Negative pole piece and secondary battery

The invention provides a negative electrode pole piece which comprises a negative electrode current collector and a negative electrode active material layer arranged on at least one side surface of the negative electrode current collector, the negative electrode active material layer contains a negative electrode active material, and the following parameter k is defined: k is in a range of 10.00-20.00; wherein Dv10, Dv50 and Dv90 respectively represent corresponding particle size values when the cumulative volume distribution percentage of the negative electrode active material reaches 10%, 50% and 90%, and the unit is [mu] m; x represents the average length-diameter ratio of particles of the negative electrode active material. The tortuosity of the negative pole piece is proper, so that the cycle performance of the battery prepared from the negative pole piece can be ensured, the safety performance is relatively good, and the energy density is relatively high. The invention also provides a secondary battery.