# Anode-Less (Anode-Free) Batteries: From Fundamental Principles to Practical Pathways Toward Solid-State Implementation

## TL;DR

This paper reviews anode-less battery designs, focusing on their potential for high energy density and safety, and outlines strategies for overcoming challenges like dendrite growth and interface instability.

## Contribution

The paper provides a structured roadmap for advancing anode-less batteries by integrating fundamental research with industrial implementation strategies.

## Key findings

- Solid-state electrolytes are identified as a promising path for safer and higher-energy anode-less cells.
- Plating/stripping efficiency and dendrite growth are highlighted as key challenges in anode-less battery systems.
- The development pyramid framework links fundamental research to practical implementation priorities.

## Abstract

What are the main findings?
A comprehensive review on anode-less battery design for metal-ion systems.Detailed analysis of electrolyte design (liquid and solid) and interface engineering.Critical assessment of advanced operando characterization techniques for anode-less cells.Identifies plating/stripping efficiency and dendrite growth as key challenges.Solid-state electrolytes offer a promising path for safer, high-energy anode-less cells.

A comprehensive review on anode-less battery design for metal-ion systems.

Detailed analysis of electrolyte design (liquid and solid) and interface engineering.

Critical assessment of advanced operando characterization techniques for anode-less cells.

Identifies plating/stripping efficiency and dendrite growth as key challenges.

Solid-state electrolytes offer a promising path for safer, high-energy anode-less cells.

What are the implications of the main findings?
Provides a roadmap for developing next-generation, high-energy-density batteries.Highlights the critical importance of current collector and interlayer functionalization.Underlines the necessity for standardized performance evaluation protocols.Bridges fundamental material insights with industrial scale-up requirements.Positions the anode-less architecture as a viable strategy for sustainable batteries.

Provides a roadmap for developing next-generation, high-energy-density batteries.

Highlights the critical importance of current collector and interlayer functionalization.

Underlines the necessity for standardized performance evaluation protocols.

Bridges fundamental material insights with industrial scale-up requirements.

Positions the anode-less architecture as a viable strategy for sustainable batteries.

Anode-less battery architectures, which eliminate the host anode material, have attracted considerable attention as a promising approach to increase energy density, simplify cell manufacturing, and improve safety in next-generation energy storage systems. This review provides a structured and integrative overview on the current research landscape of anode-less cells, spanning both liquid- and solid-electrolyte technologies. It first introduces the fundamental principles, key advantages, and inherent challenges of the anode-less concept. Advanced characterization techniques, including electrochemical, interfacial, morphological, and operando approaches, are then discussed as essential tools for probing metal plating/stripping behavior and degradation mechanisms. The core of the review examines how system design governs performance, addressing strategies for liquid electrolytes, including current collector design, electrolyte formulation, and deposition control, as well as solid electrolytes, with an emphasis on interfacial engineering, fundamental limitations, and extensions to Na- and K-based batteries. By integrating insights across these systems, the review identifies critical challenges, including unstable solid-electrolyte interphases, dendrite formation, and interfacial contact loss. Finally, a development pyramid is introduced as a conceptual framework linking fundamental research to practical implementation, outlining key priorities from interface control and full-cell compatibility to long-term reliability while also highlighting industrial pathways toward hybrid and fully solid-state anode-less batteries.