Amorphous metal oxides have emerged as a promising class of materials for advanced energy storage applications, owing to their unique structural characteristics including abundant defects/vacancies, highly permeable diffusion networks, and isotropic stress distribution. However, many studies have provided detailed descriptions and explanations of crystalline metal oxides, there is a lack of corresponding reviews on amorphous metal oxide materials, especially in terms of their applications in lithium-ion electrochemical energy storage and conversion. This comprehensive review systematically summarizes recent advancements in pseudocapacitive amorphous metal oxide anodes for high-performance lithium-ion batteries. We particularly highlight key mechanisms contributing to exceptional electrochemical performance from both theoretical and experimental perspectives: (1) excess pseudocapacitive lithium storage through more defect sites, (2) the evolution from conventional intercalation to surface-dominated pseudocapacitive charge storage, (3) enhanced interfacial lithium storage capacity, and (4) beneficial microstrain effects that improving structural stability and enhancing Li+ diffusion. Furthermore, we critically discuss the remaining challenges for practical implementation of these materials, while providing insightful perspectives on future research directions. This review aims to establish fundamental design principles for developing cost-effective, durable, and high-performance alkali metal batteries, offering valuable guidance for next-generation energy storage systems.

Enhancing the electronic and ionic conductivity of Li4Ti5O12 electrode materials, as well as suppressing the interface reaction between Ti4+ on the surface of Li4Ti5O12 and the electrolyte, is one of the key factors in preparing high-power and long-life Li4Ti5O12 lithium-ion batteries. To tackle these challenges, fluorine ions with strong electronegativity was chosen as dopants to engineer fluorine-doped Li4Ti5O12 electrode materials. Fluorine ion doping changes the surface state of Li4Ti5O12, increases the interface compatibility, suppresses the reactivity between Li4Ti5O12 and the electrolyte, and forms a uniform SEI film during cycling. Moreover, fluorine ion doping induces the generation of oxygen vacancies and improves the crystallinity of Li4Ti5O12, thereby fostering improved electronic and ionic transport kinetics. The above appealing features enables the prepared fluorine-doped Li4Ti5O12 material demonstrates exceptional high-rate performance, delivering specific capacities of 175 mAh·g-1/0.5C, 159 mAh·g-1/10C, and 138 mAh·g-1/50C. In essence, the fluoride ion doping strategy holds profound implications for enhancing electrode interface characteristics, transport kinetics, and the fabrication of high-power lithium-ion batteries.

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.

Spinel lithium titanate (Li4Ti5O12, LTO), with the merits of safety operation voltage, stable crystal structure, and minor lattice volume changes, becomes an optimal anode material for high-power Li-ion batteries. However, the inherent wide bandgap and low lithiation reactivity of Li4Ti5O12 bring about poor conductivity and lithiation dynamics, limiting its further applications. Herein, we design and prepare unique Li4Ti5O12 anode materials with extremely low dopant content of Na+ utilizing the amorphous precursors. The resultant Li4Na0.008Ti5O12.004 sample (denoted as NLTO-0.008) presents superior rate performances and cycle ability, with a reversible capacity of 149.4 mAh·g−1 at the current rate of 10.0C. NLTO-0.008 retains the charge capacity of 151.3 mAh·g−1 with a capacity loss of 0.5

The pulverization of Sn-based electrode materials, caused by the large volume effect during the charging/discharging process, seriously affects their battery life. Compounding electrospun carbon fibers with a porous structure is an effective means of solving this problem. In this work, porous carbon nanofibers (PCNFs) containing Sn and tin antimonide (SnSb) alloy nanoparticles are prepared by electrospinning using self-made highly dispersed Sb–SnO2 (denoted as antimony-doped tin oxide) wet gel as the precursor of Sn and Sb and polyacrylonitrile (PAN) and polyvinylpyrrolidone (PVP) as the carbon sources. The porous structure is constructed using the difference in solubility in water between PAN and PVP. The results indicate that the as-fabricated PCNFs have a large number of pore structures and an even distribution of Sn and SnSb alloy nanoparticles, which are conducive to an increase in the content of Sn–SnSb electrode active materials. The porous structure both increases the specific surface area of the electrode material and effectively alleviates volume change. Therefore, the as-fabricated Sn–SnSb/PCNFs exhibit high specific capacities and outstanding rate performance and cycling retention, delivering specific capacities of 922 mAh g−1 and 266 mAh g at 50 mA g−1 and 5 A g−1, respectively, as well as a high cycle stability (71%) for 600 cycles at 1 A g−1. This demonstrates their potential application as anode materials in high-energy-density lithium-ion batteries.

