New zinc-air battery architecture boosts energy density by up to 80%

Scientists have invented a new technology that increases battery energy density by up to 80% without changing its fundamental chemistry. The Institute of Materials Science of Barcelona (ICMAB-CSIC), in collaboration with ICN2 and the National University of La Plata, has developed a new zinc-air battery architecture that boosts power output without altering the core chemistry. Decades of battery design have coalesced into one non-negotiable rule: keep the electrolyte electrically non-conductive. Free electrons in the liquid would cause a short circuit, rendering the battery useless. A team led by Nieves Casañ-Pastor and Marc Mosqueda has shown that adding unconnected conductive metal elements to the electrolyte can safely improve performance.

Specifically, the research found that introducing conductive metal sheets into the liquid of a membrane-free zinc-air battery creates wireless bipolar electrodes. This design strategy opens new avenues for boosting the power and charging capability of other battery technologies, beyond zinc-air systems.

Innovative design of wireless bipolar electrodes

Breaking the non-conductive barrier, the battery uses two different electrode materials separated by an electrolyte that transports only ions, not electrons. When the battery activates, the internal field instantly polarizes the metal islands, one side positive, the opposite side negative. This wireless response creates new pathways in the electrolyte, accelerating charge motion and lowering internal resistance. The end result is a significantly faster, more efficient flow of electrical energy, without any physical wiring. Casañ-Pastor said: "Usually, if a material can transport electrons in the electrolyte, it causes a short circuit, and the battery ceases to exist.

Surprisingly, these conductors are not connected to any device: they are simply placed inside the system, yet they still produce a beneficial effect, significantly altering power or charging capability."

Key to boosting battery efficiency

Zinc-air systems are cheap, pose no explosion risk, and rely on earth-abundant materials. Safety is their strong suit, but speed has always been their weak point. Zinc-air batteries have long been constrained by slow oxygen reactions, limiting their power output. By inserting these wireless bipolar electrodes, the research team cut internal resistance to a fraction of its normal level. As a result, energy moves through the system much faster. The battery's overall efficiency and speed improve markedly. In the study, platinum (Pt) and zinc (Zn) were tested as small metal sheets placed directly in the battery's liquid electrolyte to act as wireless bipolar electrodes.

Reducing internal resistance, the induced dipole moment lowered ohmic internal resistance by up to 64% and further reduced charge-transfer resistance, facilitating energy flow within the battery. Changing materials and geometric configuration yielded significant performance gains on key battery metrics. Volumetric power density increased by up to 80%, while limiting current density rose by more than 50%. The system also achieved an overpotential reduction of up to 300 mV, making energy transfer faster and more efficient. High-power zinc-air batteries offer an eco-friendly alternative for renewable energy grid storage — such as solar and wind integration — relying entirely on non-toxic, non-flammable chemistry.

The researchers say this development reflects a broader strategy for battery optimization, not a single fixed solution, and similar benefits have already been observed in other storage technologies beyond zinc-air systems. The researchers will continue exploring new applications of this wireless bipolar electrode architecture to enhance various battery parameters. The study has been published in the journal Energy Storage Materials.