storage capacities of 875.67 mAh g−1 for Ca ions and 1167.75 mAh g−1 for Li ions, surpassing the benchmarks set by recent MBene systems. These promising results strongly advocate for V2BCl2 as a viable candidate for anode material in both LIB and CIB applications, highlighting its potential significance in advancing battery technology.

Breaking new ground in metal-ion battery anodes: First principles design of Dirac nodal line semimetallic carbon materials

With the rapid development of electronic devices, the demand for batteries has gradually increased, and existing batteries can no longer satisfy it. In this paper, a three-dimensional honeycomb carbon material is designed and termed pmma-C32. The mechanical stability, dynamic stability, thermal stability, and mechanical stability were investigated through first-principles molecular dynamics, phonon spectrum, and the Born-Huangkun criterion. The calculation results show that pmma-C32 not only has good thermodynamic stability, but also has static stability. Similar to graphene, pmma-C32 exhibits semi-metallic characteristics, featuring two Dirac node lines with high Fermi velocity, indicating a high capacity for electron transport. As a metal-ion battery material, pmma-C32 exhibits higher theoretical capacity(836.8, 732.2, and 418.4 mA h/g for Li, Na, and K), lower diffusion barrier (0.06–0.12 eV for Li, 0.10–0.11 eV for Na, and 0.05–0.06 eV for K), and lower open circuit voltage (0.34 V for Li, 0.37 V for Na, and 0.74 V for K). These remarkable properties endow semimetallic pmma-C32 as a promising anode material for metal-ion batteries, providing fast charge and discharge rates. This research not only broadens the family of three-dimensional carbon materials, but also greatly improves the performance for universal metal-ion battery anode materials through material structure design.

Two-dimensional BC12 as an ultra-high performance anode material for lithium-ion batteries

With the gradual development of renewable energy, search for high-performance energy storage materials as anodes for lithium-ion batteries (LIBs) has become urgent. Two-dimensional (2D) materials are considered as candidates for anode materials due to their unique structure and physicochemical properties. Based on first-principles calculations, we propose a 2D material, BC12 monolayer, as an excellent anode for LIBs. BC12 exhibits outstanding dynamic, mechanical, and thermal stability. In addition, BC12 monolayers show not only remarkably high storage capacity (2767.57 mA h g−1) but also low diffusion barrier energy (0.175 eV) and appropriate open circuit voltage (0.3 V). A small volume expansion (0.38%) is also observed during the lithiation process. Furthermore, we undertake a comprehensive analysis on the impact of carbon vacancy in BC12. The presence of carbon vacancy makes the adsorption and diffusion of Li relatively weak, which should be carefully handled in the experimental synthesis process. The above-mentioned investigation offers valuable insights and guidance for the future development and application of 2D anode materials in metal-ion batteries.

Potential Application of 2D Haeckelite MoS2 as an Anode Material for Mg Ion Batteries.

The design and preparation of anode materials with structural stability, fast ion transmission, and low open-circuit voltage are critical to the development of magnesium ion batteries (MIBs). The feasibility of the unique phase Haeckelite MoS2 (Hae-MoS2) monolayer with Haeckelite structure as a potential anode material for MIBs was investigated using density functional theory (DFT) calculations. The Hae-MoS2 monolayer exhibits excellent structural stability and semimetallic characteristics with a Dirac cone located at the Gamma point of band structure. Mg ion is easily adsorbed on the Hae-MoS2 monolayer surface with an adsorption energy of -2.06 eV and can diffuse rapidly with a low diffusion energy barrier (0.3 eV), indicating excellent charge and discharge rates. Most importantly, the Hae-MoS2 monolayer exhibits a suitable open-circuit voltage, which falls within the desired voltage range and ensures the safety of battery performance. These exceptional properties indicate that the Hae-MoS2 monolayer can be proposed as a candidate for anode material for MIBs.

Amphipathic Astaxanthin Additive for Low Voltage-loss Perovskite Solar Cells With Enhanced Quasi-Fermi Level Splitting and Solar Hydrogen Production Application.

