Liu Mengchuang, Ma Fenfen, Liu Wei, Zeng Ziqi, Wu Yuanke, Chen Xin, Cheng Shijie, Xie Jia
State Key Laboratory of Advanced Electromagnetic Technology, School of Electrical and Electronic Engineering, Huazhong University of Science and Technology, Wuhan, 430074, China.
School of Chemistry and Chemical Engineering, Huazhong University of Science and Technology, Wuhan, 430074, China.
Angew Chem Int Ed Engl. 2025 Jul 21;64(30):e202502745. doi: 10.1002/anie.202502745. Epub 2025 May 26.
Safety hazard induced by flammable electrolytes are troubling the advancement of practical sodium-ion batteries (SIBs). Non-flammable phosphate electrolytes are competent to address this issue, yet current designs struggle to balance the interfacial chemistry and high ionic conductivity due to the untamed interaction between Na and anion. Herein, we evaluate the effect of dielectric constant (DC) and binding energy (E) of solvents on this interaction, revealing a systematic approach to achieve desired designs. It is shown that incorporating solvents with high DC and moderate E forms anion-rich solvation structure for stabilizing the anode interface and achieving necessary salt dissociation for high ionic conductivity. Specifically, propylene carbonate is incorporated as the eligible solvent into triethyl phosphate, affording non-flammable electrolytes with low cost and high ionic conductivity of 6.22 mS cm. Consequently, 1.25 Ah hard carbon (HC)|NaNiFeMnO (NFM) pouch cell delivers a high-power discharge of 5C rate and maintains an impressive capacity retention of 87.1% after 700 cycles at 2C rate. Moreover, 6.61 Ah HC|NFM pouch cell with 152.3 Wh kg avoids smoke production and volume expansion during nail penetration. This work discloses an advanced strategy for deigning practical phosphate electrolytes, paving the way for developing high-performance SIBs.
易燃电解质引发的安全隐患困扰着实用型钠离子电池（SIB）的发展。不可燃的磷酸盐电解质有能力解决这一问题，但由于钠与阴离子之间难以控制的相互作用，目前的设计难以平衡界面化学和高离子电导率。在此，我们评估了溶剂的介电常数（DC）和结合能（E）对这种相互作用的影响，揭示了一种实现理想设计的系统方法。结果表明，引入具有高DC和适度E的溶剂可形成富含阴离子的溶剂化结构，以稳定阳极界面并实现高离子电导率所需的盐解离。具体而言，将碳酸丙烯酯作为合适的溶剂加入磷酸三乙酯中，可提供低成本且离子电导率高达6.22 mS cm的不可燃电解质。因此，1.25 Ah的硬碳（HC）|NaNiFeMnO（NFM）软包电池可实现5C倍率的高功率放电，并在2C倍率下循环700次后保持87.1%的出色容量保持率。此外，6.61 Ah的HC|NFM软包电池在针刺过程中不冒烟且不发生体积膨胀，能量密度为152.3 Wh kg。这项工作揭示了一种设计实用型磷酸盐电解质的先进策略，为开发高性能SIBs铺平了道路。
