期刊
JOURNAL OF COLLOID AND INTERFACE SCIENCE
卷 619, 期 -, 页码 65-74出版社
ACADEMIC PRESS INC ELSEVIER SCIENCE
DOI: 10.1016/j.jcis.2022.03.064
关键词
Single-crystal NCM811 cathode; Dielectric CEI; High rate performance; Cyclic stability; Nanosized tetragonal BaTiO3
资金
- National Natural Science Founda-tion of China [21503131, 51711530162, 52002238]
- Shanghai Municipal Science and Technology Commission [19640770300, 20dz1201102]
- Engineering Research Center of Material Composi-tion and Advanced Dispersion Technology, Ministry of Education
- Shanghai Municipal Education Commission
Nanosized tetragonal BaTiO3 modification of single-crystal Ni-rich cathodes improves the diffusion coefficient of lithium ions, enhances charge distribution, and stabilizes the cathode-electrolyte interface, leading to increased discharge capacity and improved cycle performance.
The single-crystal Ni-rich Li(NixCoyMn1_x_y)O-2 cathode (NCM) demonstrates better cycle performance, enhanced tap density and improved mechanical structure stability, compared with polycrystalline NCM. However, limited Li+ transports, (003) plane slips and microcracks in large single particles hinder rate capability and cycle performance. To overcome these shortcomings, single-crystal NCM cathodes have been modified by nanosized tetragonal BaTiO3. Due to the dielectric properties, BaTiO3 particles induce electric field concentration at the BaTiO3-NCM-electrolyte interface. Thus, a large amount of lithium vacancies can be formed, providing sufficient sites for the hopping diffusion of lithium ions, thereby significantly enhancing the diffusion coefficient of Li+. Moreover, the redistribution of charges can inhibit the formation and accumulation of cathode-electrolyte-interface. Owing to the synergetic effect of BaTiO3, the BT-modified single-crystal NCM with the optimized loading shows a remarkable initial discharge capacity of 138.5 mAh g(_1) and maintains 53.8% of its initial discharge capacity after 100 cycles under 5C at 4.5 V cut-off voltage. Overall, the proposed dielectric cathode-electrolyte-interface strategy can enhance Li+ ion transport and stabilize the interface structure, leading to improved rate performance. Meanwhile, the diffusion-induced state of charge gradient can also be inhibited, resulting in high structure stability of single-crystal NCMs under high rate and cut-off voltage cycling. (C) 2022 Elsevier Inc. All rights reserved.
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