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Compared with aqueous single‐ion batteries, rechargeable aqueous hybrid ion batteries, especially Li+/Zn2+hybrid ion batteries, are receiving extensive interest owing to their low cost, high operating voltage, and energy density. However, their working voltage and lifespan are limited by the decomposition of water and the growth of Zn dendrites. Herein, detrimental side reactions induced by the water reduction and the Zn dendrite growth are successfully suppressed by a poly(propylene glycol) (PPG)‐based hybrid ion electrolyte [(1 m Zn(TFSI)2 + 10 m LiTFSI) in PPG/H2O]. The addition of PPG in the electrolyte can not only enhance the bonding strength of hydrogen‐bond in water but also tailor the solvation sheath of Zn2+ as revealed by synchrotron X‐rays. The participated solvation of PPG with Zn2+ can weaken Zn−H2O interactions and redistribute Zn2+ flux on the surface of the Zn anode, thus inducing favorably even deposition of Zn. In addition, the decomposition of TFSI− contributes a ZnF2 ‐enriched solid electrolyte interface at the Zn anode to further prevent water decomposition and restrain Zn dendrites. The PPG‐based electrolyte enables 2.1 V LiMnO2//Zn batteries to deliver high specific capacities (121.7 mAh g−1 for a coin cell and 90 mAh g−1 for a pouch cell), and maintain 80% of the capacity over 700 cycles at 0.5 C, suggesting a promising pathway for highly reversible aqueous hybrid ion batteries. [ABSTRACT FROM AUTHOR]

Abstract Compared with aqueous single‐ion batteries, rechargeable aqueous hybrid ion batteries, especially Li+/Zn2+hybrid ion batteries, are receiving extensive interest owing to their low cost, high operating voltage, and energy density. However, their working voltage and lifespan are limited by the decomposition of water and the growth of Zn dendrites. Herein, detrimental side reactions induced by the water reduction and the Zn dendrite growth are successfully suppressed by a poly(propylene glycol) (PPG)‐based hybrid ion electrolyte [(1 m Zn(TFSI)2 + 10 m LiTFSI) in PPG/H2O]. The addition of PPG in the electrolyte can not only enhance the bonding strength of hydrogen‐bond in water but also tailor the solvation sheath of Zn2+ as revealed by synchrotron X‐rays. The participated solvation of PPG with Zn2+ can weaken Zn−H2O interactions and redistribute Zn2+ flux on the surface of the Zn anode, thus inducing favorably even deposition of Zn. In addition, the decomposition of TFSI− contributes a ZnF2 ‐enriched solid electrolyte interface at the Zn anode to further prevent water decomposition and restrain Zn dendrites. The PPG‐based electrolyte enables 2.1 V LiMnO2//Zn batteries to deliver high specific capacities (121.7 mAh g−1 for a coin cell and 90 mAh g−1 for a pouch cell), and maintain 80% of the capacity over 700 cycles at 0.5 C, suggesting a promising pathway for highly reversible aqueous hybrid ion batteries.

LiNi0.80Co0.15Al0.05O2 (NCA) is explored to be applied in a hybrid Li+/Na+ battery for the first time. The cell is constructed with NCA as the positive electrode, sodium metal as the negative electrode, and 1 M NaClO4 solution as the electrolyte. It is found that during electrochemical cycling both Na+ and Li+ ions are reversibly intercalated into/de-intercalated from NCA crystal lattice. The detailed electrochemical process is systematically investigated by inductively coupled plasma-optical emission spectrometry, ex situ X-ray diffraction, scanning electron microscopy, cyclic voltammetry, galvanostatic cycling, and electrochemical impedance spectroscopy. The NCA cathode can deliver initially a high capacity up to 174 mAh g−1 and 95% coulombic efficiency under 0.1 C (1 C = 120 mA g−1) current rate between 1.5-4.1 V. It also shows excellent rate capability that reaches 92 mAh g−1 at 10 C. Furthermore, this hybrid battery displays superior long-term cycle life with a capacity retention of 81% after 300 cycles in the voltage range from 2.0 to 4.0 V, offering a promising application in energy storage. [ABSTRACT FROM AUTHOR]

P2-structure sodium manganese oxide is synthesized by a facile reduction reaction. We provide new data on the direct use of sodium manganese oxide instead of lithium analogues as a low-cost electrode for lithium/sodium hybrid ion batteries after an ion-exchange process. Ion exchange occurs in sodium manganese oxide through the electrolyte during cell stabilization, as observed by X-ray diffraction analysis. The self ion-exchanged material delivers a high discharge capacity of 195 mA h g −1 and a stable plateau at 3.0 V for 50 cycles with stable cyclability. In-situ X-ray diffraction and ex-situ X-ray absorption near edge structure studies also confirm reversible redox reactions and stable structural changes. The ex-situ inductively coupled plasma atomic emission spectroscopy analysis verifies that residual sodium ions in the structure act as pillars during cycling. [ABSTRACT FROM AUTHOR]