| dc.description.abstract | Previous research on lithium batteries found that the key to the physical properties of lithium-ion batteries mainly stems from the solid electrolyte interface (SEI). The ideal SEI needs to be able to protect the electrode from unnecessary side reactions between the electrode and the electrolyte. In addition, it does not hinder lithium. For the insertion/extraction of ions, SEI needs to have good ionic conductivity so as not to affect the electrical properties of the battery.
In view of this, this study explores the compound electric field effect with special modifying additives and discusses its effect on the formation of SEI and the improvement of the physical properties of lithium-ion batteries. First of all, in terms of additives, in this experiment, the compound AM and the compound BM were copolymerized to form the additive o-AB with a highly branched network structure. Composition Li[Ni1/3Mn1/3Co1/3]O2/Li half-cell test using scanning electron microscope (SEM), X-ray photoelectron spectroscopy (XPS), cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) Discuss. This experiment confirms that o-AB does participate in the formation of SEI and can reduce the decomposition of electrolyte and the consumption of lithium salt. With the addition of 1% and 3%, the battery capacity increased from 63.3 (mAh/g) to 96.7 (mAh/g) and 109.1 (mAh/g) after 100 cycles.
The electric field effect is used to induce the inorganic substances to be arranged in the forward direction to increase the pores of the electrode. It can be seen from the scanning electron microscope (SEM) that the pores of the electrode of the external applied electric field do increase. In addition to the easier penetration of the electrolyte, it also provides an extra diffusion channels for lithium ion to make the active material will not be destroyed in the battery charging and discharging process. Under the action of electric field strength of 3000, 4500 and 6000 (V/cm) (e3000, e4500, e6000), the capacity retention rate increases from 60.46% to 89.56% (e3000), 100.76% (e4500) and 100.48% (e6000) after 100 cycles.
Finally, we apply the additive compound electric field effect to lithium-ion batteries, hoping to combine the two technical advantages to bring better performance to lithium-ion batteries. Through the 500 cycle life test, it can be seen that the battery without any modification can no longer be charged and discharged after 350 cycles, and the capacity retention rate of the 0% e4500 battery after 500 cycles is only 15.51%. But at the same time, the capacity retention rate under the two ratios of 1% e3000 and 3% e3000 for the combined application of the additive and the electric field effect are 52.56% and 72.14%, respectively. The results show that increasing the pores through the electric field also allows the additives to more easily penetrate into the electrode and allows the active material to produce the SEI reaction more uniformly, so that the battery can continue to maintain good power after long cycles. | en_US |