Lithium Insertion Research Articles

Theoretical study on the magnetic properties of cathode materials in the lithium-ion battery.

The layered LiMO2 (M = Co, Ni, and Mn) materials are commonly used as the cathode materials in the lithium-ion battery due to the distinctive layer structure for lithium extraction and insertion. Although their electrochemical properties have been extensively studied, the structural and magnetic properties of LiNiO2 are still under considerable debate, and the magnetic properties of monoclinic LiMnO2 are seldom reported. In this work, a detailed study of LiNiO2, LiMnO2, and a half-doped material LiNi0.5Mn0.5O2 is performed via both first-principles calculations and Monte Carlo simulations based on the effective spin Hamiltonian model. Through considering different structures, it is verified that a structure with a zigzag-type pattern is the most stable one of LiNiO2. Moreover, in order to figure out the magnetic properties, the spin exchange interactions are calculated, and then magnetic ground states are predicted in these three systems. The results show that LiNiO2 forms a spiral order that is caused by the competition from both the short-range and long-range spin exchange interactions, whereas the magnetic ground state of LiMnO2 is collinearly antiferromagnetic due to its nearest and next-nearest neighbor antiferromagnetic spin exchange interactions. However, LiNi0.5Mn0.5O2 is collinearly ferrimagnetic because of the ferromagnetic nearest neighbor Ni-Ni and Mn-Mn exchange interactions. Our work demonstrates the competition between the different exchange interactions in these cathode materials, which may be relevant to the performance of the lithium-ion battery.

Cyclically formed dual mechanical/functional interface stabilizing silicon with enhanced lithium complementary effect

Silicon has been focused as a potential candidate in practical lithium-ion batteries due to its amiable feature of high theoretical specific capacity and environmental friendliness. However, its long-term stability requires further improvements for the significant volumetric expansion during lithium insertion. A novel strategy of a complementary effect created by the special extra lithium-storage capability of transition metal oxides is proposed and explored for the modification of silicon in the study. Si@MnO/C composite with highly compact structure is thus prepared by a facile electrostatic process combined with heat treatment. The results demonstrate that the strategical introduction of ultrafine MnO plays a crucial role in the generation of the complementary effect, which outstandingly enhances the durability as well as the kinetics of silicon anode. A reversible capacity of 1085.7 mAh g−1 with a Coulombic efficiency over than 99% has been obtained after 500 cycles at the current density of 200 mA g−1. Even at a high current density of 2000 mA g−1, a retention capacity of 946.3 mAh g−1 could be maintained after 920 cycles.

Electrochemical Lithium Insertion into TiO2 Anatase ALD Thin Films for Li‐Ion Microbatteries: An Atomic‐Scale Picture Provided by Raman Spectroscopy

AbstractElectrochemical lithium (de)intercalation in an atomic layer deposited (ALD) TiO2 anatase thin film deposited on a planar Si /Al2O3/Pt substrate is investigated by Raman spectroscopy. An initial discharge capacity of 63 µAh cm−2 µm−1 (0.5 Li+ mole−1) is reached at C/10 rate, which increases up to 77 µAh cm−2 µm−1 upon further cycles. An excellent capacity retention is achieved over at least 100 cycles, showing the good adherence of the ALD thin film. Raman spectra of LixTiO2 (0 ≤ x ≤ 0.5) thin film electrodes point to the nucleation of the orthorhombic lithiated titanate (LT) Li0.5TiO2 phase from x = 0.1. This LT phase coexists with tetragonal TiO2 in the 0.1 ≤ x ≤ 0.4 composition domain to be pure for x = 0.5. A fully reversible transformation from orthorhombic LT to tetragonal TiO2 is observed upon the charge. The high quality of the Raman spectra allows identifying for the first time 12 modes in the 100–800 cm−1 region for the electrochemically formed LT phase. Furthermore, an appropriate Raman spectra analysis allows a reliable and quantitative determination of the thin film composition during discharge and charge. These results illustrate Raman spectroscopy is a powerful probe to scrutinize the Li insertion/extraction mechanism in TiO2 thin films.

