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Silicon, an anode material for lithium ion batteries, has the highest theoretical specific capacity ($\sim 4200$ mAh/g). The actual lithium storage capacity of $\sim 3579$ mAh/g is about 10 times that of the graphite anode materials class. This study involves magnesium heat reduction of the SiO₂ preparation of silicon carbon composites. The Si/SiC composite shows a high initial specific capacity of 1406.7 mAh/g with a current density of 0.1 A/g. The morphology and pore size inherited from the SiO₂ aerogel counteracts the volume expansion during the lithiation/delithiation process. This paper provides an articulate methodology for designing silicon anode material for high-performance rechargeable lithium-ion batteries.

Intercalation mechanism of Li into cubic Co₄N₄ has been investigated by the first-principles calculations. Lattice constants, ratio of volume expansion, and formation energies of Li${}_x$Co₄N₄ (x = 0, 1, 2, 3, 4) were calculated. Results indicate that Li prefers to fill the octahedral interstitial site $(O_h)$ rather than the tetrahedral interstitial site $(T_h)$. With the increase in intercalation Li, the ratio of volume expansion increases from 8.29% (x = 1) to 31.58% (x = 4). Ternary phase Li₄Co₄N₄ has the most stability with the negative intercalation energy, and the corresponding theoretical specific capacity reaches 367 mA/g. Furthermore, the analysis of density of states, valence electron density distribution maps, and electron localization function (ELF) of Co₄N₄ and Li₄Co₄N₄ indicates that Li intercalation enhances the electrical conductivity of Co₄N₄ and weakens the bonding of Co and N. Finally, Li-ion migration dynamics in the Co₄N₄ bulk were investigated with nudged elastic band (NEB) methods. Results show that the migration path of Li-ion is along $O_h\to T_h\to O_h$ with the energy barrier of 0.44 eV.

Carbon nano-coated LiNi_0.8Co_0.15Al_0.05O₂/C (LNCAO/C) cathode-active materials were prepared by a sol–gel method and investigated as the cathode material for lithium ion batteries. Electrochemical properties including the galvanostatic charge–discharge ability and cyclic voltammogram behavior were measured. Cyclic voltammetry (2.7–4.8 V) showed that the carbon nano-coating improved the "formation" of the LNCAO electrode, which was related to the increased electronic conductivity between the primary particles. The carbon nano-coated LNCAO/C exhibited good electrochemical performance at high C-rate. Also, the thermal stability at a highly oxidized state of the carbon nano-coated LNCAO was remarkably enhanced. The carbon nano-coating layer can serve as a physical and/or (electro-)chemical protection shell for the underlying LNCAO, which is attributed to an increase of the grain connectivity (physical part) and also to the protection of metal oxide from chemical reactions (chemical part).

The spinel LiMn₂O₄ powders were prepared by sol–gel technique using lithium acetate (Li(CH₃COO) · 2H₂O) and manganese acetate (Mn(CH₃COO)₂ · 4H₂O) as starting materials, citric acid as a chelating agent, and acrylamide as a gel formatting agent. In order to improve the electrochemical performance of lithium ion batteries and prevent structural disintegration from Mn dissolution generated by undesirable acid production, conductive agents were additionally coated on the surface of active material coated on pure aluminum foil as a current collector. Also, it was comparatively investigated using different conductive agents with different particle sizes as well as adopting the cells into the different thermal environments. The electrochemical performance of the Li/LiMn₂O₄ cells demonstrated that the spinel LiMn₂O₄ might be effectively shielded from acid, resulting in improved electrochemical capacity characteristics at room temperature as well as elevated temperature of 55°C.

We report direct growth of vertically aligned carbon nanotubes (VCNTs) on Cu foils using thermal chemical vapor deposition and present the feasibility of possible applications as anode materials in lithium ion batteries. The VCNTs were vertically standing on the Cu foils which were covered with catalytic iron and alumina buffer layers. The growth temperature was 725°C and acetylene under atmospheric pressure was used as a hydrocarbon source. The VCNT grown had mean diameter of 5.8 nm and showed electrical ohmic contact to Cu foils. Electrochemical properties of Li ion battery cell using VCNT anode were examined and high capacitance was observed.

