Benchmarking operando neutron diffraction for high-power Li-ion battery

Abstract

Neutron powder diffraction is a powerful method for probing structural changes, localizing and quantifying lithium in battery electrode materials, but acquiring high-quality patterns during operando type measurement remains challenging due to the need for both good electrochemistry and large active material amount for optimal signal-to-noise ratio. However, this technique is rarely applied during fast cycling of high-rate electrode material despite the growing demands of high-power batteries. Herein, we benchmarked two cell designs for operando measurement, a coin-type and cylindrical cells on two different diffractometers (high-resolution and high-flux instruments) using the high-rate Wadsley-Roth FeNb11O29 as a model electrode material. The coin-type cell provides excellent signal-to-noise ratio and ease of assembly, yet it relies on deuterated electrolytes. In contrast, a cylindrical cell delivers reliable electrochemistry at fast cycling rates while still providing neutron diffraction data of sufficient quality for structural analysis even when using conventional organic electrolyte. The two diffractometers also exhibit complementary capability: the high-flux instrument enabled fast data acquisitions in only a few minutes, while the high-resolution one was successfully employed in in situ mode for the first time with clearer peak separation. These results validate cylindrical cell as a promising setup for realistic, high-rate cycling, paving the way towards more accessible and cost-effective operando neutron studies in battery research.