Li-ion Battery Applications Research Articles

Enhanced electrochemical performance and storage mechanism of LiFePO4 doped by Co, Mn and S elements for lithium-ion batteries

How to improve the diffusion coefficient of Lithium ions in active materials is very necessary, which is responsible for the electrochemical performance. In this present contribution, LiFe10/12Co1/12Mn1/12P11/12S1/12 O4(LF(CM)P(S)O) are designed and the stability, lithium ion diffusion rate, lithium intercalation potential, discharge curve, and electronic performances are systematically explored. The LF(CM)P(S)O shows the better stability with the formation energy of 2.01 eV. The lithium ion diffusion barrier of the system is reduced from 1.02 to 0.57 eV after doping, predicting that the lithium ion diffusion rate in LF(CM)P(S)O is 10 orders of magnitude faster than that of intrinsic system. The characteristic transition from p-type to n-type semiconductor is present due to the doping of S, and the doping of Mn and Co leads to the generation of impurity bands and the reduction of band gap from 3.78 to 0.737 eV. The effective mass of electrons in the doped system is 1.59m0, much greater than 1m0, which is conducive to the improvement of its conductivity. The charge density difference and electron localization function (ELF) demonstrates that the disappearance of electron enrichment and the decrease of the localization are responsible for the rapid migration of the lithium ion. The high operating voltage, charge-discharge platform of 4.7 V and the voltage difference contribute to the promotion of electrochemical performance, which open a window for the commercialization application of Li-ion battery.

Hierarchically porous MXene decorated carbon coated LiFePO4 as cathode material for high-performance lithium-ion batteries

As a promising cathode material for high-power lithium-ion batteries, LiFePO4 (LFP) suffers from low lithium-ion diffusivity and poor electronic conductivity. In this work, hierarchically porous Ti3C2Tx MXene decorated LFP@C (LFP@C/MXene) composite was successfully synthesized by a facile and efficient electrostatic self-assemble method at room temperature with the help of CTAB to regulate charge state. The introduction of MXene sheets realized the formation of hierarchically porous structure and “dot-to-surface” conductive network, enabling the fast ion and electrons transfer for redox reactions, meanwhile, MXene will be partially oxidized into TiO2 and carbon during cycling, which further improved the diffusion of lithium-ion. Together with the optimized structure of LFP@C nanoplates, the resulting LFP@C/MXene exhibits robust high-rate capability (139 mAh·g−1 at 20 C) as well as a long-life cycling stability (156.6 mAh·g−1 at 1 C with superior capacity retention of 94.8% for 500 cycles). This ingenious design highlights the great potential of 2D MXene for facilely constructing multifunctional electrode materials for application in high-rate Li-ion batteries.

Growth of large-area petal-like V2O5 thin nanosheets for superior lithium storage

There is a need for simple and rapid methods of controllably fabricating large-area V2O5 thin nanosheets for applications in high-energy Li-ion batteries (LIBs). Here, we report a novel growth-induced synthesis of two-dimensional (2D) petal-like V2O5 nanosheets with a thickness of approximately 15 nm and lateral size exceeding 5 µm. The mechanism of formation of the nanosheets is systematically investigated by studying the effects of reagent concentrations on the nanosheet morphology. The resultant V2O5 nanosheets were effective cathode materials for LIBs, giving high reversible capacities of 291.7 and 101 mAh g−1 at current densities of 0.1 and 3.0 A g−1, respectively, in the voltage window of 2.0–4.0 V. Furthermore, the cathode operated stably for 200 cycles at 1.5 A g−1, with a reversible capacity of 139.6 mAh g−1 at the 200th cycle, corresponding to a capacity fading of 0.03% per cycle. The enhanced lithium storage is attributed to the increased electrode/electrolyte contact area, the enhanced strain tolerability, and shortened charge transport path of the unique nanosheet structure. The influence of the electrochemical reaction kinetics on the performance is also discussed in detail. These findings will accelerate the development of V2O5 cathodes for next generation high-energy LIBs.

