A Rice University study flips battery design assumptions, revealing that material chemistry—not just structure—governs performance in thick electrodes, the discovery could transform how next-gen lithium-ion batteries are built for EVs and smartphones.
In a breakthrough that challenges long-standing battery design norms, researchers at Rice University have found that the internal chemistry of electrode materials—not just their structural design—plays a critical role in determining lithium-ion battery performance, especially in thick electrodes.
Thicker electrodes, often hailed for their higher energy density, are seen as a path toward longer-lasting electric vehicles and smartphones. But as the new study reveals, thicker isn’t always better—unless the material’s thermodynamic properties support even energy flow.
“Thick electrodes are like big sponges,” explained Zeyuan Li, lead author and Rice doctoral alumnus. “They can store more, but if the energy only penetrates partway, you’re not getting the full benefit.” Li likens the problem to water soaking only part of a sponge, leaving much of it dry.
The study compared two widely used cathode materials—lithium iron phosphate (LFP) and nickel manganese cobalt oxide (NMC). Structurally similar, the two behave very differently when cycled under identical conditions. LFP exhibited more degradation and uneven lithium distribution, while NMC showed much more uniform energy use.
Using advanced X-ray imaging at Brookhaven National Laboratory, the team visualized lithium-ion movement during charge cycles. LFP electrodes showed concentrated activity near the surface facing the separator, while deeper layers remained largely inactive. NMC, by contrast, demonstrated balanced internal reactions.
The team mentioned that this isn’t just about how you pattern the electrode.The reaction uniformity is dictated by the material’s thermodynamic fingerprint. To quantify this behavior, the team introduced a new evaluation tool: the “reaction uniformity number,” which captures how both structure and internal chemistry affect performance. It’s a design metric aimed at helping battery engineers select materials better suited for thick electrode applications.
As batteries get denser, the cost of poor internal uniformity becomes higher. Their findings offer a new lens to design thick electrodes that last longer and perform more efficiently. For engineers racing to pack more power into smaller spaces, this could be the next game-changing insight.