Carbon Confined Mesoporous Catkin-like SnPS3 Nanostructure for Lithium Storage with Great Superiority

Metal phosphosulfides (MPSs) are members of a category of emerging energy storage and conversion materials, particularly having significant potentials in lithium storage due to their phosphorus and sulfur dual anion centers and unique two-dimensional channels. Nevertheless, it is still very challenging for the controllable design and synthesis of MPSs nanomaterials with complex-element components. Herein, a distinctive carbon confined mesoporous catkin-like SnPS3 nanostructure (SnPS3@C) is controllably synthesized and fabricated based on the partial volatilization of the reduced tin and the following bottom-up phosphosulfuration by a chemical vapor deposition method. As the anode material of lithium ion batteries, the catkin-like SnPS3@C offers multiple active centers for lithium insertion, complete carbon shell to protect inner active materials, interlaced fibrous networks for efficient electron transfer as well as abundant inner mesopores for Li+ diffusion and volume buffer, thus showing prominent structure advantages in lithium storage. The catkin-like SnPS3@C electrode demonstrated superior electrochemical capability with a very high reversible capacity (1302 mAh g–1 at 300 mA g–1), excellent rate property (630 mAh g–1 at 8000 mA g–1) and distinguished cycling stability (1030 mAh g–1 after 1000 cycles at 1000 mA g–1). This work offers a new avenue to develop high-performance MPSs materials for advanced lithium ion batteries.

Bonding Lithium Metal with Garnet Electrolyte by Interfacial Lithiophobicity/Lithiophilicity Transition Mechanism over 380 °C.

Garnet electrolytes, possessing high ionic conductivity (10-4 -10-3 S cm-1 at room temperature) and excellent chemical/electrochemical compatibility with lithium metal, are expected to be used in solid-state lithium metal batteries. However, the poor solid-solid interfacial contact between lithium and garnet leads to high interfacial resistance, reducing the battery power capability and cyclability. Garnet electrolytes are commonly believed to be intrinsically lithiophilic, and lithiophobic Li2 CO3 on the garnet surface accounted for the poor interfacial contact. Here, it is proposed that the interfacial lithiophobicity/lithiophilicity of garnets (LLZO, LLZTO) can be transformed above a temperature of ≈380 °C. This transition mechanism is also suitable for other materials such as Li2 CO3 , Li2 O, stainless steel, and Al2 O3 . By using this transition mechanism, uniform and even lithium can be strongly bonded no-surface-treated garnet electrolytes with various shapes. The Li-LLZTO interfacial resistance can be reduced to ≈3.6 Ω cm2 and sustainably withstood lithium extraction and insertion for up to 2000h at 100µA cm-2 . This high-temperature lithiophobicity/lithiophilicity transition mechanism can help improve the understanding of lithium-garnet interfaces and build practical lithium-garnet solid-solid interfaces.

Highly Active Depleting Agent of Lithium Enabled High-Rate and Long-Life Lithium Metal Batteries

Lithium metal is a highly potential anode material for developing high specific energy density battery systems, but the uncontrollable generation and growth of lithium dendrites upon plating/stripping reduces the reversible capacity of batteries and Coulombic efficiency and possibly leads to short circuit or even fire, all of which retard the commercial application of lithium metal batteries (LMBs). In this work, a modified separator with a thin layer of Li4Ti5O12 (LTO) inserted between two traditional polypropylene (PP) separators was presented to effectively eliminate the influence of lithium dendrites and improve the rate performance and lifetime of LMBs. Benefiting from the good wettability to the electrolyte, high conductivity of lithium ions, and quick depletion of lithium dendrites due to the insertion of lithium into the LTO lattice, LMBs with LTO-modified separator display excellent electrochemical performances, e.g., in the Li–Li cells, and an ultralong and stable operation over 1000 h at an areal current density of 0.5 mA/cm2 can be realized. More interestingly, in Li/LFP full cells, a high discharge capacity of 135 mAh/g at 1C with a lifetime over 600 cycles and 120 mAh/g at 5C with a lifetime over 300 cycles can be achieved. These inspiring results suggest a feasible route to achieve a safer, longer-life, and higher-rate LMB.

Self-Assembled Surfactant-Polyoxovanadate Soft Materials as Tuneable Vanadium Oxide Cathode Precursors for Lithium-Ion Batteries.

