Li Dejun, Tu Haifeng, Zhang Shiqi, Guo Yuyue, Zhao Jiawei, Cai Xianshu, Xue Jiang-Yan, Lu Suwan, Liu Lingwang, Zhang Xin, Peng Keyang, Xu Jingjing, Wu Xiaodong
School of Nano-Tech and Nano-Bionics, University of Science and Technology of China, Hefei 230026, China.
i-Lab, Suzhou Institute of Nano-Tech and Nano Bionics (SINANO), Chinese Academy of Sciences, Suzhou 215123, China.
ACS Appl Mater Interfaces. 2025 Jul 23;17(29):42268-42277. doi: 10.1021/acsami.5c06988. Epub 2025 Jul 11.
The pursuit of high-energy-density portable electronic applications has intensified the development of high-voltage LiCoO (LCO) cathodes. However, the LCO cathode undergoes severe side reactions with the electrolyte at elevated cutoff voltages, leading to significant interface degradation and structural collapse. Modifying the cathode/electrolyte interface is a very good strategy to restrain interfacial side reactions and stabilize the structure. Herein, we proposed a high-voltage-stable polyionic liquid (PIL) as an artificial solid electrolyte interface, achieved by in situ bulk polymerization of a diallyldimethylammonium bis(trifluoromethanesulfonyl)imide (DMDA) monomer to form a polymer-containing cross-linked structure on the LCO cathode surface. The polymerized DMDA (PDMDA) coating layer forms a thin, dense cathode-electrolyte interphase (CEI) that effectively isolates the LCO from direct contact with the electrolyte and suppresses side reactions. Consequently, the PDMDA-modified LCO cathode retains 80% of its initial capacity over 500 cycles at 1C within a voltage range of 3 to 4.5 V, significantly outperforming the bare-LCO cathode. Additionally, the PDMDA layer also enhances the thermal stability of the LCO cathode, offering substantial value for safe lithium battery applications. This PDMDA modification strategy provides a promising pathway for practical deployment of high-voltage LCO cathodes.
对高能量密度便携式电子应用的追求加速了高压钴酸锂（LCO）阴极的发展。然而，在较高的截止电压下，LCO阴极与电解质会发生严重的副反应，导致显著的界面退化和结构坍塌。修饰阴极/电解质界面是抑制界面副反应和稳定结构的一种非常好的策略。在此，我们提出了一种高压稳定的聚离子液体（PIL）作为人工固体电解质界面，通过二烯丙基二甲基氯化铵双（三氟甲磺酰）亚胺（DMDA）单体的原位本体聚合，在LCO阴极表面形成含聚合物的交联结构来实现。聚合后的DMDA（PDMDA）涂层形成了一层薄而致密的阴极-电解质界面（CEI），有效地将LCO与电解质直接接触隔离开来，并抑制了副反应。因此，PDMDA修饰的LCO阴极在3至4.5 V的电压范围内，在1C下500次循环后仍保留其初始容量的80%，明显优于裸LCO阴极。此外，PDMDA层还提高了LCO阴极的热稳定性，为安全锂电池应用提供了重要价值。这种PDMDA修饰策略为高压LCO阴极的实际应用提供了一条有前景的途径。
