A snug compression might resolve the main challenge for solid-state batteries in vehicles and electronic devices.

      A straightforward mechanical solution could replace complicated chemical methods to enhance the safety, speed, and reliability of solid-state batteries.

      Solid-state batteries have long been hailed as the ultimate solution for energy storage, promising to double the energy density compared to conventional alternatives, significantly reduce charging times, and eliminate the risk of thermal fires. However, despite these promises, the technology has not seen widespread commercial use, primarily due to dendrites. These tiny, needle-like formations develop inside solid-state batteries during charging, penetrating the solid ceramic electrolyte and connecting the electrodes, which leads to short circuits.

      Recently, researchers from SLAC National Accelerator Laboratory and Stanford University have identified an unexpectedly simple remedy for this ongoing issue. A study published in the journal Nature reveals that applying controlled mechanical pressure to the ceramic electrolyte can prevent these short circuits, enabling test cells to endure thousands of charge cycles without failure.

      Redirecting internal growth

      Researchers have debated for years whether dendrites initiate at the electrolyte's surface or deep within its internal structure. Utilizing advanced X-ray techniques at SLAC, the team resolved this question, demonstrating that dendrites actually originate from nanoscopic internal pores and defects within the material.

      To address this, the researchers employed basic principles of fracture mechanics. They placed a shape-memory alloy ring around the solid electrolyte and heated it to 170 degrees Celsius. As the ring contracted, it applied a strong, continuous lateral pressure on the cell.

      A cross-sectional view of the electrolyte shows horizontal dendrites throughout its thickness. The vertical positioning of these horizontal dendrites indicates the depth at which they begin within the solid electrolyte. Greg Stewart/SLAC National Accelerator Laboratory

      The outcome was impressive. Although dendrites still developed at internal defect locations under mechanical compression, the applied physical stress altered their growth trajectory. Instead of growing vertically towards the electrodes and causing short circuits, the dendrites grew horizontally. Confined safely within the electrolyte, they were unable to bridge the gap between the components and compromise the battery.

      Impact on everyday technology

      Although the research is currently in the laboratory phase, utilizing mechanical pressure to inhibit dendrites presents a clear opportunity for practical applications across several critical sectors.

      Electric vehicles: For electric vehicles, increased energy density translates to significantly longer driving ranges and reduced vehicle weight. Preventing short circuits allows these battery packs to accommodate rapid charging protocols while alleviating drivers' range anxiety.

      Consumer electronics: Smartphones, laptops, and wearables could see markedly extended battery life in slimmer designs once manufacturing scales up.

      Grid energy storage: Large energy grids necessitate storage capable of lasting thousands of cycles. Solid ceramic electrolytes will provide non-flammable stability, and mechanical compression could help guarantee long-term reliability.

      This research demonstrates that eliminating dendrites may not require an ideal, defect-free ceramic material. By utilizing fundamental mechanical pressure, it offers engineers a practical and achievable path forward. Creating batteries with an integrated compression mechanism could be the necessary shortcut to advance solid-state batteries from lab conditions into real-world applications.