The mixing of [V10 O28 ]6- decavanadate anions with a dicationic gemini surfactant (gem) leads to the spontaneous self-assembly of surfactant-templated nanostructured arrays of decavanadate clusters. Calcination of the material under air yields highly crystalline, sponge-like V2 O5 (gem-V2 O5 ). In contrast, calcination of the amorphous tetrabutylammonium decavanadate allows isolation of a more agglomerated V2 O5 consisting of very small crystallites (TBA-V2 O5 ). Electrochemical analysis of the materials' performance as lithium-ion intercalation electrodes highlights the role of morphology in cathode performance. The large crystallites and long-range microstructure of the gem-V2 O5 cathode deliver higher initial capacity and superior capacity retention than TBA-V2 O5 . The smaller crystallite size and higher surface area of TBA-V2 O5 allow faster lithium insertion and superior rate performance to gem-V2 O5 .

Self‐Assembled Surfactant‐Polyoxovanadate Soft Materials as Tuneable Vanadium Oxide Cathode Precursors for Lithium‐Ion Batteries

AbstractThe mixing of [V10O28]6− decavanadate anions with a dicationic gemini surfactant (gem) leads to the spontaneous self‐assembly of surfactant‐templated nanostructured arrays of decavanadate clusters. Calcination of the material under air yields highly crystalline, sponge‐like V2O5 (gem‐V2O5). In contrast, calcination of the amorphous tetrabutylammonium decavanadate allows isolation of a more agglomerated V2O5 consisting of very small crystallites (TBA‐V2O5). Electrochemical analysis of the materials’ performance as lithium‐ion intercalation electrodes highlights the role of morphology in cathode performance. The large crystallites and long‐range microstructure of the gem‐V2O5 cathode deliver higher initial capacity and superior capacity retention than TBA‐V2O5. The smaller crystallite size and higher surface area of TBA‐V2O5 allow faster lithium insertion and superior rate performance to gem‐V2O5.

Modelling and experimental investigation of Nb2O5 as a high-rate battery anode material

Modelling and understanding the battery electrochemical performance at high rates is a great challenge. Known for its fast rate and good cyclability, niobium pentoxide (Nb2O5) is a promising anode material for lithium-ion batteries and is specifically modelled and investigated in this work. Commercially sourced Nb2O5 was characterised using scanning electron microscopy, X-ray diffraction, and micro-computed tomography. The Nb2O5 material was found to contain large rod- and ball-like polycrystalline particles of tens of microns in size and have mixed T-Nb2O5 and H-Nb2O5 phases. The electrochemical performance of the material after ball milling was tested via cyclic voltammetry and constant-current cycling at different C-rates up to 50C (10,000 mA g−1). The material achieved a similar charge capacity (143 mAh g−1) to T-Nb2O5 at 0.5C and this capacity could be retained by more than 55% when C-rate was increased to 10C. The experimental results were used to support the development of the Doyle-Fuller-Newman electrochemical model for Nb2O5. By model parameterization, the reference exchange-current density and solid-state diffusivity of the present Nb2O5 were estimated to be 9.6 × 10−4 A m−2 and 6.2 × 10−14 m2 s−1, respectively. The model achieved accurate prediction of the battery performance up to currents of 5C with the obtained constant properties. However, the properties of Nb2O5 were found to be rate-dependent at higher C-rates when good agreements between the model and experiment were maintained. The decrease of the two properties at 10−50C revealed that there was a change of dominant charge storage mechanism from diffusion-controlled lithium insertion to capacitive effects, which was experimentally observed in the cyclic voltammetry.

Analisis Porositas, Tekstur, dan Morfologi Karbon Tempurung Nipah Hasil Pirolisis Suhu Tinggi Untuk Anoda Baterai Sekunder

Lithium-ion batteries are the recent main store of electrochemical energy that have been widely used for electronic equipment, electric vehicles, and also renewable energy storage such as wind and solar. Lithium-ion batteries have many electrochemical advantages but lithium availability in nature is reduced very quickly and its distribution is uneven throughout the world. Sodium is attractive as an alternative to lithium insertion for secondary batteries because of its abundant availability and oxidation reduction potential to standard hydrogen electrodes only 0.3 volts higher than lithium. This study aims to synthesize hard carbon from nipah shell biomass using thermal methods of low-temperature pyrolysis (lower than 200 oC) followed by high-temperature pyrolysis (higher than 1000 oC). Characterization is carried out by iodine number analysis to determine porosity and SEM-EDX to determine texture and morphology. The result of the analysis of carbon iodine number is 346.86 mg/g while SEM-EDX analysis showed that carbon has a structure similar to a combination of graphene and nano-tube carbon.

