Yang Fujie, Wang Pipi, Huang Qizhang, Luo Juan, Hu Ridong, Huang Qiujie, Mao Chong, Yang Lewen, Liang Guanjie, Li Yang, Chen Xudong
College Chemistry and Chemical Engineering, Zhongkai University of Agriculture and Engineering, Guangzhou, 510275, P. R. China.
Jieyang Branch of Chemistry and Chemical Engineering Guangdong Laboratory (Rongjiang Laboratory), Jieyang, 515200, P. R. China.
Small. 2024 Aug;20(32):e2311961. doi: 10.1002/smll.202311961. Epub 2024 Mar 10.
Optimizing the electrode/electrolyte interface structure is the key to realizing high-voltage Li-metal batteries (LMBs). Herein, a functional electrolyte is introduced to synergetically regulate the interface layer structures on the high-voltage cathode and the Li-metal anode. Saccharin sodium (NaSH) as a multifunctional electrolyte additive is employed in fluorinated solvent-based electrolyte (FBE) for robust interphase layer construction. On the one hand, combining the results of ex-situ techniques and in-situ electrochemical dissipative quartz crystal microbalance (EQCM-D) technique, it can be seen that the solid electrolyte interface (SEI) layer constructed by NaSH-coupled fluoroethylene carbonate (FEC) on Li-metal anode significantly inhibits the growth of lithium dendrites and improves the cyclic stability of the anode. On the other hand, the experimental results also confirm that the cathode-electrolyte interface (CEI) layer induced by NaSH-coupled FEC effectively protects the active materials of LiCoO and improves their structural stability under high-voltage cycling, thus avoiding the material rupture. Moreover, theoretical calculation results show that the addition of NaSH alters the desolvation behavior of Li and enhances the transport kinetics of Li at the electrode/electrolyte interface. In this contribution, the LiCoOǁLi full cell containing FBE+NaSH results in a high capacity retention of 80% after 530 cycles with a coulombic efficiency of 99.8%.
优化电极/电解质界面结构是实现高压锂金属电池（LMBs）的关键。在此，引入一种功能性电解质来协同调节高压正极和锂金属负极上的界面层结构。将糖精钠（NaSH）作为多功能电解质添加剂用于基于氟化溶剂的电解质（FBE）中，以构建坚固的界面层。一方面，结合非原位技术和原位电化学耗散石英晶体微天平（EQCM-D）技术的结果可以看出，由NaSH与氟代碳酸乙烯酯（FEC）在锂金属负极上构建的固体电解质界面（SEI）层显著抑制了锂枝晶的生长，并提高了负极的循环稳定性。另一方面，实验结果也证实，由NaSH与FEC诱导形成的正极-电解质界面（CEI）层有效地保护了LiCoO的活性材料，并提高了它们在高压循环下的结构稳定性，从而避免了材料破裂。此外，理论计算结果表明，NaSH的添加改变了Li的去溶剂化行为，并增强了Li在电极/电解质界面处的传输动力学。在本研究中，含有FBE+NaSH的LiCoOǁLi全电池在530次循环后具有80%的高容量保持率，库仑效率为99.8%。
