First-ever design principles to boost solid-state battery energy density

A team of Korean researchers has unveiled the first-ever universal design principles for solid-state batteries, marking a paradigm shift in the field.

They have also developed a solid-state battery design toolkit using the design principles.

This breakthrough addresses a critical gap in battery design research, which previously lacked standardized benchmarks.

“Presenting the first universal design principles for solid-state batteries with developing and sharing a design toolkit will greatly benefit the field of solid-state battery design,” stated the researchers.

It can potentially accelerate the development and adoption of solid-state batteries, which are widely considered to be the future of energy storage. Besides, solid-state batteries, with their higher energy density compared to lithium-ion batteries, promise to increase EV range while offering enhanced safety and faster charging.

Rise of solid-state batteries

The global drive toward electrification has intensified the demand for advanced battery technology. And solid-state batteries, which present a more secure and energy-dense option compared to traditional lithium-ion batteries, have become the center of attraction.

Their use of non-flammable solid electrolytes mitigates the risk of fire. Moreover, their efficient cell and system design enables substantial increases in energy density.

Although fundamental research on solid-state batteries has advanced, the shift from experimental findings to real-world applications has encountered obstacles due to an absence of established scientific design principles.

Researchers have largely relied on experience to combine materials and control design parameters. This, in turn, can sometimes lead to inefficiencies.

Overcoming design challenges

The Korean research team has established quantitative design parameters for batteries. They include the balance threshold, percolation threshold, and loading threshold.

These parameters form the foundation of the first universal principles for designing solid-state batteries.

Interestingly, a 0.5Ah pouch cell built on these principles achieved an impressive energy density of 310Wh/kg and obtained third-party certification. Notably, it exceeded the energy density of commercial lithium batteries (around 250Wh/kg).

“We hope that many researchers can use these principles to design solid-state batteries efficiently, promote significant performance improvements, and overcome the current technological barriers,” added the researchers.

Quantitative design parameters

The energy density of solid-state batteries is influenced by the density of active materials in the cathode. The “balance threshold” defines the ideal ratio of solid electrolyte filling spaces between active material particles in the cathode.

The research team used the concept of ‘cubic closed packing’ to define this standard ratio, which guides the balance between energy density and power density.

The “percolation threshold” establishes the minimum condition for lithium ion conduction in the composite cathode. It ensures contact between composite particles of active materials and solid electrolytes.

Meanwhile, the “loading threshold” defines the ideal conditions for minimizing voltage drop within the cathode. It aids in the design of optimal electrode thickness.

The researchers additionally created ‘SolidXCell,’ a toolkit for designing solid-state batteries that is accessible to the public.

The platform, characterized by its multi-scale and multi-parameter capabilities, promotes an intuitive and systematic approach to design, thereby enhancing accessibility to solid-state battery technology for a broader audience.

Future implications

The implementation of these design principles, along with the associated design toolkit, signifies a notable advancement in the development of solid-state batteries.

The researchers expect that these instruments will facilitate the design procedures and enhance performance advancements.

The design principles and the versatile design toolkit have been created by Dr. Jinsoo Kim of the Ulsan Advanced Energy Technology R&D Center of the Korea Institute of Energy Research (KIER), along with Professor Sung-Kyun Jung’s research team from the Ulsan National Institute of Science and Technology (UNIST).