Lithium Storage Behavior Research Articles

Binder- and conductive additive-free Ga2O3 nanowires as a self-healing anode for lithium storage

High-capacity anode materials have stimulated much attention to developing high-performance lithium-ion batteries. However, high-capacity anode materials commonly suffer from the pulverization matter that greatly hinders their practical applications, especially in terms of the high proportion of active materials. In this work, a Ga2O3 nanowire electrode is synthesized by thermal evaporation and immediately used as an anode without the aid of binders and conductive additives. The 3D interconnected architecture of the Ga2O3 nanowire electrode shortens lithium diffusion lengths and expedites reaction kinetics. The Ga2O3 nanowires exhibit high elasticity and a self-healing ability which is inherited from metallic Ga formed during the electrochemical transition process, thus circumventing the formidable pulverization issue to a certain extent. Benefiting from the unique structural, mechanical, and chemical attributes, the as-grown Ga2O3 nanowire electrode gives a high initial lithiation capacity of 1462 mAh g−1 under a current density of 0.1 ​A ​g−1. It delivers good cyclic stability with a reversible capacity of 445 mAh g−1 after 200 cycles at 0.5 ​A ​g−1. Furthermore, the investigation of lithium storage behaviors indicates the high rate capability of Ga2O3 nanowires. This paper contributes to understanding binder- and conductive additive-free electrodes consisting of high-capacity active materials from various viewpoints.

Research Progress of Cathode Materials for Graphene-based Fuel Cells

Graphite is the most widely used cathode material for commercial lithium-ion batteries at present, and the increasing market demand puts forward higher requirements for lithium storage performance of graphite cathode materials. Graphene is a kind of cathode material with great development potential, and its lithium storage performance is influenced by many factors such as structural characteristics, oxygen-containing functional groups and impurity atoms, which leads to complex lithium storage behavior and mechanism. When the polymer with lithium storage activity is compounded with graphene as cathode material, the lithium storage performance is affected by the reversibility of polymer redox and the composite structure. In this article, the working principle of Li-lon and the lithium intercalation mechanism of graphite are introduced, and the research status and progress of graphite cathode materials in surface modification and structural regulation in recent years are emphatically reviewed.

High pseudocapacitive lithium-storage behaviors of amorphous titanium oxides with titanium vacancies and open channels

Amorphous titanium oxides have emerged as potential substitutable anode materials for high-rate lithium-ion batteries with the merits of abundant lithiation sites and accessible short ion diffusion channels. However, extreme differences in electrochemical properties and a poor understanding of the structure-property relationship for amorphous titanium oxides prepared via various synthetic strategies, hinder their further application. We designed amorphous titanium oxides with a unique structure and provided a moderate understanding of how titanium vacancies /open pore channels affect lithium ions (Li+) transportation behaviors in the amorphous titanium oxides. Galvanostatic charge/discharge curves and cyclic voltammetry (CV) tests revealed that two-step pseudo-capacitive behaviors, different from the diffusion-controlled process in anatase TiO2, mainly control Li+ insertion/extraction capacity in amorphous titanium oxides. Surface chemistry and structure analysis with FTIR and 1H solid-state NMR reveal that amorphous titanium oxides are rich in protons bonded to bridging hydroxyl groups. Density functional theory (DFT) calculations imply that the titanium vacancies and open channels promote lithium insertion/de-insertion processes with the two-step storage behaviors, favoring the pseudo-capacitive type in the amorphous titanium oxides. Our study may provide greater insight into the lithiation behaviors in amorphous materials and helpful guidelines in designing other high-capacity amorphous-oxide electrode materials for alkali-ion batteries.