LiFePO₄ nanocrystals were synthesized in various polyol media without any further post-heat treatment. The LiFePO₄ samples synthesized using three different polyol media namely, diethylene glycol (DEG), triethylene glycol (TEG), and tetraethylene glycol (TTEG), exhibited plate and rod-shaped structures with average sizes of 50–500 nm. The X-ray diffraction (XRD) patterns were indexed on the basis of an olivine structure (space group: Pnma). The samples prepared in DEG, TEG, and TTEG polyol media showed reversible capacities of 123, 155, and 166 mAh/g, respectively, at current density of 0.1 mA/cm² with no capacity fading and exhibited excellent capacity retention up to the 50th cycle. In particular, the samples showed excellent performances at high rates of 30 and 60 C with high capacity retention. It is assumed that the nanometer size materials (~50 nm) possessing a highly crystalline nature may generate improved performance at high rate current densities.

The Co₃O₄ nanorod bundles are synthesized by a hydrothermal method. The samples are characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), electron diffraction (ED), X-ray powder diffractometer (XRD), and nitrogen adsorption. It is important that the as-obtained Co₃O₄ nanorod bundles are assembled by nanoparticles. The porous nanorod bundle electrode exhibits a higher rate capacity and a higher reverse capability for lithium ion battery than the solid nanorods, which is attributed to the high surface area and the porous structure.

This study investigates the optimal conditions for the synthesis of battery-grade ferrous oxalate as a raw material for preparing cathode material. Ferrous oxalate was prepared by liquid-phase precipitation method using ferrous sulfate and oxalic acid. Central composite design (CCD) was used to determine the effects of three preparation variables on purity and particle size: reaction temperature, aging time and concentration of ferrous sulfate. Based on CCD, the significant factors on each experimental design response identified the analysis of variance (ANOVA). The optimum ferrous oxalate preparation conditions were obtained reaction temperature of 31.32${}^{\circ }$C, aging time of 56.52min, and ferrous sulfate concentration of 5%. Under these optimum conditions, ferrous oxalate with purity of 99.69% and particle size of 4.92$\mu$m was obtained as best product which met and exceed the requirements of battery-grade ferrous oxalate. In addition, the special morphologies of ferrous oxalate prepared under different dispersant proportion was characterized by scanning electron microscope (SEM) to analyze the mechanism of synthesis. Morphology control study revealed that the dispersant could effectively change the surface energy between crystallographic planes, then result in anisotropic growth of the crystal structure and change the morphology of synthetic products.

A novel three-dimensional porous conductive papers have been successfully synthesized via a simple physical route. Multi-walled carbon nanotubes (MWCNTs)@SnO₂ composite anode materials are embedded in porous conductive papers. The peculiar structure can accommodate the huge volume expansion of MWCNTs@SnO₂ composite anode materials during charge–discharge process. The framework formed by MWCNTs and cellulose can greatly improve the strength, stability and flexibility of the electrode. In addition, the structure successfully prevent the aggregation of SnO₂ nanoparticles and collapse of MWCNTs@SnO₂ composite electrode, leading to the improvement in electrochemical utilization and stable cyclability. The samples were characterized by X-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM), respectively. The electrochemical properties and application were evaluated by galvanostatic discharge–charge testing and cycling voltammetry. As a result, the MWCNTs@SnO₂ composite electrode showed excellent rate performance. The discharge capacity remains about 680mAh g${}^{-1}$ after 100 cycles at 200mA g${}^{-1}$, and even around 300mAh g${}^{-1}$ at 1000mA g${}^{-1}$.

Nano-porous Ta₂O₅ thin film electrodes are prepared by magnetron sputtering at low pressure in the presence of an oxygen atmosphere with an inert gas. The sputtered Ta₂O₅ thin film is subsequently annealed at 350^∘C for 2h in high pure N₂ (Ta₂O₅-350) to introduce oxygen deficiency. The Ta₂O₅-350 electrode possesses highly reversible lithium ion storage and good rate capability, which has high specific capacities of about 480mAh g${}^{-1}$ at a rate of 0.1C. Furthermore, after 2000 cycles at a rate of 5C the Ta₂O₅-350 electrode shows no obvious capacity decay and retains specific capacity of about 160mAhg${}^{-1}$. The excellent lithium storage properties of Ta₂O₅-350 electrode can be correlated to the nano-porous electrode architecture and oxygen deficiency.

