Journal of Energy Chemistry
·
2024
·
IF 14
Yueming Xia,Jianrui Feng,Jinhui Li,Yan Li,Zhengfeng Zhang,Xiaoqi Wang,Jianli Shao,Manling Sui,Pengfei Yan
Constructing robust surface and bulk structure is the prerequisite for realizing high performance high voltage LiCoO 2 (LCO). Herein, we manage to synthesize a surface Mg-doping and bulk Al-doping core-shell structured LCO, which demonstrates excellent cycling performance. Half-cell shows 94.2% capacity retention after 100 cycles at 3.0–4.6 V (vs. Li/Li + ) cycling, and no capacity decay after 300 cycles for full-cell test (3.0–4.55 V). Based on comprehensive microanalysis and theoretical calculations, the degradation mechanisms and doping effects are systematically revealed. For the undoped LCO, high voltage cycling induces severe interfacial and bulk degradations, where cracks, stripe defects, fatigue H2 phase, and spinel phase are identified in grain bulk. For the doped LCO, Mg-doped surface shell can suppress the interfacial degradations, which not only stabilizes the surface structure by forming a thin rock-salt layer but also significantly improves the electronic conductivity, thus enabling superior rate performance. Bulk Al-doping can suppress the lattice “breathing” effect and the detrimental H3 to H1-3 phase transition, which minimizes the internal strain and defects growth, maintaining the layered structure after prolonged cycling. Combining theoretical calculations, this work deepens our understanding of the doping effects of Mg and Al, which is valuable in guiding the future material design of high voltage LCO.
研究领域:
材料科学
·
电化学
✓ 已验证
DOI
高影响因子
ACS Applied Materials & Interfaces
·
2023
·
IF 9.5
Zhiqiang Yang,Enyue Zhao,Na Li,Lei Gao,Lunhua He,Baotian Wang,Fangwei Wang,Yusheng Zhao,Jinkui Zhao,Songbai Han
Increasing the charging cutoff voltage is a viable approach to push the energy density limits of LiCoO2 and meet the requirements of the rapid development of 3C electronics. However, an irreversible oxygen redox is readily triggered by the high charging voltage, which severely restricts practical applications of high-voltage LiCoO2. In this study, we propose a modification strategy via suppressing surface ligand-to-metal charge transfer to inhibit the oxygen redox-induced structure instability. A d0 electronic structure Zr4+ is selected as the charge transfer insulator and successfully doped into the surface lattice of LiCoO2. Using a combination of theoretical calculations, ex situ X-ray absorption spectra, and in situ differential electrochemical mass spectrometry analysis, our results show that the modified LiCoO2 exhibits suppressed oxygen redox activity and stable redox electrochemistry. As a result, it demonstrates a robust long-cycle lattice structure with a practically eliminated voltage decay (0.17 mV/cycle) and an excellent capacity retention of 89.4% after 100 cycles at 4.6 V. More broadly, this work provides a new perspective on suppressing the oxygen redox activity through modulating surface ligand-to-metal charge transfer for achieving a stable high-voltage ion storage structure.
研究领域:
材料科学
·
电化学
·
储能技术
✓ 已验证
DOI
PubMed
高影响因子
JOURNAL OF THE ELECTROCHEMICAL SOCIETY
·
2017
·Vol. 164
·期 14
·A3454
·
IF 3.259
Jun Ma,Zhaolin Liu,Bingbing Chen,Longlong Wang,Liping Yue,Haisheng Liu,Jianjun Zhang,Zhihong Liu,Guanglei Cui
Interface stability between cathode and electrolyte is closely related to the interface resistance and electrochemical performance of all-solid-state lithium ion batteries (LIBs). However, the significant interface issues between cathode and all-solid-state polymer electrolyte have been researched rarely. Here, we demonstrate that severe interface decomposition reactions occur continually and deteriorate the cycling life of high voltage LiCoO2/cellulose-supported poly(ethylene oxide) (PEO)-lithium difluoro(oxalato)borate (LiDFOB)/Li battery between 2.5 and 4.45 V vs. Li/Li+. To improve the interface stability between LiCoO2 and PEO-LiDFOB electrolyte, we modify the LiCoO2 surface by a thin layer of high ionic conducting and electrochemical oxidation resistant poly(ethyl cyanoacrylate) (PECA) through in-situ polymerization method. The PECA coating layer significantly suppresses the continuous decomposition of lithium difluoro(oxalato)borate (LiDFOB) salt in PEO electrolyte. As a result, the PECA-coated LiCoO2/PEO-LiDFOB/Li battery shows decreased interface resistance and enhanced cycling stability. This work will enlighten the understanding of interface stability and enrich the modification strategy between cathode and polymer electrolyte as well as boost the further development of all-solid-state LIBs.