MoSx surface-modified, hybrid core-shell structured LiFePO4 cathode for superior Li-ion battery applications

A hybrid core-shell cathode, composed of MoSxshell and carbon-coated lithium iron phosphate core (MoSx@c-LiFePO4or MoSx@c-LFP) is obtained by the post-annealing of a thermally decomposable ammonium thiomolybdate and commercial carbon-coated LiFePO4 (c-LFP) powder. The specific capacity of the commercially available amorphous carbon-coated LFP (c-LFP) is typically around 120–160 mAhg−1, which is usually lower than the theoretical values ~170 mAhg−1 due to the limited Li+ phase-boundary diffusion and low electrical conductivity. In the present investigation, we report that the specific capacity of surface-modified (~1.2 wt% of layered MoSx) c-LFP (MoSx@c-LFP) material can reach as high as ~228 mAhg−1 delivering high gravimetric energy density ~750–770 Whkg−1. The excess capacity can be attributed to the partial Li-ions intercalated/de-intercalated through the MoSx layers within a specific potential range (2.0–3.8 V). MoSx coating helps increase the c-LFP surface's stability by forming strong covalent bonding and is believed to enhance the electronic conduction by reducing the interparticle contact. During charge and discharge the hysteresis is substantially reduced by MoSx coating. The approach may open up a universal route to increase the cathode capacity, potentially attractive for further Li-ion battery research and industrial applications.

Nitrogen-doped porous graphitized carbon from antibiotic bacteria residues induced by sodium carbonate and application in Li-ion battery

Graphitic porous carbons with high electronic conductivity and abundant pores show great potential in many fields due to their unique physical and chemical properties. The traditional technique for the acquirement of artificial graphite is always conducted under high temperature above 2700 °C, leading to serious energy loss and high costs. In this study, antibiotic bacteria residues (ABRs), a kind of solid waste generated upon the production of antibiotics, are recycled into hollow-tunneled graphitic carbon derived from ABRs with N-doping (N-GC) using Na2CO3 as catalyst at 900 °C. Compared with graphitic carbon (G-AC) derived from ABRs at 2800 °C, the obtained N-GC shows a decent graphitization degree (69.8% vs. 57.0% of G-AC), high electronic conductivity (36.90 S cm−1 vs. 17.06 S cm−1 of G-AC at 20 MPa), well-developed porous structure as well as a high N containing amount (1.26% vs. 0.50% of G-AC). When used as anode material for Li-ion batteries (LIBs), the N-GC sample shows excellent electrochemical properties including good cyclability, long durability and good rate performance.

Electrochemical characteristics of Ge incorporated Li4Ti5O12 as an anode for Li-ion battery applications

Lithium titanate (LTO) is recognized to be a promising anode material for lithium-ion batteries due to its remarkable structural benefits. However, the poor electronic conductivity and lower capacity hindered its widespread commercialization. To analyze the possibility of enhancing the performance of LTO through doping, pristine LTO (Li4Ti5O12), as well as germanium (Ge4+) doped LTO (Li4GexTi5-xO12; x = 0.1 and 0.2) were synthesized by conventional solid-state reaction. Characterizations confirmed the partial replacement of Ti4+ by Ge4+ evenly throughout the material without making any stress or deformation to the host lattice. The electrochemical characterization results established that the presence of germanium effectively reduced the cell impedance as well as improved Li+ ion diffusion. The doping was able to enhance capacity compared to pristine LTO. The best of the doped compositions (Li4Ge0.1Ti4.9O12) was able to deliver a capacity of 159 mA h g−1 at 0.1 C rate and 145 mA h g-1 at 1 C with more than 85 % retention after 300 cycles.

