The science and technology of ultracapacitors are reviewed for a number of electrode materials, including carbon, mixed metal oxides, and conducting polymers. More work has been done using microporous carbons than with the other materials and most of the commercially available devices use carbon electrodes and an organic electrolytes. The energy density of these devices is 3¯5 Wh/kg with a power density of 300¯500 W/kg for high efficiency (90¯95%) charge/discharges. Projections of future developments using carbon indicate that energy densities of 10 Wh/kg or higher are likely with power densities of 1¯2 kW/kg. A key problem in the fabrication of these advanced devices is the bonding of the thin electrodes to a current collector such the contact resistance is less than 0.1 cm2. Special attention is given in the paper to comparing the power density characteristics of ultracapacitors and batteries. The comparisons should be made at the same charge/discharge efficiency.

Ultracapacitors: Why, How, and Where is the Technology

Über die Adsorption in Lösungen

The ever-growing demand for advanced rechargeable lithium-ion batteries in portable electronics and electric vehicles has spurred intensive research efforts over the past decade. The key to sustaining the progress in Li-ion batteries lies in the quest for safe, low-cost positive electrode (cathode) materials with desirable energy and power capabilities. One approach to boost the energy and power densities of batteries is to increase the output voltage while maintaining a high capacity, fast charge–discharge rate, and long service life. This review gives an account of the various emerging high-voltage positive electrode materials that have the potential to satisfy these requirements either in the short or long term, including nickel-rich layered oxides, lithium-rich layered oxides, high-voltage spinel oxides, and high-voltage polyanionic compounds. The key barriers and the corresponding strategies for the practical viability of these cathode materials are discussed along with the optimization of electrolytes and other cell components, with a particular emphasis on recent advances in the literature. A concise perspective with respect to plausible strategies for future developments in the field is also provided.

High-voltage positive electrode materials for lithium-ion batteries

As one important component of sulfur cathodes, the carbon host plays a key role in the electrochemical performance of lithium-sulfur (Li-S) batteries. In this paper, a mesoporous nitrogen-doped carbon (MPNC)-sulfur nanocomposite is reported as a novel cathode for advanced Li-S batteries. The nitrogen doping in the MPNC material can effectively promote chemical adsorption between sulfur atoms and oxygen functional groups on the carbon, as verifi ed by X-ray absorption near edge structure spectroscopy, and the mechanism by which nitrogen enables the behavior is further revealed by density functional theory calculations. Based on the advantages of the porous structure and nitrogen doping, the MPNC-sulfur cathodes show excellent cycling stability (95% retention within 100 cycles) at a high current density of 0.7 mAh cm −2 with a high sulfur loading (4.2 mg S cm −2 ) and a sulfur content (70 wt%). A high areal capacity (≈3.3 mAh cm −2 ) is demonstrated by using the novel cathode, which is crucial for the practical application of Li-S batteries. It is believed that the important role of nitrogen doping promoted chemical adsorption can be extended for development of other high performance carbon-sulfur composite cathodes for Li-S batteries.

Nitrogen-Doped Mesoporous Carbon Promoted Chemical Adsorption of Sulfur and Fabrication of High-Areal-Capacity Sulfur Cathode with Exceptional Cycling Stability for Lithium-Sulfur Batteries

Recent progress in high-voltage lithium ion batteries

Mesoporous hollow carbon spheres boosted, integrated high performance aqueous Zn-Ion energy storage

Ethylene glycol reduced graphene oxide/polypyrrole composite for supercapacitor

Aqueous rechargeable zinc-ion hybrid supercapacitors are considered to be a promising candidate for large-scale energy storage devices owing to their high safety, long life, and low price. In this paper, a nitrogen doped hierarchical porous carbon is evaluated as the cathode for aqueous rechargeable zinc-ion hybrid supercapacitors. Benefiting from the synergistic merits of excellent structural features of N-HPC and tiny zinc dendrite of Zn anode in ZnSO4 electrolyte, the zinc-ion hybrid supercapacitor exhibits excellent energy storage performance including high capacity of 136.8 mAh·g−1 at 0.1·Ag−1, high energy density of 191 Wh·kg−1, large power density of 3,633.4 W·kg−1, and satisfactory cycling stability of up to 5,000 cycles with a capacity retention of 90.9%. This work presents a new prospect of developing high-performance aqueous rechargeable zinc ion energy storage devices.

Rational design of nitrogen doped hierarchical porous carbon for optimized zinc-ion hybrid supercapacitors

Ultra-highly stable zinc metal anode via 3D-printed g-C3N4 modulating interface for long life energy storage systems

In situ fabrication of nickel aluminum-layered double hydroxide nanosheets/hollow carbon nanofibers composite as a novel electrode material for supercapacitors

Kaiyu Liu

Papers

Mesoporous hollow carbon spheres boosted, integrated high performance aqueous Zn-Ion energy storage

Ethylene glycol reduced graphene oxide/polypyrrole composite for supercapacitor

Rational design of nitrogen doped hierarchical porous carbon for optimized zinc-ion hybrid supercapacitors

Ultra-highly stable zinc metal anode via 3D-printed g-C3N4 modulating interface for long life energy storage systems

In situ fabrication of nickel aluminum-layered double hydroxide nanosheets/hollow carbon nanofibers composite as a novel electrode material for supercapacitors