The scalable multifunctional solid electrolyte (MSE) composed of poly(ethylene oxide)-solid oxide lithium-ion conductor Li7La3Zr2O12-succinonitrile (PEO18-LiTFSI-LLZO-SN) is demonstrated as a promising candidate for high performance all-solidstate batteries. Among these electrolytes, PEO18-LiTFSI-7.5% LLZO-10% SN presents a highest ionic conductivity of 1.19 x 10(-4) S . cm(-1) at room temperature and a much higher Li+ transference number. Moreover, this MSE has a good electrochemical stability of 5.5 V vs. Li/Li+, and exhibits excellent interfacial compatibility against lithium electrode. Owing to the improved interface contact and enhanced Li+ transference, theMSE-based ASSLBs present outstanding cycling and rate performance at 60 degrees C. Notably, the initial discharge capacity at 1 C is 130.2 mAh . g(-1), and after 500 cycles 80.0% capacity is retained. The cell can be operated normally at lower temperatures (30 degrees C and 45 degrees C) while still delivering a relatively high specific capacity. (C) 2018 The Electrochemical Society.