Anomalous Si-based composite anode design by densification and coating strategies for practical applications in Li-ion batteries

Si-based Li-ion battery (LIB) anode materials often possess porous structures to accommodate the intrinsic volumetric expansion of Si upon cycling. However, the porous structure may cause poor initial coulombic efficiency (ICE), inadequate cycle life due to the continuous generation of a solid-electrolyte interface, and incompatibility with calendaring processes. To overcome these issues, we designed an optimized Si/C (P–Si/C) composite anode consisting of Si nanoparticles, graphite, and pitch, with a highly densified structure, suppressing Si expansion and enabling compatibility with the calendaring process. To further enhance the cycle life, the surface of the P–Si/C composite was modified by chemical vapor deposition using CH4 gas (C–Si/C). The P–Si/C anode exhibited a high ICE of 88.0% with a rapid surge up to 99.0% after only the 4th cycle. The C–Si/C anode presented an improved capacity retention of 49.5% after the 39th cycle, compared with 46.0% for the P–Si/C anode after the 31st cycle, while maintaining the same ICE. Moreover, anodes prepared with 8 wt% P–Si/C or C–Si/C and 92 wt% graphite (m-P-Si/C and m-C-Si/C, respectively) showed higher capacity retentions compared with pure Si/C anodes. The m-C-Si/C anode exhibited a higher capacity retention of 80.1% after the 40th cycle, compared with 71.2% for the m-P-Si/C anode. The m-C-Si/C anode also displayed an extremely low expansion rate and the majority of the expansion was elastically recovered. This C–Si/C composite provided a controllable means to modify the performance of LIBs by simple mixing with graphite.

Flexible Carbon Nanotubes Confined Yolk-Shelled Silicon-Based Anode with Superior Conductivity for Lithium Storage.

The further deployment of silicon-based anode materials is hindered by their poor rate and cycling abilities due to the inferior electrical conductivity and large volumetric changes. Herein, we report a silicon/carbon nanotube (Si/CNT) composite made of an externally grown flexible carbon nanotube (CNT) network to confine inner multiple Silicon (Si) nanoparticles (Si NPs). The in situ generated outer CNTs networks, not only accommodate the large volume changes of inside Si NPs but also to provide fast electronic/ionic diffusion pathways, resulting in a significantly improved cycling stability and rate performance. This Si/CNT composite demonstrated outstanding cycling performance, with 912.8 mAh g−1 maintained after 100 cycles at 100 mA g−1, and excellent rate ability of 650 mAh g−1 at 1 A g−1 after 1000 cycles. Furthermore, the facial and scalable preparation method created in this work will make this new Si-based anode material promising for practical application in the next generation Li-ion batteries.

Local structure modulation via cation compositional regulation for durable Li-rich layered cathode materials

A series of manganese-based lithium-rich layered oxide (LLO) cathode materials with different local structures have been synthesized by adjusting the stoichiometric ratios of Mn/Ni. One of the as-synthesized cathode materials with an Mn/Ni ratio of 7 to 2 (Li1.3Mn0.7Ni0.2Co0.1O2.4, denoted as MNC-721) showed an appropriate degree of cation mixing, thereby exhibiting superior cycling stability, better rate capability, and much slower voltage decay when compared with the other two cathode materials with different Mn/Ni ratios. More importantly, a full cell was assembled using the MNC-721 cathode material and it rendered mass-energy density retention of 90.0% after 300 cycles. An appropriate amount of mixing of the Li+ ions and the transition metal (TM) in the Li layers improved the electrochemical performance of the material. The TM ions in the lithium layers can support the layered structure as well as weaken the repulsion between neighboring oxygen layers during processes of charge and discharge. The proposed method in this project is promising to be used to improve LLO cathode materials’ electrochemical performance by modifying their local structures, thereby promoting their further practical applications in Li-ion batteries with high performance.

Fabrication of Mesoporous C60/Carbon Hybrids with 3D Porous Structure for Energy Storage Applications.

