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北京大学深圳研究生院潘锋教授学术报告通知

编辑:admin 日期:2017-05-23 12:12 访问次数:1284

 报告题目:Insight into crystal/interface structure vs. properties of Li-ion batteries

报告人:  国家千人计划学者北京大学深圳研究生院潘锋教授
报告时间:2017年5月23日(周二)上午10:00
报告地点:材料学院曹光彪楼326会议室
邀请人: 潘洪革教授
 
报告人简介:
 
Prof. Feng Pan, National 1000-plan Professor, Founding Dean of School of Advanced Materials,Peking University Shenzhen Graduate School, Director of National Center of Electric Vehicle Power Battery and Materials for International Research, got B.S. from Dept. Chemistry, Peking University in1985 and PhD from Dept. of P&A Chemistry,University of Strathclyde, Glasgow, UK, with "Patrick D. Ritchie Prize” for the best Ph.D. in 1994. With more than a decade experience in large international incorporations, Prof. Pan has been engaged in fundamental research and product development of novel optoelectronic and energy storage materials and devices. As Chief Scientist, Prof. Pan led 8 entities in Shenzhen to win the 150 million RMB grant for the national new energy vehicles (power battery) innovation project from 2013 to end of 2015. As Chief Scientist, Prof. Pan led 12 entities to win National Key project of Material Genomic Engineering for Solid State Li-ion Battery in China in 2016.
 
报告摘要:
Insight into relationship between Crystal/Interface structure and properties of capacity, stability and rate capability are important for developing advanced Li-ion batteries. (Ref. 1-2)Charging/discharging rate is a key battery parameter that dictates how fast energy can be harnessed or released, and is critical for the applications such as vehicle-electrification and renewable energy grids. The rate capability is closely associated with the kinetic of Li-ion diffusion in batteries. Using theoretical calculations combined with experimental in-situ tests, we did extensive studies on the kinetic of Li-ion diffusion for two representative cathode materials: layered Li(NixMnyCoz)O2 (NMC) (x + y + z = 1) and LiFePO4. We not only focus on the bulk kinetics, but also the kinetics across electrode/electrolyte solid-liquid interface and in the electrolytes. For example, we systematically studied the Li-ion diffusivity properties and first reported how to tune the kinetics of Li-ion diffusion in layered materials. We first proposed that "Janus" solid-liquid interface would facilitate the Li-ion transport in battery and introducing some disordering in non-active cathode materials would activate them for Li-ion storage. We found that the solution intrinsic diffusion coefficient, efficiency porosity, and electrode thickness would play a dominant role in the equivalent diffusion coefficient with the electrode beyond a certain thickness, which determines the whole kinetic process in LIBs. All these finding share helpful guidance to design cathode materials with high rate performance. Finally, we also developed some in-situ technologies for battery studies. For example, using electrochemical quartz crystal microbalance (EQCM), we achieve an in situ experimental investigation of the LiFePO4 (LFP) and NaFePO4 (NFP)/electrolyte interfacial kinetics for Li(Na)-batteries. (Ref. 3-11)
With the rapid development of lithium batteries, major concerns are raised over their cycling life, safety, cost, and environmental compatibility.For high energy and power density applications (e.g., EVs), the safety becomes especially important. The safety is usually determined by the thermal stability of the cathode materials, which is reflected by the structure decomposition and phase transformation. We recently did extensive studies on the thermal stability for two representative cathode materials: layered NMC and Li2FeSiO4. Using ab initio calculations combined with experiments, we clarified how the thermal stability of NMC materials can be tuned by the most unstable oxygen, which is determined by the local coordination structure unit (LCSU) of oxygen (TM(Ni, Mn, Co)3-O-Li3-x’): each O atom bonds with three of transition metal (TM) from the TM-layer and three to zero of Li from fully discharged to charged states from the Li-layer. Under this model, how the lithium content, valence states of Ni, contents of Ni, Mn, and Co, and Ni/Li disorder to tune the thermal stability of NMC materials by affecting the sites, content, and the release temperature of the most unstable oxygen is proposed. We also found that the optimized Ti(IV) doped in Fe sites for Li2FeSiO4 can enhance the coupling effect among the tetrahedra by the strong d-orbital hybridization and like “spring” to hold these tetrahedra and prohibit structure fracture. Besides this, we also studied the surface structure stability of cathode materials. For example, we first reported that a prelithiation process to layered NMC materials can form electrolyte interface (SEI) on the surface and activate astructure containing two Li layers near the surface of NMC particles, lead to the protection of NMC particles fromMn(II)-dissolution and the activation of NMC for extra Listorage. We also developed other methods (e.g., ALD technology, aligned Li+ tunnels in Core−Shell Li(NixMnyCoz)O2@LiFePO4) to improve the structure stability of the surface for cathode materials. (Ref. 12-17)
 
References
1.     Jun Lu, Zonghai Chen, Zifeng Ma, Feng Pan,*,Nature Nanotechnology 2016, 11, 1031-1038(review article). Larry Curtiss* and Khalil Amine*
2.     J Zheng, J Lu, K Amine*, F Pan*; Nano Energy 2017, 33, 497–507(review article).
3.     Feng Pan*, et al., J. Am. Chem. Soc., 2015, 137, 8364–8367.
4.     Feng Pan*, et al., Adv. Energy Mater., 2015, 1501309(1-9).
5.     Feng Pan*, et al., Nano Lett., 2015, 15 (9), 6102–6109.
6.     Feng Pan*, et al., Nano Lett., 2015, 16, 601–608.
7.     Feng Pan*, et al., Nano Lett., 2014,14 (8), 4700–4706.
8.     Feng Pan*, et al., Adv. Energy Mater., (Front page), 2016, 1601894.
9.     Feng Pan*, et al., Adv. Energy Mater. (Front page ), 2016,1600856,
10.   Feng Pan*, et al., J. Mater. Chem. A, 2016, 10.1039/c6ta01111j.
11.   Feng Pan*, et al., Nano Energy (revised).
12.   Feng Pan*, et al., J. Am. Chem. Soc.,2016, 138 (40), 13326–13334,
13.   Feng Pan*, et al., Nano Lett., 2016, 16 (10), 6357–6363
14.   Feng Pan*, et al., Nano Lett., 2015, 15, 5590–5596.
15.   Feng Pan*, et al., ACS Appl. Mater. & Interfaces, 2016, DOI: 10.1021/acsami.6b03730.
16.   Feng Pan*, et al., ACS Appl. Mater. & Interfaces, 2015, 7, 25105–25112.
Feng Pan*, et al., Nano Energy, 2016, 20, 117–


 
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