Yang Yihang, Wang Qing, Hou Jingrong, Liu Jie, Sun Tianyi, Tang Mingxue, Chen Chien-Te, Kuo Chang-Yang, Hu Zhiwei, Zheng Tingting, Yan Guochun, Ma Jiwei
Shanghai Key Laboratory for R&D and Application of Metallic Functional Materials, Institute of New Energy for Vehicles, School of Materials Science and Engineering, Tongji University, Shanghai, 201804, China.
Sorbonne Université, 4 Place Jussieu, 75005, Paris, France.
Angew Chem Int Ed Engl. 2024 Oct 21;63(43):e202411059. doi: 10.1002/anie.202411059. Epub 2024 Sep 10.
Anionic redox chemistry can surpass theoretical limits of conventional layered oxide cathodes in energy density. A recent model system of sodium-ion batteries, O3-NaLiMnO, demonstrated full anionic redox capacity but is limited in reversibility and kinetics due to irreversible structural rearrangement and oxygen loss. Solutions to these issues are missing due to the challenging synthesis. Here, we harness the unique structural richness of sodium layered oxides and realize a controlled ratio of P2 structural intergrowth in this model compound with the overall composition maintained. The resulted O3 with 27 % P2 intergrowth structure delivers an excellent initial Coulombic efficiency of 87 %, comparable to the state-of-the-art Li-rich NMCs. This improvement is attributed to the effective suppression of irreversible oxygen release and structural changes, evidenced by operando Differential Electrochemical Mass Spectroscopy and X-ray Diffraction. The as-prepared intergrowth material, based on the environmentally benign Mn, exhibits a reversible capacity of 226 mAh g at C/20 rate with excellent cycling stability stemming from the redox reactions of oxygen and manganese. Our work isolates the role of P2 structural intergrowth and thereby introduces a novel strategy to enhance the reversibility and kinetics of anionic redox reactions in sodium layered cathodes without compromising capacity.
阴离子氧化还原化学在能量密度方面可以超越传统层状氧化物阴极的理论极限。钠离子电池最近的一个模型体系O3-NaLiMnO展现出了完全的阴离子氧化还原容量，但由于不可逆的结构重排和氧损失，其可逆性和动力学受到限制。由于合成具有挑战性，这些问题的解决方案尚不存在。在此，我们利用了钠层状氧化物独特的结构丰富性，并在保持整体组成的情况下，在该模型化合物中实现了P2结构共生的可控比例。所得具有27% P2共生结构的O3具有87%的优异初始库仑效率，与最先进的富锂NMC相当。这种改进归因于不可逆氧释放和结构变化的有效抑制，原位差分电化学质谱和X射线衍射证明了这一点。所制备的共生材料基于环境友好的锰，在C/20倍率下表现出226 mAh g的可逆容量，并且由于氧和锰的氧化还原反应而具有优异的循环稳定性。我们的工作分离出了P2结构共生的作用，从而引入了一种在不牺牲容量的情况下提高钠层状阴极中阴离子氧化还原反应可逆性和动力学的新策略。