研究领域:
材料科学
·
电化学
·
能量存储
✓ 已验证
DOI
高影响因子
Carbon Energy
·
2024
·
IF 19.5
Qihang Ding,Zewen Jiang,Kean Chen,Hui Li,Jingzhe Shi,Xinping Ai,Dingguo Xia
High-voltage LiCoO 2 (LCO) can deliver a high capacity and therefore significantly boost the energy density of Li-ion batteries (LIBs). However, its cyclability is still a major problem in terms of commercial applications. Herein, we propose a simple but effective method to greatly improve the high-voltage cyclability of an LCO cathode by constructing a surface LiF modification layer via pyrolysis of the lithiated polyvinylidene fluoride (Li-PVDF) coating under air atmosphere. Benefitting from the good film-forming and strong adhesion ability of Li-PVDF, the thus-obtained LiF layer is uniform, dense, and conformal; therefore, it is capable of acting as a barrier layer to effectively protect the LCO surface from direct exposure to the electrolyte, thus suppressing the interfacial side reactions and surface structure deterioration. Consequently, the high-voltage stability of the LCO electrode is significantly enhanced. Under a high charge cutoff voltage of 4.6 V, the LiF-modified LCO (LiF@LCO) cathode demonstrates a high capacity of 201 mA h g −1 at 0.1 C and a stable cycling performance at 0.5 C with 80.5% capacity retention after 700 cycles, outperforming the vast majority of high-voltage LCO cathodes reported so far.
研究领域:
材料科学
·
电化学
·
电池技术
✓ 已验证
DOI
高影响因子
ACS Applied Energy Materials
·
2022
·
IF 6.959
Yang Chen,Shujian Liu,Shaokai Cheng,Shuyu Gao,Jingchao Chai,Qiuyue Jiang,Zhihong Liu,Xueqing Liu,Jiyan Liu,Ming Xie,Wubin Dai
The polyvinylidene fluoride (PVdF) binder is the classic binder for cathodes because of its excellent electrochemical stability and superior adhesion property. However, PVdF is very expensive and sensitive to moisture. Therefore, pursuit of a cost-effective binder is highly desirable, especially for high-voltage cathode application. Polyacrylonitrile (PAN) possesses strong polar C≡N groups, endowing it with oxidation resistance and strong binding properties. Herein, the PAN binder was systematically investigated for the electrochemical performance of the 4.5 V high-voltage LiCoO2 (HV-LCO) electrode. The results showed that the HV-LCO-PAN electrode delivered superior rate capability and cycling stability to the corresponding HV-LCO-PVdF. The PAN binder was highly tolerant of moisture and was capable of forming uniform coating on the cathode materials. Moreover, the PAN binder had ultrahigh mechanical modulus (8.01 GPa) and hardness (381.45 MPa) in a liquid electrolyte, thereby improving cycling stability and rate capability. X-ray photoelectron spectroscopy analysis further demonstrated that PAN formed uniform coating on the surface of LiCoO2 and played a role of an artificial cathode–electrolyte interphase layer, suppressing decomposition of the liquid electrolyte under high cutoff voltage.
研究领域:
材料科学
·
电化学
·
能源存储
✓ 已验证
产品关联
DOI
高影响因子
危险品化学品经营许可证（带存储）