A Bifunctional-Modulated Conformal Li/Mn-Rich Layered Cathode for Fast-Charging, High Volumetric Density and Durable Li-Ion Full Cells

• 作者: Zedong Zhao Minqiang Sun Tianqi Wu Jiajia Zhang Peng Wang Long Zhang Chongyang Yang Chengxin Peng Hongbin Lu
• 来源期刊: 纳微快报（英文版）
• 年，卷（期）: 2021,（8）
• 页码范围: 40-55
• 页数: 16页
• 语种: 英文

摘要

Lithium- and manganese-rich (LMR) layered cath-ode materials hold the great promise in designing the next-genera-tion high energy density lithium ion batteries. However, due to the severe surface phase transformation and structure collapse, stabiliz-ing LMR to suppress capacity fade has been a critical challenge. Here, a bifunctional strategy that integrates the advantages of sur-face modification and structural design is proposed to address the above issues. A model compound Li1.2Mn0.54Ni0.13Co0.13O2 (MNC) with semi-hollow microsphere structure is synthesized, of which the surface is modified by surface-treated layer and graphene/car-bon nanotube dual layers. The unique structure design enabled high tap density (2.1 g cm-3) and bidirectional ion diffusion pathways. The dual surface coatings covalent bonded with MNC via C-O-M linkage greatly improves charge transfer efficiency and mitigates electrode degradation. Owing to the synergistic effect, the obtained MNC cathode is highly conformal with durable structure integrity,exhibiting high volumetric energy density (2234 Wh L-1) and predominant capacitive behavior. The assembled full cell, with nanograph-ite as the anode, reveals an energy density of 526.5 Wh kg-1, good rate performance (70.3％ retention at 20 C) and long cycle life (1000 cycles). The strategy presented in this work may shed light on designing other high-performance energy devices.