As state-of-the-art electrochemical energy conversion and storage(EECS)techniques,fuel cells and rechargeable batteries have achieved great success in the past decades.However,modern societies’ever-growing demand in ...As state-of-the-art electrochemical energy conversion and storage(EECS)techniques,fuel cells and rechargeable batteries have achieved great success in the past decades.However,modern societies’ever-growing demand in energy calls for EECS devices with high efficiency and enhanced performance,which mainly rely on the rational design of catalysts,electrode materials,and electrode/electrolyte interfaces in EESC,based on in-deep and comprehensive mechanistic understanding of the relevant electrochemical redox reactions.Such an understanding can be realized by monitoring the dynamic redox reaction processes under realistic operation conditions using in situ techniques,such as in situ Raman,Fourier transform infrared(FTIR),and X-ray diffraction(XRD)spectroscopy.These techniques can provide characteristic spectroscopic information of molecules and/or crystals,which are sensitive to structure/phase changes resulted from different electrochemical working conditions,hence allowing for intermediates identification and mechanisms understanding.This review described and summarized recent progress in the in situ studies of fuel cells and rechargeable batteries via Raman,FTIR,and XRD spectroscopy.The applications of these in situ techniques on typical electrocatalytic electrooxidation reaction and oxygen reduction reaction(ORR)in fuel cells,on representative high capacity and/or resource abundance cathodes and anodes,and on the solid electrolyte interface(SEI)in rechargeable batteries are discussed.We discuss how these techniques promote the development of novel EECS systems and highlight their critical importance in future EECS research.展开更多
The aluminum matrix composites(AlB2+a-Al2O3)/Al were fabricated by in situ reaction synthesis from an Al-B2 O3 system. The reaction pathways, apparent activation energies and tensile properties were analyzed by using ...The aluminum matrix composites(AlB2+a-Al2O3)/Al were fabricated by in situ reaction synthesis from an Al-B2 O3 system. The reaction pathways, apparent activation energies and tensile properties were analyzed by using differential scanning calorimetry(DSC), X-ray diffraction(XRD), scanning electron microscopy(SEM), and equipped energy dispersive spectroscopy(EDS). The results showed that there are two-step reactions in the Al-B2 O3 system. The first-step is 15 Al+7 B2 O3→7 aAl2O3+AlB12+2 B and the second-step is 2 B+AlB12+6 Al→7 AlB2. Their corresponding apparent activation energies are 352 and 444 kJ/mol, respectively. The tensile strength and elongation rate of the composites are 190.5 MPa and 6.6%, respectively.Compared with ordinary aluminum base material, the performance is superior. There are many dimple and cracked a-Al2O3 reinforcements in tensile fracture surface layer.展开更多
Titanium matrix composites reinforced with a-Al2O3 and TiB2 particles were fabricated by in situ synthesis from a Ti-Al-B2O3 system. The reaction processes and microstructure were analyzed by using differential scanni...Titanium matrix composites reinforced with a-Al2O3 and TiB2 particles were fabricated by in situ synthesis from a Ti-Al-B2O3 system. The reaction processes and microstructure were analyzed by using differential scanning calorimetry（DSC）, scanning electron microscopy（SEM） and X-ray diffraction（XRD）. The results showed that the reactions in the Ti-Al-B2O3 system can occur spontaneously and consist of three steps： 1） 15 Al ＋ 7B2O3 → 7α-Al2O3 ＋ AlB12 ＋ 2B; 2） 14 B ＋ 2Al → AlB12 ＋ AlB2 and 3） 7Ti ＋ AlB（12） ＋ AlB2 → 7TiB2 ＋ 2Al. The final reinforcements were composed of α-Al2O3 and TiB2 particles, which were uniformly distributed in the titanium matrix.展开更多
Layered LiMO_(2)(M=Ni,Co,and Mn) is a type of promising cathode materials for high energy density and high work voltage lithium-ion batteries.However,the poor rate performance and low power density hinder its further ...Layered LiMO_(2)(M=Ni,Co,and Mn) is a type of promising cathode materials for high energy density and high work voltage lithium-ion batteries.However,the poor rate performance and low power density hinder its further applications.The capacity fade is related to the structural transformation in the layered LiMO_(2).In this work,the structural changes of bi-material cathode composed of mesoporous graphene and layered LiNi_(1/3)Co_(1/3)Mn_(1/3)O_(2)(NCM) were studied via in situ X-ray diffraction(XRD).During different C-rate charge-discharge test at