Do We Finally Have Self-Assembling Battery?
With the rising popularity of electric cars, there has never been a greater push to develop sustainable yet durable battery materials. One longstanding challenge is that electrolyte layers designed to be recycled or degraded on demand often turn out too fragile for real-world use. Recently, however, Yukio Cho and colleagues reported a way to construct a battery electrolyte layer from self-assembling molecules—materials that are both mechanically strong and recyclable. This work marks an exciting proof of concept that brings us closer to sustainable energy storage solutions.
What is Self-Assembly?
As the name suggests, self-assembling molecules spontaneously organize themselves into larger, ordered structures without external force or direction. Think of it like your morning bowl of oat rings – they always clump together even when you try to separate them apart!
Self-assembly’s been an interesting research topic for many and has been in consistent use in drug delivery (Osorno et al.) and self-assembling polymers (Hu et al.). They are also part of us since phospholipid bilayers make up our cell membranes.
What Did They Do?
The researchers first had to find a self-organizing molecule that could have some varying properties as independent variable. The team decided employ methoxy polyethylene glycol-aramid amphiphiles (mPEGAAs) – which Yukio have had experience with it in the past investigating varying extent of heavy metal remediation (Christoff-Tempesta et al.).
But why mPEGAAs? The answer is in the structure of the molecule that consists of two major areas. Methoxy polyethylene glycol (polyethylene oxide) residue in the molecule was added for its ability to conduct lithium ion and its hydrophilicity, which is crucial for a working cell. However, on its own, the weak intermolecular interactions are not enough to hold up the self-assembled structure. To ameliorate this issue, a strand of aramid that consist of aromatic amide trimers were incorporated to imitate the π-π stacking interaction found in Kevlar – which, obviously, is mechanically extremely strong. At the other end of the glycol, a aliphatic tail was attached as the hydrophobic region. See the figure below for a pictorial representation.
What Did They Find Out?
The addition of the amphipathic region helped with the mechanical stability tremendously compared to other self-assembled structures. When the self-assembled structure is dried of solvent and hot pressed, it results in a flexible material that retains the nano structure – which is crucial for ion channels. The material was strong enough that it could hold its own weight (i.e. not collapse).
The team then studied how the length of the polyethylene glycol chain influenced performance. Shorter chains, such as mPEG8AA, showed a hypochromic (blue) shift in UV-vis spectroscopy, signalling stronger intermolecular interactions and enhanced mechanical stability. By contrast, longer chains improved lithium-ion conductivity because their broader cross-sectional area allowed for easier ion transport. This revealed an important trade-off: shorter chains stabilize the structure, but longer chains enhance conductivity. The optimal design, therefore, lies in a balance between the two.
Another thing to consider when developing an electrolyte is its electrochemical stability. To investigate this, they constructed three different types of cells. Two of these cells were half-cells: they were used to determine the cathodic and anodic stability. The cathodic stability was great – having negligible fluctuations in current densities over cycles – while anodic stability showed typical value of polymers derived from polyethylene oxides.
We have a solid and conductive electrolyte; but how does it perform when it comes to recycling? To test this, researchers submerged a cell made with mPEG16AA in organic solvent, which resulted in dissolution of the electrolyte layer – separating it from other cell materials. Dimethylformamide and methanol were also able to dissolve the electrolyte layer within an hour.
Is it Enough?
Battery recycling is one of the thorniest environmental problems in clean energy. Traditional electrolytes are tough to reclaim and often require harsh, polluting processes. A self-assembling, dissolvable electrolyte points to a future where recycling is as simple as giving a spent cell a solvent bath.
As pointed out in the paper itself, the electrochemical performance isn’t good enough for industrial energy storage yet. However, this research demonstrated that smart molecular design and self-assembly can tackle one of the biggest issues in battery technology.
The researched served more as a proof of concept — that self-assembled layers can be made durable enough to be used in a battery. Maybe, you and I can be the ones to figure out how to optimize this further 🥹!
References:
Cho, Yukio, et al. “Reversible Self-Assembly of Small Molecules for Recyclable Solid-State Battery Electrolytes.” Nature Chemistry, 28 Aug. 2025, http://www.nature.com/articles/s41557-025-01917-6#citeas, https://doi.org/10.1038/s41557-025-01917-6. Accessed 10 Sept. 2025.
Christoff-Tempesta, Ty, et al. “Interfacial Dynamics Mediate Surface Binding Events on Supramolecular Nanostructures.” Nature Communications, vol. 15, no. 1, 5 Sept. 2024, http://www.researchgate.net/publication/383791550_Interfacial_dynamics_mediate_surface_binding_events_on_supramolecular_nanostructures, https://doi.org/10.1038/s41467-024-51494-4.
Hu, Lina, et al. “Self-Assembly of Polymers and Their Applications in the Fields of Biomedicine and Materials.” Polymers, vol. 16, no. 15, 23 July 2024, pp. 2097–2097, http://www.mdpi.com/2073-4360/16/15/2097, https://doi.org/10.3390/polym16152097. Accessed 30 Sept. 2024.
Osorno, Laura L, et al. “Review of Contemporary Self-Assembled Systems for the Controlled Delivery of Therapeutics in Medicine.” Nanomaterials, vol. 11, no. 2, 21 Jan. 2021, pp. 278–278, https://doi.org/10.3390/nano11020278.
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