Preparation method and application of lithium cobalt oxide soft-pack battery

A preparation method for a lithium cobalt oxide soft-pack battery, comprising the following steps:

• (1) mixing a lithium cobalt oxide cathode material, polyvinylidene fluoride, carbon black and an organic solvent and stirring, then vacuumizing, sieving, coating a resulting slurry on an aluminum foil, rolling, slitting, and drying to obtain a positive electrode strip;
• (2) mixing a graphite material, a carboxymethyl cellulose salt, carbon black, a conductive agent, styrene-butadiene rubber and water, and then vacuumizing, sieving, coating a resulting slurry on a copper foil, rolling, slitting, and drying to get a negative electrode strip;
• (3) cutting an aluminum-plastic film, and then performing punching and drying to obtain an aluminum-plastic film with pits;
• wherein the drying is carried out at a temperature of 90 to 120° C. for 8-15 h;
• (4) performing screening and tab welding to the positive electrode and negative electrode strip respectively, winding the positive electrode strip, the negative electrode strip and a separator to make an electric core, and then performing hot pressing to obtain a hot-pressed electric core;
• (5) placing the hot-pressed electric core in the pit of the aluminum-plastic film, folding the aluminum-plastic film in half, heat-sealing the sides, and then vacuum drying to obtain a vacuum-dried pack;
• (6) filling the vacuum-dried pack with an electrolyte in a glove box, letting stand before performing a first sealing, then performing formation, letting stand to release gas, and performing a second sealing to obtain a battery;
• wherein after the first sealing, a process of shaping the battery is further included;
• and the formation is carried out with following procedure in a test cabinet:
• charging to 3.4-3.5 V at 0.02 or 0.05 C, leaving for 3-5 min, then charging to 3.6-3.7 V at 0.05 or 0.1 C, and leaving for 3-5 min, finally charging to 3.9-4.0 V at 0.1 or 0.33 C and stopping to complete the formation procedure;
• (7) capacity grading the battery to obtain the lithium cobalt oxide soft-pack battery;
• wherein the capacity grading is carried out with following procedure:
• charging to 4.2-4.5 V at 0.1 or 0.33 C, leaving it for 3-5 min, then discharging to 3.0-3.2 V at 0.1 or 0.33 C, finally charging to 4.0-4.2 V at 0.1 or 0.33 C and stopping to complete the capacity grading of the lithium cobalt oxide soft-pack battery.