Abstract
LiNi₀.₅Mn₁.₅O₄ (LNMO) is a high‑voltage spinel cathode that has emerged as a strong candidate for next‑generation lithium‑ion batteries, particularly for electric‑vehicle applications. Operating at roughly 4.7 V vs. Li/Li⁺, LNMO delivers an energy density near 650 Wh/kg and exhibits excellent rate capability, making it well‑suited for systems that demand fast charging and high‑power performance . Despite these advantages, its practical implementation is limited by a critical degradation mechanism: transition metal dissolution. During cycling, Mn and Ni dissolve from the LNMO surface, migrate to the graphite anode, and are reduced to their metallic states, where they obstruct Li ion diffusion pathways and accelerate capacity fade. . To address this cross talk, groups at SINTEF developed a series of functional binders capable of scavenging dissolved transition metals directly within the LNMO composite.
Transition metal dissolution in LNMO cells is typically assessed using bulk analytical techniques such as ICP OES, XRF, or post mortem electrochemical diagnostics. While informative, these methods provide only averaged values and cannot reveal where Mn and Ni accumulate within the graphite anode. This lack of spatial resolution limits our ability to directly correlate metal deposition patterns with performance loss. In contrast, LA ICP MS enables high resolution chemical mapping, allowing visualization of Mn, Ni, and Li distributions across the graphite electrode surface.
Reliable quantification by LA ICP MS depends strongly on appropriate calibration, ideally using matrix matched reference materials that ablate similarly to the samples. Such standards are often unavailable, prompting the development of non matrix matched calibration approaches, such as a recently developed methodology based on normalization to the ablated volume.
In our study, we confirmed (i) that the ablation depths were largely consistent across all analyzed samples (within approximately 2 µm), and (ii) that the concentration data would be normalized to the actual volume of material removed , ensuring a fair comparison across the different materials investigated.
By integrating LA‑ICP‑MS mapping with classical bulk ICP‑MS measurements, we could distinguish between surface‑layer enrichment and full‑depth elemental concentrations.
This combined methodology allowed us to evaluate a set of five candidate binders and to identify the best‑performing formulation, directly linking enhanced metal‑scavenging efficiency to improved electrochemical durability.