# Navigating the Catholyte Landscape in All-Solid-State Batteries

## TL;DR

This paper reviews the role of solid-state electrolytes in all-solid-state batteries, focusing on their potential and challenges as catholytes.

## Contribution

The paper provides a critical analysis of three inorganic solid-state electrolyte families for use as catholytes in all-solid-state batteries.

## Key findings

- Oxides, sulfides, and chlorides are the most studied inorganic SSE families for catholyte use.
- Each SSE family has distinct advantages and limitations in compatibility with cathode materials.
- Composite architectures may be necessary to achieve optimal performance in all-solid-state batteries.

## Abstract

All-solid-state batteries
are widely regarded as the
next frontier
in electrochemical energy storage, offering the potential to surpass
the energy density and safety limits of conventional lithium-ion batteries.
Among the factors governing their performance, paramount are the choice
and functionality of the solid-state electrolyte (SSE) as a catholyte
within the composite positive electrode. This perspective critically
examines the applicability and potential of the three most intensively
studied inorganic SSE families, namely oxides, sulfides, and chlorides,
as catholytes. We discuss their respective advantages, limitations,
and compatibility with common cathode active materials, as well as
the remaining knowledge gaps. We then assess whether any of the current
SSE classes can be employed as a stand-alone SSE for all-solid-state
batteries, or whether composite architectures combining multiple SSEs
will ultimately be required.