Lithium exchange across a lithium-less coating for high energy cathodes

Surface degradation is a major limitation in the utilization of high energy cathodes. Cathode coatings provide a promising route for achieving interfacial stability. In this case, there is interest in developing coatings which will provide efficient ion transport across the cathode-electrolyte-interface (CEI). Aluminum based coatings, particularly metal fluorides, have shown great promise for stabilizing the high voltage cathode, LiNi0.5Mn1.5O4. Despite the clear practical advantages of coatings, the chemical basis for their improved performance remains ambiguous. Here we present an in-depth investigation of a nominal AlF3 coating on LiNi0.5Mn1.5O4 based on solid state NMR spectroscopy to determine the composition and function of the Al/F coating layer. NMR results, supported by X-ray photoelectron spectroscopy and electron microscopy, reveal that the actual composition of the deposited layer is an amorphous Al–O–F phase. Isotope exchange is used to follow the spontaneous exchange of lithium ions across the CEI, revealing improved transport in coated cathodes. Finally, NMR experiments provide evidence for insertion of lithium ions in the Al/F coating following electrochemical cycling. The results suggest that lithium insertion into a nominally lithium-less coating plays a role in its improved performance, highlighting lithium content as an important factor in designing beneficial coatings for higher energy cathodes.

Effect of Film Thickness on the Kinetics of Lithium Insertion in LiMn2O4 Films Made by Multilayer Pulsed Laser Deposition for Thin‐Film All‐Solid‐State Battery Cathode Materials**

AbstractMulti‐layer pulsed laser deposition is a promising technique for producing thin films for solid‐state batteries. In this work, thin films are deposited with different numbers of pulses, leading to different thicknesses and grain sizes. We investigated “in operando” the kinetics of the transfer into films by means of dynamic impedance spectroscopy. This technique allowed us to resolve the contributions of the reaction mechanism and of the transport phenomena, as well as to quantify their equivalent resistances. Surprisingly, with increasing film thickness, the charge transfer resistance increases while the apparent diffusion coefficient of lithium increases, leading to a decrease of the mass transport resistance. It appears that both these effects are related to the dimension of the crystals in the thin films. These results provide new insights for an optimal tuning of the materials’ preparation in view of maximizing their electrochemical performances.

Modeling and performance predictions of electrochemical lithium extraction: Impact of leakage current

A comprehensive and practical model is important to the emerging electrochemical lithium extraction technology. In this study, an electrochemical model including leakage current for a LiMn2O4/Ag lithium extraction system is developed. With the consideration of leakage current, the Coulombic efficiency is below unity during charging, and the amount of lithium insertion during discharging increases, which make the model more practical and functional. The practicability of the model is validated by employing pulse and constant current profiles in charge/discharge process. It is found that the pulse current profile exhibits better electrochemical performance because of the lower overpotential, which shows higher Coulombic efficiency during charging and more lithium insertion during discharging. These simulation results fit well with experiment, demonstrating that the model with leakage current can predict the performance of different operation modes. This work may offer valuable consultation and guidance for future implementations of electrochemical lithium extraction from seawater and brine.

Mechanical characterization and modelling of lithium-ion batteries

Mechanical phenomena in lithium-ion batteries are one of the main sources of damage, as well as an indicator of battery health and charge. Then, a deep study of these phenomena may improve battery life, management and safety. Mechanical phenomena are caused by the insertion of lithium ions in the microstructure of the electrodes and can be divided into two main categories: stress and degradation of the electrode microstructure, and battery volume change. The stress and fracture behaviour of the electrode microstructure due to lithium intercalation are studied with an electrochemical-mechanical model. Stress intensity factor is computed to assess how current rate and the geometry of the electrode microstructure affect fracture and may reduce the battery life. In addition to stress in the microstructure, lithium insertion causes the swelling of the entire battery. Then, the thickness change of batteries with different chemistries is measured. These measurements carry important information on the battery states and represent an alternative to voltage to extrapolate charge and health states.

