Wavy Cooling Channels Keep Lithium-Ion Batteries Cooler With Gradient Design

Lithium-ion batteries have transformed transportation and grid-scale energy storage, but they carry an Achilles heel that engineers have wrestled with for decades: heat. Every charge and discharge cycle generates thermal energy inside the cell, and when that energy accumulates faster than it can be removed, battery performance degrades, lifespan shortens, and in the worst cases thermal runaway can trigger fires that are notoriously difficult to extinguish. A new study published in the journal Ionics by researchers at Dalian Maritime University in China now offers a deceptively elegant answer to this persistent problem, one that borrows its geometry from the smooth undulations of a sine wave and its design philosophy from the way nature distributes fluids through branching networks.

The research team, led by Ruiyang Zhang and including Shian Li, Xinping Liu, Aolong Liu, Dingding Xiao and Qiuwan Shen, set out to improve the liquid cooling plates that sit against battery cells in electric vehicles and other demanding applications. These plates contain internal channels through which coolant flows, carrying heat away from the cell surface. The most common commercial design is the serpentine channel, a single continuous passage that snakes back and forth across the plate. Serpentine channels are simple to manufacture and force the coolant to travel past every part of the battery, but they suffer from a well-known weakness: as the coolant moves along its long journey, it steadily absorbs heat and warms up, meaning the sections of the battery near the outlet are cooled by fluid that is already hot. The result is an uneven temperature distribution across the cell, and temperature non-uniformity is nearly as damaging to battery health as high temperature itself.

The Chinese team’s innovation was to replace the sharp, angular turns of the traditional serpentine channel with a continuous wavy path defined by a sine function. Instead of abrupt 180-degree bends that create flow separation, dead zones and localized turbulence, the serpentine wavy channel curves smoothly, encouraging the coolant to mix gently and maintain better contact with the channel walls. To evaluate the idea, the researchers built a three-dimensional mathematical model and used computational fluid dynamics to simulate how heat moves from a generating battery, through the cooling plate, and into the flowing coolant. This modeling approach allows them to compute the maximum battery temperature, the temperature difference across the cell, and the pressure drop along the channel, the three metrics that together determine whether a cooling design is practical.

The comparison against the conventional serpentine channel produced results that, while modest in absolute terms, are meaningful in a field where every fraction of a degree counts. The wavy design reduced the maximum battery temperature by 0.39 kelvin and reduced the temperature difference across the battery by 0.19 kelvin. In the world of battery thermal management, where the ideal target is to keep cells within a few degrees of one another, shaving nearly half a kelvin off the peak temperature without any increase in coolant flow represents genuine progress. The trade-off came in the form of a slightly increased pressure drop, meaning the pump must work a little harder to push coolant through the undulating passage. That penalty is the eternal currency of heat transfer engineering: better thermal performance almost always demands more pumping power, and the designer’s job is to find the sweet spot where the thermal gains justify the energetic cost.

What elevates the study beyond a single design comparison is its systematic exploration of the wavy channel’s geometric parameters. The researchers varied two key quantities: the amplitude of the wave, which describes how far the channel swings from its centerline, and the wavelength, which describes how tightly the waves are packed together. Their simulations revealed a consistent pattern. Increasing the amplitude improved cooling, because a deeper wave forces the coolant into more pronounced accelerations and decelerations, enhancing mixing and disrupting the thermal boundary layer that insulates the channel wall from the cooler fluid in the core of the flow. Reducing the wavelength had a similar effect, since more wave crests per unit length means more frequent perturbations of the flow and more opportunities for the coolant to sweep fresh, cool fluid against the heated surface. Both changes pushed the maximum battery temperature and the temperature difference downward, giving engineers two independent knobs to tune when optimizing a cooling plate for a specific cell geometry.

