Lithium-ion batteries, the cornerstone of modern portable electronics and electric vehicles, have traditionally grappled with critical challenges: flammability risks from organic solvents, energy-intensive production processes, and complicated recycling protocols. Currently, the reliance on volatile organic electrolytes demands strict, resource-heavy manufacturing environments such as dry rooms and glove boxes, inflating production costs and environmental footprints. Furthermore, the complex binders and electrolyte formulations used complicate recycling, often rendering valuable materials unrecoverable. The 3D-SLISE system directly addresses these pain points by presenting a safer, greener alternative without sacrificing performance.

The core of this innovation is a borate-water electrolyte created from amorphous lithium tetraborate combined with a lithium salt, carboxymethyl cellulose, and water. This concoction forms a unique slime-like quasi-solid interface, establishing a three-dimensional ion conduction network that facilitates multidirectional lithium ion mobility. Unlike traditional liquid or solid electrolytes that conduct ions in limited pathways, 3D-SLISE’s isotropic conduction enhances ionic conductivity, reaching values of approximately 2.5 milli-siemens per centimeter. Such conduction efficiency rivals advanced aqueous electrolyte systems while operating effortlessly at ambient temperature, thanks to its low activation energy of 0.25 electron volts.

Fabrication processes further emphasize the sustainability of this system. The slurries constituting 3D-SLISE are naturally dried at room temperature, a stark contrast to the high-temperature or low-humidity conditions demanded by conventional batteries. This ambient fabrication eliminates the need for energy-expensive infrastructures, enabling battery assembly in standard air conditions. Two distinct slurry types are employed: Type E, which integrates with key lithium-based active materials—including lithium cobalt(III) oxide as the cathode and lithium titanate as the anode—to form electrodes, and Type S, which composes the quasi-solid electrolyte layer. The seamless assembly under benign conditions heralds large-scale manufacturability without compromising material integrity.

Performance metrics of batteries utilizing 3D-SLISE are nothing short of remarkable. The assembled cells deliver a stable voltage of 2.35 volts at a 1C rate and consistently sustain over 400 charge-discharge cycles at 3C rates under room temperature, translating to rapid charge and discharge times—around 20 minutes per full cycle. These capabilities indicate that despite being quasi-solid and water-based, the electrolyte competes effectively with, and in some respects outperforms, traditional lithium-ion systems dependent on hazardous organic components. Such battery endurance alongside quick cycling makes 3D-SLISE an optimally practical solution for diverse applications spanning from consumer electronics to grid-scale energy storage.

Beyond performance, the recycling advantages are transformative. Common binders used in lithium-ion batteries, such as polyvinylidene difluoride (PVDF), are challenging to break down, often necessitating harsh chemical treatments. However, 3D-SLISE’s composition excludes these binders and relies solely on water-dispersible components. Used batteries can be dismantled simply by immersing electrodes in water, allowing the active materials—including cobalt, a rare and valuable element—to be directly reclaimed. This straightforward recycling process promises to substantially reduce environmental impact and resource depletion, key attributes aligned with circular economy principles.

The potential environmental benefits extend into the manufacturing chain as well. By circumventing the need for flammable organic solvents, 3D-SLISE considerably reduces fire hazards—a persistent safety concern in lithium-ion battery production and operation. The elimination of dry rooms and glove boxes, which consume significant energy and impose complex operational standards, further reduces the carbon footprint and costs associated with battery fabrication. Collectively, these characteristics place 3D-SLISE as a game-changing technology that aligns industrial scalability with environmental stewardship.

Technically, the incorporation of amorphous lithium tetraborate serves dual functions: it provides a stable structural framework for ion transport and enhances electrochemical stability of the cell. Lithium bis(fluorosulfonyl)imide (LiFSI) salt ensures efficient lithium ion availability, while carboxymethyl cellulose contributes to the desired viscoelastic properties of the quasi-solid matrix. The resulting slime-like interface bridges the gap between solid and liquid electrolyte behaviors, harnessing advantages of both to maximize ionic mobility without compromising safety or manufacturability.

