ACS Applied Materials & Interfaces
·
2025
·
IF 8.2
Yu Wu,Wenting Ji,Zhihua Xu,Yuqin Huang,De Li,Yuanchuan Li,Yong Chen
In Li-ion batteries (LIBs), the phenomenon of memory effect has only been found in a few two-phase electrode materials such as olivine LiFePO4, anatase TiO2, and Al-doped Li4Ti5O12, which is attributed to the Li-ion exchange between adjacent vacant Li and Fe sites in LiFePO4 and the Al-ion exchange between 8a and 16c sites in Al-doped Li4Ti5O12. Here, the Al-doped LiCrTiO4 was successfully synthesized by the spray-drying method and high-temperature sintering, which also exhibits the memory effect during only the charging process. The X-ray diffraction (XRD) and electrochemical results indicate that the saturated Al-doping level corresponds to the Al:Ti ratio of ca. 0.25 for LiCrTiO4, and the memory effect increases with the Al-doping level evidently. According to the in situ XRD and magic-angle spinning nuclear magnetic resonance results, the Al3+ ions are doped at the 8a sites, the Li ions hop between 8a and 16c sites during the charging and discharging processes, and the Li ions further hop from the 16c site to the 16d site after deeply discharging and move back in the subsequent charging process. Therefore, the memory effect of Al-doped LiCrTiO4 should originate from the reversible exchange of Li ions between 16c and 16d sites, and it is a common strategy to cause the memory effect in LIBs by inducing another reversible ionic migration in the electrode materials to affect the normal Li-ion extraction/insertion.
研究领域:
材料科学
·
电化学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
Materials
·
2021
·Vol. 14
·期 13
·3624
·
IF 3.623
Zhijie Xu,Fangxu Hu,De Li,Yong Chen
In the late 1960s, the establishment of Prigogine’s dissipative structure theory laid the foundation for the (electro)chemical oscillation phenomenon, which has been widely investigated in some electrochemical reactions, such as electro-catalysis and electro-deposition, while the electrochemical oscillation of Li-ion batteries has just been discovered in spinel Li4Ti5O12a few years before. In this work, spinel LiCrTiO4samples were synthesized by using a high-temperature solid-state method, characterized with SEM (Scanning electron microscope), XRD (X-ray diffraction), Raman and XPS (X-ray photoelectron spectroscopy) measurements, and electrochemically tested in Li-ion batteries to study the electrochemical oscillation. When sintering in a powder form at a temperature between 800 and 900 °C, we achieved the electrochemical oscillation of spinel LiCrTiO4during charging, and it is suppressed in the non-stoichiometric LiCrTiO4samples, especially for reducing the Li content or increasing the Cr content. Therefore, this work developed another two-phase material as the powder-sintered LiCrTiO4exhibiting the electrochemical oscillation in Li-ion batteries, which would inspire us to explore more two-phase electrode materials in Li-ion batteries, Na-ion batteries, etc.Keywords:Li-ion battery;LiCrTiO4;electrochemical oscillation;phase transition;spinel structure
研究领域:
材料科学
·
电化学
✓ 已验证
DOI
PubMed
高影响因子
ACS Applied Materials & Interfaces
·
2022
·
IF 10.383
Yuanyuan Ren,Limin Liu,Zhen Wang,De Li,Yong Chen
Compared with traditional centimeter-level electrodes, microelectrodes exhibit a small reaction area, high sensitivity, fast mass transfer rate, and low polarization current. However, current microelectrode preparation processes are very complicated and costly. Herein, we proposed a facile and universal method for fabricating single-particle microelectrodes. In the precursor solution, polyvinyl alcohol and ammonia were introduced as the polymeric binder and pore-forming agent, respectively. Through spaying-drying-sintering processes, the single-particle microelectrodes were successfully prepared for Li4Ti5O12 (LTO), LiCrTiO4 (LCTO), and LiFePO4/C (LFP/C), which showed excellent electrochemical properties. Furthermore, the single-particle microelectrode can be adopted to study the electrochemical oscillations of Li-ion batteries and assemble a full-cell microbattery as a potential next-generation microscale power source.
研究领域:
电化学
·
材料科学
·
纳米技术
✓ 已验证
DOI
高影响因子
ACS Applied Energy Materials
·
2025
·
IF 5.5
Yuanbo Han,Yuanchuan Li,Yuqin Huang,De Li,Yu Wu,Wenting Ji,Yong Chen
As a well-known two-phase material, spinel Li4Ti5O12 has been widely studied and commercially applied in lithium-ion batteries, and its zero-strain phase transition derives some unique electrochemical phenomena such as memory effect and electrochemical oscillation. Due to the same spinel structure and redox element, the spinel LiCrTiO4 presents similar electrochemical properties including memory effect and electrochemical oscillation. However, electrochemical oscillation has not yet been observed during the discharge process of LiCrTiO4. In this study, spinel LiCrTiO4 was prepared by spray-drying in a vertical tube furnace and then sintered at a high temperature, which exhibits electrochemical oscillation during both charging and discharging. According to XPS, TEM, NMR, and in-situ XRD results, the nonstoichiometric Li1–xCr1–yTiO4 (x, y = 0.2, 0.1, and 0) samples possess a good spinel structure with partial Li ions at 16d sites and take a reversible two-phase transition between the spinel and rock-salt structures. In addition, a schematic diagram is proposed to interpret the electrochemical oscillation of LiCrTiO4, in which the nucleation and phase transition processes play the rate-determining step alternatively. Therefore, it is the first time the electrochemical oscillation is achieved during both charge and discharge of LiCrTiO4, and an alternative rate-determining step is proposed to elucidate the electrochemical oscillation, which offers an original perspective for understanding two-phase reactions and their derivative phenomena in lithium-ion batteries.
✓ 已验证
DOI
高影响因子
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