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T. Miyajima - One of the best experts on this subject based on the ideXlab platform.

  • thermal Deterioration Mechanism of cofeb pdptmn spin valves
    Journal of Applied Physics, 1999
    Co-Authors: Kenichi Aoshima, Hitoshi Kanai, Junichi Kane, T. Miyajima
    Abstract:

    We clarified the Mechanism of thermal Deterioration that occurs in the CoFeB/PdPtMn spin-valve films at temperatures above 310 °C. Two kinds of CoFeB spin-valve film, Ta/NiFe/CoFeB/Cu/CoFeB/PdPtMn/Ta (B:0–3 at. %) and Ta/NiFe/CoFeB/Cu/CoFeB/FeMn/Ta (B:2 at. %), were prepared and annealed in a magnetic field. For the PdPtMn spin-valve samples, the magnetoresistance (MR) output decreased after annealing at a temperature above 330 °C and there was an increase in the interlayer coupling field of free and pin layers (Hin). There was no large change in the sheet resistance for annealing below 330 °C. For CoFe/PdPtMn(no B) spin valves, the MR output decreased during annealing at more than 310 °C and there was an increase of Hin. An addition of only 1 at. % of boron into the free and pinned layers is sufficient to obtain thermal stability. For the CoFeB/FeMn spin-valve samples, the MR output decreased for annealing above 280 °, the sheet resistance increased, and the Hin value did not change for annealing below 3...

  • Thermal Deterioration Mechanism of CoFeB/PdPtMn spin valves
    Journal of Applied Physics, 1999
    Co-Authors: Kenichi Aoshima, Hitoshi Kanai, Junichi Kane, T. Miyajima
    Abstract:

    We clarified the Mechanism of thermal Deterioration that occurs in the CoFeB/PdPtMn spin-valve films at temperatures above 310 °C. Two kinds of CoFeB spin-valve film, Ta/NiFe/CoFeB/Cu/CoFeB/PdPtMn/Ta (B:0–3 at. %) and Ta/NiFe/CoFeB/Cu/CoFeB/FeMn/Ta (B:2 at. %), were prepared and annealed in a magnetic field. For the PdPtMn spin-valve samples, the magnetoresistance (MR) output decreased after annealing at a temperature above 330 °C and there was an increase in the interlayer coupling field of free and pin layers (Hin). There was no large change in the sheet resistance for annealing below 330 °C. For CoFe/PdPtMn(no B) spin valves, the MR output decreased during annealing at more than 310 °C and there was an increase of Hin. An addition of only 1 at. % of boron into the free and pinned layers is sufficient to obtain thermal stability. For the CoFeB/FeMn spin-valve samples, the MR output decreased for annealing above 280 °, the sheet resistance increased, and the Hin value did not change for annealing below 3...

Kang Yan - One of the best experts on this subject based on the ideXlab platform.

  • High-Temperature Storage Deterioration Mechanism of Cylindrical 21700-Type Batteries Using Ni-Rich Cathodes under Different SOCs.
    ACS applied materials & interfaces, 2021
    Co-Authors: Qiyu Zhang, Jun Tian, Lai Chen, Liying Bao, Duanyun Cao, Kang Yan
    Abstract:

    The safety and energy density of lithium-ion batteries (LIBs) are important concerns. The use of high-capacity cathode materials, such as Ni-rich cathodes, can greatly improve the energy density of LIBs, but it also brings some safety hazards. Cylindrical 21700-type batteries using Ni-rich cathodes were employed here to investigate their high-temperature storage Deterioration Mechanism under different states of charge (SOCs). Electrolyte decomposition was identified as the main problem. It can be worsened by elevated storage temperatures and battery SOCs, with the latter having a more significant influence. Specifically, the decomposition of the LiPF6 solute and the carbonate solvent will induce hydrofluoric acid (HF) formation and solid-electrolyte interphase (SEI) film regeneration, respectively. HF erosion will aggravate the dissolution of transition metal ions and structural degradation of cathode materials, while the destruction/regeneration of SEI films will consume active lithium and hinder Li+ diffusion at the anode side. Besides, the self-discharge behavior will also enlarge the graphite layer spacing, thus decreasing the graphitization degree of graphite anodes and causing anode failure. These findings will aid in the development of strategies for improving the safety of LIBs with high energy density.

  • high temperature storage Deterioration Mechanism of cylindrical 21700 type batteries using ni rich cathodes under different socs
    ACS Applied Materials & Interfaces, 2021
    Co-Authors: Qiyu Zhang, Jun Tian, Lai Chen, Liying Bao, Duanyun Cao, Kang Yan, Shi Chen
    Abstract:

    The safety and energy density of lithium-ion batteries (LIBs) are important concerns. The use of high-capacity cathode materials, such as Ni-rich cathodes, can greatly improve the energy density of...

Qiyu Zhang - One of the best experts on this subject based on the ideXlab platform.

