Inorganic Na3Zr2Si2PO12 is prospective with a high ionic conductivity but suffers large interfacial resistance and stability issues against sodium metal, hindering its practical application in all‐solid‐state sodium batteries. A surface potential regulation strategy is adopted to address these issues. Na3Zr2Si2PO12 (NZSP) ceramic with homogeneously‐sintered surface is synthesized by a simple two‐step sintering method to promote its uniform surface potential, which is favorable for mitigating the potential fluctuations at the interface against Na metal and enhancing interfacial compatibility. The Na/NZSP interface can be stabilized for over 4 months with a low interfacial resistance of 129 Ω cm2 at 25 °C. The symmetrical Na/NZSP/Na cell exhibits ultra‐stable sodium platting/stripping cycling for over 1000 cycles under 0.1 mA cm−2. Superior interfacial performance is well retained even under 0.2 mA cm−2 at room temperature. The robust interface is further signified by its excellence under higher current densities of up to 0.85 mA cm−2 at 60 °C. A 4 V all‐solid‐state Na3V1.5Cr0.5(PO4)3/NZSP/Na metal battery is demonstrated at ambient conditions, which exhibits superior rate capability and delivers a high reversible capacity of 103 mA h g−1 under 100 mA g−1 for over 400 cycles with a Coulombic efficiency of over 99%.
Multidimensional folded structures with elasticity could provide spatial charge storage capability and shape adaptability for micro-supercapacitors (MSCs). Here, highly crumpled in-plane MSCs with superior conformality are fabricated in situ and integrated by a fixture-free omnidirectional elastic contraction strategy. Using carbon nanotube microelectrodes, a single crumpled MSC holds an ultrahigh volumetric capacitance of 9.3 F cm
−3
, and its total areal capacitance is 45 times greater than the initial state. Experimental and theoretical simulation methods indicate that strain-induced improvements of adsorption energy and conductance for crumpled microelectrodes are responsible for the prominent enhancement of electrochemical performance. With outstanding morphological randomicity, the integrated devices can serve as smart coatings in moving robots, withstanding extreme mechanical deformations. Notably, integration on a spherical surface is possible by using a spherical mask, in which a small area of the microdevice array (3.9 cm
2
) can produce a high output voltage of 100 V.
the distressing interfacial issues is critical to realize the smooth operation and long lifespan of SSAMBs.The unsatisfactory interface is mainly caused by the chemical mismatch and the rigid contact between the solid electrolyte and the metal anode. [13,14] Researchers have proposed various methods to boost the robust solid electrolyte/Li or Na metal interface for reduced interfacial impedance, improved critical current densities, and long-term cycling stability. [15][16][17][18][19][20][21] Among them, surface modification of the solid electrolyte proves one of the most effective ways as it introduces an active interphase to mitigate the difference between the alkaline metal and the solid electrolyte. [17,22] Functional coatings including
Achieving satisfactory performance for a solid‐state Na‐metal battery (SSNMB) with an inorganic solid electrolyte (SE), especially under freezing temperatures, poses a challenge for stabilizing a Na‐metal anode. Herein, this challenge is addressed by utilizing a Natrium super ionic conductor (NASICON) NASICON‐type solid electrolyte, enabling the operation of a rechargeable SSNMB over a wide temperature range from −20 to 45 °C. The interfacial resistance at the Na metal/SE interface is only 0.4 Ω cm2 at 45 °C and remains below 110 Ω cm2 even at −20 °C. Remarkably, long‐term Na‐metal plating/stripping cycles lasting over 2000 h at −20 °C are achieved with minimal polarization voltages at 0.1 mA cm−2. Further analysis reveals the formation of a uniform Na3−xCaxPO4 interphase layer at the interface, which significantly contributes to the exceptional interfacial performance observed. By employing a Na3V1.5Al0.5(PO4)3 cathode, the full battery system demonstrates excellent adaptability to low temperatures, exhibiting a capacity of 80 mA h g−1 at −20 °C over 50 cycles and retaining a capacity of 108 mAh g−1 (88.5% of the capacity at 45 °C) at 0 °C over 275 cycles. This research significantly reduces the temperature threshold for SSNMB operation and paves the way toward solid‐state batteries suitable for all‐season applications.
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