In this study, a one-pot sintering process incorporating sol–gel preparation route and in-situ carbon coating was proposed for the synthesis of carbon-coated nanosized LiTi 2 (PO 4 ) 3 . Experimental results show that the prepared LiTi 2 (PO 4 ) 3 particles are of high crystallinity and well-coated by turbostratic carbon. Attributed to nanosized particles and enhanced conductivity provided by turbostratic carbon coating, the carbon-coated LiTi 2 (PO 4 ) 3 showed high rate performance and good cycling life in aqueous electrolyte. Particularly, the carbon-coated LiTi 2 (PO 4 ) 3 exhibited initial specific capacities of 103 and 89 mAh g −1 , and retained 80.6% and 97% of the initial capacities after 120 cycles at 1C and 10C in aqueous electrolyte, respectively. The high rate performance and good cycling life of carbon-coated LiTi 2 (PO 4 ) 3 in aqueous electrolyte reveal its potential as negative electrode in aqueous lithium-ion batteries for electric vehicles and industrial-scale energy storage systems .
Na Liu,Zhangxing He,Xubo Zhang,Yingqiao Jiang,Yuehua Li,Jing Zhu,Wei Meng,Lei Dai,Ling Wang
In this paper, Li 1−x Na x Ti 2 (PO 4 ) 3 @carbon (x=0.01, 0.03, and 0.05) composites as anode for aqueous lithium ion batteries were synthesized by in situ coating approach. The doping of Na on Li sites did not break the lattice structure of LiTi 2 (PO 4 ) 3 , while the lattice volume was increased by doping of Na. Among Na-doped LiTi 2 (PO 4 ) 3 @carbon composites, Li 0.97 Na 0.03 Ti 2 (PO 4 ) 3 @carbon (LC-Na-3) demonstrated the best electrochemical properties . Compared with the pristine LiTi 2 (PO 4 ) 3 @carbon (LC) composite, LC-Na-3 composite exhibited better rate and cycling performance. LC-Na-3 composite delivered the discharge capacity of 98.5 mAh g −1 at 0.2 C and 45.0 mAh g −1 at 15 C, 10.9 mAh g −1 and 32.1 mAh g −1 larger than that of LC composite, respectively. Moreover, the discharge capacity retention for LC-Na-3 composite achieved 90.4%, 6.9% higher than that for LC composite at the rate of 2 C after 300 cycles. The improved electrochemical properties of Na-doped LiTi 2 (PO 4 ) 3 @carbon composite was ascribed to the decrease of charge transfer resistance and the acceleration of diffusion of lithium ions , resulting from the widening of diffusion channel for lithium ions, which was verified by XRD measurements.
LiTi2(PO4)3 (LTP) is widely recognized as a promising anode material for aqueous lithium-ion batteries due to its stable three-dimensional framework structure and working potential within the aqueous electrolyte potential window. However, the low conductivity of pure-phase LTP poses a significant challenge that must be overcome for its practical application. In this work, N-doped carbon-coated LTP (NC@LTP) composites with a layered flower-like morphology were synthesized via an organic precipitation method. The N-doped carbon layer improved the conductivity and hydrophilicity of the anode and caused carbon defects that facilitated Li+ transport. The initial specific capacity at 10 C was enhanced from 39.4 to 81.5 mAh g–1 after N-doping. The pouch cells retained 92.7% of their capacity after 150 cycles at 1 C and demonstrated excellent safety in abuse tests. In addition, the modification mechanism of the N-doped carbon layer was verified through DFT calculations. This study provides references and ideas for the modification of high-performance aqueous lithium-ion battery electrode materials.
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