The Institute of Science Tokyo’s commitment to zero-carbon energy technology illustrates the strategic focus underpinning this breakthrough. Spearheaded by Specially Appointed Professor Yosuke Shiratori and Associate Professor Shintaro Yasui, this research is expected to accelerate the transition toward sustainable energy storage by providing practical, scalable technological solutions. Their findings, detailed in the July 2025 issue of Advanced Materials, underscore an interdisciplinary approach, blending materials science, electrochemistry, and environmental engineering.

Looking forward, the adaptability of 3D-SLISE could empower a wide range of battery-dependent technologies. Portable electronics stand to benefit from safer, more durable power sources, while stationary energy storage could leverage the quick charge rates and long cycle life to enhance grid stability and integrate renewable resources more effectively. Furthermore, the ability to avoid toxic solvents and streamline recycling could transform regulatory landscapes, promoting safer consumer products and industry practices globally.

In summary, 3D-SLISE embodies a multifaceted leap forward in lithium-ion battery science. By integrating inherently safe, water-based materials into a quasi-solid matrix capable of high ionic conductivity and manufacturable under ambient conditions, the Institute of Science Tokyo researchers have charted a promising course toward truly sustainable, high-performance batteries. Their discovery not only addresses the immediate challenges of battery safety and environmental impact but also paves the way for a circular battery economy where materials are continuously recovered and reused, reducing waste and dependence on scarce resources.

Subject of Research: Not applicable

Article Title: Borate-Water-Based 3D-Slime Interface Quasi-Solid Electrolytes for Li-ion Batteries

News Publication Date: 9-Jul-2025

Web References: https://doi.org/10.1002/adma.202505649

Image Credits: Institute of Science Tokyo

Keywords

Lithium ion batteries, Electrochemistry, Applied sciences and engineering, Sustainability, Energy, Conservation of energy

At the heart of these challenges lies the process of zinc plating and stripping during battery charge and discharge cycles. Zinc anodes repeatedly undergo deposition and dissolution of metallic zinc, but this repeated action induces side reactions such as corrosion and the formation of zinc dendrites—needle-like structures that grow uncontrollably, piercing electrolyte separators and causing short circuits. Such phenomena severely degrade the cycling stability, lifespan, and overall reliability of aqueous zinc batteries, hampering their commercial viability despite their inherent safety advantages.

To tackle these fundamental issues, research has traditionally focused on engineering protective coatings designed to promote uniform zinc ion flux and suppress dendritic growth on the anode surface. While effective to an extent, conventional protective coatings often introduce new complications. Thick, dense films impede zinc ion transport, increasing ionic resistance and lowering battery performance. Moreover, manufacturing these protective layers tends to be costly and not easily scalable for larger electrode surfaces, limiting practical applications in commercial battery systems.

In an exciting development, a research group led by Associate Professor Woo-Jin Song at Chungnam National University in South Korea has introduced an innovative ultra-thin selective-ion transport layer (SITL) that addresses these limitations head-on. This groundbreaking work, published in the July 2025 edition of the Chemical Engineering Journal, unveils a nanoscale zinc-bonded polyacrylic acid (Zn–PAA) layer engineered for zinc anodes through a novel oxygen plasma treatment process. This approach capitalizes on the synergistic effects of polymer chemistry and surface engineering to produce an effective but incredibly thin ion-selective protective film.

What makes this Zn–PAA coating extraordinary is not only its remarkable thinness — at the nanoscale — but its facile and scalable fabrication method. The coating is applied to zinc anodes using a cost-effective spin-coating technique following oxygen plasma pretreatment, which fine-tunes the adhesion between the PAA polymer and the metallic zinc surface. This contrasts sharply with previous SITLs, which have suffered from complicated, multi-step, and bulky fabrication methodologies unsuitable for mass production on large electrode areas.