Uniformly confined V2O3 quantum dots embedded in biomass derived mesoporous carbon toward fast and stable energy storage

Rational composition and structural design of electrode substances are critical for lithium-ion batteries (LIBs) and supercapacitors (SCs) with good cycling steadiness and superb rate capability. Therefore, we report a novel electrode material consisting of V2O3 quantum dots (QDs, about 6.64 nm) well-distributed on mesoporous carbon (MC) nanosheets. V2O3 has high intrinsic conductivity and an open tunnel-like lattice structure, facilitating electron transfer and ion intercalation. The composite architectures can offer more electrochemical active sites, shorten ion/electron diffusion paths, and reduce volume swings during the charging/discharging process. The synergic effect of these merits significantly improves the reaction kinetics and prevents structural damage to the entire electrode. As a result, V2O3-QDs/MC nanosheets exhibit a large capacity/capacitance, excellent cycling steadiness, and high rate performance. For LIBs, V2O3-QDs/MC displays a great reversible capacity of 931 mAh g−1 at 0.2 A g−1 over 500 cycles and fast and stable lithium storage behaviors with 822 mAh g−1 at 2 A g−1 after 1000 cycles. For SCs, V2O3-QDs/MC manifests a considerable specific capacitance of 270 F g−1 at 1 A g−1 and satisfactory durability for at least 5000 cycles at 10 A g−1. This work informs a good structure design for constructing advanced metal oxide-based nanostructured electrode materials.

Ultrafine aluminum sulfide nanocrystals anchored on two-dimensional carbon sheets for high-performance lithium-ion batteries.

Aluminum sulfide is a novel light metal sulfide, which possesses multiple advantages for lithium storage, including high theoretical capacity, proper discharge potential and good conductivity. However, much research has not been done in areas related to light metal sulfide materials. Herein, we synthesized Al2S3/C nanocomposite by a facile one-step ball milling method. This simple method not only effectively achieves the uniform composite of Al2S3 nanoparticles and carbon sheets, but also controls Al2S3 into ultrafine nanocrystals. Al2S3/C electrode demonstrates very outstanding lithium storage performance with large reversible specific capacity (1249 mAh g-1 at 100mAg-1), remarkable rate capability (670 mAh g-1 at 5000mAg-1) and superior long-cycling stability (retaining 850 mAh g-1 even after 1000 cycles at 1000mAg-1). Moreover, the reversible lithium storage behavior and excellent diffusion kinetics of Al2S3/C are unveiled deeply. This work provides an inspiration to develop new light metal sulfide materials for the next-generation high-performance lithium ion battery.

Integrated Conjugated Microporous Polymers/Carbon Nanotube Composite Boosting Superior Anodic Lithium Storage Behavior

AbstractConjugated microporous polymers (CMPs) with redox‐active sites have attracted extensive notice in rechargeable lithium‐ion batteries (LIBs) due to their extended π‐conjugated structure, uniform porosity, and low solubility. However, poor electrical conductivity and low utilization of active sites limit their application in large‐scale energy storage systems (ESS). Herein, we synthesized two carbonyl‐rich imine‐based CMPs by the polycondensation reaction between tetromino‐benzoquinone and aldehydes, and integrated them with carbon nanotubes (TB‐CMP@CNT and TBP‐CMP@CNT). The composites display good electrochemical performances as anode‐active materials of LIBs, which benefits from abundant redox‐active units, stable π‐conjugated framework, and fast Li+ diffusion kinetics. Especially, TBP‐CMP@CNT has a high reversible capacity of 954.6 mAh g−1 at 50 mA g−1, a long cycle stability at 1 A g−1 with no decrease in capacity after 1000 cycles, and superior rate performance of 221.5 mAh g−1 at 2 A g−1.

