Flexible aqueous lithium-ion batteries with ultrahigh areal capacity and long cycle life

Practical application of flexible batteries have been hindered by low areal capacity, low stability, and safety concerns. This work reports a facile and scalable infiltration method to fabricate free-standing three-dimensional (3D) flexible electrodes using LiTi2(PO4)(3) (LTP) and LiMn2O4 (LMO) as examples for aqueous Li-ion batteries. Benefiting from the unique 3D electrode architecture with fast electron and ion transport, flexible LTP-LMO pouch cells deliver an ultrahigh areal capacity (e.g., 3-23 mAh cm(-2), LTP loading = 24-200 mg cm(-2)), high rate capability, and stable cycling stability (e.g., 93% and 72% capacity retention after 500 and 3000 cycles, respectively, at 14-15 mA cm(-2)). High mechanical and electrochemical stability of the cell is demonstrated with a high capacity retention of 96% after 1000 dynamic bending cycles. Pouch cells with a high capacity (0.53 Ah for 4 x 6 cm(-2) cell) and high voltage (3 V/9 V) are demonstrated. This work offers a low-cost and effective strategy to fabricate high areal capacity electrodes with stable electrochemical performance, high mechanical strength, and excellent flexibility. (C) 2020 Elsevier Ltd. All rights reserved.