近日，南开大学焦丽芳团队报道了面外对称设计阻止了可持续钠穿梭的分层框架结构演化。这一研究成果发表在2026年3月4日出版的《美国化学会志》上。

钠离子电池为应对能源转型挑战和锂资源稀缺问题提供了一种引人注目且可持续的解决方案。然而，钠过渡金属氧化物（Na_xTMyO₂）的晶体结构多样性会在脱/嵌钠过程中引发对称性重构，这对钠离子电池的稳定运行构成了巨大挑战。

研究组阐明了面外对称性在抑制Na_xTMyO₂结构演化中关键但尚未充分挖掘的作用。通过设计单斜畸变，研究组建立了一种独特的面外对称性，使得P型和O型钠离子间隙位点能够共存，从而即使在深度脱钠状态（每配方单位剩余Na⁺ <0.2个）下也能有效阻止层间氧离子滑移及随后的对称性演化。这种对称性工程从根本上了解决P3型正极固有的相不稳定性问题，并消除了由不可逆结构演化引起的累积电压滞后（100次循环内平均滞后为0.16 V），从而在高能量密度（437.1 Wh kg^-1）运行条件下实现了稳定的循环性能。

附：英文原文

Title: Out-Of-Plane Symmetry Design Arrests Structural Evolution in Layered-Type Framework for Sustainable Sodium Shuttling

Author: Qiaochu Ren, Yi Pei, Yuxuan Xiang, Yanyi Liu, Honglei Jiang, Xumiao Chen, Hai Hu, Zhifeng Huang, Yongjin Fang, Li Liu, Lifang Jiao

Issue&Volume: March 4, 2026

Abstract: Sodium-ion batteries (SIBs) offer a compelling and sustainable solution to the challenges of the energy transition and lithium resource scarcity. However, the crystallographic diversity in sodium transition metal oxides (NaxTMyO2) induces symmetry reconfigurations during de/sodiation, posing a formidable challenge to the stable operation of SIBs. Here, we elucidate the critical yet underexplored role of out-of-plane symmetry in mitigating structural evolution in NaxTMyO2. By engineering a monoclinic distortion, we establish a distinctive out-of-plane symmetry enabling the coexistence of P- and O-type interstitial sites for Na ions, effectively preventing interlayer oxygen ion slipping and subsequent symmetry evolution, even in deeply desodiated states (with <0.2 Na+ per formula remaining). This symmetry engineering fundamentally addresses the intrinsic phase instability in P3-type cathodes and eliminates cumulative voltage hysteresis arising from irreversible structural evolution (average hysteresis of 0.16 V over 100 cycles), achieving stable cycling under high-energy-density operation (437.1 Wh kg–1).

DOI: 10.1021/jacs.5c10619

Source: https://pubs.acs.org/doi/abs/10.1021/jacs.5c10619