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The effect of propylene carbonate (PC)-Li + solvation structures on graphite exfoliation was investigated over a range of concentrations of PC-based electrolytes. At low concentrations of lithium bis(trifluoromethanesulfonyl) imide (LiTFSI) in PC (1.3 M and 2.1 M), the graphite anode was exfoliated. However, the graphite exfoliation could be effectively suppressed when the concentrations of dissolved LiTFSI were increased to 2.5 M and 3.3 M. The results of spectroscopic analyses and density functional theory (DFT) calculations revealed that electrochemical exfoliation of the graphite anode is closely associated with a special spatial configuration of Li + -(PC) n (1 ≤ n ≤ 4) solvation structures at various Li-salt concentrations and corresponding solid electrolyte interface (SEI) film formation mechanisms. When the concentration of LiTFSI increased from 1.3 to 3.3 M, the spatial configuration of Li + -(PC) n (1 ≤ n ≤ 4) solvation gradually changed from a tetrahedron (occupied space of 10.19 A) to planar (occupied space of 3.05 A), which reduced the structure change for co-intercalation into the graphite interlayers of Li + -(PC) n (1 ≤ n ≤ 4) solvates. Meanwhile, the affinity between Li + -(PC) n (1 ≤ n ≤ 4) solvation cations and TFSI − anions was increased, leading to the significant contribution of TFSI − anions to SEI formation on the surface of graphite. Additionally, Al corrosion was not of concern in concentrated LiTFSI electrolyte. The 3.3 M LiTFSI/PC concentrated electrolyte exhibits promising electrochemical performance in graphite||LiNi 1/3 Co 1/3 Mn 1/3 O 2 full cells.

A novel and simple in-situ solid-state reaction route is developed to synthesize a three-dimensional (3D) porous carbon fiber film-supported Li 3 V 2 (PO 4 ) 3 membrane electrode. The carbon film is obtained via the carbonization of a bioproduct rice paper (RP). The carbon film can function as both a current collector and a 3D electronic conduction network for the loaded Li 3 V 2 (PO 4 ) 3 particles. The structure and electrochemical properties of the Li 3 V 2 (PO 4 ) 3 membrane electrode are characterized. As a free-standing membrane electrode, it exhibits good rate performance at room temperature with a specific capacity of 108 and 142 mAh g −1 at 10 C rate in the voltage range of 3.0–4.3 V and 3.0–4.8 V, respectively. It also shows good cycling performance with a specific capacity of 123 mAh g −1 after 500 cycles at 1 C rate in the voltage range of 3.0–4.8 V.

The effects of Al substitution for Ni or (and) Mn in LiNi 0.5 Mn 1.5 O 4 spinel on the structures and electrochemical properties are investigated. Powders of LiNi 0.5 Mn 1.5 O 4 , Li 0.95 Ni 0.45 Mn 1.5 Al 0.05 O 4 , LiNi 0.475 Mn 1.475 Al 0.05 O 4 and Li 1.05 Ni 0.5 Mn 1.45 Al 0.05 O 4 are synthesized by a thermopolymerization method. Their structures and electrochemical properties are studied by X-ray powder diffraction, scanning electron microscopy, infrared spectroscopy, cyclic voltammetry and galvanostatic charge–discharge testing. The introduction of Al in these LiNi 0.5 Mn 1.5 O 4 samples has resulted in structure variation, and greatly improved their cyclic performance and rate capability. The effects of Al substitutions for Ni and Mn in the LiNi 0.5 Mn 1.5 O 4 are different. Compared with LiNi 0.5 Mn 1.5 O 4 , Li 0.95 Ni 0.45 Mn 1.5 Al 0.05 O 4 demonstrates higher specific capacity at room temperature but faster capacity fading at elevated temperatures. Li 1.05 Ni 0.5 Mn 1.45 Al 0.05 O 4 displays a lower discharge capacity but better capacity retention at 55 °C. Moreover, the cyclic performance and rate capability of the Ni-substituted Li 0.95 Ni 0.45 Mn 1.5 Al 0.05 O 4 , Ni/Mn co-substituted LiNi 0.475 Mn 1.475 Al 0.05 O 4 and Mn-substituted Li 1.05 Ni 0.5 Mn 1.45 Al 0.05 O 4 at room temperature are similar, and have improved substantially compared with the Al-free LiNi 0.5 Mn 1.5 O 4 sample.

Nanosized α-Fe2O3 (ca. 50 nm) and Li–Fe composite oxides (ca. 29 nm) powders were synthesized via gel polymer route. The gels were obtained with thermal polymerization of acrylic acid solutions of iron and lithium nitrates. The calcination of these gels at temperatures from 300 °C to 500 °C results in α-Fe2O3 from Fe(NO3)3 precursor and Li–Fe composite oxides Li2O–Fe3O4–LiFeO2 from a mixed precursors of Fe(NO3)3 and LiNO3. Thermal gravimetric analysis, X-ray diffraction and transmission electron microscopy were used to investigate the precursors and products. The electrochemical performance of the Fe-based oxides was also evaluated. After 200 cycles, their capacity can be as high as 1300 mAh/g for α-Fe2O3 and 1400 mAh/g for Li–Fe oxide while the initial capacity loss is as low as 21.8%. The Li–Fe oxide electrodes exhibit better capacity retention than the α-Fe2O3 electrodes. They are interesting negative electrodes for high energy density lithium-ion batteries.

Carbon encapsulated graphite was prepared by coating polyurea on the surface of natural graphite particles via interfacial polymerization followed by a pre-oxidation at 250 °C in air and a heat treatment at 850 °C in nitrogen. FT-IR spectroscopy, X-ray diffraction (XRD) and scanning electron microscopy (SEM) were employed to investigate the structure of the graphite before and after the surface modification. Galvanostatic cycling, dc impedance spectroscopy, and cyclic voltammetry were used to investigate the electrochemical properties of the modified graphite as the anode material of lithium cells. The modified graphite shows a large improvement in electrochemical performance such as higher reversible capacity and better cycleability compared with the natural graphite. It can work stably in a PC-based electrolyte with the PC content up to 25 vol.% because the encapsulated carbon can depress the co-intercalation of solvated lithium ion. The initial coulombic efficiency of C-NG and NG in non-PC electrolyte is 74.9 and 88.5%, respectively.

The miniaturization of rechargeable lithium-ion batteries requires high quality thin-film electrodes. Electrostatic spray deposition (ESD) technique was used to fabricate LiMn2O4 thin-film electrodes with three different morphologies: sponge-like porous, fractal-like porous, and dense structures. X-ray diffraction (XRD) and scanning electron microscopy were used to analyze the structures of the electrodes. These electrodes were made into coin cells against metallic lithium for electrochemical characterization. Galvanostatic cycling of the cells revealed different rate capability for the cells with LiMn2O4 electrodes of different morphologies. It is found that the cells with LiMn2O4 electrodes of porous, especially the sponge-like porous, morphology better rate capability than those with dense LiMn2O4 electrodes. Electrochemical impedance spectroscopy (EIS) study indicates that the large surface area of the porous electrodes should be attributed to the smaller interfacial resistance and better rate capability.