A non-solvent induced phase separation (NIPS) process was used to prepare a new kind of porous nanocomposite polymer electrolyte using glycerol as non-solvent for poly(vinylidene difluoride-co-hexafluoropropylene) copolymer. TiO₂ nanoparticles were incorporated by in situ hydrolysis of Ti(OC₄H₉)₄ and dispersed uniformly in the polymer matrix. They affected the porous structure of the obtained nanocomposite polymer membranes (NCPMs). When the amount of TiO₂ arrived at 7.6 wt.%, the NCPM reached the maximum porosity of 70.5%. The resulting nanocomposite polymer electrolyte (NCPE) presents an ionic conductivity of up to 1.98 × 10^-3 S · cm^-1 at room temperature and an apparent activation energy for ion transport of 13.32 kJ · mol^-1, suggesting its promising application in lithium ion batteries.

Mesoporous ZrO₂ with pore sizes of 5–20 nm were prepared using various structure-directing agents. Nanoscale Si was combined with mesoporous ZrO₂ to be used as anodes for lithium ion batteries. In the range of the Si/ZrO₂ mole ratio from 1:1 to 6:1, electrochemical investigations indicated that the mesoporous composite film with the mole ratio of 4:1 had larger capacity and better cyclability upon cycling. Its discharge capacity preserved 1251 mAh/g after 50 cycles. It is believed that mesoporous ZrO₂ could effectively alleviate the volume change arising from Li–Si alloying during the lithiation/delithiation process and provided channels with its mesopores for lithium ions passing through. The Si/ZrO₂ composite film with a pore size of 20 nm presented the best electrochemical performance, indicating that the larger mesopores could facilitate insertion/removal of lithium ions.

Highly crystallized and microsized particles of LiNi_0.5Mn_1.5O₄ spinels with different morphologies have been successfully synthesized using polystyrene (PS) as the sacrificial template, and were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and electrochemical measurement. The spinels obtained at 700°C possess abundant porosity with about 200 nm in diameter, while the spinels calcined at 900°C exhibit a well-defined polyhedral morphology with particle size ranged from 0.2 to 2 μm. The materials prepared at 900°C display an excellent cycling performance due probably to better crystallinity and small particle size.

The cathode materials Li_1.05Cr_xMn_1.95-xO₄(x = 0, 0.05, 0.10) for lithium ion batteries were synthesized by sol–gel method and calcined at 650, 700 and 750°C, respectively. The synthesized materials were characterized with X-ray diffraction (XRD). The electrochemical performances of the materials were tested by constant-current cyclic testing at room temperature for 38 cycles. The XRD results showed that the samples of cathode materials synthesized by the method possessed pure spinel phase. The Li_1.05Cr_0.1Mn_1.85O₄ powder with better cyclic performance of initial specific discharge capacity of 113.7 mAh ⋅ g^-1 can be obtained at the calcination temperature of 700°C for 12 h, with an capacity retention of 95.5% after 38 cycles. It was evident that codoping of Li⁺ and Cr³⁺ can improve the stability of spinel structure and cycling performance.

New materials are of great importance for further development of lithium (Li) ion batteries. This paper reviews the latest development on core/shell structured nanocomposites. Due to different roles of the cores and the shells, the nanocomposites can be tailored to improve their electrochemical performance. Finally, further directions are pointed out.

Herein, a modified interfacial synthetic route has been demonstrated by synthesizing uniform poly(3,4-ethylenedioxythiophene)/MnO₂ hierarchical mesoporous nanocomposite. The in-situ generated polymer has been proven to be effective in constraining the overgrowth of nuclei. Consequently, assembled nanosheets with a thickness less than 5 nm have been prepared. At a high rate of 10 A g^-1 charge/discharge process, the nanocomposite electrode retains 73.4% of the specific capacitance exhibited at 1 A g^-1. At a current density as large as 800 mA g^-1, the nanocomposite electrode attains reversible lithium storage specific capacities of 400 mAh g^-1 after 50 cycles and 300 mAh g^-1 after 100 cycles. The excellent high-rate performance of the nanocomposite electrode is highlighted in terms of its extremely large surface area, unique microstructure and mesoporous features.

