There are two grounds in the application circuit of the MAX17055. One is the ground (CSP pin) of the MAX17055 IC, which should be connected to the negative end of the battery. The exposed pad of the IC (EP) and one end of the current sensing resistor are also connected to CSP. In addition, the system ground is connected to the load GND and the other end of the current sensing resistor, which is connected to CSN. Please see figure below from functional diagram in the datasheet: