# Defect Electrochemistry in Stabilizing Corrugated Layered NaMnO2

## TL;DR

This paper explores how lattice defects in a battery material affect its stability and performance, showing that substituting elements can control these defects to improve battery durability.

## Contribution

The study establishes a direct link between stacking fault distribution and electrochemical performance in NaMnO2 through element substitution.

## Key findings

- Cu-substitution stabilizes defect-free zigzag stacking in β-NaMnO2.
- Zn-substitution introduces randomly distributed stacking faults.
- Both substitutions improve capacity retention by suppressing α-phase defects.

## Abstract

Lattice defects in layered metal oxides critically influence
the
structural stability and electrode reversibility in rechargeable batteries.
However, the role of these defects remains poorly understood. Corrugated-layered
β-NaMnO2 provides an ideal model system because stacking
fault (SF) formation plays a key role in its thermodynamic stability.
Controlling the SF distribution thus offers a unique opportunity to
elucidate the interplay between defects and electrochemical performance.
Herein, we show that the partial substitution of Mn with Cu or Zn
effectively modulates SF formation in β-NaMnO2. Synchrotron
X-ray diffraction, scanning transmission electron microscopy, and
Raman spectroscopy revealed distinct defect structures: the pristine
material exhibited ordered SF domains, Cu-substitution stabilized
defect-free zigzag stacking, and Zn-substitution introduced randomly
distributed SFs. Both doped materials exhibited improved capacity
retention, reflecting suppressed evolution of the α-phase defects
during cycling. These findings establish a direct link between SF
distribution and electrochemical reversibility, highlighting defect
engineering as a strategy for designing durable battery materials.