the voltage range of 2.5-4.1 V,the composite cathode of NCM-graphene(NCM-G) reveals better rate performances than pure NCM cathode.The NCM-G composite electrode displays a higher rate capability of 76.7 mAh·g^(-1) at 5 C rate,compared to the pure NCM cathode of 69.8 mAh·g^(-1)discharge capacity.The in situ XRD results indicate that a reversible phase transition from hexagonal H1 to hexagonal H2 occurs in layered NCM material during 1 C chargedischarge process.With the current increasing to 2 C/5 C,the structure of layered NCM material for both electrodes reveals few changes during charge and discharge processes,which indicates the less utilization of NCM component at high C-rates.Hence,the improved rate performance for bi-material electrode is attributed to the highly conductive mesoporous graphene and the synergistic effect of mesoporous graphene and NCM material.展开更多
Li[Ni0.6Co0.2Mn0.2]O2(NCM622)is one of the best commercialized cathodes in the battery field.However,poor cyclability at relatively high temperature hinders its multiple usages.Here,operando tests were performed to in...Li[Ni0.6Co0.2Mn0.2]O2(NCM622)is one of the best commercialized cathodes in the battery field.However,poor cyclability at relatively high temperature hinders its multiple usages.Here,operando tests were performed to investigate the phase transitions and electron/ion transfer process of lavered NCM622 at 25 and 55℃.The identified spinel structure resulting in the poor cyclability at 55℃ guides the commercialization of batteries at high temperature.展开更多
基金supported by the National Key Research and Development Program of China(Nos.2020YFB1505800 and 2019YFA0705400)the National Natural Science Foundation of China(NSFC)(Nos.201925404,21902137,22005130,and 22021001)+1 种基金the Fundamental Research Funds for the Central Universities(Nos.20720210069 and 20720210043)the Science and Technology Planning Project of Fujian Province(No.2019Y4001).
文摘As state-of-the-art electrochemical energy conversion and storage(EECS)techniques,fuel cells and rechargeable batteries have achieved great success in the past decades.However,modern societies’ever-growing demand in energy calls for EECS devices with high efficiency and enhanced performance,which mainly rely on the rational design of catalysts,electrode materials,and electrode/electrolyte interfaces in EESC,based on in-deep and comprehensive mechanistic understanding of the relevant electrochemical redox reactions.Such an understanding can be realized by monitoring the dynamic redox reaction processes under realistic operation conditions using in situ techniques,such as in situ Raman,Fourier transform infrared(FTIR),and X-ray diffraction(XRD)spectroscopy.These techniques can provide characteristic spectroscopic information of molecules and/or crystals,which are sensitive to structure/phase changes resulted from different electrochemical working conditions,hence allowing for intermediates identification and mechanisms understanding.This review described and summarized recent progress in the in situ studies of fuel cells and rechargeable batteries via Raman,FTIR,and XRD spectroscopy.The applications of these in situ techniques on typical electrocatalytic electrooxidation reaction and oxygen reduction reaction(ORR)in fuel cells,on representative high capacity and/or resource abundance cathodes and anodes,and on the solid electrolyte interface(SEI)in rechargeable batteries are discussed.We discuss how these techniques promote the development of novel EECS systems and highlight their critical importance in future EECS research.
基金Supported by the National Natural Science Foundation of China(Nos.51571118 and 51371098)Natural Science Foundation of Jiangsu Province(No.BK20141308)
文摘The aluminum matrix composites(AlB2+a-Al2O3)/Al were fabricated by in situ reaction synthesis from an Al-B2 O3 system. The reaction pathways, apparent activation energies and tensile properties were analyzed by using differential scanning calorimetry(DSC), X-ray diffraction(XRD), scanning electron microscopy(SEM), and equipped energy dispersive spectroscopy(EDS). The results showed that there are two-step reactions in the Al-B2 O3 system. The first-step is 15 Al+7 B2 O3→7 aAl2O3+AlB12+2 B and the second-step is 2 B+AlB12+6 Al→7 AlB2. Their corresponding apparent activation energies are 352 and 444 kJ/mol, respectively. The tensile strength and elongation rate of the composites are 190.5 MPa and 6.6%, respectively.Compared with ordinary aluminum base material, the performance is superior. There are many dimple and cracked a-Al2O3 reinforcements in tensile fracture surface layer.
