Aqueous Rechargeable Li⁺ /Na⁺ Hybrid Ion Battery with High Energy Density and Long Cycle Life

The practical application of aqueous rechargeable batteries is hampered by the low energy density and poor cycle stability, which mostly arises from the corrosion of cathode current collector, exfoliation of active material, and narrow electrochemical stability window of aqueous electrolyte. A light-weight and low-cost cathode current collector composed of graphite and carbon nanotube coated on nylon membrane exhibiting corrosion resistance and strong adhesion is developed. Also, a modified aqueous electrolyte with the addition of urea whose window is expanded to ≈3.2 V is developed that contributes to the formation of solid-electrolyte interphase on surfaces of electrodes. LiMn₂ O₄ /NaTi₂ (PO₄ )₃ Li⁺ /Na⁺ hybrid ion battery using such aqueous electrolyte and current collector is demonstrated to cycle up to 10 000 times with low cost (60 dollars per kWh) and high energy density (100 Wh kg^-1 ) for stationary energy storage and electronic vehicles applications.