Holistic Process Development of Lithium–Manganese-Rich Layered Oxides by Hydroxide Coprecipitation Using Taylor Vortex Reactors

Abstract

Lithium–manganese-rich (LMR) layered oxides are promising next-generation cathode materials due to their high discharge capacities and reduced reliance on costly transition metals, yet scalable synthesis routes that deliver consistent performance remain limited. Here, we present a holistic process development study for LMR synthesized from Mn-rich hydroxide via continuous coprecipitation using a Taylor Vortex Reactor followed by solid-state lithiation. Systematic control of coprecipitation parameters demonstrates that pH and ammonia concentration regulate supersaturation, enabling controlled primary particle growth and the formation of spherical, high-density Mn-rich hydroxide precursors. Calcination studies reveal that both the lithium source (Li2CO3 versus LiOH) and heating protocol (one-step vs two-step) critically influence phase evolution, with two-step protocols improving electrochemical performance. Notably, LiOH-derived LMR exhibits a higher first-cycle discharge capacity (up to 240 mAh g–1), lower impedance growth, and improved cycling stability compared to Li2CO3-derived materials. Correlated in situ X-ray diffraction and X-ray absorption spectroscopy identify distinct lithiation pathways, where LiOH enables earlier lithiation through a spinel-like intermediate, while Li2CO3 proceeds via a Li-deficient phase prior to lithiation, resulting in less homogeneous Li incorporation. These findings establish direct process–structure–property relationships across different processing steps, demonstrating that LMR performance is governed by synthetic design and providing a scalable framework for high-density, high-performance cathode manufacturing.