基金Funded by National Natural Science Foundation of China(Nos.51571118 and 51371098)Natural Science Foundation of Jiangsu Province(No.BK20141308)
文摘Titanium matrix composites reinforced with a-Al2O3 and TiB2 particles were fabricated by in situ synthesis from a Ti-Al-B2O3 system. The reaction processes and microstructure were analyzed by using differential scanning calorimetry（DSC）, scanning electron microscopy（SEM） and X-ray diffraction（XRD）. The results showed that the reactions in the Ti-Al-B2O3 system can occur spontaneously and consist of three steps： 1） 15 Al ＋ 7B2O3 → 7α-Al2O3 ＋ AlB12 ＋ 2B; 2） 14 B ＋ 2Al → AlB12 ＋ AlB2 and 3） 7Ti ＋ AlB（12） ＋ AlB2 → 7TiB2 ＋ 2Al. The final reinforcements were composed of α-Al2O3 and TiB2 particles, which were uniformly distributed in the titanium matrix.
基金Thanks for the financial support from the National Nature Science Foundation of China （No. 21471091）, Academy of Sciences large apparatus United Fund （No. 11179043）, the Fundamental Research Funds of Shandong University （No. 2015JC007）, and the Taishan Scholar Project of Shandong Province （No. ts201511004）.
基金financially supported by the National Natural Science Foundation of China(Nos.51822706 and51777200)the Beijing Municipal and Technology Commission(No.Z181100000118006)。
文摘Layered LiMO_(2)(M=Ni,Co,and Mn) is a type of promising cathode materials for high energy density and high work voltage lithium-ion batteries.However,the poor rate performance and low power density hinder its further applications.The capacity fade is related to the structural transformation in the layered LiMO_(2).In this work,the structural changes of bi-material cathode composed of mesoporous graphene and layered LiNi_(1/3)Co_(1/3)Mn_(1/3)O_(2)(NCM) were studied via in situ X-ray diffraction(XRD).During different C-rate charge-discharge test at the voltage range of 2.5-4.1 V,the composite cathode of NCM-graphene(NCM-G) reveals better rate performances than pure NCM cathode.The NCM-G composite electrode displays a higher rate capability of 76.7 mAh·g^(-1) at 5 C rate,compared to the pure NCM cathode of 69.8 mAh·g^(-1)discharge capacity.The in situ XRD results indicate that a reversible phase transition from hexagonal H1 to hexagonal H2 occurs in layered NCM material during 1 C chargedischarge process.With the current increasing to 2 C/5 C,the structure of layered NCM material for both electrodes reveals few changes during charge and discharge processes,which indicates the less utilization of NCM component at high C-rates.Hence,the improved rate performance for bi-material electrode is attributed to the highly conductive mesoporous graphene and the synergistic effect of mesoporous graphene and NCM material.
基金Supported by the Project of the Foshan Xianhu Laboratory of the Advanced Energy Science and Technology Guangdong Laboratory,China(No.XH12020-003)the National Natural Science Foundation of China(No.51521001)+1 种基金the National Key Research and Development Program of China(No.2016YFA0202603)the Fundamental Rescarch Funds for the Central Universities of China(No.WUT:205201019)。
文摘Li[Ni0.6Co0.2Mn0.2]O2(NCM622)is one of the best commercialized cathodes in the battery field.However,poor cyclability at relatively high temperature hinders its multiple usages.Here,operando tests were performed to investigate the phase transitions and electron/ion transfer process of lavered NCM622 at 25 and 55℃.The identified spinel structure resulting in the poor cyclability at 55℃ guides the commercialization of batteries at high temperature.