For electrospun silicon/carbon nanofiber composites, the surface precipitation of silicon nanoparticles can cause poor cycle stability. To solve this, a carbon-coated silicon/carbon nanofiber (Si/C@C) composite with a 'sandwich' structure is constructed by hydrothermal reaction of glucose and an electrospun silicon/carbon nanofiber, followed by high-temperature carbonization. The effects of the thickness of the carbon coating layer and calcining temperature on the electrochemical performance are studied. The results showed that carbon is uniformly and continuously coated on the surface of the composite fibers, which avoid direct exposure of precipitated silicon on the surface of the nanofibers to the electrolyte, reduce the occurrence of side reactions and is conducive to the stable formation of SEI films. At the same time, the carbon shell inhibit the volume expansion of silicon to a certain extent and improve the conductivity of the composites. Consequently, the obtained Si/C@C exhibit good rate performance and cycle stability. With the optimised carbon coating thickness and calcination temperature, the obtained electrodes deliver a reversible capacity of 1120 and 683 mA h g(-1) at a current density of 0.1 and 2 A g(-1) respectively, and a specific capacity of 602 mAh.g(-1) at a current density of 1 A g(-1) after 100 cycles, a capacity retention rate of 80%. The facilely synthesised Si/C@C composite shows potential applications in high-capacity silicon-based anode materials.

The layered Li1.2Mn0.54Ni0.13Co0.13O2 lithium-rich manganese-based solid solution cathode material was synthesized by a novel co-precipitation method.The structure,morphology and electrochemical performance of Li1.2Mn0.54Ni0.13Co0.13O2 were characterized by X-ray diffraction (XRD),scanning electron microscopy (SEM) and electrochemical tests.The results show that the material has a regular polyhedron shape with the particle size below 500 nm.This material can deliver a high initial discharge specific capacity of 209.0 mAh/g at the current of 18 mA/g within 2.0-4.8 V.After 50 cycles,the sample still can keep capacity retention of 87.7％.

A-ZPC-S composite is an excellent and promising cathode for high-performance Li-S batteries. With 46 wt% sulfur loading, it exhibited a first discharge capacity of 1204 mA h g−1and a reversible capacity of 691 mA h g−1after 300 cycles, fading only 0.142% per cycle.

以碳酸锂、五氧化二钒和硝酸铜为原料,通过球磨混合结合高温固相法成功制备锂离子电池新型负极材料LiCuVO4.热重分析法(TG)、X射线衍射光谱法(XRD)、扫描电子显微镜法(SEM)和电化学测试方法对合成材料进行了研究.结果表明所制备LiCuVO4负极材料主要由微米尺寸的块状颗粒组成.在0.01～ 3.0 V充放电区间内,在50 mA/g进行充放电,所制备的材料首次充电比容量达到425.2 mAh/g,循环50次后充电比容量仍保持在370.8 mAh/g.在1A/g电流密度下,循环50次后,充电比容量仍高达288.6 mAh/g.

The layered Li1.2Mn0.54Ni0.13Co0.13O2 lithium-rich manganese-based solid solution cathode material has been synthesized by a simple solid-state method. The as-prepared material has a typical layered structure with R-3m and C2/m space group. The synthesized Li1.2Mn0.54Ni0.13Co0.13O2 has an irregular shape with the size range from 200 to 500 nm, and the primary particle of Li1.2Mn0.54Ni0.13Co0.13O2 has regular sphere morphology with a diameter of 320 nm. Electrochemical performances also have been investigated. The results show that the cathode material Li1.2Mn0.54Ni0.13Co0.13O2 prepared at 900 °C for 12 h has a good electrochemical performance, which can deliver a high initial discharge capacity of 233.5, 214.2, 199.3, and 168.1 mAh g−1 at 0.1, 0.2, 0.5, and 1 C, respectively. After 50 cycles, the capacity retains 178.0, 166.3, 162.1, and 155.9 mAh g−1 at 0.1, 0.2, 0.5, and 1 C, respectively. The results indicate that the simple method has a great potential in synthesizing manganese-based cathode materials for Li-ion batteries.

After impregnating sulfur, the porous carbon matrix prepared using ZnCl2delivers a capacity of 850 mA h g−1at 1C and retains 630 mA h g−1after nearly 200 cycles which are much higher than that of a carbon matrix prepared without ZnCl2.

Lithium zinc titanate (Li2ZnTi3O8) anode material has been synthesized via a microwave method for the first time.

Li(Ni0.4Co0.2Mn0.4)0.99Zr0.01O2 has better cyclic performance than that of LiNi0.4Co0.2Mn0.4O2 with more stable layered structure due to larger radii of Zr4+.

To improve the high-rate capacity and cycle ability, Li2ZrO3 was successfully coated on LiNi0.6Co0.2Mn0.2O2 materials via wet chemical method. The crystal structure and electrochemical properties of the bare and coated material are studied by X-ray diffractometry (XRD), scanning electron microscope (SEM), transmission electron microscopy (TEM), cyclic voltammetry, and electrochemical impedance spectroscopy (EIS). The XRD and SEM results indicated that the lattice structure of Li2ZrO3-coated materials was the same as the pristine one. Transmission electron microscopy showed that there was a thin Li2ZrO3 coating layer on the surface. Li2ZrO3-coating improves the rate performance and cycling stability. Within the cutoff voltage of 2.6–4.8 V, the 1 wt% Li2ZrO3-coated samples exhibited an initial discharge capacity of 190 mAh g−1 and with a capacity retention about 85 % after 50 cycles at 0.1 C. Minor Li2ZrO3 modification plays an important role to enhance the high-rate capability and cycle ability of LiNi0.6Co0.2Mn0.2O2.

