Lithium battery pack system and square lithium battery module thereof

The invention discloses a square lithium battery module. The battery module comprises a battery cell module, a polarity connecting sheet, an integrated plate, an upper cover plate, a left side plate,a right side plate and a bottom plate, wherein the battery cell module is formed by laminating a plurality of battery cell groups in multiple columns, an insulating plate attached to the two adjacentbattery cell groups is arranged between the two adjacent battery cell groups, a heating sheet attached to the two adjacent battery cell groups is arranged between the two adjacent battery cell groups,and each battery cell group is formed by connecting a plurality of square single battery cells in series and in parallel through a flexible circuit board. The battery cell groups in the square lithium battery module have the same heat dissipation physical field, mutual heat transfer between the battery cell groups is blocked, the heating uniformity of the square single battery cells is better, and the consistency of the sq