Zhao Tingkai, She Shengfei, Ji Xianglin, Guo Xinai, Jin Wenbo, Zhu Ruoxing, Dang Alei, Li Hao, Li Tiehu, Wei Bingqing
School of Materials Science and Engineering, Northwestern Polytechnical University, Xi'an 710072, China.
Department of Mechanical Engineering, University of Delaware, Newark DE 19716, United States.
Sci Rep. 2016 Sep 27;6:33833. doi: 10.1038/srep33833.
The development of high capacity and long-life lithium-ion batteries is a long-term pursuing and under a close scrutiny. Most of the researches have been focused on exploring electrode materials and structures with high store capability of lithium ions and at the same time with a good electrical conductivity. Thermal conductivity of an electrode material will also have significant impacts on boosting battery capacity and prolonging battery lifetime, which is, however, underestimated. Here, we present the development of an expanded graphite embedded with Al metal nanoparticles (EG-MNPs-Al) synthesized by an oxidation-expansion process. The synthesized EG-MNPs-Al material exhibited a typical hierarchical structure with embedded Al metal nanoparticles into the interspaces of expanded graphite. The parallel thermal conductivity was up to 11.6 W·m·K with a bulk density of 453 kg·m at room temperature, a 150% improvement compared to expanded graphite (4.6 W·m·K) owing to the existence of Al metal nanoparticles. The first reversible capacity of EG-MNPs-Al as anode material for lithium ion battery was 480 mAh·g at a current density of 100 mA·g, and retained 84% capacity after 300 cycles. The improved cycling stability and system security of lithium ion batteries is attributed to the excellent thermal conductivity of the EG-MNPs-Al anodes.
高容量和长寿命锂离子电池的开发是一个长期追求且备受密切关注的目标。大多数研究都集中在探索具有高锂离子存储能力且同时具有良好导电性的电极材料和结构。然而，电极材料的热导率对提高电池容量和延长电池寿命也会产生重大影响，而这一点却被低估了。在此，我们展示了一种通过氧化膨胀法合成的嵌入铝金属纳米颗粒的膨胀石墨（EG-MNPs-Al）的开发情况。合成的EG-MNPs-Al材料呈现出一种典型的分级结构，铝金属纳米颗粒嵌入到膨胀石墨的间隙中。在室温下，其平行热导率高达11.6 W·m·K，堆积密度为453 kg·m，由于铝金属纳米颗粒的存在，与膨胀石墨（4.6 W·m·K）相比提高了150%。EG-MNPs-Al作为锂离子电池负极材料的首次可逆容量在电流密度为100 mA·g时为480 mAh·g，在300次循环后仍保留84%的容量。锂离子电池循环稳定性和系统安全性的提高归因于EG-MNPs-Al负极优异的热导率。
