Solid-state electrolytes are regarded as the “holy grail” of next-generation batteries because of the enhanced electrochemical stability, broaden operating temperature, prolong cycling life, and safety. However, solid ceramic electrolyte and solid polymer electrolyte are still plagued by high electrolyte/electrode interfacial resistance and low ionic conductivity, respectively. The pairing of pristine Na3Zr2Si2PO12 (NASICON) ceramic electrolyte with Na anode leads to large interfacial resistance and poor interface wettability that result in non-uniform Na+ flux. Here, we demonstrate for the first time the direct growth of an ultrathin graphene-like layer on NASICON by chemical vapor deposition. The graphene-like interlayer serves as a uniform and conductive Na+ network. Consequently, the interface modified NASICON significantly decreased the interfacial resistance by more than ten-fold, improved Na plating/stripping cycling stability and enabled uniform Na plating with minimized uncontrolled dendrite-like formation after many cycles. The Na/Na symmetric cells with modified NASICON delivered remarkably stable stripping/plating cycling behavior at a rate of 1 mA/cm2 with 1 mAh/cm2 capacity over 1000 cycles that, to the best of our knowledge, is the best performing all-solid-state Na symmetric cells reported. Moreover, SEM images revealed Na electrodes cycled with modified NASICON remained smooth on the surface, while Na electrodes cycled with pristine NASICON exhibited dendrite-like morphology. Subsequently, this interface modified NASICON was applied as active ion-conducting filler to enhance the performance of PEO-based solid polymer electrolyte. The synergetic effects of the modified ceramic and optimized polymer electrolytes lead to improvement in both interfacial wettability and ionic conductivity. This novel composite polymer electrolyte effectively stabilized all-solid-state Na plating/stripping voltage, reduced cycling overpotential, and improved the specific capacity of a Na full cell. Hence, this work represents a step forward from the conventional solid PEO electrolyte.

Electrochemically stable all-solid-state sodium metal battery enabled by chemically engineered solid electrolytes

2019 Fall National Meeting

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