Electrochemical energy storage system with high energy density, stringent safety and reliability is highly desirable for the next-generation energy storage devices. Here aqueous rechargeable alkaline CoxNi2-xS2 // TiO2 battery system is designed by integrating two reversible electrode processes associated with OH- insertion/extraction in cathode part and Li ion insertion/extraction in anode part, respectively. The prototype CoxNi2-xS2 // TiO2 battery is able to deliver high energy/power densities of 83.7 Wh/kg at 609 W/kg (based on the total mass of active materials) and good cycling stabilities (capacity retention 75.2% after 1,000 charge/discharge cycles). A maximum volumetric energy density of 21 Wh/l (based on the whole packaged cell) has been achieved, which is comparable to that of thin film battery and better than that of typical commercial supercapacitors, benefiting from the unique battery and hierarchical electrode design. This hybrid system would enrich the existing aqueous rechargeable LIB chemistry, and be a promising battery technology for large-scale energy storage.