We report on the synthesis of 3D mesoporous fullerene/carbon hybrid materials with ordered porous structure and high surface area by mixing the solution of fullerene and sucrose molecules in the nanochannels of 3D mesoporous silica, KIT-6 via nanotemplating approach. The addition of sucrose molecules in the synthesis offers a thin layer of carbon between the fullerene molecules which enhances not only the specific surface area and the specific pore volume but also the conductivity of the hybrid materials. The prepared hybrids exhibit 3D mesoporous structure and show a much higher specific surface area than that of the pure mesoporous fullerene. The hybrids materials are used as the electrodes for supercapacitor and Li-ion battery applications. The optimised hybrid sample shows an excellent rate capability and a high specific capacitance of 254 F/g at the current density of 0.5 A/g, which is much higher than that of the pure mesoporous fullerene, mesoporous carbon, activated carbon and multiwalled carbon nanotubes. When used as the electrode for Li-ion battery, the sample delivers the largest specific capacity of 1067 mAh/g upon 50 cycles at the current density of 0.1 A/g with stability. These results reveal that the addition of carbon in the mesoporous fullerene with 3D structure makes a significant impact on the electrochemical properties of the hybrid samples, demonstrating their potential for applications in Li-ion battery and supercapacitor devices.

MoS2 nanosheets uniformly grown on polyphosphazene-derived carbon nanospheres for lithium-ion batteries

With the discovery and application of graphene, layered inorganic materials such as MoS2 has attracted increasing interest. However, the rational design of a novel electrode structure with a high capacity, fast charge/discharge rate, and long cycling lifetime remains a great challenge. Herein, we report a method of growing layered MoS2 nanosheets on polyphosphazene microspheres. The uniform polyphosphazene microspheres have a rich and uniform hydroxyl structure on the surface, which are effective as hard templates for the growth of two-dimensional MoS2 nanosheets. The uniform adsorption of the initial molybdenum disulfide nanosheets induced a uniform growth, hence a high stable electrochemical performance. Moreover, the obtained hollow carbon microspheres not only exhibited higher electrical conductivity, but also stronger the structural stability. The composites shows a high capacity (882 mAh•g−1) at a current density of 2 A•g−1 and a long cycle life of 1000 cycles with 85 % capacity retention as well. The composites might be a promising MoS2-based anode material for Li-ion battery applications.

Computational insight of ZrS2/graphene heterobilayer as an efficient anode material

A density functional theory-based study is carried out to examine the electrochemical performance of ZrS2 and graphene monolayers and ZrS2/graphene heterobilayer for anodic applications in rechargeable Li ion batteries (LIBs). The energetic and dynamic stabilities of the heterobilayer have been confirmed first. The low Li diffusion barrier (0.24 eV), low half-cell voltage (0.7 V) and high Li storage capacity (700 mAh/g) of ZrS2 monolayer makes it a prospective 2D anode material for the LIBs. However, the large energy gap of ZrS2 monolayer may reduce the reversibility, while large structural changes are on high Li load can lead to short cycle life. To handle these issues, the ZrS2 monolayer is capped with graphene. The graphene thus provides mechanical strength and conducting channels to the electron flow. It is well known that graphene is unable to store Li for LIBs applications. However, by making its interface with ZrS2 enables it to store Li ion reversibly. Furthermore, the graphene caping provides mechanical strength to the ZrS2 monolayer to insure long cycle life and high recyclability. Thus, the hybrid of ZrS2 and graphene makes a highly efficient 2D anode material for Li ion batteries.

Interplay of quantum capacitance with Van der Waals forces, intercalation, co-intercalation, and the number of MoS2 layers