Even though the power conversion efficiency (PCE) of perovskite solar cells (PSCs) is nearly approaching the Schottky-Queisser limit, low open-circuit voltage (Voc) and severe Voc loss problems continue to impede the improvement of PCEs. Astaxanthin (ASTA) additive is introduced in the formamidinium lead triiodide (FAPbI3)perovskite film as an additive, which can facilitate the transportation of charge carriers and interact with Pb2+ by its distinctive groupings. Furthermore, the addition of ASTA decreases the defect's active energy, regulates the deep-level defect by filling up the grain boundaries (GBs), and promotes the crystallization of perovskite film. Remarkably, an enhanced quasi-Fermi level splitting (QFLS) of 1.164eV and a reduced Voc loss of only 96mV are realized. The champion PCE of 24.56% is attained by ASTA-modified PSCs on the basis of 22.75% PCE. Moreover, the PSCs that underwent ASTA modification demonstrate improved operational stability, ensuring consistent output in real-world scenarios. Furthermore, PSCs with an active area of 1 cm2 are used for water electrolysis to produce hydrogen and exhibit a PCE of 22.41%. This work offers an environmentally benign solution to address the inherent issues of FAPbI3 PSCs and lays the groundwork for the development of a prospective solar hydrogen production application.

Theoretical prediction of two-dimensional metallic AM2B8 (AM = K, Rb, Cs) as anode materials for Na-ion batteries

The development of two-dimensional anode materials with superior performance is becoming a critical undertaking for the advancement of Na-ion battery technology. Using isoelectronic substitution strategies, we predicted three alkali metal borides AM2B8 (AM = K, Rb, Cs) based on the SrB8 monolayer. Ab initio molecular dynamics simulations and phonon dispersion relationship calculations demonstrated their stability. Using density functional theory, we predict the feasibility of these three new metal nanosheets as anodes for Na-ion batteries. The AM2B8 monolayer retains its metallicity after the insertion of Na ions, ensuring that the anode has good electrical conductivity. In addition, AM2B8 has a low diffusion barrier and open circuit voltage (K2B8 is 0.08 eV and 0.26 V) during charge/discharge. In the voltage range that inhibits dendrite growth, K2B8 can reach the maximum theoretical specific capacity (326 mAh/g). These results indicate that AM2B8, especially K2B8, is a promising anode material for Na-ion batteries.

Additive engineering for efficient wide-bandgap perovskite solar cells with low open-circuit voltage losses.

High-performance wide-bandgap (WBG) perovskite solar cells are used as top cells in perovskite/silicon or perovskite/perovskite tandem solar cells, which possess the potential to overcome the Shockley-Queisser limitation of single-junction perovskite solar cells (PSCs). However, WBG perovskites still suffer from severe nonradiative recombination and large open-circuit voltage (Voc) losses, which restrict the improvement of PSC performance. Herein, we introduce 3,3'-diethyl-oxacarbo-cyanine iodide (DiOC2(3)) and multifunctional groups (C=N, C=C, C-O-C, C-N) into perovskite precursor solutions to simultaneously passivate deep level defects and reduce recombination centers. The multifunctional groups in DiOC2(3) coordinate with free Pb2+ at symmetric sites, passivating Pb vacancy defects, effectively suppressing nonradiative recombination, and maintaining considerable stability. The results reveal that the power conversion efficiency (PCE) of the 1.68eV WBG perovskite solar cell with an inverted structure increases from 18.51% to 21.50%, and the Voc loss is only 0.487V. The unpackaged device maintains 95% of its initial PCE after 500h, in an N2 environment at 25°C.

