Lithium-ion batteries are currently the most established and competitive technology for energy storage in the market, particularly in applications such as electric vehicles and portable electronics. Over the past decade, significant advancements have been made in increasing their energy density, safety, and performance. For example, in the automotive industry, the average energy density of lithium-ion batteries has increased from around 150 Wh/kg to 250 Wh/kg in the span of a decade, mainly driven by improvements in battery materials and design.  

Despite the rapid and consistent improvements seen in the R&D of lithium-ion batteries, the potential for further optimization is starting to diminish, and it is estimated that the limits of this technology may be reached within the coming decade. Next-generation battery solutions will be needed in the future to keep up with the growing demand for increasingly efficient and safe energy storage options.  

Solid-state batteries (SSBs) are emerging as a promising alternative to traditional lithium-ion batteries, offering the potential for substantial improvements in energy density, safety, and long-term stability.  

Solid-State Batteries

They key difference between solid-state batteries and traditional lithium-ion batteries lies on the electrolyte, which is the material that enables the transfer of ions between electrodes, making energy storage and release possible. While traditional lithium-ion batteries contain a liquid electrolyte, solid-state batteries rely on a solid electrolyte.  

Solid electrolytes currently under development can be categorized into four main groups:

• Oxide electrolytes: known for their mechanical and chemical stability but require high-temperature processing and tend to be brittle, with relatively low ionic conductivity.

• Sulfide electrolytes: easier to process and more malleable than oxide electrolytes, but present chemical compatibility challenges with electrodes.

• Polymer electrolytes: the most established in terms of production and availability, however they have limited ionic conductivity at room temperature and face compatibility issues with high-potential cathodes.

• Other materials in early research stages, such as halides, borates, and gel electrolytes.

The use of solid electrolytes could unlock the potential for batteries with higher energy density, longer life cycles and improved safety. Improvements in energy density will be particularly relevant for mobile applications, where solid-state batteries could potentially outperform lithium-ion batteries by reaching energy densities of up to 500 Wh/kg in batteries where solid electrolytes are combined with lithium metal anodes.  

In terms of long-term stability and battery lifespan, solid-state batteries are expected to compare to or even exceed lithium-ion batteries. This is largely due to the absence of liquid materials, which would reduce electrolyte degradation over time. Safety is also expected to be improved, as solid-state batteries do not contain flammable liquids.  

However, solid-state battery technology is still in early stages of development, and there are multiple challenges to overcome before it can be competitive in the global market. For instance, solid-state batteries are more prone to experience significant volume changes during charge and discharge, which would need to be compensated in commercial applications. Fast charging capabilities may be limited by the relatively low ionic conductivity of many solid electrolyte materials at room temperature, a challenge that will require further R&D efforts to be resolved.

In addition, achieving large-scale adoption of solid-state batteries will require scaling up production to reach competitive costs. Initial prices for solid-state batteries are expected to be higher than for traditional lithium-ion batteries, likely limiting early applications to premium or niche markets before spreading to consumer or automotive sectors.  

In the medium and long term, the main application for solid-state batteries will be the automotive industry. Currently, solid-state batteries with polymer electrolytes are already used in limited applications like electric buses. However, these batteries can only operate at higher temperatures (50-80°C), restricting their applications to systems that are in regular use. The market for solid-state batteries may also include consumer electronics like smartphones and laptops, where the performance and safety benefits outweigh the higher initial costs.

The Future of Battery R&D

Currently, the global production capacity for solid-state batteries is below 2 GWh, covering almost exclusively polymer-based electrolytes. However, it is expected that the total capacity of the market will grow to up to 40 GWh by 2030, and 120 GWh by 2035. These figures will still be relatively small compared to the total lithium-ion battery market, as solid-state batteries are projected to account for just over 1% of the total market by 2035.  

Companies like Toyota, Mercedez-Benz and Volkswagen have announced plans to develop solid-state battery technology, with manufacturing expected to start around 2027 for most of these projects.  

Nevertheless, solid-state batteries will take longer to become a major technology in the global market. Achieving this will require R&D efforts to overcome the multiple technical challenges associated with each type of solid electrolyte, while the industry will have to efficiently scale up production to achieve competitive prices. This will be essential as state-of-the-art lithium-ion batteries continue to improve as well.

The potential for mass adoption of this technology hinges on these advancements, allowing solid-state batteries to become more attractive for applications such as electric vehicles, stationary energy storage, and, in the longer term, even passenger aviation.

In recent years, chemical simulations have been established as a valuable tool for the development and optimization of battery materials, with increasing presence in the industry thanks to their ability to enable rational design while decreasing the time and cost of R&D workflows.  

As research into solid-state batteries ramps up, chemical simulations are increasingly being used to investigate the complex processes within these batteries, aiming to overcome key performance challenges. In particular, the use of computational simulations combined with machine learning is a cutting-edge area of research that promises to accelerate the design and optimization of the next generation of batteries.  

Within this context, machine learning can be used to sort through large datasets and predict the behavior of solid-state battery cells at the microscopic level, and to infer how these affect the overall performance of the battery. This approach can be useful, for example, to study the impact of defects or damage to the solid electrolyte on the degradation and decreased performance of solid-state battery materials.  

The evolution of computational tools and the increasing integration of machine learning into battery R&D is expected to drive major improvements in the understanding and development of next-generation solid-state battery technologies. Although still in its early stages, this approach could be pivotal in addressing current limitations of solid-state batteries, propelling the technology into mainstream use.