Polymorph MoS2 attracts great attention for supercapacitor and Li-ion battery applications. Although the capacitance origin is usually attributed to the intercalation process, MoS2 exhibits a well-defined electrical double layer (EDL) behavior. Nonetheless, the nature of the EDL behavior of MoS2 is yet to be revealed. Herein, we investigate the quantum capacitance (CQ) of the three main phases of MoS2 (the semiconductor 2H and 3R phases and the metallic 1T phase). Interestingly, the number of MoS2 layers greatly affects the CQ of the material. In addition, the absence of Van der Waals (VdW) interactions overestimates the bandgap and CQ, emphasizing the importance of the VdW correction in the CQ calculations. As MoS2 usually stores charges via the intercalation of cations, the effect of H+, Na+, Li+, and K+ intercalation on the CQ of the three phases of MoS2 is thoroughly investigated. The intercalation of all studied alkali metal cations leads to the transformation of the 2H and 3R phases into the metallic 1T phase and increases its stability. Importantly, the K+ and Na+ intercalations show the greatest impact in enhancing the CQ of the studied phases. However, the charging process of K+ and Na+ ions is not as reversible as that of Li+ as revealed from the estimated binding energies. To this end, herein, we demonstrate the co-intercalation of Li+/Na+ ions as a strategy to enhance the overall capacitance performance. The Li+/Na+ co-intercalation shows a CQ of 3163 F/g with a more thermodynamically stable adsorption process. Finally, the study recommends the use of 2H–MoS2 only as a positive electrode and 1T-MoS2 as a negative and/or positive electrode in energy storage devices. Also, K+ intercalation is recommended to achieve the highest CQ and the Li+/Na+ co-intercalation for the best overall performance.

Synthesis and characterization of LAGP-glass-ceramics-based composite solid polymer electrolyte for solid-state Li-ion battery application

Solid State Electrolytes (SSEs) are the future alternatives of the present conventional liquid electrolytes in terms of safety, high temperature stability and also good electrochemical performance. Glass (G), based on Lithium Aluminium Germanium Phosphate (LAGP) was prepared and converted into glass-ceramics (GC) by optimized heating schedule. The crystalline LAGP has Na Super Ionic CONductor (NASICON) type unit cell where the lithium ions hop between two different positions providing long range ionic motion. To improve the inter-electrode surface resistance and cell performance, Composite Solid Electrolyte (CSE) was prepared with poly(vinylidene fluoride-co-hexaflurophoaphate) (P(VDF-HFP)), 20wt% LAGP, Lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) and 1-Ethyl-3-methylimidazolium bis-(trifluoromethylsulfonyl)-imide (EMITFSI). X-ray diffraction patterns confirm the formation of the NASICON phase in LAGP GC and the amorphous nature of the CSE. NMR studies confirm formation of the Ge/AlO6 octahedra and PO4 tetrahedra inside the crystal. 7Li NMR also confirmed two different Lithium sites in LAGP crystal. The ionic conductivity values of CSE and LAGP GC are (4.49±0.31) × 10−3Scm−1 and (2.70±0.04) × 10−4Scm−1, respectively. The thermal stability of the prepared CSE is tested upto 315°C without any degradation. Two cells (Cell-I & Cell-II) were fabricated using the LAGP GC and CSE respectively. Cell-II shows the specific discharge capacity of 151mAhg−1 at 50th cycle which is higher as compared to Cell-I (129mAhg−1) when tested at the C-rate of 0.05C.

Bulk Mg-doping and surface polypyrrole-coating enable high-rate and long-life for Ni-rich layered cathodes

The severe capacity deterioration of Ni-rich oxides (content of Ni ≥ 90%) limits the practical application for high-energy and long-life Li-ion batteries due to structure pulverization and surface parasitic reactions. Herein, a dual-modification tactic of bulk Mg-doping and surface poly-pyrrole (PPy)-coating is applied to enhance layered Ni-rich cathode materials. The as-formed pinning ions of Mg effectively inhibit the anisotropic lattice changes and the Li/Ni disorder, therefore stabilizing the crystal and phase structures. The thin and uniform PPy coating layer physically prevents the detrimental parasitic reactions, and meantime accelerates the charge transfer rate at cathode-electrolyte interface. These two advantages endow the modified Ni-rich oxides with a superior reversible capacity of 213.0 mAh g−1 at 0.2 C and 144.7 mAh g−1 at 10 C. Impressively, the capacity retention can reach 99.2% after 100 cycles at 0.2 C without voltage drop and structure damage. This dual-modification strategy may be further extended to other cathode materials to improve their high-rate and cycling performances.