Structure and lithium insertion in oxides of molybdenum

Oxides of molybdenum, MoOx, have a rich structural chemistry arising from the accommodation of oxygen deficiency as MoO3 is reduced and varied redox behavior arising from the ability of Mo to take on several different oxidation states. We review MoO3, MoO2, and all the reduced Mo oxides with intermediate compositions for their performance as Li-ion battery electrode materials. These reduced oxides are perhaps the most structurally diverse in the field of energy storage materials, taking on structures ranging from ones with crystallographic shear to bronze-like structures and distorted rutile. The crystal structure can have a significant impact on the performance of battery materials, which makes the reduced Mo oxides a promising domain of study. Electrochemical studies of these oxides from as early as 1971 to as recently as 2022 are compiled, and characteristics of capacity, capacity retention, and rate performance are compared. We find that certain oxides indeed display promising and highly reversible capacities for Li+ storage. Typical redox voltages for Mo oxides lie in a regime that hinders maximizing energy density when they are paired with higher-voltage cathodes or lower-voltage anodes. The possibility of decreasing the redox voltage in the future will expand the promise of these materials while offering an alternative to more critical elements such as Nb.

Toward efficient electrodes for a high-performance fast-charge Li-ion battery: molecular dynamics simulation and DFT calculations.

Due to the increasing demand for electrochemical energy storage, rechargeable lithium-ion batteries (LIBs) are gaining more and more attention. However, much research still needs to be conducted to enhance their cycling and storage capacity. Recently, computational studies have provided valuable information for LIB development, which is very difficult and expensive to obtain experimentally. In this study, molecular dynamics (MD) simulation and first-principles calculations are performed to investigate the potential of a Cu-BHT MOF and phosphorene as the cathode and anode, respectively. An external electrical field is applied to simulate the charging process and study lithium-ion behavior during migration from the cathode to the anode in an electrolyte. Time and space-dependent variables such as energy, radial distribution function, mean square displacement (MSD), density, and so on have been used to evaluate the studied system. The MSD calculations showed that there are two different regimes in the MSD curves of Li-ions; diffusion and cage. In the designed LIB, the cathode has a better performance in the presence of a high electric field, whereas under an external electric field of 1.5 V Å-1, more lithium ions move from the cathode to the anode. By using first-principles calculations the lithium insertion in phosphorene and Cu-BHT is studied in various configurations and concentrations. The obtained results indicated that the adsorption energy of lithium on the cathode in the most stable configuration is -3.21 eV which is enough to prevent the clustering effect. Furthermore, the interaction of Li with phosphorene is strong enough and forms a stable complex. It is found that by insertion of Li into the anode the band gap is decreased which indicates the possibility of fast charging of LIBs. Investigation of different concentrations of ions reveals that the Li-Li repulsive interactions lead to a decrease in the adsorption energy of Li with the anode and cathode. The results of this study provide an in-depth insight into LIBs.

Local structure transformations promoting high lithium diffusion in defect perovskite type structures

Defect perovskites, AxBO3 such as (Li3xLa2/3-x)TiO3, are attracting attention as high capacity electrodes in lithium-ion batteries. However, the mechanism enabling high lithium storage capacities has not been fully investigated. In this work, the reversible insertion and removal of lithium up to an average A-site cavity occupancy of 1.71 in the defect perovskite (Li0.18Sr0.66)(Ti0.5Nb0.5)O3 is investigated. It was shown that subtle lithium reorganization during lithiation has a significant impact on enabling high capacity. Contrary to previous studies, lithium was coordinated to triangular faces of Ti/Nb oxygen octahedra and offset from O4 windows between A-site cavities in the as-synthesised material. Upon electrochemical lithiation Li-Li repulsion redistributes of all the lithium towards the O4 window position resulting in a loss of lithium mobility. Surprisingly, the mobility is regained during over-lithiation and following multiple electrochemical cycles. It is suggested that lithium reorganisation into the center of the O4 window alleviates the Li-Li repulsion and modifies the diffusion behavior from site percolation to bond percolation. The results obtained provide valuable insight into the chemical drivers enabling higher capacities and enhanced diffusion in defect perovskites. More broadly the study delivers fundamental understanding on the non-equilibrium structural transformations occurring within electrode materials during repeated electrochemical cycles.

