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Synthesis of Carbon Coated Li 2 ZnTi 3 O 8 Anode Material Using Chitosan As Carbon Source for Lithium-Ion Batteries
| Content Provider | Semantic Scholar |
|---|---|
| Author | Tang, Haoqing Tang, Zhiyuan |
| Copyright Year | 2014 |
| Abstract | Cubic spinel structure Li2ZnTi3O8 with a space group P4332 exhibits favorable cycling stability. The lithium storage theoretic capacity of Li2ZnTi3O8 is 227 mAh g , and it has lower discharge voltage plateau (around 0.5 V vs. Li/Li). Nonetheless, its electronic conductivity and high rate performance are still not much too perfect. Therefore, our work is to improve the intrinsic poor electronic conductivity by different ways. Carbon coating method is a common and effective approach, which could enhance the electronic conductivity and significant improve electrochemical performance. Chitosan(poly-β-(1,4)-2-amino-2-deoxy-glucopyranose) is a product of the de-acetylation of chitin, which is the second abundant natural biopolymer on earth after cellulose. The percentage of carbon in the chitosan is as high as 45 %. These results suggest that chitosan may act as a carbon source in preparing anode materials. In this study, we have successfully prepared Li2ZnTi3O8/C composite using chitosan as carbon source via a modified solid-state reaction route. Fig. 1 (a) shows the XRD patterns of pristine Li2ZnTi3O8 and Li2ZnTi3O8/C. The diffraction peaks of both samples can be indexed to a cubic spinel structure of Li2ZnTi3O8 (JCPDS#44-1037), demonstrating that the presence of carbon does not influence the structure of Li2ZnTi3O8. It is clearly shown that no other impurities peaks can be figured out through the XRD patterns. The absence of carbon in Li2ZnTi3O8 is most likely due to the low content amorphous carbon or carbon. The absence of a new lithium titanium phase even at the high temperature suggests that parent Li2ZnTi3O8 is very stable under an inert atmosphere. On the other hand, the low XRD diffraction intensity of Li2ZnTi3O8/C composite can be attributed to its poor crystallinity. Fig. 1 (b) shows the initial charge and discharge curves of Li2ZnTi3O8/C electrode which was measured ranging from 0.05 V to 3.0 V. The initial discharge capacities of Li2ZnTi3O8/C are 257.3 and 203.3 mAh g -1 at 0.1 and 1.0 A g, respectively. In addition, it can be seen that a charge plateau appears at 1.39 V and a discharge plateau appears at 0.59 V for Li2ZnTi3O8/C at 0.1 A g . On the other hand, the difference between charge and discharge plateau is increase with the current increasing, indicating the polarization of electrode become serious. Cycling performances of Li2ZnTi3O8 and Li2ZnTi3O8/C at different charge-discharge rates are shown in Fig. 1 (c) and (d). After 50 cycles, the reversible capacities for Li2ZnTi3O8/C are 225.3 and 190.2 mAh g -1 at 0.1 and 1.0 A g, respectively, and improved by 37.6 and 108.7 mAh g compared with Li2ZnTi3O8 (187,7 and 81.5 mAh g -1 at 0.1 and 1.0 A g). Such improvement may be summarized as the following three reasons: (1) Amorphous carbon layer is beneficial to enhance the electronic conductive and effectively decrease transfer resistance of electrons, and hence ensure high specific capacity and rate capability. (2) The presence of carbon inhibits the growth of Li2ZnTi3O8 particles during the high temperature calcination process and leads to small particles, which can shorten the transport path lengths for Li to migrate inside of the active material. (3) The commercial LiPF6-based lithium-ion battery electrolyte solution always contains a trace amount of water. The LiPF6 can be reacted with water and produce a certain amount of HF. However, the carbon layer can stabilize the surface of Li2ZnTi3O8 and prevent the active material from HF attack. |
| Starting Page | 58 |
| Ending Page | 58 |
| Page Count | 1 |
| File Format | PDF HTM / HTML |
| DOI | 10.1149/ma2014-03/2/58 |
| Alternate Webpage(s) | https://ecs.confex.com/data/abstract/ecs/ecee2014/Paper_28921_abstract_8915_0.pdf |
| Alternate Webpage(s) | https://doi.org/10.1149/ma2014-03%2F2%2F58 |
| Language | English |
| Access Restriction | Open |
| Content Type | Text |
| Resource Type | Article |
