High Performance TiP2O7 Based Intercalation Negative Electrode for Aqueous Lithium-Ion Batteries Via a Facile Synthetic Route

Combining high energy mechanical alloying with intimate carbon coating has proven effective in improving electrochemical performance of polyanion-based materials (1, 2). Ball milling with intimate carbon helps to prepare a homogenous mixture of precursors and reduce particle size during following thermal treatment (3, 4). In addition, this combination can decrease the thermal treatment time needed (5). In this study, we demonstrated TiP₂O₇/graphite prepared by high energy mechanical alloying combined with intimate carbon coating has superior cycling performance in aqueous lithium-ion electrolyte.

The TiP₂O₇/graphite composite material was prepared by an intensive mechanical mixing solid state synthesis method at 700^°C. Physical properties were characterized via powder X-ray diffraction, Rietveld refinement, SEM, BET and TGA. Electrochemical performance was evaluated in both a three electrode test setup and two electrode coin cells via cyclic voltammetry and galvanostatic cycling tests. The TiP₂O₇/Graphite composite demonstrates excellent cycling performance in 1M Li₂SO₄ when matched with LiMn₂O₄ as a positive electrode: when cycled at C/2 for 150 cycles, the capacity retention is over 91% with coulombic efficiencies exceeding 99%. The initial discharge capacity obtained at a C/10 rate is 91mAh/g which was about 75% of theoretical capacity 121mAh/g.

Reference:

1.            W. Wu, A. Mohamed and J. F. Whitacre, Journal of The Electrochemical Society, 160, A497 (2013).

2.            W. Wu, J. Yan, A. Wise, A. Rutt and J. F. Whitacre, Journal of The Electrochemical Society, 161, A561 (2014).

3.            J.-K. Kim, G. Cheruvally, J.-W. Choi, J.-U. Kim, J.-H. Ahn, G.-B. Cho, K.-W. Kim and H.-J. Ahn, Journal of Power Sources, 166, 211 (2007).

4.            J.-K. Kim, J.-W. Choi, G. Cheruvally, J.-U. Kim, J.-H. Ahn, G.-B. Cho, K.-W. Kim and H.-J. Ahn, Materials Letters, 61, 3822 (2007).

5.            L.-X. Yuan, Z.-H. Wang, W.-X. Zhang, X.-L. Hu, J.-T. Chen, Y.-H. Huang and J. B. Goodenough, Energy & Environmental Science, 4, 269 (2011).