An aliphatic hyper-branched polycarbonate (HBPC) was synthesized as a novel host material for solid polymer electrolytes (SPEs). The HBPC was synthesized through A(2) + B-3 polymerization to yield a branched polycarbonate structure. HBPC-based SPE films were prepared by drying mixed solutions of HBPC and 1-60 mol% LiCIO4. The temperatures for 5% weight loss (T(d5)s) of the HBPC-based SPEs were in the range of 174.4-189.3 degrees C, higher than those in normal use. The HBPC-based SPE exhibited higher ionic conductivities (1.86 x 10(-4)S.cm(-1) at 70 degrees C and 8.52 x 10(-6)S.cm(-1) at 30 degrees C) than a poly(trimethylene carbonate) (LPC)-based SPE (4.79 x 10(-6)S.cm(-1) at 70 degrees C and 8.32 x 10(-s)S.cm(-1) at 30 degrees C) for 20mol% lithium content. Activation energies of lithium ion transport for the HBPC- and LPC-based SPEs were estimated to be 11.47 and 15.88 kj-mol(-1), respectively. Introduction of this branched structure in polycarbonates is effective for promoting lithium ion transport. (C) 2018 Elsevier Ltd. All rights reserved.