Stable lithium storage behavior observed in Mn-doped MgCo2O4 anode materials

Cation substitution strategy is considered to be an effective way to create defect structure in the spinel structure for improving the performance of Li-ion batteries. In this work, a series of MgMnxCo2-xO4 (x = 0, 0.5, 1, 1.5, 2) materials with Mn ions replacing Co ions were synthesized by a facile hydrothermal method. The collected X-ray diffraction and scanning electron microscope results show that the lattice parameters and particle size of the materials increase with the increase of Mn doping concentration. The O 1s X-ray photoelectron spectra results show that there are more oxygen vacancies and interstitial hydroxyl groups in MgMn0.5Co1.5O4 samples, which is conducive to the improvement of conductivity of the material. Analyses of XPS spectra of Mg 1s, Mn 2p and Co 2p reveal that magnesium exists as Mg2+ ions, manganese and cobalt exist in multivalent states (Mn2+/3+/4+ and Co2+/3+), and these ions are mixed and distributed in the spinel structure. The effect of Mn doping on the inversion degree of spinel and electrochemical performance of materials is discussed. Compared with pure MgCo2O4 material, Mn-doped MgCo2O4 anode materials exhibit good cycle stability. When x = 0.5, MgMn0.5Co1.5O4 anode material has the highest cycle capacity with an initial discharge capacity of 1165.2 mAh g−1, and a capacity of 427.6 mAh g−1 after 100 cycles. Mn-doped MgCo2O4 can significantly improve the cycle stability of the material while maintaining a high specific capacity.

Lithium storage behavior and mechanism of hexagonal FePO4/C composite as a novel anode material for lithium-ion batteries

Exploring novel electrode materials is crucial for the development of high-performance lithium-ion batteries (LIBs). Herein, hexagonal FePO4/N-doped carbon (FP/C-600) composite is synthesized by a facile precipitation method and subsequent heat treatment process; the lithium ions storage performance and mechanism of hexagonal FePO4 as a novel anode material for LIBs are systematically investigated for the first time. The as-prepared FP/C-600 composite gives a high specific capacity (761.1 mA h g−1 at 0.2 A g−1), superior cyclability (433.5 mA h g−1 after 400 cycles at 0.5 A g−1), and outstanding rate capability (240.3 mA h g−1 at 5.0 A g−1) for a half cell. Ex-situ transmission electron microscopy (TEM) characterization demonstrates that the lithium storage reactions in the FePO4 anode proceed via a conversion reaction mechanism. The FP/C-600 nanocomposite has a much smaller electrochemical reaction resistance and larger Li+ diffusion coefficient than the pure FePO4 (FP-600) sample. More importantly, when evaluated as an anode material in a Li-ion full cell, the FP/C-600 composite still maintains a high specific capacity of 456.2 mA h g−1 after 50 cycles at 0.2 A g−1, implying that such FP/C-600 composite is a novel anode material with significant potential for future practical applications in LIBs.

Lithium storage behaviors and properties of the pristine and activated catkin-derived carbon microtubes

Lithium storage behaviors and properties of the pristine and activated catkin-derived carbon microtubes

The manganese oxyborate Mn3(BO3)2 as a high-performance anode for lithium-ion batteries

Borate has aroused great interest as anode materials for lithium-ion batteries (LIBs) due to its high specific capacity and abundant supply of raw materials. To further increase its energy density in LIBs, it is urgent to synthesize a new type of relatively low potential borate material. In this study, Mn3(BO3)2 with a relatively suitable discharge voltage plateau (~0.9 V vs. Li/Li+) was successfully prepared. The synthesized Mn3(BO3)2 has high charge specific capacity (544.4 mAh g−1 at 0.4 A g−1), excellent cycle stability (538.1 mAh g−1 after 400 cycles at 0.4 A g−1) and high rate performance (191.5 mAh g−1 at 3.2 A g−1). The lithium storage behavior of Mn3(BO3)2 was studied by ex-situ XRD and ex-situ XPS.

Introducing a Pseudocapacitive Lithium Storage Mechanism into Graphite by Defect Engineering for Fast-Charging Lithium-Ion Batteries.