Heterostructured and Mesoporous Nb2O5@TiO2 Core-Shell Spheres as the Negative Electrode in Li-Ion Batteries

Niobium pentoxides have received considerable attention and are promising anode materials for lithium-ion batteries (LIBs), due to their fast Li storage kinetics and high capacity. However, their cycling stability and rate performance are still limited owing to their intrinsic insulating properties and structural degradation during charging and discharging. Herein, a series of mesoporous Nb2O5@TiO2 core-shell spherical heterostructures have been prepared for the first time by a sol-gel method and investigated as anode materials in LIBs. Mesoporosity can provide numerous open and short pathways for Li+ diffusion; meanwhile, heterostructures can simultaneously enhance the electronic conductivity and thus improve the rate capability. The TiO2 coating layer shows robust crystalline skeletons during repeated lithium insertion and extraction processes, retaining high structural integrity and, thereby, enhancing cycling stability. The electrochemical behavior is strongly dependent on the thickness of the TiO2 layer. After optimization, a mesoporous Nb2O5@TiO2 core-shell structure with a ∼13 nm thick TiO2 layer delivers a high specific capacity of 136 mA h g-1 at 5 A g-1 and exceptional cycling stability (88.3% retention over 1000 cycles at 0.5 A g-1). This work provides a facile strategy to obtain mesoporous Nb2O5@TiO2 core-shell spherical structures and underlines the importance of structural engineering for improving the performance of battery materials.

A near dimensionally invariable high-capacity positive electrode material.

Delivering inherently stable lithium-ion batteries is a key challenge. Electrochemical lithium insertion and extraction often severely alters the electrode crystal chemistry, and this contributes to degradation with electrochemical cycling. Moreover, electrodes do not act in isolation, and this can be difficult to manage, especially in all-solid-state batteries. Therefore, discovering materials that can reversibly insert and extract large quantities of the charge carrier (Li+), that is, high capacity, with inherent stability during electrochemical cycles is necessary. Here lithium-excess vanadium oxides with a disordered rocksalt structure are examined as high-capacity and long-life positive electrode materials. Nanosized Li8/7Ti2/7V4/7O2 in optimized liquid electrolytes deliver a large reversible capacity of over 300 mAh g-1 with two-electron V3+/V5+ cationic redox, reaching 750 Wh kg-1 versus metallic lithium. Critically, highly reversible Li storage and no capacity fading for 400 cycles were observed in all-solid-state batteries with a sulfide-based solid electrolyte. Operando synchrotron X-ray diffraction combined with high-precision dilatometry reveals excellent reversibility and a near dimensionally invariable character during electrochemical cycling, which is associated with reversible vanadium migration on lithiation and delithiation. This work demonstrates an example of an electrode/electrolyte couple that produces high-capacity and long-life batteries enabled by multi-electron transition metal redox with a structure that is near invariant during cycling.

Mass and Charge Transport in Li1-δCoO2 Thin Films-A Complete Set of Properties and Its Defect Chemical Interpretation.

Lithium insertion materials are an essential class of mixed ionic and electronic conductors, and their electrochemical properties depend on the resistive and capacitive interplay of ions and electrons. However, complete sets of the corresponding elementary material parameters, that is, composition-dependent ionic and electronic conductivity, chemical capacitance, and charge-transfer resistance, are rarely reported for lithium-ion battery electrode materials. Moreover, the interpretation of these properties from a defect chemical point of view is not very common. In this work, the impedance of sputtered Li1-δCoO2 thin films is analyzed to extract the fundamental electrochemical properties as a function of state-of-charge (SOC). Within the accessible SOC range, the charge transfer resistance and ionic conductivity vary by more than 1 order of magnitude. The chemical capacitance determined from impedance spectra agrees excellently with the differential capacitance from charge/discharge curves, and, in the dilute regime, even matches the absolute values predicted by defect thermodynamics. The evolution of lithium diffusivity along the charge curve is deconvoluted into the separate contributions of ionic conductivity and chemical capacitance. Finally, we apply the principles of defect chemistry to evaluate the observed trends in terms of lithium activity and point defect concentrations and provide a tentative defect model that is consistent with our results. The consistency of impedance measurements, cycling data, and thermodynamic theory highlights the key role of the chemical capacitance as a powerful material descriptor and emphasizes the relevance of defect chemical concepts for all lithium insertion electrode materials.