Rechargeable lithium-sulfur batteries.

Electrolytes and interphases in Li-ion batteries and beyond.

Solid-state electrolytes are attracting increasing interest for electrochemical energy storage technologies. In this Review, we provide a background overview and discuss the state of the art, ion-transport mechanisms and fundamental properties of solid-state electrolyte materials of interest for energy storage applications. We focus on recent advances in various classes of battery chemistries and systems that are enabled by solid electrolytes, including all-solid-state lithium-ion batteries and emerging solid-electrolyte lithium batteries that feature cathodes with liquid or gaseous active materials (for example, lithium–air, lithium–sulfur and lithium–bromine systems). A low-cost, safe, aqueous electrochemical energy storage concept with a ‘mediator-ion’ solid electrolyte is also discussed. Advanced battery systems based on solid electrolytes would revitalize the rechargeable battery field because of their safety, excellent stability, long cycle lives and low cost. However, great effort will be needed to implement solid-electrolyte batteries as viable energy storage systems. In this context, we discuss the main issues that must be addressed, such as achieving acceptable ionic conductivity, electrochemical stability and mechanical properties of the solid electrolytes, as well as a compatible electrolyte/electrode interface. This Review details recent advances in battery chemistries and systems enabled by solid electrolytes, including all-solid-state lithium-ion, lithium–air, lithium–sulfur and lithium–bromine batteries, as well as an aqueous battery concept with a mediator-ion solid electrolyte.

Lithium battery chemistries enabled by solid-state electrolytes

A critical overview of the latest developments in the lithium ion batteries technology is reported. We first describe the evolution in the electrolyte area with particular attention to ionic liquids, discussing the expected application of these room temperature molten salts and listing the issues that still prevent their practical implementation. The attention is then focused on the electrode materials presently considered the most promising for enhancing the energy density of the batteries. At the anode side a discussion is provided on the status of development of high capacity tin and silicon lithium alloys. We show that the morphology that is the most likely to ensure commercial exploitation of these alloy electrodes is that involving carbon-based nanocomposites. We finally touch on super-high-capacity batteries, discussing the key cases of lithium-sulfur and lithium-air and attempting to forecast their chances to eventually reach the status of practically appealing energy storage systems. We conclude with a brief reflection on the amount of lithium reserves in view of its large use in the case of global conversion from gasoline-powered cars to hybrid and electric cars.

Lithium-ion batteries. A look into the future

Despite the imminent commercial introduction of Li-ion batteries in electric drive vehicles and their proposed use as enablers of smart grids based on renewable energy technologies, an intensive quest for new electrode materials that bring about improvements in energy density, cycle life, cost, and safety is still underway. This Progress Report highlights the recent developments and the future prospects of the use of phases that react through conversion reactions as both positive and negative electrode materials in Li-ion batteries. By moving beyond classical intercalation reactions, a variety of low cost compounds with gravimetric specific capacities that are two-to-five times larger than those attained with currently used materials, such as graphite and LiCoO(2), can be achieved. Nonetheless, several factors currently handicap the applicability of electrode materials entailing conversion reactions. These factors, together with the scientific breakthroughs that are necessary to fully assess the practicality of this concept, are reviewed in this report.

Beyond Intercalation-Based Li-Ion Batteries: The State of the Art and Challenges of Electrode Materials Reacting Through Conversion Reactions

An oxide thermoelectric device was fabricated using Gd-doped Ca3Co4O9 p-type legs and La-doped CaMnO3 n-type legs on a fin. The power factors of p legs and n legs were 4.8×10−4 Wm−1 K−2 and 2.2×10−4 Wm−1 K−2 at 700 °C in air, respectively. With eight p–n couples the device generated an output power of 63.5 mW under the thermal condition of hot side temperature Th=773 °C and a temperature difference ΔT=390 °C. This device proved to be operable for more than two weeks in air showing high durability.

Fabrication of an all-oxide thermoelectric power generator

Dense BaTiO3 ceramics consisting of submicrometer grains were prepared using the spark plasma sintering (SPS) method. Hydrothermally prepared BaTiO3 (0.1 and 0.5 µm) was used as starting powders. The powders were densified to more than similar/congruent95% of the theoretical X-ray density by the SPS process. The average grain size of the SPS pellets was less than similar/congruent1 µm, even by sintering at 1000-1200°C, because of the short sintering period (5 min). Cubic-phase BaTiO3 coexisted with tetragonal BaTiO3 at room temperature in the SPS pellets, even when well-defined tetragonal-phase BaTiO3 powder was sintered at 1100° and 1200°C and annealed at 1000°C, signifying that the SPS process is effective for stabilizing metastable cubic phase. The measured permittivity was similar/congruent7000 at 1 kHz at room temperature for samples sintered at 1100°C and showed almost no dependence on frequency within similar/congruent100-106 Hz; the permittivity at 1 MHz was 95% of that at 1 kHz.

Preparation of Dense BaTiO3 Ceramics with Submicrometer Grains by Spark Plasma Sintering

All-solid-state lithium secondary battery with ceramic/polymer composite electrolyte

Some basic but important guidelines for the development of sheet-type all-solid-state batteries using a practical slurry coating process are described in this paper. Li3PS4 glass powder that had been passed through a 25 μm sieve was prepared. Positive and negative electrode sheets with capacities of more than 1.5 mAh cm−2 were developed. An all-solid-state full cell was constructed using the electrode sheets and the self-standing solid electrolyte sheets. The energy density of the cell was ca. 155 Wh kg−1, where the weight of the current collectors and the exterior package was excluded from the weight for calculation.

https://iopscience.iop.org/article/10.1149/2.0951712jes/pdf

Tomonari Takeuchi

Papers

Fabrication of an all-oxide thermoelectric power generator

Preparation of Dense BaTiO3 Ceramics with Submicrometer Grains by Spark Plasma Sintering

All-solid-state lithium secondary battery with ceramic/polymer composite electrolyte

All-Solid-State Battery Electrode Sheets Prepared by a Slurry Coating Process

Electrode morphology in all-solid-state lithium secondary batteries consisting of LiNi1/3Co1/3Mn1/3O2 and Li2S-P2S5 solid electrolytes