BATTERY MODULE, BATTERY PACK, ELECTRICAL APPARATUS, AND MANUFACTURING METHOD AND MANUFACTURING DEVICE OF BATTERY MODULE

The present application relates to a battery module, including a first-type battery cell and a second-type battery cell electrically connected at least in series, the first-type battery cell and the second-type battery cell are battery cells of different chemical systems, the first-type battery cell includes N first battery cell(s), the second-type battery cell includes M second battery cell(s); the first battery cell includes a first negative electrode plate, the second battery cell includes a second negative electrode plate, a ratio of a conductivity of an electrolyte solution (25° C.) of the first battery cell to a coating mass per unit area of the first negative electrode plate is denoted as Ml, and a ratio of a conductivity of an electrolyte solution (25° C.) of the second battery cell to a coating mass per unit area of the second negative electrode plate is denoted as M2, M1>M2, and 0.08≤M1≤11, 0.03≤M2≤4.62.