Rational design of mechanically robust Ni-rich cathode materials via concentration gradient strategy

Abstract

Mechanical integrity issues such as particle cracking are considered one of the leading causes of structural deterioration and limited long-term cycle stability for Ni-rich cathode materials of Li-ion batteries. Indeed, the detrimental effects generated from the crack formation are not yet entirely addressed. Here, applying physicochemical and electrochemical ex situ and in situ characterizations, the effect of Co and Mn on the mechanical properties of the Ni-rich material are thoroughly investigated. As a result, we successfully mitigate the particle cracking issue in Ni-rich cathodes via rational concentration gradient design without sacrificing the electrode capacity. Our result reveals that the Co-enriched surface design in Ni-rich particles benefits from its low stiffness, which can effectively suppress the formation of particle cracking. Meanwhile, the Mn-enriched core limits internal expansion and improve structural integrity. The concentration gradient design also promotes morphological stability and cycling performances in Li metal coin cell configuration.

Structural Reconstruction Driven by Oxygen Vacancies in Layered Ni‐Rich Cathodes

“…[8][9][10] Notably, both the structure formation during calcination and the structure change during attenuation were directly related to the properties for NCM cathodes. [11,12] Currently, much efforts have been done on the structure evolution in the formation (high-temperature lithiation reaction) and degradation (charging/discharging) of NCM cathodes. For NCM formation, Wang and coworkers revealed that the structure change was actually a topological phase transformation process during the high-temperature lithiation of LiNi 0.77 Co 0.1 Mn 0.13 O 2 and involved multiple phase transformations.…”

Leveraging Advanced X-ray Imaging for Sustainable Battery Design

“…Furthermore, multiple coexisting TM (Ni, Mn, and Co) cations could experience a complicated electrochemical reaction, which may distort their electronic structures during battery cycling . In fact, it is the change in electronic structure that leads to particle cracking, voltage hysteresis, reaction heterogeneities, and chemo-mechanical degradation. ,− …”

“…Advanced electrode architectures should be proposed to mitigate the microstructure limitation and enhance structural stability. − Liu et al . tackled the mechanical cracking issue via the concentration gradient design of a Co-enriched surface and Mn-enriched core, effectively improving the electrochemical cycling performance …”

“…186−190 Liu et al tackled the mechanical cracking issue via the concentration gradient design of a Co-enriched surface and Mn-enriched core, effectively improving the electrochemical cycling performance. 178 Additionally, the sluggish Li-ion transmission in the electrolyte is argued to be the key reason for the undesirable LIB performance in the case of low-temperature conditions. Thus, much effort has been made to increase the Li-ion diffusion rate in the electrolytes in order to improve low-temperature performance.…”

Three-dimensional operando optical imaging of single particle and electrolyte heterogeneities inside Li-ion batteries

“…A key factor in enhancing the performance of Li-ion batteries is the development of high energy density cathode materials such as Ni-rich Lithium Nickel Manganese Cobalt Oxides (NMCs). A long debate still remains into the nature of ion (de)intercalation in such materials [1][2][3][4] with heterogeneities and irreversibilities in intercalation driving degradation and capacity fade [5][6][7][8] . Until such effects are thoroughly understood the necessary advances in battery performance are unlikely to be realised.…”