The interaction between cathode and anode materials is critical for developing a high-performance asymmetric supercapacitor (SC). Significant advances have been made for cathode materials, while the anode is comparatively less explored for SC applications. Herein, we proposed a high-performance binder-free anode material composed of two-dimensional ZnFe₂O₄ nanoflakes supported on carbon cloth (ZFO-NF@CC). The electrochemical performance of ZFO-NF@CC as an anode material for supercapacitor application was examined in a KOH solution via a three-electrode configuration. The ZFO-NF@CC electrode demonstrated a specific capacitance of 509 F g⁻¹ at 1.5 A g⁻¹ and was retained 94.2% after 10,000 GCD cycles. The ZFO-NF@CC electrode showed exceptional charge storage properties by attaining high pseudocapacitive-type storage. Furthermore, an asymmetric SC device was fabricated using ZFO-NF@CC as an anode and activated carbon on CC (AC@CC) as a cathode with a KOH-based aqueous electrolyte (ZFO-NF@CC||AC@CC). The ZFO-NF@CC||AC@CC yielded a high specific capacitance of 122.2 F g⁻¹ at a current density of 2 A g⁻¹, a high energy density of 55.044 Wh kg⁻¹ at a power density of 1801.44 W kg⁻¹, with a remarkable retention rate of 96.5% even after 4000 cycles was attained. Thus, our results showed that the enhanced electrochemical performance of ZFO-NF@CC used as an anode in high-performance SC applications can open new research directions for replacing carbon-based anode materials.

Developing argyrodite-type, chlorine-rich, sodium-ion, solid-state electrolytes with high conductivity is a long-term challenge that is crucial for the advancement of all-solid-state batteries (ASSBs). In this study, chlorine-rich, argyrodite-type Na_6−xPS_5−xCl_1+x solid solutions were successfully developed with a solid solution formation range of 0 ≤ x ≤ 0.5. Na_5.5PS_4.5Cl_1.5 (x = 0.5), displaying a highest ionic conductivity of 1.2 × 10⁻³ S/cm at 25 °C, which is more than a hundred times higher than that of Na₆PS₅Cl. Cyclic voltammetry and electrochemical impedance spectroscopy results demonstrated that the rich chlorine significantly enhanced the ionic conductivity and electrochemical stability, in addition to causing a reduction in activation energy. The Na_5.5PS_4.5Cl_1.5 composite also showed the characteristics of a pure ionic conductor without electronic conductivity. Finally, the viability of Na_5.5PS_4.5Cl_1.5 as a sodium electrolyte for all-solid-state sodium batteries was checked in a lab-scale ASSB, showing stable battery performance. This study not only demonstrates new composites of sodium-ionic, solid-state electrolytes with relatively high conductivity but also provides an anion-modulation strategy to enhance the ionic conductivity of argyrodite-type sodium solid-state ionic conductors.

Solid polymer electrolytes have been considered as promising candidates for solid-state batteries (SSBs), owing to their excellent interfacial compatibility and high mechanical toughness; however, they suffer from intrinsic low ionic conductivity (lower than 10⁻⁶ S/cm) and large thickness (usually surpassed over 100 μm or even 500 μm), which has a negative influence on the interface resistance and ionic migration. In this work, ceria quantum dot (CQD)-modified composite polymer electrolyte (CPE) membranes with a thickness of 20 μm were successfully manufactured via 3D printing technology. The CQD fillers can reduce the crystallinity of the polymer, and the oxygen vacancies on CQDs can facilitate the dissociation of ion pairs in the NaTFSI salt to release more free Na⁺, improving the ionic conductivity. Meanwhile, tailoring the thickness of the CPE-CQDs membrane via 3D printing can further promote the migration and transport of Na⁺. Furthermore, the printed NNM//CPE-CQDs//Na SSB exhibited outstanding rate capability and cycling stability. The combination of CQD modification and thickness tailoring through 3D printing paves a new avenue for achieving high performance solid electrolyte membranes for practical application in Na SSBs.

3D-printed functional materials have emerged as ideal candidates for energy storage devices owing to their advanced structural integrity, miniaturization and enhanced functional properties. This chapter presents a thorough examination of recent advancements in enhancing the structural integrity and functional properties of 3D printed materials, emphasizing novel methods that improve mechanical strength and durability, focusing on the use of advanced composite materials and state-of-the-art printing techniques. This discussion includes significant breakthroughs in additive manufacturing, enabling the integration of multifunctional characteristics into printed objects. This chapter highlights the key applications in energy storage devices and demonstrates the benefits and transformative potential of these systems. Furthermore, it addresses current challenges in the field and suggests future research directions to further optimize the performance and reliability of 3D printed materials, thereby paving the way for more robust and adaptable 3D printing materials in energy storage systems.