Exploring the potential of 2D [formula omitted]-SiC[formula omitted] monolayer as an anode material for Li-ion batteries: Ab initio investigation

In the development of energy storage in 2D materials, low cost, high storage capacity, and fast ion diffusion remain desirable challenges. In this context, this study aims to systematically investigate the potential of α-SiC7 monolayer as an anode material for lithium-ion batteries through first-principles calculations. The results imply that α-SiC7 nanosheets have good electrical conductivity, outstanding dynamic and thermal stability. In addition, the α-SiC7 monolayer showed a high theoretical capacity of 1194.91 mA h/g which is almost three times that of graphite. Our findings also indicate that lithium-ion diffusion on the orthorhombic monolayer is extremely fast with a quite low energy barrier of 0.52 eV, much lower than many other anode materials reported for Li-ion batteries. Moreover, the Li atoms intercalated in the α-SiC7 monolayer show a low open-circuit voltage of 0.16 V. Ultimately, the results of our study suggest that the α-SiC7 monolayer is a promising anode material, offering high capacity and high-rate capability for the next generation of high-performance lithium-ion batteries.

Theoretical Investigation of a Novel Two-Dimensional Non-MXene Mo3C2 as a Prospective Anode Material for Li- and Na-Ion Batteries.

A new two-dimensional (2D) non-MXene transition metal carbide, Mo3C2, was found using the USPEX code. Comprehensive first-principles calculations show that the Mo3C2 monolayer exhibits thermal, dynamic, and mechanical stability, which can ensure excellent durability in practical applications. The optimized structures of Lix@(3×3)-Mo3C2 (x = 1-36) and Nax@(3×3)-Mo3C2 (x = 1-32) were identified as prospective anode materials. The metallic Mo3C2 sheet exhibits low diffusion barriers of 0.190 eV for Li and 0.118 eV for Na and low average open circuit voltages of 0.31-0.55 V for Li and 0.18-0.48 V for Na. When adsorbing two layers of adatoms, the theoretical energy capacities are 344 and 306 mA h g-1 for Li and Na, respectively, which are comparable to that of commercial graphite. Moreover, the Mo3C2 substrate can maintain structural integrity during the lithiation or sodiation process at high temperature. Considering these features, our proposed Mo3C2 slab is a potential candidate as an anode material for future Li- and Na-ion batteries.

A first-principles research on the properties of two-dimensional penta-BP2 as an anode material for both Na and K ion batteries

The escalating demand for large-scale energy storage solutions has sparked significant interest in metal-ion batteries, particularly in the realm of high-performance anode materials. This work explores the potential of penta-BP2 as an anode material for sodium and potassium-ion batteries through first-principles calculations. The two-dimensional metallic structure of penta-BP2 exhibits favorable electrical conductivity, making it an ideal candidate for anode materials. Theoretical analysis reveals that penta-BP2 can adsorb two layers of Na and three layers of K, resulting in high storage capacities of 1105 and 1473 mAh/g, along with low open-circuit voltages of 0.40 and 0.30 V, respectively. These characteristics enable the production of high energy density in sodium and potassium-ion batteries. Additionally, the material's small Young's modulus and low diffusion energy barriers further establish penta-BP2 as a flexible anode material capable of rapid charge/discharge processes.

Ultrahigh Potassium Storage Capacity of Ca2Si Monolayer with Orderly Multilayered Growth Mechanism.

As the rising renewable energy demands and lithium scarcity, developing high-capacity anode materials to improve the energy density of potassium-based batteries (PBBs) is increasingly crucial. In this work, a unique orderly multilayered growth (OMLG) mechanism on a 2D-Ca2Si monolayer is theoretically demonstrated for potassium storage by first-principles calculations. The global-energy-minimum Ca2Si monolayer is a semiconductor with isotropic mechanical properties and remarkable electrochemical properties, such as a low potassium ion migration energy barrier of 0.07eV and a low open circuit voltage ranging from 0.224 to 0.003V. Most notably, 2D-Ca2Si demonstrates an ultrahigh theoretical specific capacity of 5459mAhg-1 and a total specific capacity of 610mAhg-1, reaching up to 89% of the capacity of a potassium metal anode. Remarkably, the OMLG mechanism facilitates stable, dendrite-free deposition of hcp-K metal layers on the 2D-Ca2Si surface, where the ultrahigh and gradually converging lattice match as the layers increase is the key to achieving theoretically near-infinite growth. The study theoretically demonstrates the Ca2Si monolayer a highly promising anode material, and offers a novel potassium storage strategy for designing 2D anode materials with high specific capacity, rapid potassium-ion migration, and good safety.

