Abstract: A stable smart laser hair-growing instrument with independent light sources includes a shell, a laser emitting assembly and a control system; the shell is provided with a cavity disposed above a user's head, the laser emitting assembly includes light sources, a first circuit board and multiple second circuit boards, the first circuit board is disposed in the shell at a position aligned at a center of a user head; a gap is arranged between the adjacent second circuit boards; the light sources are evenly distributed on the first circuit board and those of the second circuit boards; the control system includes a circuit control and a multi-group of independent control units electrically connected with the circuit control; all the independent control units are electrically connected to the corresponding driving circuit of the second circuit boards and that of the first circuit board, respectively.

Abstract: The present application discloses a positive electrode and a battery, which can solve safety problems faced by a high-energy-density battery, and prevent the problems that an initial direct-current internal resistance (DCIR) of the battery is too large, an increase change rate of the DCIR is large and a cycle performance deteriorates during cycle process. The present application provides a positive electrode piece, including a positive electrode current collector, a safety layer and an active substance layer, where the safety layer is arranged on a surface of the positive electrode current collector; the active substance layer is arranged on a surface of the safety layer; the safety layer and the active substance layer each contain Co and Al, where a mass ratio of a total amount of Co to a total amount of Al in the safety layer and the active substance layer is (12-85):1.