The extreme fast-charging capability of lithium-ion batteries (LIBs) is very essential for electric vehicles (EVs). However, currently used graphite anode materials cannot satisfy the requirements of fast charging. Herein, we demonstrate that intrinsic lattice defect engineering based on a thermal treatment of graphite in CO2 is an effective method to improve the fast-charging capability of the graphite anode. The activated graphite (AG) exhibits a superior rate capability of 209 mAh g-1 at 10 C (in comparison to 15 mAh g-1 for the pristine graphite), which is attributed to a pseudocapacitive lithium storage behavior. Furthermore, the full cell LiFePO4||AG can achieve SOCs of 82% and 96% within 6 and 15 min, respectively. The intrinsic carbon defect introduced by the CO2 treatment succeeds in improving the kinetics of lithium ion intercalation at the rate-determining step during lithiation, which is identified by the distribution of relaxation times (DRT) and density functional theory (DFT) calculations. Therefore, this study provides a novel strategy for fast-charging LIBs. Moreover, this facile method is also suitable for activating other carbon-based materials.

Atomically dispersed Sn incorporated into carbon matrix for stable electrochemical lithium storage

Although possessing a high specific capacity, the practical implementation of SnO2 nanoparticles as a promising anode for lithium-ion batteries (LIBs) is hampered by their poor cyclability. This work demonstrates that incorporating single atomic Sn (SASn) species into a carbon matrix can address this issue effectively. The SASn/C composite was synthesized via polymerization of formaldehyde and 3-aminophenol in the presence of Tin(II) chloride, followed by pyrolysis. The SASn atoms were homogeneously dispersed in the carbon matrix. Each Sn atom coordinated with two O and two C atoms, forming the Sn-O-C and Sn-C bonds, providing channels for fast electron/ion transfer and boosting electrochemical kinetics. The SASn/C anode exhibited unique lithium storage behaviors, enhanced lithium storage capability, and excellent cyclic stability with a capacity fading rate of 0.0031% per cycle at 1000 mA g−1 after 7000 cycles. Density functional theory calculations reveal that one SASn atom can adsorb three Li+ ions at the fully discharged state during the discharging process. Subsequently, the Li+ ions are directly desorbed from the SASn atom, which is different from the traditional multi-step de-alloying process. This facile strategy represents a significant advancement in developing high-performance Sn-based anode materials for LIBs.

Revealing the unconventional lithium storage mechanism of ordered mesoporous NiO for lithium-ion batteries

Transition metal oxides have been intensively developed for use as anode materials to overcome the capacity limitations of commercial graphite. In this study, a highly ordered mesoporous NiO electrode material is fabricated using a hard templating method, and exhibits a reversible capacity of approximately 940 mAh g−1 that is much higher than the theoretical value based on the conversion reaction (717 mAh g−1). Combined analyses that include synchrotron-based X-ray techniques and controlled X-ray photoelectron spectroscopies attribute the lithium storage behaviors to both the conversion reaction of NiO framework and the reversible electrolyte-derived surface layer. Interestingly, the contribution of the reversible electrolyte-derived surface layer (∼440 mAh g−1) to the capacity is comparable to that of the conversion reaction with NiO (∼500 mAh g−1). The results also demonstrate that incomplete conversion occurs due to the high bonding energy of Ni–O in the framework during the electrochemical reaction, and prove that the distinctive nano-structural characteristics of the mesoporous NiO surface cause the reversible behavior of the electrolyte-derived surface layer.

Bonding dependent lithium storage behavior of molybdenum oxides for next-generation Li-ion batteries

Metallic lithium storage occurs in MoO2, whereas MoO3 store lithium by conversion reaction. First-principles calculations demonstrate that the different electrochemical properties originated from the different metal–oxygen bonding of MoO2 and MoO3.

