A new approach to energy storage could keep advanced electronics running in environments where conventional batteries and capacitors begin to fail. Researchers have developed a dielectric capacitor that maintains high energy efficiency at temperatures as low as 4 kelvin, a regime only a few degrees above absolute zero. The device stores energy through the reversible displacement of electric charges inside a solid material rather than through chemical reactions or the movement of ions. According to the study published in Nature Nanotechnology, it combines an energy efficiency above 88% with an energy density of 211 joules per cubic centimetre at an electric field of 9 megavolts per centimetre. It also reportedly survives more than 100 million charge–discharge cycles and can operate on microsecond timescales, a combination that could attract attention in quantum technologies, space systems and other electronics designed for extreme environments.
Cryogenic energy storage is becoming increasingly important as engineers push electronic devices into colder and more demanding settings. Deep-space missions may require hardware to function at temperatures approaching 90 kelvin, while quantum computers often operate at 4 kelvin or below to preserve delicate quantum states. At such temperatures, standard rechargeable batteries and electrochemical capacitors face a fundamental obstacle: the ions that carry charge through their electrolytes move increasingly slowly as thermal energy falls. This loss of ionic mobility raises internal resistance, reduces power delivery and can make conventional electrochemical storage impractical. Dielectric capacitors avoid this particular limitation because they store electrical energy through polarization, the slight separation and rearrangement of positive and negative charges within an insulating material. Their challenge is not ion transport, but controlling how microscopic dipoles respond to a rapidly changing electric field.
The most advanced dielectric capacitors are often based on relaxor ferroelectrics, materials containing nanoscale regions with local electric polarization. When an electric field is applied, these polar nanoregions can reorient or grow, allowing the material to store substantial energy. When the field is removed, however, the response must reverse with minimal loss. The difference between the charging and discharging paths is known as polarization hysteresis, and the area enclosed by a polarization–electric-field loop represents energy dissipated as heat. Relaxor materials can achieve efficiencies above 80% at temperatures above roughly 200 kelvin, but their behaviour changes dramatically in the extended cryogenic regime below about 120 kelvin. Polar nanodomains can freeze, expand or become more strongly correlated, making them less responsive and increasing hysteresis. The result is a capacitor that wastes more of its stored energy precisely where cryogenic electronics need it most.
The new study addresses that problem by engineering what the researchers describe as a unit-cell-level dipole-glass state close to the boundary between antiferroelectric and paraelectric phases. In a conventional ferroelectric, microscopic dipoles tend to align in the same direction, producing a large net polarization. In an antiferroelectric, neighbouring dipoles preferentially arrange in opposing directions, so the overall polarization can remain small even though the local electric interactions are strong. A paraelectric, by contrast, lacks persistent long-range polarization under ordinary conditions. The material studied by the team occupies a highly frustrated region between these states, where competing interactions prevent dipoles from settling into a simple, extended arrangement. Instead of forming large, cooperative polar domains, the dipoles remain disordered in a glass-like configuration.
The term “dipole glass” refers to a frozen or slowly evolving pattern of local electric dipoles whose interactions are disordered and frustrated. The concept resembles a spin glass in magnetism, where magnetic moments experience competing forces and cannot achieve a single, uniform alignment. In the engineered dielectric, this disorder occurs at the scale of the crystal unit cell, the smallest repeating structural block of the material. That distinction is important. Conventional strategies often focus on controlling larger grains, interfaces or nanoscale domains, whereas unit-cell disorder directly modifies the local energy landscape experienced by each dipole. By increasing the complexity of dipole–dipole interactions, the researchers suppress the long-range ferroelectric order that would otherwise encourage polar nanodomains to grow as the temperature falls.
This microscopic disorder changes how the capacitor responds to an electric field. Rather than forcing a large population of dipoles to switch collectively, the material supports a more distributed and reversible polarization process. Individual or small groups of dipoles can respond without triggering extensive domain growth, reducing the irreversible rearrangements associated with hysteresis. The resulting polarization–electric-field loop remains narrow even under cryogenic conditions, indicating that less energy is lost during each cycle. The approach does not eliminate polarization; instead, it prevents polarization from becoming excessively cooperative and structurally locked. That balance is central to the device’s performance: enough local polarizability remains to provide high energy density, while the absence of long-range order helps maintain efficiency during rapid charging and discharging.
The reported figures place the technology among the more ambitious dielectric-storage demonstrations for low-temperature operation. At 4 kelvin, the capacitor achieves an energy efficiency exceeding 88%, meaning that more than 88% of the energy supplied during charging can be recovered during discharge. Its reported energy density reaches 211 joules per cubic centimetre at an applied field of 9 megavolts per centimetre. Energy density describes how much energy can be stored in a given volume, while the electric field indicates the voltage difference applied across the material relative to its thickness. A high field can substantially increase the energy stored in a dielectric, but it also increases the risk of electrical breakdown. The reported performance therefore reflects not only polarization control but also the material’s ability to withstand intense fields without losing its insulating character.
The capacitor’s endurance and speed could be as significant as its low-temperature efficiency. The device remains stable for more than 10⁸ charge–discharge cycles, a durability level relevant to systems that repeatedly deliver short bursts of power. Its microsecond-scale charging and discharging capability also distinguishes it from electrochemical storage, where chemical kinetics and ion diffusion generally limit rapid operation. In a cryogenic instrument, such a capacitor could potentially provide fast pulses for signal processing, control electronics or communication systems without introducing the thermal and mechanical complexity of warming a battery. In quantum computing, where unwanted heat and electromagnetic noise can disrupt fragile operations, a compact, efficient and fast storage element could support local control hardware. Spacecraft could likewise benefit from components able to operate directly in cold environments rather than relying on heaters or thermally isolated power systems.
The researchers’ broader contribution is a design principle for managing disorder in functional materials. Disorder is often treated as a defect that must be minimized, but the dipole-glass strategy uses carefully engineered disorder to prevent an unwanted collective phase. The key is not random damage, but controlled modification of local interactions near a phase boundary, where small structural or chemical changes can determine whether dipoles align, oppose one another or remain frustrated. The study suggests that unit-cell-level polar disorder can be used to tune the trade-off between energy density, efficiency, speed and temperature stability. Before such capacitors can be deployed widely, researchers will need to examine manufacturing uniformity, long-term reliability under realistic thermal cycling, behaviour in integrated circuits and performance at larger device scales. Even so, the results point toward a new route for cryogenic energy storage: instead of fighting the freezing of polar domains after it occurs, engineer the crystal so that large-scale freezing never develops.
Subject of Research: Cryogenic dielectric energy storage using a unit-cell-level dipole-glass state.
Article Title: Cryogenic energy storage enabled by dipole glass with unit-cell-level polar disorder.
Article References: Si, Y., Li, D., Li, Y. et al. “Cryogenic energy storage enabled by dipole glass with unit-cell-level polar disorder.” Nature Nanotechnology (2026). https://doi.org/10.1038/s41565-026-02260-8
Image Credits: AI Generated
DOI: https://doi.org/10.1038/s41565-026-02260-8
Keywords: cryogenic energy storage, dielectric capacitors, dipole glass, polar disorder, antiferroelectricity, paraelectricity, relaxor ferroelectrics, quantum computing, deep-space electronics, energy efficiency, polarization hysteresis, nanoelectronics
