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.
Zhangxing He,Yingqiao Jiang,Jing Zhu,Yuehua Li,Zhen Jiang,Huizhu Zhou,Wei Meng,Ling Wang,Lei Dai
In this paper, LiTi 2-x Sn x (PO 4 ) 3 /C (x = 0, 0.2, 0.3, 0.4) composites were synthesized by sol-gel approach, and were investigated as anodes for aqueous lithium ion battery . Sn doping with proper content has no obvious influence on phase and morphology of the composite, while excessive dosage of Sn can affect its crystal structure. Sn doping can enhance the electrochemical properties of LiTi 2 (PO 4 ) 3 /C (LC). Among LiTi 2-x Sn x (PO 4 ) 3 /C composites, LiTi 1.7 Sn 0.3 (PO 4 ) 3 /C (LC-Sn-0.3) demonstrates the best electrochemical properties. Most importantly, the rate performance of LC can be improved dramatically by Sn doping on Ti sites. LC-Sn-0.3 delivers a discharge capacity of 118.9, 115.3, and 104.2 mAh g −1 at 0.2, 6, and 20 C (1 C = 150 mA g −1 ), respectively, with significant increase of 15.2, 27.4, and 41.9 mAh g −1 compare with LC. In addition, LC-Sn-0.3 exhibits superior cycling performance. The capacity retention for LC-Sn-0.3 can keep 76.8% after 1000 cycles at relatively high rate of 10 C, while only 51.7% of initial discharge capacity is retained for LC. Our study reveals that Sn doping on Ti sites is an efficient and facile method to improve the performance of LiTi 2 (PO 4 ) 3 /C composite for aqueous lithium ion battery.
He Zhangxing,Jiang Yifan,Sun Dan,Dai Lei,Wang Haiyan
Inferior rate capability is a big challenge for LiTi 2 (PO 4 ) 3 anode for aqueous lithium-ion batteries. Herein, to address such issue, we synthesized a high-performance LiTi 2 (PO 4 ) 3 /carbon/carbon nanotube (LTP/C/CNT) composite by virtue of high-quality carbon coating and incorporation of good conductive network. The as-prepared LTP/C/CNT composite exhibits excellent rate performance with discharge capacity of 80.1 and 59.1 mAh g −1 at 10 C and 20 C (based on the mass of anode, 1 C = 150 mA g −1 ), much larger than that of the LTP/C composite (53.4 mAh g −1 at 10 C, and 31.7 mAh g −1 at 20 C). LTP/C/CNT also demonstrates outstanding cycling stability with capacity retention of 83.3 % after 1000 cycles at 5 C, superior to LTP/C without incorporation of CNTs (60.1 %). As verified, the excellent electrochemical performance of the LTP/C/CNT composite is attributed to the enhanced electrical conductivity, rapid charge transfer, and Li-ion diffusion because of the incorporation of CNTs.
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