The exponential growth of renewable energy sources and the need to transform electric mobility are driving the interest in next-generation storage technologies for electrical energy. Currently, lithium-ion batteries (LIB) are widespread and promising candidates for future applications. These batteries have several advantages, such as long life cycle, high power density, low self-discharge property, high gravimetric, and volumetric energy. However, they suffer from raw materials availability and corresponding high cost, and safety concerns.
Another technology is an emerging option for next-generation lithium-based batteries promising low cost, high performance, and high safety: the “solid-state” battery. In contrast to common battery technologies, solid-state cells with a solid electrolyte do not show various drawbacks of a lithium-ion battery and allow higher operating temperatures due to better thermal stability. This alternative to LIBs promises to improve vehicle range, decrease charging times, and eliminate risk of battery fires.
So, is the solid-state battery another next-generation technology that will change electric vehicles (EVs) and bring us toward a carbon-neutral society? In this blog post I provide an overview of the solid-state battery and technology behind it.
What is a solid-state battery?
The first generation of solid-state batteries was conceptualized in the 1960s. However, the limitations relating to power density, processing and cost inhibited its use in broader applications, and solid-state electrolytes for the most part were set aside for the superior electrochemical performance of liquid electrolyte-based systems that utilize lithium salts dissolved in organic solvents. Nevertheless, recent developments in solid-state electrolytes have led to a renewed interest in the field.
Solid-state batteries represent a paradigm shift in terms of technology. In modern lithium batteries, ions move from one electrode to another across the liquid electrolyte (also called ionic conductivity). In solid-state batteries, the liquid electrolyte is replaced by a solid compound that nevertheless allows lithium ions to migrate within it.
Solid-state batteries are not only inherently safer due to the lack of flammable organic components, but also offer the potential for a dramatic improvement in energy density, allowing the battery to store a greater amount of energy within the same volume.
Figure 1: Structure of a lithium-ion battery (left) vs. solid-state battery (right).
What is the difference compared to a conventional battery?
State-of-the-art lithium-ion cells consist of two porous electrodes (anode and cathode) and a polymer separator (Figure 1). The ion transfer requires a liquid electrolyte, which is composed primarily of organic solvents and a conductive salt. Many issues lithium batteries face can be traced back to the liquid electrolytes. In fact, most safety concerns arise from the flammability of the solvents. In addition, side reactions of used solvents and the conductive salt lead to capacity fading and aging.
A solid-state battery replaces the polymer separator and electrolyte used in conventional lithium-ion batteries with a solid-state separator. A solid-state separator acts as an electrical insulator and ionic conductor at the same time. This modification enables the carbon or silicon anode used in conventional lithium-ion batteries to be replaced with a lithium-metal anode. The use of a compact solid electrolyte acting as a physical barrier for lithium dendrites — metallic microstructures that form on the negative electrode of a conventional lithium-ion battery during the charging process — also enables the use of lithium metal as the anode material.
What are the advantages and challenges of solid-state batteries?
There are several advantages to solid-state battery technology compared to that of the conventional lithium-ion battery. Probably the most important one: solid-state batteries are not flammable since no dendrites can form on the surface of the cathode, which could otherwise cause a short circuit. A short can cause a battery to get hotter (best case) or explode (worst case).
The solid electrolyte prevents the formation of dendrites. In addition, the solid-state battery has a higher energy density, due to the design of directly stackable battery cells. It enables use of a lithium metal anode, which results in longer life, increased cell voltage and capacity. However, it is important to remember that this technology is still in the development phase and, to date, lithium-ion batteries remain the best-performing technology, with a variety of chemistries, each used for different purposes, readily available and mass produced.
Analytical techniques for battery development?
Invention of new functional materials is vital to the advancement in technologies that will move society toward a carbon neutral future. Electrode materials have played a crucial role in the development of novel battery technology. The vast number of compositions potentially available from the periodic table poses an overwhelming challenge for the scientific community to find new battery electrodes. Solid-state chemistry is the art of building the desired atomic arrangements based on information hidden in the periodic table.
Here I would like to briefly highlight various analytical techniques that are applied in battery material analysis:
Discover here how to perform elemental and structural analysis in battery material testing.
Find out more about the battery material analysis portfolio here >
Solid electrolytes possess a much higher thermal stability, making the solid-state battery one of the best choices for the next generation of batteries. Inorganic solid electrolytes can work in hostile environments — such as in the temperature range from −50 to 200°C or even higher — in which organic electrolytes fail due to freezing, boiling or decomposition. Theoretically, solid-state batteries can replace lithium-ion batteries in EVs.
However, basic research is still ongoing with consequent uncertainties and concerns related to production cost and scalability. Nonetheless, battery manufacturers and EV producers hope to commercialize solid-state batteries by the end of the decade. To meet this goal, considerable research and development need to happen to solve serious performance issues. Still, solid-state battery technology has the potential to significantly reduce the environmental impact of battery production and improve sustainability, energy storage and mobility.
Webpage: Chemical Analysis for Battery Manufacturing
Brochure: Battery solutions brochure - Analytical technologies that help build better batteries
Website: Advanced battery technology enabled with Thermo Scientific tools and instruments
Website: Elemental analysis solution for battery material testing
Webinars: PowerUp webinars – Solutions for lithium-ion battery analysis and testing
Blog post: Challenges in Lithium-ion Battery Manufacturing and Quality Analysis – Part 1
Blog post: Challenges in Lithium-ion Battery Manufacturing and Quality Analysis – Part 2
Blog post: Could the Sodium-ion Battery Eventually Displace Lithium Batteries?
Publication: The Future of All Solid State Battery, 2020 IOP Conf. Ser.: Mater. Sci. Eng.
Publication: Solid state chemistry for developing better metal-ion batteries, Nature Communications volume 11, Article number: 4976 (2020)