A Spinel (FeNiCrMnMgAl)3O4 High Entropy Oxide as a Cycling Stable Anode Material for Li-Ion Batteries

Recently, high entropy oxides (HEO) with special stabilization effects have been widely investigated as new anode materials for lithium-ion batteries. However, the lithium storage mechanism of HEO is still under debate. In this work, we applied a modified solution combustion synthesis method with a subsequent ball milling refinement process to prepare a six-component (FeNiCrMnMgAl)3O4 spinel high entropy oxide (6-SHEO). The novel 6-SHEO anode features outstanding electrochemical performance, enabling a stable capacity of 657 mAh g−1 at a current rate of 0.2 A g−1 after 200 cycles, and good high-rate capability with 350 mAh g−1 even at 4 A g−1. In addition, the lithium storage behavior of this 6-SHEO anode was explored in detail through in-situ XRD and ex-situ TEM approaches. Surprisingly, a reversible spinel to rock salt phase transition behavior and spinel phase residue phenomenon was firstly observed by this route. Furthermore, for better understanding of the phase change behavior in this 6-SHEO anode, a high-energy ball milling approach was applied to induce a similar spinel to rock salt phase transformation for the first time, which generates fresh insight into the mechanism of the phase change behavior in this 6-SHEO anode.

In situ measurement and mechanism analysis of the lithium storage behavior of graphene electrodes

Graphene has attracted widespread attention for development of high-performance lithium-ion battery anode materials. In this paper, the lithium storage mechanisms of multilayer graphene, few-layer graphene, and reduced graphene oxide electrodes are investigated, and the influences of layers and defects in the microstructure are analyzed. The evolution of microstructure deformation of different graphene electrodes, combined with the diffusivity and distribution of lithium, is systemically investigated by in-situ Raman spectroscopy during lithiation and delithiation. The results show that graphene electrodes with different structures exhibit different mechanical behaviors and thus different lithium storage capacities. Mechanical analysis indicates that although the surfaces and defects are active, interlayer lithium insertion contributes the most lithium storage capacity. As the number of graphene layers increases and/or defects decrease, more interlayer spaces would be provided. Thus, the lithium storage capacity of multilayer graphene is significantly higher than those of few-layer graphene and reduced graphene oxide. An in-depth understanding of the effect of the microstructure on the lithium storage behavior of graphene electrodes will provide an experimental basis for development of high-performance graphene electrodes.

SnO2/SnxMo1−xO3−x solid solution nanocomposites: Demonstration of enhanced lithium storage behavior with general synergistic effects

SnO2/SnxMo1−xO3−x solid solution-based nanocomposites have been prepared via a two-step hydrothermal and following annealing processes. At a Sn/Mo molar ratio of 1:2 (the Sn/Mo = 1:2), a single-phase SnxMo1−xO3−x with ionic flake-like structure can be obtained; while, a SnO2/SnxMo1−xO3−x solid solution nanocomposite can be obtained at a Sn/Mo molar ratio of 1:1 (the Sn/Mo = 1:1), which combines with iconic sphere and flake-like structure. Then, electrochemical properties are systematically studied with pure SnO2 and pure MoO3 comparisons as anodes for LIBs. The after cycled Sn/Mo = 1:1 electrode could contain three phases of metallic Sn, MoO2 and an amorphous Sn-Mo oxides, which provide a general synergistic effect to enhance the surface charge contribution, reduce the charge transfer resistance and increase the reaction kinetics. Specifically, the Sn/Mo = 1:1 electrode exhibits a high initial coulombic efficiency of 73.5% with an excellent reversible lithium storage capacity of 735 mAh g−1 at a current density of 0.4 A g−1 after 500 cycles, and a high-rate performance with a specific capacity of 337 mAh g−1 can be obtained at current density of 4 A g−1. This work could provide some inspirations to design solid solution-based nanocomposite with a general synergistic effect to enhance the electrochemical performance for lithium storage application.

