Sheng Yijin, Hu Fangxu, Wu Yu, Li De, Ji Wenting, Chen Yong
State Key Laboratory of Marine Resources Utilization in South China Sea, Key Laboratory of Research on Utilization of Si-Zr-Ti Resources of Hainan Province, School of Materials Science and Engineering, Hainan University Haikou 570228 China
National Laboratory of Solid State Microstructures, Nanjing University Nanjing 210093 China
RSC Adv. 2024 Jul 9;14(30):21799-21807. doi: 10.1039/d4ra03331k. eCollection 2024 Jul 5.
The electrochemical oscillation in Li-ion batteries has been reported for two-phase electrode materials of LiTiO and LiCrTiO, which is originated from the group-by-group phase transition in a multi-particle electrode. For both LiTiO and LiCrTiO, the electrochemical oscillation exhibits usually during charging, while rarely for discharging. Herein, a series of Zr-modified LiTiO samples are prepared by using the spray-drying combined with high-temperature sintering method, and the electrochemical oscillation is observed during not only the charging process, but also the discharging process, which gradually grows up and then disappears by increasing the Li content. Compared with LiTiO, the specific capacity of Zr-modified LiTiO decreases gradually by increasing the Zr/Ti ratio, owing to the impurity phases. According to the XRD, XPS and STEM results, the Zr element tends to accumulate on the surface to form ZrO nanoparticles, rather than dope into the bulk phase of LiTiO, which makes LiTiO particles well dispersive. In contrast to the Li deficiency for only charging, the electrochemical oscillation during both charging and discharging should be attributed to the Li excess, but too much LiTiO phase will suppress the electrochemical oscillation. Therefore, the Li excess can induce the electrochemical oscillation during both charging and discharging of Zr-modified LiTiO, which can be adopted to investigate the electrochemical oscillation of other materials in LIBs.
锂离子电池中的电化学振荡已在LiTiO和LiCrTiO的两相电极材料中被报道，其源于多颗粒电极中的逐组相变。对于LiTiO和LiCrTiO两者，电化学振荡通常在充电过程中出现，而在放电过程中很少出现。在此，通过喷雾干燥结合高温烧结法制备了一系列Zr改性的LiTiO样品，并且不仅在充电过程中，而且在放电过程中都观察到了电化学振荡，该振荡随着Li含量的增加逐渐增强然后消失。与LiTiO相比，由于杂质相，Zr改性的LiTiO的比容量随着Zr/Ti比的增加而逐渐降低。根据XRD、XPS和STEM结果，Zr元素倾向于在表面积累形成ZrO纳米颗粒，而不是掺杂到LiTiO的体相中，这使得LiTiO颗粒具有良好的分散性。与仅充电时的锂不足相反，充电和放电过程中的电化学振荡应归因于锂过量，但过多的LiTiO相会抑制电化学振荡。因此，锂过量可诱导Zr改性的LiTiO在充电和放电过程中产生电化学振荡，这可用于研究锂离子电池中其他材料的电化学振荡。
