Enhancing the electrochemical properties of LiTi2(PO4)3/C anode for aqueous rechargeable lithium battery by Li vacancy

In this paper, Li 1–x Ti 2 (PO 4 ) 3 /C composites (x   =   0, 0.03, 0.05, 0.07) were synthesized by sol-gel approach, and the influence of Li vacancy on electrochemical performance of LiTi 2 (PO 4 ) 3 /C anode for aqueous rechargeable lithium battery was studied. Li vacancy hardly influences the crystal structure and morphology of the composite. Electrochemical measurement results demonstrated that Li 1–x Ti 2 (PO 4 ) 3 /C exhibited better performance compared with pristine LiTi 2 (PO 4 ) 3 /C, and Li 0.95 Ti 2 (PO 4 ) 3 /C has the best properties. Li 0.95 Ti 2 (PO 4 ) 3 /C delivered the discharge capacity of 104.3, 92.6, and 71.8   mAh   g −   1 at 0.2, 5, and 20   C (1   C   =   150   mA   g −   1 ), 4.1, 27.3, and 34.4   mAh   g −   1 larger than that of Li 0.95 Ti 2 (PO 4 ) 3 /C at corresponding rates, respectively. After 1000   cycles at 5   C, the discharge capacity retention for Li 0.95 Ti 2 (PO 4 ) 3 /C can reach 75.3%, 15.4% larger than that for LiTi 2 (PO 4 ) 3 /C. Our study reveals that Li vacancy is an efficient method to enhance the electrochemical properties of LiTi 2 (PO 4 ) 3 -based materials.