He Xin, Ni Youxuan, Ma Wenjiao, Zhang Qiu, Hao Zhenkun, Hou Yunpeng, Li Haixia, Yan Zhenhua, Zhang Kai, Chen Jun
Frontiers Science Center for New Organic Matter, Renewable Energy Conversion and Storage Center, Key Laboratory of Advanced Energy Materials Chemistry (Ministry of Education), College of Chemistry, Nankai University, Tianjin 300071, China.
State Key Laboratory of Chem/Bio-Sensing and Chemometrics, College of Chemistry and Chemical Engineering, Hunan University, Changsha 410082, China.
Proc Natl Acad Sci U S A. 2024 Jun 4;121(23):e2320012121. doi: 10.1073/pnas.2320012121. Epub 2024 May 29.
Rechargeable sodium-oxygen (Na-O) battery is deemed as a promising high-energy storage device due to the abundant sodium resources and high theoretical energy density (1,108 Wh kg). A series of quasisolid electrolytes are constantly being designed to restrain the dendrites growth, the volatile and leaking risks of liquid electrolytes due to the open system of Na-O batteries. However, the ticklish problem about low operating current density for quasisolid electrolytes still hasn't been conquered. Herein, we report a rechargeable Na-O battery with polyvinylidene fluoride-hexafluoropropylene recombination Nafion (PVDF-HFP@Nafion) based quasisolid polymer electrolyte (QPE) and MXene-based Na anode with gradient sodiophilic structure (M-GSS/Na). QPE displays good flame resistance, locking liquid and hydrophobic properties. The introduction of Nafion can lead to a high Na migration number ( = 0.68) by blocking the motion of anion and promote the formation of NaF-rich solid electrolyte interphase, resulting in excellent cycling stability at relatively high current density under quasisolid environment. In the meantime, the M-GSS/Na anode exhibits excellent dendrite inhibition ability and cycling stability. Therefore, with the synergistic effect of QPE and M-GSS/Na, constructed Na-O batteries run more stably and exhibit a low potential gap (0.166 V) after an initial 80 cycles at 1,000 mA g and 1,000 mAh g. This work provides the reference basis for building quasisolid state Na-O batteries with long-term cycling stability.
由于钠资源丰富且理论能量密度高（1108 Wh/kg），可充电钠氧（Na-O）电池被视为一种很有前景的高能量存储设备。由于Na-O电池的开放体系，人们不断设计一系列准固态电解质来抑制枝晶生长以及液态电解质的挥发和泄漏风险。然而，准固态电解质低工作电流密度这个棘手问题仍未得到解决。在此，我们报道了一种具有基于聚偏氟乙烯-六氟丙烯复合Nafion（PVDF-HFP@Nafion）的准固态聚合物电解质（QPE）和具有梯度亲钠结构的MXene基钠阳极（M-GSS/Na）的可充电Na-O电池。QPE具有良好的阻燃性、锁液性和疏水性。Nafion的引入可通过阻止阴离子的运动导致较高的钠迁移数（ = 0.68），并促进富含NaF的固体电解质界面的形成，从而在准固态环境下相对较高的电流密度下具有出色的循环稳定性。同时，M-GSS/Na阳极表现出优异的枝晶抑制能力和循环稳定性。因此，在QPE和M-GSS/Na的协同作用下，构建的Na-O电池运行更稳定，在1000 mA g和1000 mAh g下初始80次循环后具有低电位差（0.166 V）。这项工作为构建具有长期循环稳定性的准固态Na-O电池提供了参考依据。
