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Weak Ionization Induced Interfacial Deposition and Transformation towards Fast‐Charging NaTi 2 (PO 4 ) 3 Nanowire Bundles for Advanced Aqueous Sodium‐Ion Capacitors
Author(s) -
Tan Jianfeng,
Zhu Weihua,
Gui Qiuyue,
Li Yuanyuan,
Liu Jinping
Publication year - 2021
Publication title -
advanced functional materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 6.069
H-Index - 322
eISSN - 1616-3028
pISSN - 1616-301X
DOI - 10.1002/adfm.202101027
Subject(s) - materials science , anode , nanowire , nanotechnology , aqueous solution , chemical engineering , capacitor , electrolyte , nanosheet , analytical chemistry (journal) , electrode , voltage , electrical engineering , chemistry , engineering , chromatography
Aqueous sodium‐ion capacitors (ASICs) offer great promise for inexpensive and safe energy storage. However, their development is plagued by a kinetics imbalance at high rates between battery and capacitive electrodes and a narrow voltage window due to water electrolysis. Here a unique nanowire bundles anode is designed that simultaneously affords ultrahigh rate capability and manifests robust Na + insertion to suppress hydrogen evolution, enabling an advanced ASIC. The NaTi 2 (PO 4 ) 3 (NTP) is grown on thin titanium foil by elaborately utilizing the weak ionization chemistry of NaH 2 PO 4 (NHP), where single‐agent NHP not only partially etches titanium to release TiO 2+ , but also induces the interfacial phase‐transformation of pre‐deposited orthomorphic Na 4 Ti(PO 4 ) 2 (OH) 2 cubes to hexagonal NTP nanowires. This anode has hierarchical architectures to facilitate charge and mass transport, thus working stably at considerably high rates of 15–150 C with high capacities. The first 2.4 V flexible solid‐state NTP‐based ASIC is designed with high energy densities (5.8–12.8 mWh cm −3 ; 57.9–62.1 Wh kg −1 ; total mass loading up to 8.1 mg cm −2 ) comparable to NASICON‐based devices using organic electrolytes, demonstrating outstanding stability of 10 000 cycles and no performance decay even after continuous bending at 180 o . This work presents a versatile strategy to construct NASICON phosphate electrodes for advanced energy storage.