The most forward-looking element of the work, however, is its investigation of gradient designs. Rather than making the amplitude or wavelength uniform along the entire channel length, the team explored channels in which these parameters change progressively from inlet to outlet. The logic mirrors the physics of the problem: coolant enters cold and exits hot, so the sections of channel near the outlet are working with thermally exhausted fluid and could benefit from more aggressive geometry precisely where the cooling demand is hardest to meet. The simulations confirmed this intuition. Designs with an increasing gradient in amplitude, where the waves grow taller toward the downstream end, reduced both the maximum battery temperature and the temperature difference. So did designs with a decreasing gradient in wavelength, where the waves become more tightly packed along the flow direction. In both cases, the channel becomes more capable of stirring the coolant in exactly the region where stirring is most needed.

This gradient philosophy connects the work to a broader and rapidly growing movement in thermal engineering that draws inspiration from biological fluid distribution systems. Blood vessels, leaf veins and plant xylem do not maintain uniform diameters; they taper and branch in ways that balance transport efficiency against distribution uniformity. Recent years have seen a wave of bio-inspired cooling channel designs, including leaf-vein type channels, snowflake-shaped flow networks, fractal channels modeled on lung architecture, and porous structures derived from morpho butterfly wings. The Dalian study adds a mathematically clean variant to this family: instead of copying a specific organism, it applies a smooth mathematical function and then gradients its parameters, offering a design language that is easy to parameterize, simulate and optimize computationally.

The stakes for this kind of research are rising quickly. Electric vehicle adoption continues to accelerate worldwide, and fast charging, which is central to consumer acceptance of electric cars, pushes heat generation rates to levels that challenge conventional cooling. Marine applications add further demands, with large-capacity battery packs on ships requiring robust thermal management in confined spaces. Studies cited by the authors document how thermal runaway propagates through battery modules, how fast charging and low-temperature cycling degrade cell health, and how temperature non-uniformity within a pack causes cells to age at different rates, ultimately shrinking the range and lifespan of the entire system. A cooling plate that keeps cells a fraction of a degree cooler and, more importantly, keeps them more uniform, translates directly into longer-lasting, safer and more predictable battery packs.

There are, of course, caveats that separate the simulation from the showroom. The study relies on a three-dimensional mathematical model rather than physical prototypes, and while computational fluid dynamics is a mature and validated tool, real manufacturing tolerances, coolant impurities, contact resistances and long-term fouling can all erode the theoretical gains. The slight increase in pressure drop, though small in the reported configuration, would need to be weighed against pump energy consumption over the lifetime of a vehicle, particularly in designs where amplitude is pushed high or wavelength compressed to extremes. The authors also note that no experimental datasets were generated in the current study, which means the next logical step is fabrication and testing of gradient wavy channel plates under realistic duty cycles, including the transient heat loads of rapid acceleration and fast charging.

Even so, the study demonstrates a principle that could shape the next generation of battery thermal management hardware: the geometry of a coolant channel is not a fixed constraint but a designable variable, and gradients within that geometry can be matched to the thermal gradient of the battery itself. As electric vehicles, marine vessels and grid storage installations demand ever more from their cells, the difference between a good battery pack and a great one may come down to details as subtle as the shape of a wave. The Dalian team’s sine-inspired, gradient-tuned channels show that sometimes the most powerful engineering ideas are the ones that flow smoothly, quite literally, from mathematics into metal.

Subject of Research: Gradient-designed serpentine wavy channel liquid cooling plates for lithium-ion battery thermal management

Article Title: Thermal performance analysis of lithium-ion batteries with gradient-designed serpentine wavy channel liquid cooling plates

Article References: Zhang, R., Li, S., Liu, X., Liu, A., Xiao, D., & Shen, Q. (2026). Thermal performance analysis of lithium-ion batteries with gradient-designed serpentine wavy channel liquid cooling plates. Ionics. https://doi.org/10.1007/s11581-026-07503-1

Image Credits: AI Generated

DOI: 10.1007/s11581-026-07503-1

Keywords: lithium-ion batteries, battery thermal management, liquid cooling, wavy channels, serpentine channel, sine function, gradient design, temperature difference, pressure drop, computational fluid dynamics, electric vehicles, thermal runaway