A binder free battery type supercapacitor electrode composed of 3D hierarchical dandelion-fiber flake-like structure has been synthesized by cost-effective, layer by layer (LbL) method for 10, 20, 30, 40 and 50 LbL cycles on flexible stainless-steel substrate. Among all the synthesized working electrodes, 40 LbL cycles shows the prominent electrochemical performance with a wide operating potential window (−1.0 to +1.0 V) in 1.0 M aq. Na2SO4 electrolyte. The maximum specific capacity of 958 C g−1 (maximum specific capacitance 479 F g−1) for 1 mA current rate has been achieved by using the three-electrode system. The novel composite material Al(OH)3/MnO2 shows the battery type supercapacitor electrode that comprises the high electronic conductivity with a better electrocapacitive performance that improves the energy storage capability. For having the deeper insight of charge storage mechanism, we evaluate the contribution of charges coming from the individual surface capacitive and diffusion-controlled process. The galvanostatic charge discharge illustrates good cyclic reversibility of composite film whereas electrochemical impedance spectroscopy (EIS) demonstrate the capacitive behavior of nanocomposite thin film with a low value of Rct ∼ 0.01 Ω cm−1. Therefore, it could be anticipated that Al(OH)3/MnO2 nanocomposite thin film is a promising electrode material for flexible and portable electronic devices, electric vehicles, etc.