The ZnSn(OH)6 nanocube-graphene composite as an anode material for Li-ion batteries.

ZnSn(OH)6 (ZSH) nanocubes with a uniform size of 40-80 nm were synthesized by using a simple hydrothermal route and then combined with graphene sheets (rGO) via the electrostatic interaction. The formed composite of ZnSn(OH)6 nanocube-graphene (ZSH-rGO) was used as an anode material for Li-ion batteries and it exhibited significantly enhanced electrochemical performance. For instance, a capacity of 540 mA h g(-1) at 500 mA g(-1) was retained after 40 cycles.

Stabilizing Li-rich layered oxide cathode interface by using silicon-based electrolyte additive.

In this study, we investigate the efficacy of 2,4,6,8-tetramethyl-2,4,6,8-tetravinylcyclotetrasiloxane (ViD4) as an electrolyte additive to enhance the electrochemical stability of Li-rich (LRO)/Li cells. The LRO/Li cell in the 1 vol% ViD4 electrolyte displays a mere 27.9 % capacity loss after 100 cycles at 0.5C (1C = 300 mAh-1), in comparison with the 66 % observed in the baseline electrolyte. Theoretical calculations reveal that ViD4 possesses a lower calculated oxidation potential than the electrolyte solution, signifying its preferential oxidation propensity. Physical characterization results demonstrate the formation of a uniform ViD4-derived film spanning 2-3 nm on the LRO cathode surface. This film enhances the stability of the cathode/electrolyte interface and safeguards the structural integrity of LRO. Moreover, ViD4 acts as a scavenger for hydrogen fluoride (HF), which is a decomposition product of LiPF6. Theoretical calculations verify the feasibility of ViD4 in effectively eliminating HF.

Effect of Tributyl Borate on Electrochemical Performance at an Elevated Temperature of High-Voltage LiNi0.5Mn1.5O4 Cathode.

Tributyl borate (TBB) is studied as a protective additive that enhances the interfacial stability of a LiNi0.5Mn1.5O4 cathode/electrolyte at 5 V and 55 °C. Upon addition of 0.5 vol % TBB to the electrolyte (1.0 M LiPF6/EC:EMC:DMC, 1:1:1 wt %), the LiNi0.5Mn1.5O4/Li cell maintains a discharge capacity of 99.4 mAh g-1 at the 50th cycle at 55 °C, compared to that of the electrolyte without an additive, i.e., 36.6 mAh g-1. Furthermore, the TBB-enhanced Li/LiNi0.5Mn1.5O4 cell exhibits a higher discharge capacity of 96 mAh g-1 at 3C, whereas the cell without TBB delivers only 84 mAh g-1. Theoretical calculations and differential capacity (dQ/dV) versus voltage (V) analysis show that TBB improves the electrochemical performance at 5 V and 55 °C by preferentially oxidizing on the LiNi0.5Mn1.5O4 surface. The results obtained from electrochemical impedance spectroscopy, scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, X-ray diffraction, and inductively coupled plasma-mass spectroscopy measurements reveal that TBB generates a thin, less resistive film on the surface of LiNi0.5Mn1.5O4. This TBB-derived film inhibits the decomposition of the carbonate solvent, while suppressing the dissolution of Ni and Mn ions from LiNi0.5Mn1.5O4.

Di(methylsulfonyl) Ethane: New Electrolyte Additive for Enhancing LiCoO2/Electrolyte Interface Stability under High Voltage.

In the work reported in this article, di(methylsulfonyl) ethane (DMSE) was examined as a neoteric S-related electrolyte additive to elevate LiCoO2/electrolyte interfacial stability at 3.0-4.5 V (compared to Li/Li+). DMSE, when added to the electrolyte, can significantly enhance the high-voltage performance of LiCoO2/graphite cells. Meanwhile, capacity retention increased from 20.8 to 66.5% after 100 cycles owing to the adjunction of 0.5 wt % DMSE to the electrolyte (carbonate solvents and lithium salt). The density functional theory calculation results indicate that DMSE has a greater highest occupied molecular orbital energy in contrast to ethylene carbonate, dimethyl carbonate, and ethyl methyl carbonate. Differential capacity versus voltage analysis and linear sweep voltammetry result indicate that DMSE is decomposed in preference to the electrolyte solvents. DMSE's effects are distinguished by electrochemical impedance spectroscopy, Fourier transform infrared spectroscopy, X-ray-diffraction spectroscopy, scanning electron microscopy, transmission electron microscopy, and X-ray photoelectron spectroscopy. The outcomes indicate that the enhanced cycling performance is attributed to the involvement of DMSE in the generation of a thinner film on LiCoO2, which results in lower interfacial impedance and it protects the electrolyte from decomposition at high voltage.

Waterborne polyurethane as a carbon coating for micrometre-sized silicon-based lithium-ion battery anode material.

Waterborne polyurethane (WPU) is first used as a carbon-coating source for micrometre-sized silicon. The remaining nitrogen (N) and oxygen (O) heteroatoms during pyrolysis of the WPU interact with the surface oxide on the silicon (Si) particles via hydrogen bonding (Si-OH⋯N and Si-OH⋯O). The N and O atoms involved in the carbon network can interact with the lithium ions, which is conducive to lithium-ion insertion. A satisfactory performance of the Si@N, O-doped carbon (Si@CNO) anode is gained at 25 and 55°C. The Si@CNO anode shows stable cycling performance (capacity retention of 70.0% over 100 cycles at 25°C and 60.3% over 90 cycles at 55°C with a current density of 500 mA g-1) and a superior rate capacity of 864.1 mA h g-1 at 1000 mA g-1 (25°C). The improved electrochemical performance of the Si@CNO electrode is attributed to the enhanced electrical conductivity and structural stability.

Enhancing the High-Voltage Cycling Performance of LiNi1/3Co1/3Mn1/3O2/Graphite Batteries Using Alkyl 3,3,3-Trifluoropropanoate as an Electrolyte Additive.

The present study demonstrates that the use of alkyl 3,3,3-trifluoropropanoate, including methyl 3,3,3-trifluoropropanoate (TFPM) and ethyl 3,3,3-trifluoropropanoate (TFPE), as new electrolyte additive can dramatically enhance the high-voltage performance of LiNi1/3Co1/3Mn1/3O2/graphite lithium-ion batteries (3.0-4.6 V, vs Li/Li+). The capacity retention was significantly increased from 45.6% to 75.4% after 100 charge-discharge cycles due to the addition of 0.2 wt % TFPM in the electrolyte, and significantly increased from 45.6% to 76.1% after 100 charge-discharge cycles due to the addition of 0.5 wt % TFPE in the electrolyte, verifying their suitability in this application. Electrochemical impedance spectroscopy, X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, and X-ray photoelectron spectroscopy were employed to study the effect of TFPM and TFPE on cell performance. The data indicates that the improved cycling activity can be ascribed to the participation of TFPM or TFPE in the formation of a thinner cathode/electrolyte interfacial film, thereby enhancing the cell cycling performance owing to a reduced interfacial resistance at high voltage.