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In this work the self-discharge characteristics are evaluated through resting OCV (open-circuit voltage)-SOC (state-of-charge) hysteresis and storage aging behavior for pouch NCM|graphite lithium-ion battery. A weak peak is found on the OCV-SOC curve of incremental capacity and differential voltage analysis. A low free-energy complex model involving the formation of an absorbed electron-lithium-ion solvation sheath on the graphite surface is proposal for this weak reaction. The electrons are shared between the graphite and electrolyte via lithium-ion. Results of batteries aging tests reveal a strong linear relation of OCV vs. square-root of time, where the dissociation of complex is considered as the mechanism. The dependency of the square-root of time demonstrates that a new concept of voltage drop rate (mV h−1/2) is more feasible by reducing the influence of OCV checking time from 120% to 26%.

For lithium-ion batteries (LIBs), the current collectors are indispensable components for loading electrode materials. The electrolytic copper foils with different tensile strength were selected to study the strengthening mechanism of copper foil. Through refining crystal grains and strengthen the crystal orientation of copper foils, the tensile strength can be considerably improved. For normal strength copper foil, the crystal orientation is (200) plane and the average grain size is 1.428 µm. For high strength and super strength copper, the crystal orientation are both (220) plane, and the average grain sizes are 1.09 µm and 862 nm. Moreover, the influence mechanism of texture to strength was studied by characterizing the dislocation density of the copper foils. Through which, the dislocations and substructures inside the crystal grains that produced by the release of residual internal stress can be observed, and the deformation of the crystal grains can be hindered during a stretch process.

Cyclic aging tests of LiNi1/3Co1/3Mn1/3O2 batteries are performed at 25℃, 45℃ and 60℃. Several non-invasive electrochemical techniques, such as incremental capacity analysis, differential voltage analysis and capacity difference analysis, are employed to deduce degradation mechanism. The degradation mechanism of batteries is similar at different temperatures. Loss of active positive material follows a linear function at all conditions and increases by elevating temperature. Due to the graphite's volume expansion and contraction, loss of active negative material is observed at the first 100 full cycle equivalents. Then, it disappears until the appearance of a dense lithium-containing passivation layer. This covering layer is mainly from lithium deposition on the negative electrode surface. With this lithium-impermeable covering layer's growth, the homogeneity of active lithium distribution is successively reduced, and loss of negative material increases gradually. Moreover, a worst cyclic performance is found at 45℃, where the homogeneity of electrodes reduces rapidly. All results reveal that loss of active materials and lithium inventory loss only influence capacity loss. The evolution of the covering layer on the negative electrode surface is the deciding factor for cycle life.

An electrochemical investigation of As(III) in hydrochloric acid solution was carried out using cyclic voltammetry (CV) and potentiostatic methods. The generation of arsine is closely related to the reduction of H+ and the preformed elementary As. The cathodic peak corresponding to the evolution of arsine was remarkably decreased by the addition of ammonium citrate. Potentiostatic experiments showed that the ammonium citrate had a strong inhibition on the evolution of arsine and could benefit the deposition of elementary As. A low-activity As layer with larger grains was formed in the presence of ammonia citrate, accounting for the inhibitory effect on arsine evolution. Keywords: Arsenic, Arsine, Ammonium citrate, Cyclic voltammetry, Potentiostatic deposition