Integrated Uniformly Microporous C4 N/Multi-Walled Carbon Nanotubes Composite Toward Ultra-Stable and Ultralow-Temperature Proton Batteries.

Abstract

Benefiting from the proton's small size and ultrahigh mobility in water, aqueous proton batteries are regarded as an attractive candidate for high-power and ultralow-temperature energy storage devices. Herein, a new-type C4 N polymer with uniform micropores and a large specific surface area is prepared by sulfuric acid-catalyzed ketone amine condensation reaction and employed as the electrode of proton batteries. Multi-walled carbon nanotubes (MWCNT) are introduced to induce the in situ growth of C4 N, and reaped significantly enhanced porosity and conductivity, and thus better both room- and low-temperature performance. When coupled with MnO2 @Carbon fiber (MnO2 @CF) cathode, MnO2 @CF//C4 N-50% MWCNT full battery shows unprecedented cycle stability with a capacity retention of 98% after 11000 cycles at 10 A g-1 and even 100% after 70000 cycles at 20 A g-1 . Additionally, a novel anti-freezing electrolyte (5 m H2 SO4 +0.5m MnSO4 ) is developed and showed a high ionic conductivity of 123.2 mScm-1 at -70°C. The resultant MnO2 @CF//C4 N-50% MWCNT battery delivers a specific capacity of 110.5mAhg-1 even at -70°C at 1Ag-1 , the highest in all reported proton batteries under the same conditions. This work is expected to offer a package solution for constructing high-performance ultralow-temperature aqueous proton batteries.