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A binder-free cobalt phosphate hydrate (Co(PO)·8HO) multilayer nano/microflake structure is synthesized on nickel foam (NF) via a facile hydrothermal process. Four different concentrations (2.5, 5, 10, and 20 mM) of Co and PO were used to obtain different mass loading of cobalt phosphate on the nickel foam. The Co(PO)·8HO modified NF electrode (2.5 mM) shows a maximum specific capacity of 868.3 C g (capacitance of 1578.7 F g) at a current density of 5 mA cm and remains as high as 566.3 C g (1029.5 F g) at 50 mA cm in 1 M NaOH. A supercapattery assembled using Co(PO)·8HO/NF as the positive electrode and activated carbon/NF as the negative electrode delivers a gravimetric capacitance of 111.2 F g (volumetric capacitance of 4.44 F cm). Furthermore, the device offers a high specific energy of 29.29 Wh kg (energy density of 1.17 mWh cm) and a specific power of 4687 W kg (power density of 187.5 mW cm).

High performance thin film lithium batteries using structurally stable electrodeposited V2O5 inverse opal (IO) networks as cathodes provide high capacity and outstanding cycling capability and also were demonstrated on transparent conducting oxide current collectors. The superior electrochemical performance of the inverse opal structures was evaluated through galvanostatic and potentiodynamic cycling, and the IO thin film battery offers increased capacity retention compared to micron-scale bulk particles from improved mechanical stability and electrical contact to stainless steel or transparent conducting current collectors from bottom-up electrodeposition growth. Li(+) is inserted into planar and IO structures at different potentials, and correlated to a preferential exposure of insertion sites of the IO network to the electrolyte. Additionally, potentiodynamic testing quantified the portion of the capacity stored as surface bound capacitive charge. Raman scattering and XRD characterization showed how the IO allows swelling into the pore volume rather than away from the current collector. V2O5 IO coin cells offer high initial capacities, but capacity fading can occur with limited electrolyte. Finally, we demonstrate that a V2O5 IO thin film battery prepared on a transparent conducting current collector with excess electrolyte exhibits high capacities (∼200 mAh g(-1)) and outstanding capacity retention and rate capability.

Access to the full text of the published version may require a subscription. phase and material interconnectivity is maintained over thousands of cycles. Consequently, this report offers insight into the importance of optimizing the relationship between the structure and morphology on improving electrochemical performance of this abundant and low environmental impact material. TiO2 IOs show gradual capacity fading over 1000 and 5000 cycles, when cycled at specific currents of 75 and 450 mA/g, respectively, while maintaining a high capacity and a stable overall cell voltage. TiO2 IOs achieve a reversible 2 capacity of ~ 170 and 140 mAh/g after the 100 th and 1000 th cycles respectively, at a specific current of 75 mA/g, corresponding to a capacity retention of ~ 82.4%. The structural stability of the 3D IO phase from pristine rutile TiO2 to the conductive orthorhombic Li0.5TiO2 is remarkable and maintains it structural integrity. Image analysis shows conclusively that volumetric swelling is accommodated into the predefined pore space, the IO periodicity remains constant and does not degrade over 5000 cycles. Rights

No abstract

Simultaneous heterogeneous growth of one-dimensional nanorod supported three-dimensional microflower structures on nickel foam enhanced the non-capacitive faradaic energy storage performance due to the synergistic contribution from the hierarchical hybrid nanostructure.

We present the formation of a carbon-coated honeycomb ternary Ni-Mn-Co-O inverse opal as a conversion mode anode material for Li-ion battery applications. In order to obtain high capacity via conversion mode reactions, a single phase crystalline honeycombed IO structure of Ni-Mn-Co-O material was first formed. This Ni-Mn-Co-O IO converts via reversible redox reactions and Li2O formation to a 3D structured matrix assembly of nanoparticles of three (MnO, CoO and NiO) oxides, that facilitates efficient reactions with Li. A carbon coating maintains the structure without clogging the open-worked IO pore morphology for electrolyte penetration and mass transport of products during cycling. The highly porous IO was compared in a Li-ion half-cell to nanoparticles of the same material and showed significant improvement in specific capacity and capacity retention. Further optimization of the system was investigated by incorporating a vinylene carbonate additive into the electrolyte solution which boosted performance, offering promising high-rate performance and good capacity retention over extended cycling. The analysis confirms the possibility of creating a ternary transition metal oxide material with binder free accessible open-worked structure to allow three conversion mode oxides to efficiently cycle as an anode material for Li-ion battery applications.

The supercapattery is an ideal energy storage device that combines excellent power density and rate capability of supercapacitors and the greater energy density of batteries. With superior storage capacity and long life, this device can be employed in next-generation artificial cardiac pacemakers as a rechargeable energy source for the lifetime of the pacemaker (at least 15−20 years). However, current hybrid energy storage devices are often limited by less than ideal performance of either the supercapacitor or battery. Here, we develop a low cost and scalable prototype supercapattery with cobalt phosphate as positive and activated carbon as negative electrodes. This positive electrode exhibits a maximum specific capacity of 215.6 mAh g −1 (≈1990 F g −1 ), ever reported in a metal phosphate based electrode. The supercapattery delivers a high energy density of 3.53 mWh cm −3 (43.2 Wh kg −1 ) and a power density of 425 mW cm −3 (5.8 kW kg −1 ). Furthermore, the device can retain 79% voltage even after 4 min self-discharge, enough to provide power during cardiac emergencies. This hybrid device provides excellent performance and stability under physiological temperature range (35−41 °C), retaining 68% of specific capacity after 100 000 cycles at room temperature (25 °C) and up to 81.5% after 20 000 cycles at 38 °C, demonstrating its effectiveness as a potential power source for the next-generation implanted medical devices.