S.H. Zheng, H. Huang, Y.F. Dong, S. Wang, F. Zhou, J.Q. Qin, C.L. Sun, Y. Yu,* Z.-S. Wu*, X.H. Bao

Energy & Environmental Science, 2020, 13, 821-829.

DOI: 10.1039/C9EE03219C [PDF]

The rapid development of microelectronics and microsystems has stimulated continuous evolution of high-performance and cost-effective micro-batteries. Despite of its competitiveness with huge application potential, sodium ion micro-batteries (NIMBs), are still underdeveloped. Herein, we demonstrate one prototype ofquasi-solid-stateplanar ionogel-based NIMBs constructed by separator-free interdigital microelectrodes of sodium titanate anode and sodium vanadate phosphate cathode, both of which are embedded into three-dimensional interconnected graphene scaffold. Meanwhile, a novel NaBF₄-based ionogel electrolyte with robust ionic conductivity of 8.1 mS/cm was used. Benefited from the synergetic merits from the planar architecture, dominated pseudocapacitance contribution, and 3D multi-directional Na-ion diffusion mechanism, the as-assembled NIMBs exhibit high volumetric capacity of30.7mAh/cm³at 1 C, and high rate performance with15.7mAh/cm³at 30 C at room temperature and13.5mAh/cm³at 100 C at high temperature of 100^oC. Moreover, thequasi-solid-stateNIMBs present outstanding flexibility, tunable voltage and capacity output, and remarkableareal energy density of 145 μWh/cm²(55.6 mWh/cm³). Therefore, this work will provide numerous chances to construct planar NIMBs for microsystems.