литий-ионный аккумулятор

The influence of the composition, the thickness and the surface morphology of Li3V2(PO4)3 or Li4Ti5O12 based electrode composites with carbon nanomaterial and polyvinylidene fluoride on their electrochemical performance was examined. The thickness and the surface morphology of the electrodes were jointly controlled by rolling with different gaps and monitored using 3D laser microscopy and scanning electron microscopy.

An approach for constructing mathematical models of the current dependence of the capacity of electrode materials is proposed. The approach involves analyzing the probabilities of favorable and unfavorable events occurring on the elements of electrical equivalent circuits that can be used to model the electrode. Several probabilistic models that correspond to different combinations of a capacitor, a Warburg element and a constant phase element in an electrical circuit are proposed.

Features of lithiated iron phosphate behavior (PH/P1, Phostech Lithium Inc, Canada) used as positive electrode of lithium-ion battery with LiPF₆-based electrolyte were investigated. It was shown that lihiated iron phosphate potential does not depend of lithium contents in active material. It was shown that cycle life of the positive electrode strongly depends on charge/discharge current. Fast degradation of the positive electrode takes place at low current rates (0.25 and 0.5C). At the same time degradation is considerably lower at 1 and 2.5C rates.

The additive into electrolyte SO₂ allowing to realize the intercalation of lithium ions into spectral-pure graphite is shown in the work given. The monolayer of SO₂ restoration products possessing the properties of solid inter phase electrolyte is formed on the material given. The formation of the surface layer requires 160±15 mA·h/g.

Behavior of PH/P1 lithiated iron phosphate (Phostech Lithium Inc, Canada) used as positive electrode material for Li-ion battery with LiPF₆-based electrolyte was investigated. Specific capacity of the material reached 130 mA·h/g at a rate of 0.5С and 20°C, 105 mA·h/g (1С) and 95 mA·h/g (2.1C). Cell capacity increased by 20% during first 50 cycles and minor capacity fade at a rate of 0.04% per cycle is observed after 300 cycle when cycled at 2C rate versus carbon negative electrode (CMS, PRC).

The flash point tester PE-TVZ was modernized. The sample volume was reduced from 70 to 5 ml. Mixing of the condensed and gas-vapor phases was done simultaneously. The mercury thermometer was replaced by an electronic one. The correctness of the flash point measurement by the modernized device was tested on the samples with the flash point in the range of 25–170°C.

The publications of the recent 15 years devoted to using lithium metal in rechargeable batteries are analyzed and their short overview is presented.

Characterization by in situ or operando methods is very important to deeper understand the chemical and electrochemical processes, as well as the degradation processes that occur during the operation of a lithium-ion battery.

Doped lithium titanate is known to be able to reversibly cycle in the potential range from 3 to 0.01 V and this ability depends both on the nature of the dopant and the doping level. In this work Li₄Ti₅O₁₂ samples doped with Nd in the amount of 0.5 to 2.0% were studied. It was shown that while being cycled in the extended potential range, the samples with the doping level from 0.5 to 1.0% demonstrated the highest capacity.