Provided is an alkali metal-ion battery, comprising: (a) an anode having an anode active material dispersed in a first liquid electrolyte disposed in pores of a 3D porous anode current collector having at least 80% by volume of pores; (b) a cathode having a cathode active material dispersed in a second liquid electrolyte disposed in pores of a 3D porous cathode current collector wherein the cathode thickness-to-current collector thickness ratio is from 0.8/1 to 1/0.8; (c) a separator disposed between the anode and the cathode; wherein the anode or cathode active material loading is greater than 10 mg/cm2, the anode and cathode active materials combined exceeds 40% by weight of the battery, and/or the 3D porous anode and/or cathode current collector has a thickness no less than 200 μm (preferably greater than 500 μm and more preferably greater than 700 μm) and is in physical contact with the separator.