Mechanistically, the polyacrylic acid (PAA) component plays a crucial role in stabilizing the zinc anode. PAA’s hydrophilic nature enhances the interaction between the aqueous electrolyte and the zinc surface by promoting uniform ion transfer and distribution. Simultaneously, it forms a barrier that prevents the direct contact of the zinc metal with water, curbing corrosion and suppressing side reactions such as the hydrogen evolution reaction—a major source of irreversible capacity loss and electrolyte decomposition. Furthermore, the PAA protective layer considerably inhibits the formation of passivation layers originating from unwanted reactions with anionic electrolyte components that otherwise degrade the anode surface and exacerbate non-uniform zinc growth.

Yet, PAA alone suffers from solubility issues in aqueous environments, which traditionally undermines its protective functions during long-term cycling. The research team ingeniously addressed this problem by applying oxygen plasma treatment to the zinc anode prior to PAA deposition, a process that chemically modifies the zinc surface, increasing bonding sites and thus greatly enhancing the adhesion and stability of the PAA layer. Subsequent gentle heating induces the formation of zinc-bonded PAA (ZHP), a cross-linked, stable protective polymeric interface that resists dissolution even under harsh ultrasonic agitation in aqueous solutions, signaling robust mechanical and chemical resilience.

Electrochemical testing of the Zn@ZHP anodes revealed remarkable enhancements in cycling performance compared to bare zinc controls. The SITL effectively curtails dendritic growth during repeated plating and stripping processes, encouraging the deposition of uniform zinc crystals preferentially oriented along the (002) crystallographic plane. This crystalline orientation is known for its superior electrochemical activity, contributing to the observed improvements in performance. Impressively, symmetric cell configurations employing Zn@ZHP anodes sustained stable operation exceeding 2200 hours—significantly outlasting conventional zinc anodes under similar conditions.

More practically, full-cell zinc-ion batteries incorporating the ZHP-coated anodes sustained 95% of their initial capacity even after 500 charge-discharge cycles at a current density of 1 A g⁻¹. This level of stability at commercially relevant current rates is a compelling indicator of the technology’s readiness for real-world applications. Extending beyond laboratory-scale coin cells, the team also demonstrated pouch-cell configurations that maintained stable cycling for over 300 cycles under a demanding current density of 10 mA cm⁻², spotlighting the scalability and robustness of the approach.

Dr. Song underscores the broader implications of this advancement: “The enhanced stability of water-based electrolytes makes ZHP-based ZIBs ideal for safety-critical industries such as grid-scale energy storage systems and detection sensors. Furthermore, their low cost and toxicity render these batteries promising candidates for portable electronics and wearable devices.” This multifaceted applicability—from large energy storage grids requiring safe, cost-effective solutions to compact consumer electronics demanding reliability—makes the Zn–PAA nanolayer innovation a pivotal breakthrough.

This innovative protective polymer layer effectively bridges a long-standing gap in aqueous zinc battery research. By harmoniously balancing the need for uniform zinc ion transport, corrosion inhibition, side reaction mitigation, and practical manufacturability, this study paves the way for zinc-ion batteries to transition from niche laboratory curiosities to commercially viable, next-generation energy storage solutions. Given the ever-increasing demand for safe, affordable, and sustainable battery technologies, this pioneering work undoubtedly marks a major milestone.

The synergy of polymer chemistry, surface modification, and scalable engineering highlighted in this research resonates across the broader landscape of energy storage material science. It not only advances the zinc-ion battery domain but offers a blueprint for future innovations aiming to reconcile performance with manufacturability in emerging battery technologies. As demand intensifies for batteries that are safer and environmentally benign, the Zn–PAA nanoscale SITL represents a promising stride toward sustainable, high-performance alternatives capable of redefining how we store and deploy energy in the years to come.

Subject of Research: Not applicable

Article Title: Development of artificial zincophilic polymeric nanolayers on zinc anodes for high-performance zinc batteries

News Publication Date: 1-Jul-2025

Web References: https://doi.org/10.1016/j.cej.2025.162948

References: DOI: 10.1016/j.cej.2025.162948

Keywords

Batteries, Nanotechnology, Energy storage, Materials science, Electrochemistry, Chemical engineering, Electronics, Renewable energy, Biotechnology, Anodes