近日，中国科学院宁波材料技术与工程研究所刘兆平团队研究了负热膨胀与氧氧化还原电化学。这一研究成果于2025年4月16日发表在《自然》杂志上。

由于材料的热力学和电化学性质的复杂相互作用，材料内部的结构无序会产生令人着迷的现象。氧氧化还原（OR）电化学在容量限制方面取得了突破，同时引发了电化学可逆性降低的结构紊乱。固体热膨胀的传统解释依赖于Grüneisen关系，将膨胀系数与晶格的非谐性联系起来。然而，由于此类系统中未探索的动态无序-有序转变，这种范式可能不适用于OR材料。

研究组揭示了OR活性材料中存在负热膨胀，其系数值为-14.4（2）×10⁻⁶°C⁻¹，这归因于热驱动的无序-有序转变。OR行为的调节不仅可以精确控制材料的热膨胀系数，还可以为零热膨胀功能材料的设计建立一个实用的框架。此外，研究组证明，材料内部结构紊乱的恢复也可以通过电化学驱动力来实现。通过调整截止电压，对放电电压变化的评估表明，结构恢复的可能性接近100%。这一发现为通过操作电化学过程将OR活性材料恢复到原始状态提供了一条途径，提出了一种新的缓解策略来解决电压衰减的持续挑战。

附：英文原文

Title: Negative thermal expansion and oxygen-redox electrochemistry

Author: Qiu, Bao, Zhou, Yuhuan, Liang, Haoyan, Zhang, Minghao, Gu, Kexin, Zeng, Tao, Zhou, Zhou, Wen, Wen, Miao, Ping, He, Lunhua, Xiao, Yinguo, Burke, Sven, Liu, Zhaoping, Meng, Ying Shirley

Issue&Volume: 2025-04-16

Abstract: Structural disorder within materials gives rise to fascinating phenomena, attributed to the intricate interplay of their thermodynamic and electrochemical properties1,2. Oxygen-redox (OR) electrochemistry offers a breakthrough in capacity limits, while inducing structural disorder with reduced electrochemical reversibility3,4,5. The conventional explanation for the thermal expansion of solids relies on the Grüneisen relationship, linking the expansion coefficient to the anharmonicity of the crystal lattice6. However, this paradigm may not be applicable to OR materials due to the unexplored dynamic disorder–order transition in such systems7,8. Here we reveal the presence of negative thermal expansion with a large coefficient value of 14.4(2)×106°C1 in OR active materials, attributing this to thermally driven disorder–order transitions. The modulation of OR behaviour not only enables precise control over the thermal expansion coefficient of materials, but also establishes a pragmatic framework for the design of functional materials with zero thermal expansion. Furthermore, we demonstrate that the reinstatement of structural disorder within the material can also be accomplished through the electrochemical driving force. By adjusting the cut-off voltages, evaluation of the discharge voltage change indicates a potential for nearly 100% structure recovery. This finding offers a pathway for restoring OR active materials to their pristine state through operando electrochemical processes, presenting a new mitigation strategy to address the persistent challenge of voltage decay.

DOI: 10.1038/s41586-025-08765-x

Source: https://www.nature.com/articles/s41586-025-08765-x