The Vanadium-doped TiNb2O7 (TNO) samples have been investigated as novel anode active materials for application in lithium-ion batteries. The samples are characterized by X-ray diffraction patterns (XRD), raman spectrum, scanning electron microscopy (SEM), transmission electron microscopy (TEM), galvanostatic charge-discharge tests, and cyclic voltammetry (CV) tests. The XRD results indicate that V-doping expands the lattice parameters of TiNb2O7 samples and facilitates the enhanced lithium ion diffusion. SEM and TEM results show that lattice expansion caused by V-doping doesn’t significantly change the particle size distribution of TiNb2O7 samples. The electrochemical measurements indicate that the TiNb1.98V0.02O7 anode material displays a highly reversible capacity and excellent cycling stability. The initial discharge capacities of TiNb1.98V0.02O7 are 298.48mAhg−1 and 171.99mAhg−1 at 0.3C and 10C, respectively, indicating that the TiNb1.98V0.02O7 material can be utilized as a promising anode material for lithium-ion batteries.

Li2MoO4 modified Li4Ti5O12/C anode material has been synthesized by a ball-milling assisted rheological phase reaction method. The structures, morphologies and electrochemical properties of the as-prepared materials have been analyzed by different physical and electrochemical methods. The results show that the amorphous carbon is successfully coated on the surface of Li4Ti5O12 nanoparticles with partial doping of Mo6+ into the Li4Ti5O12 structure. Electrochemical results indicate that Li2MoO4 modified Li4Ti5O12/C samples deliver improved rate capability and decreased charge transfer resistance. Among the investigated samples, the one with 5 wt% Li2MoO4 sample exhibits the optimal electrochemical properties and it shows a large capacity of 167.5 mAh g(-1) at 1C rate, which is close to its theoretical capacity. Even at 10C, its charge capacity is up to 137.5 mAh g(-1) with a high capacity retention of 92.5% after 200 cycles. The excellent electrochemical properties should be attributed to the improvement of electrochemical kinetics by the synergistic employment of reducing particle size, partial Mo6+ doping and Li2MoO4/C modification. (C) 2015 Elsevier Ltd. All rights reserved.

Li3V2(PO4)3/C composites (LVP/C) are synthesized by rheological phase reaction (RPR) method using alginic acid (HAlg) as the carbon source. Different process media are applied in the synthetic process to assess the possible effects on LVP/C composite. And the whole synthetic route is discussed in detail with qualitative and instrumental analysis, in terms of ball-milling process, rheology phase reaction process and thermogravimetric analysis of precursors. The much different morphological properties of as-prepared LVP/C composites demonstrate that process medium indeed has some effects on the synthetic process, especially on the refinement and dispersion of particles. According to these investigations, ethylene glycol (EG) is revealed more proper for preparing LVP/C using this method attributed to its moderate viscosity, surface activity and synergistic effects with HAlg. The corresponding LVP/C composite shows nanoscaled particles with smooth surfaces and uniform size distribution. Besides, LVP-EG sample exhibits excellent electrochemical performances under different voltage windows as well. Between 3.0 and 4.3 V, when charge/discharge at 20/50 C, the composite exhibits relatively high capacity and stable cycling performance for 300 cycles. Within 3.0–4.8 V, it can cycle for 200 times at a high rate of 20 C without obvious capacity fading. The outstanding performances can be attributed to the enhanced electronic/ionic conductivities of LVP/C benefitting from the influences of EG and HAlg via the RPR method.

Lithium boron oxide glass (LBO-glass) coated LiNi0.5Mn1.5O4 cathode materials have been synthesized by a solution method to enhance the electrochemical performances.

Li2Zn0.6Cu0.4Ti3O8 anode material was synthesized by a sol-gel method and the precursor calcinations. The sample is characterized by X-ray diffraction patterns (XRD), scanning electron microscope (SEM), Transmission Electron microscopy(TEM), galvanostatic charge-discharge tests, cyclic voltammetry (CV) tests, and electrochemical impedance spectroscopy (EIS). The results shows the nanoparticles were high crystalline and their size was found to be ca. 50-100 nm. The electrochemical measurements indicate that the anode material made of Li2Zn0.6Cu0.4Ti3O8 displayed a highly reversible capacity and excellent cycling stability. The initial charge capacities of Li2Zn0.6Cu0.4Ti3O8 are 239.5 mAh g(-1), 225.8 mAh g(-1), 217.4 mAh g(-1),190.5 mAh g(-1) and 171.6 mA h g(-1) at 50 mA g(-1), 100 mA g(-1), 300 mA g(-1), 500 mA g(-1) and 1000 mA g(-1), respectively. After 50 cycles, the charge capacity of 196.3 mAh g(-1), 190.1 mAh g(-1), 177.3 mAh g(-1), 161.5 mAh g(-1) and 154.8 mAh g(-1) could be retained. This indicates that the Li2Zn0.6Cu0.4Ti3O8 material is a promising anode material for lithium-ion batteries. (C) 2015 Elsevier Ltd. All rights reserved.