Effective surface treatment for efficient and stable inverted inorganic CsPbI2Br perovskite solar cells

The interest in all-inorganic perovskite solar cells (PSCs) featuring a p-i-n structure is on the rise, attributed to their superior heat resistance and adaptability with tandem cell methods. However, their progress has been far from the regular structure owing to the comparatively low open circuit voltage (Voc). This research employs phenylethylammonium iodide, incorporating various side groups, as passivators to tackle the previously mentioned problems and investigate their effects on passivation. It is found that a reduction of trap-state density in perovskite film was accomplished due to the PEAI effective passivation effect by establishing coordination with the under-coordinated Pb2+ ions. Furthermore, there was an enhancement in the alignment of energy levels at the CsPbI2Br perovskite/PCBM junction, resulting in better charge extraction from the CsPbI2Br layer to the charge transport layer. As a result, an improved champion efficiency of 14.26 % with a Voc of 1.11 V, Jsc of 16.21 mA/cm2, and FF of 79.28 % was yielded for the PEAI treatment inverted CsPbI2Br device, compared with the 12.15 % efficiency of the control device. Superior device stability was exhibited for the optimal PEAI-treated devices without encapsulation. This research validates the significance of a side group on a surface passivation molecule to effectively passivate defects and optimize energy levels, especially for boosting Voc.

Air processed, high open‐circuit voltage indoor organic photovoltaic cells based on side chain modified N‐annulated perylene diimides

AbstractTo achieve high‐performance indoor organic photovoltaics (OPVs), it is important to match the photoactive layer optical absorption with the light‐source emission. This can be accomplished by developing organic photoactive materials that can efficiently absorb visible light and thus minimize energy losses. While indoor OPVs have achieved efficiencies above 33% under low light intensities, the power output is limited by low open circuit voltages (VOC), often well below 1 V. In this study, we present a series of visible‐light absorbing (energy gap &gt;1.90 eV) non‐fullerene acceptors (NFAs) based on perylene diimide dimers, which have been systematically modified with side chains of varying polarity and steric bulk (trimethyl benzyl, ethyl adamantane, trialkoxyl phenyl, and oligo ethylene glycol). Our results show that the incorporation of sterically bulky side chains such as ethyl adamantane and trimethyl benzyl, blended with the common widegap polymer PTQ10, provides photoactive layers with absorption greater than 2.0 eV, and consequently, VOCs higher than 1.2 V are achieved under AM 1.5 G illumination. Importantly, we found that the NFA with ethyl adamantane based side chains (tPDI2N‐ethyl adamantane, compound 4) exhibited the best performance, with minimized energy loss. As a result, devices using PTQ10:tPDI2N‐ethyl adamantane photoactive layers demonstrated excellent indoor efficiencies of over 16% and 18 μW cm−2 power output under a 2700 K LED lamp at 300 lux, and showed better repeatability compared to other systems. The PTQ10:tPDI2N‐ethyl adamantane based devices maintained a high VOC (&gt;1.0 V) across a wide range of indoor lighting conditions, including 2700 K and 6500 K LED lamps. Overall, this work provides a sidechain engineering method to create NFAs for efficient indoor OPV devices.

Theoretical prediction on Irida-graphene monolayer as promising anode material for lithium-ion batteries

With the growing interest in energy storage technologies, the demand for alternative rechargeable batteries has become increasingly urgent. We evaluate the feasibility of a two-dimensional (2D) material, Irida-graphene (IG) monolayer, as an anode for lithium-ion batteries (LIBs) through first-principles calculations. IG monolayer, after Li adsorption, exhibits metallic property, suggesting the good electrical conductivity. Additionally, in comparison with IG bilayer, IG monolayer possesses low diffusion barriers (0.19–0.24 eV), high theoretical capacity (1115.8mA h/g), and low average open circuit voltage (0.317 V). Furthermore, under the influence of solvent effects, the adsorption performance becomes even more stable, and the theoretical capacity increases. These intriguing findings make IG monolayer great potentials for the anode of LIBs.