Research On The Preparation Of Lithiun-ion Battery Ultra-thin Electrode

With the miniaturization of electronic devices continue to develop in the directionof small power consumption, the new flat micro-cell has attracted people’s attention. Allsolid-state thin film lithium ion batteries has became the most promising micro-cellsystem because of light weight, small size, long cycle life, high energy density, widetemperature range and so on. At present, researchers used electrode preparationtechniques such as RF magnetron sputtering, pulsed laser deposition or chemicaldeposition, but the problems are that high cost, the equipment complex, can not beindustrialized. In contrast, ink-jet printing technology not only has its specialadvantages of economy, fast, high efficiency, but aslo can join in a conductive agent toimprove the electrode conducts electricity, getting rid of the high temperature heattreatment process to optimize the preparation process.This thesis has a similar α-NaFeO₂layer structure LiCo_0.8Ni_0.2O₂and peridot typeLiFePO₄for electrochemical activity materials, AES-A as dispersant agent, CMCS asadhesive. Adjusting pH value, after ultrasonic dispersion, scanning electron microscopyand particle size analysis test, the results showed that electrochemical activity materialcould disperse evenly. Two kinds of ultrathin electrodes were LiCo_0.8Ni_0.2O₂andLiFePO₄were successfully fabricated by ink-jet printing technique, the electrodes wereporous electrode, in the ultrasonic and printing processes, the crystal structure ofLiCo_0.8Ni_0.2O₂and LiFePO₄were maintained very well in ultrathin electrode.Then ultrathin electrode with a minor follow-up heat treatment（under the infraredlamp baked1h）, because of the thermal decomposition of dispersants and adhesivesmaking the inter-particle porosity increased. Electrode properties as follows:（1）5-layer and10-layer printed LiCo_0.8Ni_0.2O₂electrode powder thickness arerespectively2μm,3.5μm. The initial discharge capacity were158mAh·g^-1,153mAh·g^-1at charge current of2μA·cm^-2in the potential range of3.2～4.2V, the results are similarwith the electrode impedance results. LiCo_0.8Ni_0.2O₂ultrathin electrodes with excellentcharge-discharge performance, the cycle discharge capacity maintained at98.6%after100cycles. （2） After20times of ink-jet printing LiFePO₄electrode powder thickness is about5.8μm. Different thickness of the LiFePO₄electrodes first discharge capacity are150mAh·g^-1,152mAh·g^-1,150mAh·g^-1at charge current of2μA·cm^-2in the potentialrange of3.0～4.0V. The10times printed LiFePO₄electrode has good charge anddischarge properties, and after100cycles, the electrode still has a discharge capacity of142mAh·g^-1.