We have prepared a lithium excess carbon composite material, Li_4+xTi_5-xO_12-δ/C (LTO/C), using various amounts of sucrose as a carbon source by the spray-drying method. The prepared materials were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), and elemental analysis. The prepared material had the Li₄Ti₅O₁₂ phase including 3.9–18.4 wt.% carbon. Transmission electron microscopy images and the selected area diffraction (SAD) pattern showed that the prepared materials consisted of a carbon nanonetwork in the LTO/C composite. The charge–discharge cycling tests were carried out using the R2032 coin-type cell under the following conditions; 1.2–3.0 V, 0.1 C–10 C (1 C = 175 mA g^-1), 25°C. Based on the electrochemical results, the electrode performance of the prepared material was improved with increasing amounts of residual carbon, in particular, LTO/C including 6.2 wt.% residual carbon exhibited the best electrode performance of 156 mAh g^-1 at 1 C during 50 cyclings when compared to the other materials.

Hollandite-type MnO₂ and its Co-substituted samples have been synthesized by hydrothermal method from MnSO₄, CoSO₄ and K₂S₂O₈ solutions. The hydrothermal products from MnSO₄ and K₂S₂O₈ solutions consisted of the hollandite-type [2 × 2] tunnel structure at 100°C–150°C for 12 h, which was transformed to pyrolusite-type [1 × 1] tunnel structure by hydrothermal treatment at 150°C for longer times of 24–48 h or at a higher temperature of 180°C. On the other hand, the hydrothermal products from MnSO₄, CoSO₄ and K₂S₂O₈ solutions at 150°C–180°C for 12–48 h consisted of the hollandite-type MnO₂ phase. The Co-substituted samples showed higher initial discharge capacity (180–200 mAh (g-oxide)^-1) than that of non-substituted hollandite-type MnO₂ (130–160 mAh (g-oxide)^-1) at 50 mA g^-1.

Li₂FeSiO₄/C composites have been successfully prepared by a combination of solution route and high-temperature solid-state reaction processes. The morphology and crystalline structure were characterized using scanning electron microscope (SEM) and X-ray diffraction (XRD). Effects of calcination temperature on the electrochemical properties of Li₂FeSiO₄/C composite cathodes were investigated by cyclic voltammetry (CV), galvanostatic charge–discharge and electrochemical impedance measurements. The XRD patterns indicate that high-purity Li₂FeSiO₄ with well-developed crystallinity are obtained above 600°C. The primary particle size was increased by elevating the calcination temperature from 600°C to 750°C. The Li₂FeSiO₄/C composite synthesized at 650°C delivers the largest initial discharge capacity of 153.2 mAh g^-1 with a capacity retention of 93.5% after 30 cycles when tested at a current density of C/16 (1C = 166 mAh g^-1) between 1.5 and 4.8 V (vs. Li⁺/Li).

Shell spinel LiNi${}_{0.5}$Mn${}_{1.5}$O₄ hollow microspheres were successfully synthesized by MnCO₃ template, and characterized by XRD, SEM, and TEM. The results show that the hollow LiNi${}_{0.5}$Mn${}_{1.5}$O₄ cathode has good cycle stability to reach 124.5, 119.8, and 96.6mAh/g at 0.5, 1, and 5 C, the corresponding retention rate of 98.1%, 98.2%, and 98.0% after 50 cycles at 20${}^{\circ }$C, and the reversible capacity of 94.6mAh/g can be obtained at 1 C rate at 55${}^{\circ }$C, 83.3% retention after 100 cycles. As the temperature decreases from 10${}^{\circ }$C to $-20^{\circ }$C, the resistance of $R_{\mathrm{\text{SEI}}}$ increases from 5.5 $\mathrm{\Omega }$ to 135 $\mathrm{\Omega }$, $R_e$ from 27 $\mathrm{\Omega }$ to 353.2 $\mathrm{\Omega }$, and $R_{\mathrm{\text{ct}}}$ from 12.7 $\mathrm{\Omega }$ to 73.0 $\mathrm{\Omega }$. Moreover, the B constant and $E_a$ activation energy are 4480K and 37.22KJ/mol for the NTC spinel material, respectively.