Emerging hydroxylated borophene-mediated gel electrolyte for enhanced quasi-solid zinc-ion supercapacitors

Poor transport kinetics, structural degradation, and an unstable electrode-electrolyte interface are the primary issues that significantly deteriorate the electrochemical performance of zinc-ion supercapacitors (ZISCs). To address these issues, we propose the concept of a hydroxylated borophene-bonded transport network embedded within a polyvinyl alcohol (PVA)/ZnSO 4 gel electrolyte (PVA/B) to construct a robust gel electrolyte. To elucidate the mechanism of this rationally designed gel electrolyte in regulating ion transport and interphase chemistry, comprehensive investigations, including simulations and diverse characterization techniques, were conducted. The results demonstrate that the formation of a C-O-B covalent bond network between the hydroxylated borophene modifier and PVA polymer facilitates rapid and uniform ion and electron transport. Moreover, the covalent bond, combined with a rough and porous surface, enhances interfacial transport kinetics. The use of the PVA/B gel electrolyte results in stable adsorption/desorption behavior and increased electric double-layer capacitance (EDLC). Additionally, gel and solid-state MXene//PVA/B//MXene ZISCs exhibit superior rate performance and cycling stability (20000 cycles). This approach provides valuable insights into gel electrolyte design and advances the development of high-performance quasi-solid ZISCs.