Laser Direct Writing of MnO2/Carbonized Carboxymethylcellulose- Based Composite as High-Performance Electrodes for Supercapacitors

Manganese dioxide and its derivatives are widely used as promising electrode materials for supercapacitors. To achieve the environmentally friendly, simple, and effective material synthesis requirements, the laser direct writing method is utilized to pyrolyze the MnCO3/carboxymethylcellulose (CMC) precursors to MnO2/carbonized CMC (LP-MnO2/CCMC) in a one-step and mask-free way successfully. Here, CMC is utilized as the combustion-supporting agent to promote the conversion of MnCO3 into MnO2. The selected materials have the following advantages: (1) MnCO3 is soluble and can be converted into MnO2 with the promotion of a combustion-supporting agent. (2) CMC is an eco-friendly and soluble carbonaceous material, which is widely used as the precursor and combustion-supporting agent; (3) the redundant part of the MnCO3/CMC precursor can be removed by deionized water, which is simple and convenient. The different mass ratios of MnCO3 and CMC-induced LP-MnO2/CCMC(R1) and LP-MnO2/CCMC(R1/5) composites are investigated in the electrochemical performance toward electrodes, respectively. The LP-MnO2/CCMC(R1/5)-based electrode showed the high specific capacitance of 74.2 F/g (at the current density of 0.1 A/g) and good electrical durability for 1000 times charging-discharging cycles. Simultaneously, the sandwich-like supercapacitor which was assembled by LP-MnO2/CCMC(R1/5) electrodes presents the maximum specific capacitance of 49.7 F/g at the current density of 0.1 A/g. Moreover, the LP-MnO2/CCMC(R1/5)-based energy supply system is used to light a light-emitting diode, which demonstrates the great potential of LP-MnO2/CCMC(R1/5)-based supercapacitors for power devices.