Capacity loss analysis of the causes of charging is charging so-called charging more than the prescribed termination voltage (usually 4.2 V) and continue to charging process. In the case the overcharge causes battery casio np-20 battery capacity attenuation, basically has the following factors: (1) the graphite of negative overcharge response; (2) positive overcharge response; (3) when electrolyte oxidation reaction in overcharge. The battery in the overcharge, lithium ion easy reductive deposition in Li++ e > anode surface: Li (s) deposition of lithium wrapped in negative surface, blocked the lithium embedded. Lead to discharge low efficiency and capacity loss, reasons are: (1) the circulating lithium decreases; (2) the metal lithium and sedimentary solvents or supporting electrolyte Li2CO3, LiF reaction formation or other products; (3) metal lithium usually forms in between anode and diaphragm, may increase the porosity of the obstruction diaphragm internal battery. Fast charging excessive, current density, negative serious polarization, lithium deposits will be more apparent. Positive overcharge cause capacity loss is mainly because electrochemical inert substance (such as Co3O4, etc) Mn2O3 produced, destroyed the capacity balance between electrode, its capacity loss is irreversible.
> (1 - y) / 3 [Co3O4 + O2 (g)] + and positive materials in seal of lithium-ion battery casio np-100 battery to break the oxygen produced don't exist again due to combined reaction (such as generating H2O) and electrolyte decomposition inflammable gas engendered and accumulation, consequence will be unimaginable. Overcharge also lead to electrolytes, the oxidation rate oxidation reaction with positive material surface area size, set electricity body material and add conductive agent (such as carbon black) has the very big relations, meanwhile, the type and size of carbon surface of electrolytic liquid oxygen is also affect one of the important factors, the surface area is larger, more easily in solvent surface oxidation. When the pressure when than 4.5 V electrolyte will oxidation generating insoluble, (such as Li2Co3) and gas, these insoluble, can jam the microporous inside the electrode block lithium ion migration and cause circulation process capacity loss.
Electrolyte decomposition by solvent and electrolyte supporting electrolyte component in the positive decomposition usually forms of insoluble products such as Li2Co3 and LiF electrode, through the obstruction of the pore and reduce battery capacity, electrolyte reduction reactions battery capacity and circle life will produce the bad influence, and because the reductive produced gas will make a battery inner pressure increases, leading to security issues. Electrolyte in graphite and other intercalated-li anode carbon on stability is not high, easy to the reaction that produces the irreversible capacity. When first charging and discharging electrolyte decomposition form in the electrode surface passivation membrane, passivating film electrolyte and carbon can be separated stop electrolyte anode further decomposition. Thus maintaining the structure of carbon cathode stability. The ideal conditions electrolyte reduction in the formation of limited passivation membrane, when circulation stabilization stage after this process is no longer occur. Electrolyte salt reduction in the formation of passivating film, to the stabilization of passivating film, but reduction of insoluble, produced using solvents recovery detrimental effects, and electrolyte salt reductive when the concentration of electrolyte, reduced, eventually lead to battery capacity loss (LiF, LixPF5 LiPF6 reductive generation x, PF3O and - PF3), meanwhile, the formation of passivating film consumes lithium ion, that leads to the poles caused by the unbalance between capacity battery BiRongLiang reduced. The type of process using carbon, electrolyte ingredients and electrode or electrolyte of additives are influence factors of film capacity loss. Electrolyte middling often contains oxygen, water and carbon dioxide and other substances. Trace amounts of water on the graphite electrode performance didn't influence, but water content is exorbitant generates Li2O LiOH (s) and, to the detriment of sedimentary lithium ion embedded, causes irreversible capacity loss: H2O + e - OH - + 1/2H222 OH - + Li + - LiOH (s) Li++ e LiOH + Li2O (s) and the CO2 in negative + solvent can generate CO and LiCO3 reduction (s) : 2CO2 + 2e + 2Li + - Li2CO3 + will make a battery inner pressure increases, and Li2CO3 (s) make a battery resistance increases affect battery performance.
Self-discharge self-discharge refers to the battery casio np-60 battery in unused natural condition, the phenomenon of electric capacity loss. Lithium ion battery self-discharge cause capacity loss divide kind of case: one is reversible capacity loss; 2 it is not reversible capacity loss. Reversible capacity loss means loss of capacity can recover in charge, but not reversible capacity loss, by contrast, such as lithium manganese oxide anode and solvent will occur microcells effects self-discharge causes irreversible capacity loss. By approximately 400mah life.low self-discharge degree, battery manufacturing process, electrolyte properties, temperature and such factors. If self-discharge rate by solvent oxidation rate control mainly, so the stability of the solvent storage life affects the battery anode in enough electricity, if the state and positive happen, battery capacity balance within life.low self-discharge are destroyed, will lead to permanent capacity loss. Long time or often self-discharge, lithium likely increase in carbon deposition on two levels, imbalance between capacity levels. Pistoia life.low self-discharge oxidation product that such as electrode material of the blockage, lithium microporous embedding and emerge difficulties and make resistance increases and discharge low efficiency, thus cause irreversible capacity loss. casio np-40 battery
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