In the process of lithium battery cutting, the quality of the cutting edge of the pole piece has an important impact on the performance and quality of the battery, including: (1) burrs and impurities will cause short circuits in the battery, causing self-discharge or even thermal runaway; (2) size Poor accuracy, it is impossible to ensure that the negative electrode completely wraps the positive electrode, or the separator completely separates the positive and negative pole pieces, causing battery safety issues; (3) Material thermal damage, coating peeling, etc., causing the material to lose activity and fail to function; (4) Cut The unevenness of the edge causes the unevenness of the charging and discharging process of the pole piece. Therefore, the lithium battery pole piece cutting process needs to avoid these problems and improve the process quality.

　　1. Disc cutter slitting

　　Disc slitting mainly includes upper and lower disc knives, which are installed on the knife shaft of the slitting machine, and use the rolling shear principle to slit the positive and negative pole pieces with a thickness of 0.01 to 0.1 mm.

　　2. Die cutting

　　The die-cutting process of lithium battery pole piece is divided into two kinds: (1) The punching of the wood board knife die, the sharp blade is installed on the wood board, and the blade cuts the pole piece under a certain pressure. This process mold is simple and low cost, but the punching quality is not easy to control, and it is gradually eliminated. (2) Metal mold punching, using the extremely small gap between the punch and the lower die to cut the pole piece. The coating particles are connected together by a binder. During the punching process, the coating particles peel off under the action of stress, and the metal foil undergoes plastic strain. After reaching the breaking strength, cracks are generated and the cracks propagate and separate. The cross-section of the metal material punching piece is divided into 4 parts: collapse, shear zone, fracture zone and burr. The wider the shear band of the section, the smaller the collapse angle and burr height, and the higher the section quality of the punched part.

　　3. Laser cutting of lithium battery pole pieces

　　Both disc slitting and die cutting have tool wear problems, which can easily cause process instability, lead to poor cutting quality of pole pieces, and reduce battery performance. Laser cutting has the characteristics of high production efficiency and good process stability. It has been used in the cutting of lithium-ion battery pole pieces in industry. The basic principle is to use high-power density laser beams to irradiate the cut battery pole pieces to make the pole pieces It is quickly heated to a very high temperature, quickly melted, vaporized, ablated or reached the ignition point to form a hole. As the beam moves on the pole piece, the hole continuously forms a narrow slit to complete the cutting of the pole piece.

　　Among them, laser energy and cutting movement speed are the two main process parameters, which have a huge impact on cutting quality. When the laser power is too low or the moving speed is too fast, the pole piece cannot be completely cut, and when the power is too high or the moving speed is too low, the laser's action area on the material becomes larger and the slit size is larger.

　　Since the lithium battery pole piece is a double-sided coating with a metal layer in the middle of the current collector, and the properties of the coating and the metal foil are different, the response to the laser action is also different. When the laser acts on the anode graphite layer or the anode active material layer, they have high laser absorption rate and low thermal conductivity. Therefore, the coating requires relatively low melting and vaporization laser energy. It has a reflective effect and heat conduction is fast, so the melting and vaporization of the metal layer increases the laser energy.

　　When the cutting process parameters of the lithium battery pole piece are not suitable, problems may occur: (1) The trimming coating falls off and the metal foil is exposed; (2) A large number of chips and foreign objects appear around the trimming. These will lead to battery performance degradation, safety and quality problems. Therefore, when laser cutting is used, it is necessary to optimize the appropriate process parameters according to the characteristics of the active material and the metal foil to completely cut the pole piece and form a good trimming quality without leaving metal chips and impurities.