Patent CN215610864U - Large-Capacity Vacuum Slurry Mixer

In lithium-ion battery production, the mixing and dispersion of the cell slurry determines more than 30% of final product quality - the specification calls it the most important link in the entire production process. Yet the mixers in use delivered only an average stirring effect: under-dispersed active particles travel unevenly between the two electrodes, and that unevenness follows the slurry all the way into the coated electrode, the dried coating and finally cell capacity and cycle life.

CN215610864U, filed on 26 August 2021, attacks the problem at the machine level: a vacuum mixer whose slurry chamber is sealed by lifting one barrel onto another, whose stirrer combines three sets of stirring rods with three wall-scraping bars, and whose reducer lets the controller assign a different stirring speed to each stage of the batch.

Patent Information

The Production Problem This Patent Solves

Cathode slurry is built from binder, conductive agent and cathode material; anode slurry from binder and graphitic carbon. Each batch is a succession of liquid-liquid and liquid-solid mixing, dissolving and dispersing steps, all accompanied by changes in temperature, viscosity and the surrounding environment. If the granular active materials are not dispersed evenly, lithium-ion transport between the electrodes suffers - and so does every downstream process.

The specification names the weak point directly: the stirring effect of the cell slurry was only ordinary in the equipment then available, and slurry that is not fully homogenised makes battery quality uneven across the market. The device in CN215610864U is designed to close that gap before the slurry ever reaches the coater.

How the Mechanism Works

Lift-and-seal twin-barrel chamber

The mixer has no bottom door. A lower mixing barrel (4) sits on a lifting table (3) inside the base (101) of the frame (1). A lifter (7) at the lower right of the frame raises the table until the lower barrel meets the fixed upper barrel (5), where a sealing ring between the two barrels closes the chamber so it can be evacuated. The lower and upper barrels are made of SUS304 stainless steel, chosen in the specification for stable physical and chemical behaviour and corrosion resistance.

Stirrer with rods and wall scrapers

Inside the upper barrel, the stirrer (6) carries three sets of stirring rods (601) on its inner side and three wall-scraping bars (602) on its outer side. The rods disperse the slurry; the scrapers lift material off the barrel wall and push it back into the flow, so no stagnant layer is left at the wall and the batch is stirred thoroughly rather than merely agitated in the middle.

Vacuum line, sight port and control

A vacuum line (503) connects the front of the upper barrel to the vacuum unit inside the frame, so air is drawn out of the sealed chamber before and during mixing. A sight port (501) at the lower left of the upper barrel - closed by a sealing cover (502) with a tempered-glass centre - lets the operator watch the slurry in real time. The controller (2) on the front of the frame carries an LED display (202) for the working parameters and an emergency stop button (203).

Chain-driven reducer and stage-controlled speed

The motor (8), fixed to the frame wall through a motor fixing seat, sits above a reducer (9). The reducer passes power to the stirrer through a chain, which the specification notes runs smoothly and quietly. Because the reducer output speed is adjusted from the controller, the machine can assign different speeds to different stirring stages of the same batch - the second half of the specification's two-part answer to mixing quality.

Operating sequence

Raw materials are loaded into the lower barrel while it stands on the lowered table. The lifter then raises the lower barrel into sealing contact with the upper barrel, the vacuum unit evacuates the chamber, and the motor starts. The stirrer runs the slurry through the assigned speed stages while the operator watches through the sight port. When mixing is finished, the table descends, the barrels separate, and the batch is discharged.

Claimed Benefits

How It Compares with Conventional Slurry Mixing Vessels

Each slurry batch is a succession of mixing, dissolving and dispersing steps with changing temperature and viscosity. If granular active material is not fully dispersed, electrode quality suffers - so the mixer itself is where consistency is won or lost.

Where This Technology Is Used Today

This patent covers the slurry-mixing architecture behind TOB's large vacuum mixers. The combination it protects - a lift-sealed barrel chamber, wall-scraping agitation and stage-controlled speed - is how our mixing equipment delivers the homogeneous electrode slurry that coating quality depends on.

• 2000L planetary vacuum mixer and dispersing machine - production-scale mixing and dispersion for battery slurry
• Electrode preparation equipment - slurry mixing, testing, coating, rolling and slitting equipment

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Frequently Asked Questions

Full specification and drawings: CN215610864U on Google Patents