Li-ion batteries have transformed portable electronics and will play a key role in the electrification of transport. However, the highest energy storage possible for Li-ion batteries is insufficient for the long-term needs of society, for example, extended-range electric vehicles. To go beyond the horizon of Li-ion batteries is a formidable challenge; there are few options. Here we consider two: Li-air (O(2)) and Li-S. The energy that can be stored in Li-air (based on aqueous or non-aqueous electrolytes) and Li-S cells is compared with Li-ion; the operation of the cells is discussed, as are the significant hurdles that will have to be overcome if such batteries are to succeed. Fundamental scientific advances in understanding the reactions occurring in the cells as well as new materials are key to overcoming these obstacles. The potential benefits of Li-air and Li-S justify the continued research effort that will be needed.

Li-O2 and Li-S batteries with high energy storage.

The Li-S battery has been under intense scrutiny for over two decades, as it offers the possibility of high gravimetric capacities and theoretical energy densities ranging up to a factor of five beyond conventional Li-ion systems. Herein, we report the feasibility to approach such capacities by creating highly ordered interwoven composites. The conductive mesoporous carbon framework precisely constrains sulphur nanofiller growth within its channels and generates essential electrical contact to the insulating sulphur. The structure provides access to Li+ ingress/egress for reactivity with the sulphur, and we speculate that the kinetic inhibition to diffusion within the framework and the sorption properties of the carbon aid in trapping the polysulphides formed during redox. Polymer modification of the carbon surface further provides a chemical gradient that retards diffusion of these large anions out of the electrode, thus facilitating more complete reaction. Reversible capacities up to 1,320 mA h g(-1) are attained. The assembly process is simple and broadly applicable, conceptually providing new opportunities for materials scientists for tailored design that can be extended to many different electrode materials.

http://dns2.asia.edu.tw/~ysho/YSHO-English/1000%20WC/PDF/Nat%20Mat8,%20500.pdf

A highly ordered nanostructured carbon–sulphur cathode for lithium–sulphur batteries

Li-ion battery materials: present and future

Sustainable hydrogen production is an essential prerequisite of a future hydrogen economy. Water electrolysis driven by renewable resource-derived electricity and direct solar-to-hydrogen conversion based on photochemical and photoelectrochemical water splitting are promising pathways for sustainable hydrogen production. All these techniques require, among many things, highly active noble metal-free hydrogen evolution catalysts to make the water splitting process more energy-efficient and economical. In this review, we highlight the recent research efforts toward the synthesis of noble metal-free electrocatalysts, especially at the nanoscale, and their catalytic properties for the hydrogen evolution reaction (HER). We review several important kinds of heterogeneous non-precious metal electrocatalysts, including metal sulfides, metal selenides, metal carbides, metal nitrides, metal phosphides, and heteroatom-doped nanocarbons. In the discussion, emphasis is given to the synthetic methods of these HER electrocatalysts, the strategies of performance improvement, and the structure/composition-catalytic activity relationship. We also summarize some important examples showing that non-Pt HER electrocatalysts could serve as efficient cocatalysts for promoting direct solar-to-hydrogen conversion in both photochemical and photoelectrochemical water splitting systems, when combined with suitable semiconductor photocatalysts.

Noble metal-free hydrogen evolution catalysts for water splitting

Rechargeable lithium-sulfur batteries.

Energy-storage technologies such as lithium-ion batteries and supercapacitors have become fundamental building blocks in modern society. Recently, the emerging direction toward the ever-growing market of flexible and wearable electronics has nourished progress in building multifunctional energy-storage systems that can be bent, folded, crumpled, and stretched while maintaining their electrochemical functions under deformation. Here, recent progress and well-developed strategies in research designed to accomplish flexible and stretchable lithium-ion batteries and supercapacitors are reviewed. The challenges of developing novel materials and configurations with tailored features, and in designing simple and large-scaled manufacturing methods that can be widely utilized are considered. Furthermore, the perspectives and opportunities for this emerging field of materials science and engineering are also discussed.

