 Graphene nanosheets (GNs) with large specific surface area, high conductivity, and excellent flexibility were integrated with negative active materials (NAM) as backbones to construct a continuous conductive network to suppress the sulfation of negative plates and improve the cycle-life of lead–acid batteries (LABs) under high-rate partial state-of-charge (HRPSoC) condition. The microstructure of GNs was characterized by scanning electron microscopy (SEM), nitrogen adsorption–desorption techniques, fourier transform infrared (FTIR), and Raman spectroscopy. The effect of GNs at different contents in the electrochemical performances of negative plates and LABs is investigated. The electrochemical tests show that the cycle-life of LABs under HRPSoC conditions has improved by more than 370% and the utilization ratio of NAM has been raised to 63.7%, when 0.9 wt% additions of GNs was added to NAM. It is found that the GNs will be a promising carbonaceous additive for long cycle-life of LABs under HRPSoC conditions.