Ultrafast green microwave-assisted synthesis of high-entropy oxide nanoparticles for Li-ion battery applications

In this study, a novel ultrafast facile green microwave-assisted method was developed for the synthesis of high-entropy oxide (HEO) (Mg, Cu, Ni, Co, Zn)O nanoparticles for the first time. The results indicated that all the five metallic elements were uniformly distributed in the single-phase rocksalt structure of the HEO nanoparticles. The particle-size distribution was within the range of 20–70 nm, with the average size of 44 nm. When used as anode materials for Li-ion batteries, the HEO nanoparticles exhibited remarkable lithium storage properties with the impressive stability as was demonstrated during 1000 cycles at 1 A/g. The exceptional advantages of the proposed method in this work, including ultrafast speed (few minutes), low temperature, nanoscale and high-purity products, and low cost, make it an excellent synthesis technique for application in newly developed high-entropy ceramics, particularly for Li-ion batteries.

Mesoporous Silica Template-Assisted Synthesis of 1T-MoS2 as the Anode for Li-Ion Battery Applications

The development of the MoS2-based catalyst is receiving more attention in recent years, especially with enriched metallic (1T) phase because of their improvized electrocatalytic behavior. However, ...

Improved tin oxide nanosphere material via co-precipitation method as an anode for energy storage application in Li-ion batteries

The present proposed work, a design and fabrication of tin oxide nanosphere (SnO2) using tin(II) oxyhydroxide and terephthalic acid composite materials, for the first time, via co-precipitation method. The morphology of the materials is found to be a well-crystalline nature and agglomerated with nanospherical shapes; it exhibits a 20–30-nm particle size. The electrochemical discharge–charge studies have been done using a half-cell (2032-sized coin type) at current rate 100 mA g−1 and within the potential range of 0.01 and 2.0 V vs. Li/Li+. The impedance spectroscopy (EIS) and cyclic voltammetry (CV) studies are showing high resistance and a good oxidation–reduction properties. The cycle number vs. capacities illustrates the initial discharge capacity of 1149 mAh g−1 and the charge capacity retention from the second cycle (91%), respectively; it have been maintained up to the end of cycling. Thus, the prepared electrode can be developed for reversibility properties and possibly used as an anode for Li-ion batteries.

Valorization of carbon fiber waste from the aeronautics sector: an application in Li-ion batteries

Recycled carbon fibers coming from the aerospace industry are integrated as the backbone of a high energy density free-standing electrode.

Chemical reactions on surfaces for applications in catalysis, gas sensing, adsorption-assisted desalination and Li-ion batteries: opportunities and challenges for surface science.

The study of chemical processes on solid surfaces is a powerful tool to discover novel physicochemical concepts with direct implications for processes based on chemical reactions at surfaces, largely exploited by industry. Recent upgrades of experimental tools and computational capabilities, as well as the advent of two-dimensional materials, have opened new opportunities and challenges for surface science. In this Perspective, we highlight recent advances in application fields strictly connected to novel concepts emerging in surface science. Specifically, we show for selected case-study examples that surface oxidation can be unexpectedly beneficial for improving the efficiency in electrocatalysis (the hydrogen evolution reaction and oxygen evolution reaction) and photocatalysis, as well as in gas sensing. Moreover, we discuss the adsorption-assisted mechanism in membrane distillation for seawater desalination, as well as the use of surface-science tools in the study of Li-ion batteries. In all these applications, surface-science methodologies (both experimental and theoretical) have unveiled new physicochemical processes, whose efficiency can be further tuned by controlling surface phenomena, thus paving the way for a new era for the investigation of surfaces and interfaces of nanomaterials. In addition, we discuss the role of surface scientists in contemporary condensed matter physics, taking as case-study examples specific controversial debates concerning unexpected phenomena emerging in nanosheets of layered materials, solved by adopting a surface-science approach.