Nanostructured LiTi₂(PO₄)₃ anode with superior lithium and sodium storage capability aqueous electrolytes

Aqueous alkali metal ion batteries show great promise as the next generation secondary batteries with low cost, high power density and better safety. However, they suffer from inferior cycle stability at a higher current density and displays poor coulombic efficiency. In this work, LiTi₂(PO₄)₃@C/CNTs (LTP@C/CNTs) with three-dimensional mesoporous nanostructure was investigated in both aqueous lithium-ion batteries (ALIBs) and aqueous sodium-ion battery (ASIBs). Improved rate and cycling performance at high current densities were demonstrated in contrast to LiTi₂(PO₄)₃@C (LTP@C). Typically, the LTP@C/CNTs electrode achieves a discharge capacity of 97.37 mAhg⁻¹ and 90.88 mAhg⁻¹ in ALIBs and ASIBs half cells at 3 A g^-1 current density. LTP@C/CNTs//LiMn₂O₄ and LTP@C/CNTs//Na_0.44MnO₂ full cells show the capacity retention of 72.9% and 79.4% after 500 cycles. Besides, new electrochemical behavior is reported for the first time, that the anode materials present a two-step sodium ion insertion/extraction in ASIBs. After cycling, LTP anode converts into (NaTi₂(PO₄)₃) NTP phase with maintained crystallinity. LTP@C/CNTs composite anode thus shows a great potential application in next-generation aqueous energy storage systems.