Flexible and Stretchable Energy Storage: Recent Advances and Future Perspectives

Hydrogen storage properties of mutiwalled carbon nanotubes (MWCNTs) with Ni nanoparticles were investigated. The metal nanoparticles were dispersed on MWCNTs surfaces using an incipient wetness impregnation procedure. Ni catalysts have been known to effectively dissociate hydrogen molecules in gas phase, providing atomic hydrogen possible to form chemical bonding with the surfaces of MWCNTs. Hydrogen desorption spectra of MWCNTs with 6 wt % of Ni nanoparticles showed that ∼2.8 wt % hydrogen was released in the range of 340−520 K. In Kissinger's plot to evaluate the nature of interaction between hydrogen and MWCNTs with Ni nanoparticles, the hydrogen desorption activation energy was measured to be as high as ∼31 kJ/mol·H2, which is much higher than the estimates of pristine SWNTs. C−Hn stretching vibrations after hydrogenation in FTIR further supported that hydrogen molecules were dissociated when bound to the surfaces of MWCNTs. During cyclic hydrogen absorption/desorption, there was observed no significa...

Hydrogen storage in ni nanoparticle-dispersed multiwalled carbon nanotubes.

https://ro.uow.edu.au/cgi/viewcontent.cgi?article=1001&context=aiimpapers

A study on the charge-discharge mechanism of Co3O4 as an anode for the Li ion secondary battery

In order to bestow high electronic conductivity and prevent dissolution of sulfur into the electrolyte, multiwalled carbon nanotubes (MWNTs) were prepared by thermal chemical vapor deposition as an inactive additive material for elemental sulfur positive electrodes for lithium/sulfur rechargeable batteries. The initial discharge capacity of elemental sulfur positive electrode with MWNT is 485 mAh/g sulfur at 2.0 V vs. The cycle life and rate capability of sulfur cathode is increased with addition of MWNT. The MWNT shows a vital role on polysulfide adsorbtion and is a good electric conductor for a sulfur cathode. © 2003 The Electrochemical Society. All rights reserved.

https://iopscience.iop.org/article/10.1149/1.1576766/pdf

Effect of Multiwalled Carbon Nanotubes on Electrochemical Properties of Lithium/Sulfur Rechargeable Batteries

In order to prevent polysulfide dissolution into liquid electrolytes and to promote the Li/S redox reaction (16Li + S 8 ↔ Li 2 Sn ↔ Li 2 S), nanosized Mg 0.6 Ni 0.4 O, which has the catalytic effect of chemical bond dissociating and is expected to have an adsorbing effect due to the effect of retaining liquid electrolyte of MgO in a Li/iron sulfide secondary battery, 16 was prepared by the sol-gel method as an electrochemically inactive additive for an elemental sulfur cathode for Li/S rechargeable batteries. The Li/S battery using an elemental sulfur cathode with a nanosized Mg 0.6 Ni 0.4 O added showed the improvement of not only the discharge capacity but also cycle durability (maximum discharge capacity: 1185 mAh/g sulfur, C 50 /C 1 = 85%).The rate capability of the sulfur cathode was also increased with the addition of the nanosized Mg 0.6 Ni 0.4 O. From the msults. it is confirmad that the nanosized Mg 0.6 Ni 0.4 O had the polysulfide adsorbing effect and the catalytic elfect of promoting Lt/S redox reaction. Furthermore, it is found that the nanosized Mg 0.6 Ni 0.4 O also increased the porosity of the sulfur cathode.

/pdf/effects-of-nanosized-adsorbing-material-on-electrochemical-2b79i548fv.pdf

Min-Sang Song

Papers

Flexible and Stretchable Energy Storage: Recent Advances and Future Perspectives

Hydrogen storage in ni nanoparticle-dispersed multiwalled carbon nanotubes.

A study on the charge-discharge mechanism of Co3O4 as an anode for the Li ion secondary battery

Effect of Multiwalled Carbon Nanotubes on Electrochemical Properties of Lithium/Sulfur Rechargeable Batteries

Effects of Nanosized Adsorbing Material on Electrochemical Properties of Sulfur Cathodes for Li/S Secondary Batteries