New finding about the mechanics of solid-state batteries

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Batteries are fundamental to our day-to-day life, powering everything from our gadgets to our cars. However, like all things, they wear out over time.

As electricity flows through a battery, it gradually wears down the materials inside.

Other influences, like stress and strain from regular use, also affect how long a battery lasts and how well it performs, although we don’t fully understand all these impacts yet.

A team led by researchers at the Department of Energy’s Oak Ridge National Laboratory (ORNL) decided to dig deeper into this, developing a strategy for creating solid-state batteries (SSBs) with these mechanical aspects in mind.

Mechanics and Batteries: An Overlooked Relationship

Sergiy Kalnaus, a scientist at ORNL, emphasized the often-overlooked role of mechanics in battery performance.

While numerous studies have delved into the chemical or electric properties of batteries, the mechanical side of things hasn’t received as much attention.

The team, bringing together expertise from computational, chemical, and materials science disciplines, aims to understand better the conditions that affect SSBs from a multifaceted scientific viewpoint.

SSBs, unlike their liquid counterparts found in devices like electric cars, don’t contain flammable liquids, making them potentially safer and more robust.

Kalnaus noted, “True solid-state batteries don’t have flammable liquids inside,” presenting a less risky alternative to batteries commonly used today.

However, creating effective solid electrolytes (the materials through which charged particles move within a battery) is tricky.

The SSB components change size during charging, which can alter the system and eventually damage the solid electrolytes, especially since they’re typically made from brittle materials.

Techniques that allow these materials to flow rather than crack under stress are pivotal for overcoming this challenge.

Anodes, Electrolytes, and the Challenges Ahead

Anodes are components through which electrons exit a battery. In SSBs, anodes can be made from lithium, a metal that is incredibly energy-dense but can create pressure that damages electrolytes.

Erik Herbert from ORNL’s Mechanical Properties and Mechanics group explained, “During charging, nonuniform plating and an absence of stress-relief mechanisms can create stress concentrations.”

In order to enhance the performance and life of SSBs, the next generation of anodes and solid electrolytes need to be engineered to manage these stresses and pressures without damaging the electrolyte separator.

Reflecting on ORNL’s rich history of materials research for SSBs, Nancy Dudney, an ORNL scientist, recalled the development of a glassy electrolyte known as lithium phosphorous oxynitride (LiPON) in the early 1990s.

LiPON is now widely used in thin-film batteries due to its ability to manage many charge-discharge cycles without failure, thanks largely to its ductility – its ability to flow instead of crack when under stress.

Paving the Road Ahead

The researchers’ work underscores an often under-explored aspect of SSBs, shedding light on factors that influence their lifespan and efficacy.

“The research community needed a roadmap,” Kalnaus concluded, expressing hope that their work, which outlines the mechanics of materials for solid-state electrolytes, will inspire scientists to consider these mechanics in future battery designs.

As we march into a future that promises an even greater reliance on battery power, understanding, and innovating in this field becomes crucial.

This meticulous effort to understand the underpinning mechanics of batteries isn’t just a scientific endeavor; it is a step towards designing robust, safe, and durable power storage systems that will fuel our devices, vehicles, and perhaps even our cities in the future.

The research findings can be found in Science.

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Source: Oak Ridge National Laboratory