# High‐Efficiency Thermal Battery Regulated by Ultralow Magnetic Fields

## TL;DR

A new thermal battery uses a low magnetic field to control heat release efficiently, outperforming existing systems.

## Contribution

The first noncontact phase transition in a thermal battery using an ultralow magnetic field of ≈0.04 T.

## Key findings

- The composite achieves a colossal entropy change of 507.6 J kg−1 K−1.
- It exhibits a temperature rise of 47.6 K and an enthalpy change of 181.1 J g−1.

## Abstract

Controllable thermal storage has emerged as a central theme in advanced energy management, where external stimuli such as light, stress, and pressure can be exploited to precisely regulate heat release. Yet, realizing efficient and practical deployment requires the development of simpler noncontact actuation methods and the enhancement of heat‐transfer efficiency, both of which remain major challenges. Herein, a magneto‐responsive phase‐change composite is presented by integrating a supercooled plastic crystal, 2‐amino‐2‐methyl‐1,3‐propanediol (AMP), with dispersed NdFeB particles. This design enables noncontact triggering of supercooled phase transitions under ultralow magnetic fields as small as ≈0.04 T. Meanwhile, the dispersed magnetic particles enhance thermal conduction and promote synchronous multipoint crystallization, thereby markedly accelerating heat release. The optimized 20% AMP/NdFeB composite achieves a colossal entropy change of 507.6 J kg−1 K−1, a corresponding enthalpy change of 181.1 J g−1, and a rapid temperature rise of 47.6 K, substantially outperforming leading magnetocaloric systems under far milder field conditions. This work establishes a transformative and generalizable route to noncontact, high‐efficiency, and controllable thermal batteries, paving the way for their practical deployment in advanced energy systems.

A magneto‐responsive composite is reported that, for the first time, achieves a noncontact phase transition with an ultralow magnetic field (≈0.04 T). It exhibits a colossal entropy change of ≈507.6 J kg−1 K−1, an enthalpy of 181.1 J g−1, and a ≈47.6 K temperature rise, alongside enhanced thermal conductivity and heat‐release efficiency, making it promising for thermal batteries.© 2026 WILEY‐VCH GmbH