고성능 슈퍼캐패시터용 표면기능화 맥신/이원금속 옥살레이트 복합체 기반 무바인더 전극 제조 및 전기화학적 특성 평가 = Fabrication and Electrochemical Characterization of Surface-Functionalized MXene/Bimetallic Oxalate Composite-Based Binder-Free Electrodes for High- Performance Supercapacitors

다국어 초록 (Multilingual Abstract)

Two-dimensional MXenes offer an electrically conductive, solution-processable framework with inherent charge-storage capability, making them attractive scaffolds for redox-active, metal-based compounds. In practice, however, their benefits are frequently compromised by lamellar restacking and insufficient chemical coupling to the partner phase.
In this study, I adopt a mussel-inspired surface-engineering route: levodopa undergoes in situ oxidative polymerization on MXene, forming an adhesive poly(levodopa) nanolayer. This conformal coating mitigates layer restacking and strengthens interfacial bonding while preserving the high conductivity and aqueous dispersibility characteristic of pristine MXene. The modified material (f-MXene) was combined with nickel cobalt oxalate (NCO) to fabricate a binder-free composite electrode (f-MXene/NCO). The composite delivers a markedly higher specific capacitance of 1,756 F g⁻¹, compared with 1,200 F g⁻¹ for MXene/NCO and 772 F g⁻¹ for NCO alone. Furthermore, an asymmetric supercapacitor assembled with f-MXene/NCO as the positive electrode and activated carbon as the negative electrode attains an energy density of 146.4 Wh kg⁻¹ at a power density of 775 W kg⁻¹ in an alkaline aqueous electrolyte.
Collectively, these results demonstrate that poly(levodopa) functionalization is an effective strategy to suppress MXene restacking, reinforce interfacial interactions, and realize high-performance, binder-free composite electrodes for aqueous supercapacitors.

목차 (Table of Contents)

• Ⅰ. Introduction 1
• Ⅱ. Experimental Section 3
• 1. Materials 3
• 2. Synthesis of nickel cobalt oxalate (NCO) 3
• 3. Synthesis of Ti₃C₂Tₓ MXene nanosheets 3
• 4. Synthesis of poly(levodopa)-functionalized MXene (f-MXene) 4
• 5. Preparation of MXene/NCO and f-MXene/NCO composites 4
• 6. Materials characterization 4
• 7. Electrochemical characterization 5
• Ⅲ. Results and Discussion 7
• 1. Synthesis and characterization of Poly(levodopa)-functionalized MXene (f-MXene) 9
• 2. Synthesis and characterization of f-MXene integrated nickel cobalt oxalate (f-MXene/NCO) 23
• 3. Electrochemical characteristics of f-MXene/NCO 31
• 4. Electrochemical performance of the f-MXene/NCO//activated carbon asymmetric supercapacitor 35
• Ⅳ. Conclusions 39