Search

A composite anode material is fabricated from mesoporous carbon and synthesized Li4Ti5O12 nanoflakes for application in lithium ion batteries. Li4Ti5O12 is used as a capacity contributing conductive additive because of the change in its electronic structure from insulating to metallic as it undergoes lithiation. Cyclic voltammetry, galvanostatic charge–discharge, and electrochemical impedance spectroscopy are used to analyze the electrochemical properties of the mesporous carbon/Li4Ti5O12 nanoflakes composite material, and synergistic results have been confirmed. The composite achieves high specific capacity and excellent cyclability with a capacity stabilizing at 300 mA h g−1 after 100 cycles at a current density of 175 mA g−1 and 200 mA h g−1 after 500 more cycles at a high current density of 500 mA g−1. This research shows the applicability of using LTO as a conducting agent with significant capacity contribution as a composite material with anode materials discharged to 0.01 V for high energy storage with fast charge–discharge capability.

Electrochemical characterization was conducted on poly(vinyl alcohol) (PVA)-ceramic composite (PVA–CC) separators for supercapacitor applications. The PVA–CC separators were fabricated by mixing various ceramic particles including aluminum oxide (Al2O3), silicon dioxide (SiO2), and titanium dioxide (TiO2) into a PVA aqueous solution. These ceramic particles help to create amorphous regions in the crystalline structure of the polymer matrix to increase the ionic conductivity of PVA. Supercapacitors were assembled using PVA–CC separators with symmetric activated carbon electrodes and electrochemical characterization showed enhanced specific capacitance, rate capability, cycle life, and ionic conductivity. Supercapacitors using the PVA–TiO2 composite separator showed particularly good electrochemical performance with a 14.4% specific capacitance increase over supercapacitors using the bare PVA separator after 1000 cycles. With regards to safety, PVA becomes plasticized when immersed in 6 M KOH aqueous solution, thus there was no appreciable loss in tear resistance when the ceramic particles were added to PVA. Thus, the enhanced electrochemical properties can be attained without reduction in safety making the addition of ceramic nanoparticles to PVA separators a cost-effective strategy for increasing the ionic conductivity of separator materials for supercapacitor applications.

Lithium sulfonyl silica (LSS) was synthesized by replacing the surface H group in fumed silica with (CH2)3SO3Li and adopted as electrolyte additive for lithium ion battery. 3 wt% of the synthesized particles in 1 M LiPF6 (EC/DMC = 1:1) showed improved ionic conductivity and better potential stability over the pristine electrolyte. The discharge capacity of the LiCoO2/graphite is particularly enhanced with the addition of LSS at higher C-rates due to the enhanced ionic conductivity at room temperature. The LiCoO2/graphite cells using 1.0 M LiPF6/EC/DMC (1: 1) and 1.0 M LiTFSI/EC/DMC (1: 1) with LSS also showed superior performance for the self-discharge test carried out at 45 °C for 200 days. These positive impacts of LSS on LiCoO2/graphite cells warrant its use in lithium ion batteries.

Supercapacitors provide us with enormous power output for energy storage. Their energy output however still remains quite low compared to other energy storage materials like the batteries. This paper reports a highly stable liquid electrolyte which is composed of mixtures of 1-ethyl-3-methylimidazolium tetrafluoroborate(EMIBF 4 ) ionic liquid with highly stable lithium bis(oxalate)borate LiBOB/acetonitrile(ACN). The electrolytes display remarkable supercapacitive performance at a high voltage of 3 V. The electrochemical impedance spectroscopy shows that EMIBF 4 helps to reduce the bulk resistance and charge transfer resistance across the electrode surfaces by facilitating high ionic diffusions across the electrode/electrolyte interface. The high stability and high ionic conductivity of the electrolytes reflected in the good cycling performance tests at 2.8 V with a maximum delivery capacitance of 19.5Fg -1 after 1000cycles at a high scan rate of 200 mVs -1 .

Liquid electrolyte consisting of 1 M LiPF 6 in ethylene carbonate (EC)/dimethyl carbonate (DMC) and 0.1 wt% benzotriazole (BzTz) is studied in LiCoO 2 //graphite battery system at room temperature. Benzotriazole addition introduces excellent electrochemical stability (5.6 V vs Li) and good ionic conductivity properties at room temperature. Also, this electrolyte shows good cycling performance and better discharge capacities at high C-rates relative to the pristine electrolyte. Furthermore, the additive allows the formation of a good solid electrolyte interphase (SEI) per cyclic voltammetry (CV) examination. These specialized properties make this liquid electrolyte ideal for high power and high voltage applications.

Zwitterionic lithium-silica sulfobetaine silane is fabricated by first synthesizing zwitterion sulfobetaine silane, grafting it onto hydrophilic silica to form silica sulfobetaine silane, and then lithiating the silica sulfobetaine silane. The resultant lithium-silica sulfobetaine silane additive is used as a liquid electrolyte additive in lithium-ion batteries with varying weight percentages in 1 M LiPF6 (ethylene carbonate/dimethyl carbonate = 1:1). The electrolytes with the lithium-silica sulfobetaine silane shows higher ionic conductivities (1.92 × 10−2 S cm−1 at RT and 1.62 × 10−3 S cm−1 at −20 °C) and greater electrochemical stability (anodic limit at ~5.5 V vs. Li/ Li + ) than the pure electrolyte (anodic limit at ~4.6 V vs. Li/ Li + ). The discharge capacity of the lithium nickel cobalt manganese oxide/graphite cell is improved at higher C-rates with the addition of lithium-silica sulfobetaine silane due to increased ionic conductivity. The lithium nickel cobalt manganese oxide/graphite cells with the lithium-silica sulfobetaine silane additive also show stable cycling performance. These findings warrant the use of lithium-silica sulfobetaine silane as an electrolyte additive in lithium-ion batteries.