Synthetic Pathway Determines the Nonequilibrium Crystallography of Li- and Mn-Rich Layered Oxide Cathode Materials

Ashok S Menon,Seda Ulusoy,Germán Salazar-Alvarez,William R Brant,Christophe Didier,Kristina Edström,Dickson O Ojwang,Lars Riekehr,Vanessa K Peterson,Cesar Pay Gomez,Peter Svedlindh

doi:10.1021/acsaem.0c03027

Abstract

Li- and Mn-rich layered oxides show significant promise as electrode materials for future Li-ion batteries. However, an accurate description of its crystallography remains elusive, with both single...

Highlights

The search for novel high energy density positive electrode materials for Li-ion batteries has led to the discovery of several promising but increasingly complex materials, such as the Liand Mn-rich layered transition metal oxide system.[1]
This work demonstrates that Li1.2Mn0.54Ni0.13Co0.13O2 (LMNCO) can exist in multiple nonequilibrium crystallographic forms, with the synthesis route being a major determinant
The solid-state synthesized LMNCO (SSLMNCO) crystallizes as a multiphase structure, with Li2MnO3 and Li[NiyCozMn1−y−z]O2 (y, z ≥ 0.33) phases integrated to varying degrees ranging from crystallographic intergrowths to distinct particles

Summary

■ INTRODUCTION

The search for novel high energy density positive electrode materials for Li-ion batteries has led to the discovery of several promising but increasingly complex materials, such as the Liand Mn-rich layered transition metal oxide system.[1]. Considering that the ICP-OES results establish the conformity of the overall stoichiometry to the expected value, SS-LMNCO may be represented as (x)Li2MnO3·(1 − x)Li[NiyCozMn1−y−z]O2 where 0.5 ≤ x ≤ 1 and y, z ≥ 0.33 This agrees well with the Raman spectra, which show the peaks for pure Li2MnO3 and LiNi0.33Mn0.33Co0.33O2 phases (Figure S3). Considering the different X-ray and neutron scattering of constituent elements (Table S7) and risk of model overparametrization, structural refinements against powder diffraction data must be constrained to produce statistically reliable results. As described in this work, in addition to the local cation ordering, the different synthesis routes can affect the degree of structural integration between the two phases (as in the multiphase model) This has recently been shown to affect the structural and electrochemical properties of solid-state synthesized Li1.2Mn0.6Ni0.2O243 and may be thought to influence LMNCO as well. Article expectedly lower than that of SG-LMNCO, primarily because of the larger micrometer-sized particles and their heterogeneous morphology

■ CONCLUSION

■ ACKNOWLEDGMENTS

■ REFERENCES