Advanced energy storage device: a hybrid BatCap system consisting of battery-supercapacitor hybrid electrodes based on Li4Ti5O12-activated-carbon hybrid nanotubes

The battery-supercapacitor hybrid electrode, consisting of both faradaic rechargeable battery components and non-faradaic rechargeable supercapacitor components in a single electrode, is successfully developed using Li4Ti5O12-activated carbon (LTO-AC) hybrid nanotubes in a negative electrode for an advanced energy storage device. Li4Ti5O12 and PVA-derived activated carbon are hybridized with morphological control over the one-dimensional (1D) tubular structures via an in situ sol-gel reaction combined with electrospinning, followed by a hydrothermal reaction and appropriate heat treatment. The prepared LTO-AC hybrid nanotubes are tested at a variety of charge-discharge rates as anode materials for use in lithium-ion rechargeable batteries that deliver a specific capacity in the range of 128-84 mA h g(-1) over a 100-4000 mA g(-1) charge-discharge rate in the potential range 1.0-2.5 V vs. Li/Li+. The hybridized LTO-AC hybrid nanotubes electrode is included in a new type of hybrid energy storage cell, denoted as BatCap, as the negative electrode using commercialized activated carbon (AC) as the positive electrode. The hybrid BatCap cell exhibits a high energy density of 32 W h kg(-1) and a high power density of 6000 W kg(-1), comparable to the properties of a typical AC symmetric capacitor.