Polyvinylpyrrolidone regulated synthesis of mesoporous titanium niobium oxide as high-performance anode for lithium-ion batteries

TiNb2O7 (TNO) as a promising candidate anode for lithium-ion batteries (LIBs) shows obvious advantages in terms of specific capacity and safety, but which undergoes the intrinsic poor electrical and ionic conductivity. Herein, we propose a simple synthesis strategy of mesoporous TNO via a polymeric surfactant-mediated evaporation-induced sol-gel method, using polyvinylpyrrolidone (PVP) with different molecular weights (average Mw: 10000/58000/1300000) as the regulating agent, which greatly affects the lithium storage performance of the as-prepared TNO. The optimized TNO (i.e., PVP of 58000) delivers a high reversible capacity of 303.1 mAh/g at 1 C, with a retention rate of 73.4% (222.5 mAh/g) after 300 cycles. Even at 5 C, a high reversible capacity of 185.6 mAh/g can be achieved, with a retention rate of 72.3% after 1000 cycles. The superior lithium storage behavior is attributed to the fine mesoporous framework consisting of interconnected TNO nanocrystallites with high specific surface area and high mesoporosity, which greatly increases the active sites, improves the Li+ diffusion kinetics and alleviates volume fluctuation induced by the repetitive Li+ insertion-extraction processes.

Super-theoretical capacity mechanism of hollow nano-corn cob-like cobalt oxide

The capacity densities of hollow nano-corn cob-like cobalt oxide (HNc-Co3O4) during the 1st and 78th cycles in lithium-ion batteries (LIBs) are 1887 and 900 mAh g−1, respectively, with a coulombic efficiency of ∼ 98%. The electrochemical mechanism of the exciting, outstanding super-theoretical capacity (STC) can not only improve the capacity density but also exceed the current limit of LIBs. STC is commonly achieved during the conversion reaction of the electrodes in LIBs, and it is necessary to explore the source of the STC and determine how to maintain this level of capacity. The STC of HNc-Co3O4 is mainly due to the reversible reaction of ROCO2Li in the solid electrolyte interphase (SEI), pseudocapacitance at the Li2O/Co interface, and the contribution of carbon at low potentials. Regulating the composition of the SEI is very important for maintaining the STC, as it improves the cycle life and capacity density of the HNc-Co3O4 electrode. The analysis of the contribution and influencing factors of the STC for Co3O4 has guided the analysis of the additional lithium storage behavior of other metal oxides, and it is beneficial for increasing the energy density and power density and promotes the commercialization of conversion-type reaction electrode materials.

Nitrogen/oxygen codoped hierarchical porous Carbons/Selenium cathode with excellent lithium and sodium storage behavior

A nitrogen/oxygen codoped carbon derived from sweet potato (SPC) with interconnected micro-mesopores is applied to encapsulate selenium composite (SPC/Se) with a high Se loading (74.3%). As a cathode for advanced Li-Se and Na-Se batteries, the SPC/Se exhibits superior electrochemical behavior in low-cost carbonate electrolyte. Including the hierarchically porous structure of SPC and the chemical bonding between Se and carbon, the strong binding energy between SPC and Li2Se/Na2Se is also proved by DFT method, which results in the effective mitigation of shuttle reaction and volume change for SPC/Se cathode. For Li-Se batteries, the SPC/Se composite shows the initial specific charge capacity of 668 mAh g−1 with a high initial coulombic efficiency of 78%, and maintains a stable reversible capacity of 587 mAh g−1 after 1000 cycles with a weak capacity decay of 0.082% at 0.2C. It still retains a reversible specific capacity of 375 mAh g−1 even at 20C. For Na-Se battery, the SPC/Se composite displays the initial specific charge capacity of 671 mAh g−1 at 0.2C and maintains a reversible specific capacity of 412 mAh g−1 after 500 cycles with a capacity retention of 61.4%. When the current density increases to 20C, it still delivers a high reversible specific capacity of 420 mAh g−1. Finally, the transformation mechanism of Se molecule is illustrated detailedly in (de)lithi/sodiation process.