Lithium batteries: Status, prospects and future

Lithium-ion batteries have had a profound impact on our daily life, but inherent limitations make it difficult for Li-ion chemistries to meet the growing demands for portable electronics, electric vehicles and grid-scale energy storage. Therefore, chemistries beyond Li-ion are currently being investigated and need to be made viable for commercial applications. The use of metallic Li is one of the most favoured choices for next-generation Li batteries, especially Li-S and Li-air systems. After falling into oblivion for several decades because of safety concerns, metallic Li is now ready for a revival, thanks to the development of investigative tools and nanotechnology-based solutions. In this Review, we first summarize the current understanding on Li anodes, then highlight the recent key progress in materials design and advanced characterization techniques, and finally discuss the opportunities and possible directions for future development of Li anodes in applications.

Reviving the lithium metal anode for high-energy batteries

Batteries are a key technology in modern society. They are used to power electric and hybrid electric vehicles and to store wind and solar energy in smart grids. Electrochemical devices with high energy and power densities can currently be powered only by batteries with organic liquid electrolytes. However, such batteries require relatively stringent safety precautions, making large-scale systems very complicated and expensive. The application of solid electrolytes is currently limited because they attain practically useful conductivities (10(-2) S cm(-1)) only at 50-80 °C, which is one order of magnitude lower than those of organic liquid electrolytes. Here, we report a lithium superionic conductor, Li(10)GeP(2)S(12) that has a new three-dimensional framework structure. It exhibits an extremely high lithium ionic conductivity of 12 mS cm(-1) at room temperature. This represents the highest conductivity achieved in a solid electrolyte, exceeding even those of liquid organic electrolytes. This new solid-state battery electrolyte has many advantages in terms of device fabrication (facile shaping, patterning and integration), stability (non-volatile), safety (non-explosive) and excellent electrochemical properties (high conductivity and wide potential window).

A lithium superionic conductor

Over the past 30 years, significant commercial and academic progress has been made on Li-based battery technologies. From the early Li-metal anode iterations to the current commercial Li-ion batteries (LIBs), the story of the Li-based battery is full of breakthroughs and back tracing steps. This review will discuss the main roles of material science in the development of LIBs. As LIB research progresses and the materials of interest change, different emphases on the different subdisciplines of material science are placed. Early works on LIBs focus more on solid state physics whereas near the end of the 20th century, researchers began to focus more on the morphological aspects (surface coating, porosity, size, and shape) of electrode materials. While it is easy to point out which specific cathode and anode materials are currently good candidates for the next-generation of batteries, it is difficult to explain exactly why those are chosen. In this review, for the reader a complete developmental story of LIB should be clearly drawn, along with an explanation of the reasons responsible for the various technological shifts. The review will end with a statement of caution for the current modern battery research along with a brief discussion on beyond lithium-ion battery chemistries.

30 Years of Lithium-Ion Batteries.

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

High ionic conductivity in lithium lanthanum titanate

To improve the cycle performance of spinel LiMn{sub 2}O{sub 4} as the cathode of 4 V class lithium secondary batteries, the quaternary spinel phases LiM{sub y}Mn{sub 2{minus}y}O{sub 4} (M = Co, Cr, Ni; y = 1/12, 1/9, 1/6, 1/3) were prepared at 750 C in air. X-ray diffraction and electrochemical studies were carried out using the Li{vert_bar}Li{sub x}M{sub y}Mn{sub 2{minus}y}O{sub 4} cells. These cathodes were more tolerant to repeated lithium extraction and insertion than a standard LiMn{sub 2}O{sub 4} spinel electrode in spite of a small reduction in the initial capacity. Considering both cycle life and capacity density, LiCo{sub 1/6}Mn{sub 11/6}O{sub 4} showed good cycle performance with an energy density of 370 Wh/kg at the 300th cycle. The improvement in cycling performance is attributed to the stabilization in the spinel structure by the doped metal cations.

The Spinel Phases LiM y Mn2 − y O 4 (M = Co, Cr, Ni) as the Cathode for Rechargeable Lithium Batteries

Amorphous MoS2 as the cathode of lithium secondary batteries

In order to obtain safer and more reversible negative electrodes for lithium secondary batteries, intensive research on various carbon materials, such as pyrolytic carbon, polyacrylonitrile- (PAN) based carbon, petroleum coke-based carbon, pitch-based carbon, etc., has been carried out in recent years. Electrochemical investigations on coal pitch-based carbon fiber (heat-treated at 2,800 C) were carried out. The open-circuit voltages of the Li{vert_bar}Li{sub x}C{sub 6} cell were lower than 0.15 V vs. Li/Li{sup +} in the range of 0.15 0.2.« less

Takashi Uchida

Papers

High ionic conductivity in lithium lanthanum titanate

The Spinel Phases LiM y Mn2 − y O 4 (M = Co, Cr, Ni) as the Cathode for Rechargeable Lithium Batteries

Amorphous MoS2 as the cathode of lithium secondary batteries

Chemical Diffusion Coefficient of Lithium in Carbon Fiber

Chemical diffusion coefficients of lithium in LiMyMn2-yO4 (M = Co and Cr)