Decoupled Synthesis Pathway via Precursor Functionalization Stabilizes High‐Voltage Nickel‐Based Cathodes

ABSTRACT Nickel‐based layered cathodes are promising candidates for high‐performance, high‐energy lithium‐ion batteries, yet their high‐voltage application is jointly limited by synthesis‐inherited structural defects and an unstable lattice oxygen framework. Here, we show that both limitations can be overcome by decoupled synthesis pathway (DSP) via La/Nb oxalate functionalization of the Ni 0.6 Co 0.1 Mn 0.3 (OH) 2 precursor. Unlike the conventional coupled synthesis pathway (CSP) where precursor dehydration and Li 2 CO 3 decomposition overlap in temperature, the DSP introduces a low‑temperature decomposition of La/Nb oxalates at 200°C, which effectively avoids localized contact between the precursor and Li 2 CO 3 and shifts Li 2 CO 3 ‐related reactions to high temperatures. This allows sequential precursor dehydroxylation, rock‑salt (RS) intermediate formation, and layered‑phase transformation over a broad temperature window. The resulting LiNi 0.6 Co 0.1 Mn 0.3 O 2 cathode with La/Nb functionalization (NCM‐LN) features a uniform surface LaNiO 3 perovskite heterostructure and a Nb‑doped layered bulk with suppressed RS and spinel defects. Consequently, under 4.5 V operation (vs. Li + /Li), NCM‐LN exhibits homogeneous Li + (de)intercalation, and a stabilized oxygen framework. In graphite||NCM‐LN full cells, NCM‐LN retains 80.1% of its capacity after 2000 cycles at 1C, substantially outperforming the pristine cathode. This decoupling strategy is broadly effective across various Ni‑based systems, providing a generalizable route toward high‑energy, long‑life cathode materials.