Exploring the Limits of the Rapid-Charging Performance of Graphite as the Anode in Lithium-Ion Batteries

Graphite is, in principle, applicable as a high-power anode in lithium-ion batteries (LIBs) given its high intralayer lithium diffusivity at room temperature. However, such cells are known to exhibit poor capacity retention and/or undergo irreversible side reactions including lithium plating when charged at current rates above ~2C (~740 mA g-1). To explore the inherent materials properties that limit graphite anodes in rapid-charge applications, a series of full-cells consisting of graphite as the anode and a standard Li[Ni0.8Mn0.1Co0.1]O2 (NMC811) cathode was investigated. Instead of a conventional cathode-limited cell design, an anode-limited approach was used in this work to ensure that the overall cell capacity is only determined by the graphite electrode of interest. The optimized N:P capacity ratio was determined as N/P = 0.67, enabling stable cycling across a wide range of charging rates (4-20C) without inhibition by the NMC811 cathode. The results show that unmodified, highly crystalline graphite can be an excellent anode for rapid-charge applications at up to 8C, even with a standard electrolyte and NMC811 cathode and in cells with 1.0 mAh cm-2 loadings. As a rule, capacity and specific energy are inversely proportional to crystallite size at high rates; performance can likely be improved by electrolyte/cathode tuning.

Electric field strength in a discharge with a liquid electrolyte cathode in air at atmospheric pressure

The electric field strength in the channel of a discharge with a liquid electrolyte cathode at atmospheric pressure in air with the current in range of 20–90 mA is measured. The dependences of the electric field strength on the value of the discharge current are found for aqueous solutions with different compositions and with different pH values, but with the same specific conductivity of 300 μS/cm. It is shown that these dependences don’t differ by much from eachother. The dependence of the electric field strength in a discharge with a liquid cathode on the discharge current, averaged over the composition of the solution, is obtained.

On the application of a discharge with liquid electrodes for polishing metal surfaces

The work investigates the electrical parameters of the discharge plasma with a liquid cathode and a combined porous anode. The discharge is carried out in the vertical position of the plasma column, has a volumetric multichannel structure with a pronounced diffuse structure of the electrode spots. The influence of the porous element on the stabilization of the discharge characteristics is revealed. Discharges with a liquid electrolyte cathode continue to be of great interest from the point of view of practical application and are studied in a wide range of changes in physical and geometric characteristics [1 - 4]. Discharge plasma with a liquid cathode can be most effectively used for cleaning, polishing, with simultaneous removal of fractured and relief layers, hardening, gas saturation, surface activation, improvement of mechanical and other characteristics of agricultural machinery parts. In this work, for plasma polishing, parts of the bearing assemblies of disc harrows were selected.

Electric arc in plasma flow of gas discharge with a liquid electrolyte

The properties of an electric arc ignited in a gas discharge plasma flow with a liquid electrolyte cathode are experimentally investigated. Aqueous solutions of sodium chloride with a specific electrical conductivity of 10-15 mS/cm were used as a liquid electrolyte. The distance between the anode and the liquid electrolyte cathode was set in the range of 5-60 mm, and the distance between the anode and the metal cathode was varied in the range of 2-30 mm. The current of gas discharge with a liquid electrolyte cathode was set in the range of 5-10 A, and the arc current varied in the range of 1-10 A. The conditions under which the arc burns with the formation of a contracted channel are revealed.

Combined electric discharge “arc + discharge with liquid electrolyte cathode”

A combination of an electric arc and discharge with a liquid electrolyte cathode in a single discharge gap has been created. The plasma column of discharge with liquid electrolyte cathode formed a “hollow cylinder”. The electric arc was burned in a vapor-gas environment inside the “hollow cylinder”. The gas discharge current with liquid electrolyte cathode was set in the range of 5-10 A, and the arc current varied in the range of 1-10 A. Aqueous solutions of sodium chloride with a specific electrical conductivity of 10-15 mS/cm were used as a liquid electrolyte. Spectral studies have been carried out in the visible range of radiation. In the experiments, copper and duralumin metal cathodes were used.