Battery pack, power tool system, and charging system

A battery pack for a power tool, comprising:

• a housing comprising a first material;
• a cell assembly disposed in the housing and comprising a plurality of cell units, wherein each of the plurality of cell units comprises a positive electrode and a negative electrode;
• a cell support comprising a second material, which is configured to support at least the cell assembly;
• and
• a buffer layer disposed between adjacent cell units and made of the second material;
• wherein the cell support is at least disposed at two ends of the cell assembly, at least part of the cell support encapsulates the positive electrode of each of the plurality of cell units and the negative electrode of each of the plurality of the cell units, and the first material is different from the second material.