Advancing the Performance of Li- and Mn-Rich Cathodes—Bulk and Surface Controls

The growing demand for electric vehicles, as well as the need for viable grid storage batteries, has initiated a world-wide search for materials that can further enable these technologies. In this regard, the development of cost-effective, and energy efficient lithium-ion battery cathodes is of critical importance. Currently, Ni-rich NMC oxides (LiNi_xMn_yCo_zO₂, x+y+z = 1) are the most advanced, high-performance materials for use as Li-ion cathodes. However, increasing concerns over sustainability, supply chain issues, and cost-effectiveness of critical elements like Co and Ni have accelerated the need for more earth-abundant options such as those based in Mn.¹
Lithium and manganese rich cathode materials (LMRs), with general formula xLi₂MnO₃ (1-x)LiMO₂, can achieve high energy densities, and thus represent attractive alternatives. ^2-3 However, there are several materials barriers, both bulk and surface related, that prevent Mn-rich cathodes from being implemented on a wider scale in commercial cells. At the bulk level, an anomalously-high area specific impedance (ASI) occurs at low states of charge (SOCs) that has, until recently, been largely overlooked.⁴ At the surface level, preventing the dissolution of Mn remains a significant challenge.
In this work, we will discuss a strategy based on ‘domain-specific’ substitutions⁵ to address the problem of high ASI at low SOCs. Furthermore, we will present a surface modification, based in atomic layer deposition (ALD) – in contrast to typical wet-chemical routes – that shows considerable promise towards mitigation of Mn dissolution, greatly extending the cycle life of cells utilizing Mn-rich cathodes.
References:
1. Communications Materials 2020, 1 (1), 99.
2. Accounts of Chemical research 2015, 48 (11), 2813-2821.
3. Journal of The Electrochemical Society 2023, 170 (3), 030509
4. Journal of the Electrochemical Society 2021, 168, 080506
5. Chemistry of Materials 2024, 36 (14), 6777-6790