Dual-cation electrolyte systems, which contain two cations [Li + and spiro-1,1′-bipyrrolidinium (SBP + ), are proposed to enhance the power capability of hybrid capacitors composed of thick Li 4 Ti 5 O 12 (LTO) negative (200 μm) and activated carbon (AC) positive electrodes (400 μm), which thus reduces the resistive overvoltage in the system. Detailed studies of the mass transport properties based on the combination of spectroscopy and electrochemical analysis have shown that the presence of SBP + , despite slower Li + transport in the electrolyte bulk, further reduces overvoltage associated with migration limitation in the thick LTO electrode macropores. This study on the dual-cation electrolyte quantifies the influence of the addition of a supporting electrolyte and shows interest in SBPBF 4 addition for increasing the output power density of hybrid capacitors with a thick electrode configuration.

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SynopsisThe tensile behaviors of polystyrene (PS), poly(styrene/acrylonitrile) (SAN), high-impact polystyrene (HIPS), and poly(acrylonitrile/butadiene/styrene) (ABS) were examined systematically in the wide range of strain rate, 1.7 X 10-4-13.1 m/s. When glassy and brittle PS was a criterion, the incorporation of a polar group (SAN) only strengthened the hardness, and the fracture mode was the same as for PS. The introduction of dispersed rubber particles (HIPS) weakened the hardness a little but offered a new deformation mechanism, i.e., microcrazing (whitening), and contributed to the improvement of impact strength. In the heterogeneous system, the enhancement of matrix strength [e.g., preorientation or blending with poly(pheny1ene oxide) for HIPS] makes possible another deformation mechanism, i.e., shear band formation (cold drawing), which is superior to microcrazing for achieving higher impact strength, ABS, which incorporates concurrently two factors (polar group to matrix phase and dispersed rubber particles), can be regarded as an enhancement of the matrix strength of HIPS, In spite of the remarkable magnitude of its impact strength compared with that of the other three polymers, the deformation mechanism of ABS was limited to microcrazing. This indicated that only the introduction of a polar group (as nitrile group) could not strengthen the matrix as much as preorientation or blending with poly(pheny1ene oxide). INTRODUCTIONThe homopolymer of styrene (PS) exhibits brittle fracture and low impact toughness at room temperature. To make up for this deficiency, two measures are taken. First, the breaking stress is reinforced by the introduction of polar groups. For example, styrene and acrylonitrile are copolymerized (SAN). Secondly, the strain up to fracture is increased without an accompanying lowering of strength. This can be performed by the addition of rubber in particle form to polystyrene. It is important that the dispersed rubber particles are grafted onto polystyrene chains (not a simple milling-in of rubber with PS matrix). Poly(acrylonitrile/butadiene/styrene) (ABS) is a two-phase material consisting of elastomer particles in a glassy polymer matrix of SAN. ABS can be interpreted as a polymer in which the two measures described above are combined.Correlations among the chemical components of PS, SAN, HIPS, and ABS are schematized (Fig. 1).The aim of the present study is to investigate how the mechanical properties of a polymer change (1) by the introduction of a polar group, (2) with the incorJournal of Applied Polymer Science, Vol. 28,2209Vol. 28, -2216Vol. 28, (1983 poration of dispersed rubber particles which are grafted onto the matrix polymer chains, and (3) by the concurrent introduction of the factors (1) and (2), when polystyrene is primarily a criterion of the mechanical properties. The mechanical testing was limited to measurements of tensile and impact tensile properties at room temperature, where the shape of specimen and the deformation mode were all the same in the wide range of de...