Understanding the Stability for LiNi0.5Mn0.5O2 as a Co-free positive electrode material

TL;DR

This study investigates the stability of Co-free LiNi0.5Mn0.5O2 as a positive electrode material, revealing different electrochemical behaviors of Ni and Mn at various particle surfaces and interiors, which impacts Li de-intercalation understanding.

Contribution

It provides new insights into the valence states and electrochemical properties of Ni and Mn in LiNi0.5Mn0.5O2, clarifying the Li de-intercalation mechanism.

Findings

Ni and Mn show different electrochemical behaviors at surface and interior.

Valence states of transition metals were accurately characterized.

The study clarifies the Li de-intercalation mechanism in LiNi0.5Mn0.5O2.

Abstract

For understanding the stability of Co-free positive electrode material, LiNi0.5Mn0.5O2 was synthesized with different addition amount of lithium during calcination. The valence states of transition metal in the prepared samples were determined by combining accurate stoichiometry analysis via ICP, magnetic moment measurement via SQUID, and element valence analysis via XPS with Ar ion etching. Unexpectedly, the transition metals, Ni and Mn, at interior and surface of LiNi0.5Mn0.5O2 particles show different electrochemical properties. This answer lingering questions of Li de-intercalation mechanism in LiNi0.5Mn0.5O2.