# A Critical Evaluation of the Limiting Current Density in Polymer Electrolytes: Interplay of Ion Transport, Mechanical Stability, and Conformal Li–Electrolyte Interfaces

## TL;DR

This paper evaluates how external conditions affect the maximum current density in polymer electrolyte batteries with lithium metal anodes.

## Contribution

The study shows that limiting current density is not an intrinsic property but depends on experimental conditions.

## Key findings

- Limiting current density values are influenced by scan rate, temperature, and cell pressure.
- Mechanical properties of PEO-based electrolytes can help suppress lithium dendrite formation.
- Experimental methods should be varied to obtain meaningful limiting current density data.

## Abstract

Solid-state batteries with lithium metal anodes are among
the promising
candidates to fulfill the actual requirements of growing energy demands
in comparison to commercially available lithium-ion batteries, despite
the current challenges of inhomogeneous lithium metal deposition upon
cycling. In the present literature, the limiting current density is
referred to as a key performance indicator for faster charging of
solid-state batteries, though from a practical point of view, it is
defined as the maximum endurable current density that might be applied
without possible cell failure. In this study, we evaluate the obtained
values of limiting current densities for lithium metal batteries operating
with polymer electrolytes. Notably, we critically compare various
experimental procedures to determine the actual limiting current density
and discuss the impact of external factors such as scan rate, temperature,
and applied cell pressure, thereby invoking model-type PEO-based electrolytes
to examine available mechanical properties that may afford suppression
of lithium dendrite formation. In fact, we demonstrate that experimentally
derived limiting current densities are not intrinsic electrolyte characteristics
but rather entities strongly dependent on the applied conditions and
hence should ideally be determined based on different techniques to
deliver meaningful data.