  • High-Temperature Storage Deterioration Mechanism of Cylindrical 21700-Type Batteries Using Ni-Rich Cathodes under Different SOCs.
    ACS applied materials & interfaces, 2021
    Co-Authors: Qiyu Zhang, Jun Tian, Lai Chen, Liying Bao, Duanyun Cao, Kang Yan
    Abstract:

    The safety and energy density of lithium-ion batteries (LIBs) are important concerns. The use of high-capacity cathode materials, such as Ni-rich cathodes, can greatly improve the energy density of LIBs, but it also brings some safety hazards. Cylindrical 21700-type batteries using Ni-rich cathodes were employed here to investigate their high-temperature storage Deterioration Mechanism under different states of charge (SOCs). Electrolyte decomposition was identified as the main problem. It can be worsened by elevated storage temperatures and battery SOCs, with the latter having a more significant influence. Specifically, the decomposition of the LiPF6 solute and the carbonate solvent will induce hydrofluoric acid (HF) formation and solid-electrolyte interphase (SEI) film regeneration, respectively. HF erosion will aggravate the dissolution of transition metal ions and structural degradation of cathode materials, while the destruction/regeneration of SEI films will consume active lithium and hinder Li+ diffusion at the anode side. Besides, the self-discharge behavior will also enlarge the graphite layer spacing, thus decreasing the graphitization degree of graphite anodes and causing anode failure. These findings will aid in the development of strategies for improving the safety of LIBs with high energy density.

  • high temperature storage Deterioration Mechanism of cylindrical 21700 type batteries using ni rich cathodes under different socs
    ACS Applied Materials & Interfaces, 2021
    Co-Authors: Qiyu Zhang, Jun Tian, Lai Chen, Liying Bao, Duanyun Cao, Kang Yan, Shi Chen
    Abstract:

    The safety and energy density of lithium-ion batteries (LIBs) are important concerns. The use of high-capacity cathode materials, such as Ni-rich cathodes, can greatly improve the energy density of...

Kenichi Aoshima - One of the best experts on this subject based on the ideXlab platform.

  • thermal Deterioration Mechanism of cofeb pdptmn spin valves
    Journal of Applied Physics, 1999
    Co-Authors: Kenichi Aoshima, Hitoshi Kanai, Junichi Kane, T. Miyajima
    Abstract:

    We clarified the Mechanism of thermal Deterioration that occurs in the CoFeB/PdPtMn spin-valve films at temperatures above 310 °C. Two kinds of CoFeB spin-valve film, Ta/NiFe/CoFeB/Cu/CoFeB/PdPtMn/Ta (B:0–3 at. %) and Ta/NiFe/CoFeB/Cu/CoFeB/FeMn/Ta (B:2 at. %), were prepared and annealed in a magnetic field. For the PdPtMn spin-valve samples, the magnetoresistance (MR) output decreased after annealing at a temperature above 330 °C and there was an increase in the interlayer coupling field of free and pin layers (Hin). There was no large change in the sheet resistance for annealing below 330 °C. For CoFe/PdPtMn(no B) spin valves, the MR output decreased during annealing at more than 310 °C and there was an increase of Hin. An addition of only 1 at. % of boron into the free and pinned layers is sufficient to obtain thermal stability. For the CoFeB/FeMn spin-valve samples, the MR output decreased for annealing above 280 °, the sheet resistance increased, and the Hin value did not change for annealing below 3...

  • Thermal Deterioration Mechanism of CoFeB/PdPtMn spin valves
    Journal of Applied Physics, 1999
    Co-Authors: Kenichi Aoshima, Hitoshi Kanai, Junichi Kane, T. Miyajima
    Abstract:

    We clarified the Mechanism of thermal Deterioration that occurs in the CoFeB/PdPtMn spin-valve films at temperatures above 310 °C. Two kinds of CoFeB spin-valve film, Ta/NiFe/CoFeB/Cu/CoFeB/PdPtMn/Ta (B:0–3 at. %) and Ta/NiFe/CoFeB/Cu/CoFeB/FeMn/Ta (B:2 at. %), were prepared and annealed in a magnetic field. For the PdPtMn spin-valve samples, the magnetoresistance (MR) output decreased after annealing at a temperature above 330 °C and there was an increase in the interlayer coupling field of free and pin layers (Hin). There was no large change in the sheet resistance for annealing below 330 °C. For CoFe/PdPtMn(no B) spin valves, the MR output decreased during annealing at more than 310 °C and there was an increase of Hin. An addition of only 1 at. % of boron into the free and pinned layers is sufficient to obtain thermal stability. For the CoFeB/FeMn spin-valve samples, the MR output decreased for annealing above 280 °, the sheet resistance increased, and the Hin value did not change for annealing below 3...

Feiyu Kang - One of the best experts on this subject based on the ideXlab platform.

  • Deterioration Mechanism of LiNi0.8Co0.15Al0.05O2/graphite–SiOx power batteries under high temperature and discharge cycling conditions
    Journal of Materials Chemistry A, 2018
    Co-Authors: Cheng Liu, Kun Qian, Danni Lei, Feiyu Kang
    Abstract:

    LiNi0.8Co0.15Al0.05O2 and graphite–SiOx composites have been considered as potential cathode and anode materials for next-generation batteries due to their high specific capacity. It is significant to illustrate the degradation Mechanism of NCA/graphite–SiOx power batteries under various conditions for their wide application. In this study, 10 A h NCA/graphite–SiOx power batteries were prepared and their Deterioration Mechanism at different temperatures (25 °C, 45 °C, and 65 °C) and discharge rates (1C and 3C) was systematically investigated. The results show that the batteries experienced 15.02% and 52.17% capacity loss after 400 cycles at 25 °C and 45 °C at 1C, respectively, and 21.94% after 400 cycles at a discharge rate of 3C. The capacity loss is as high as 79.93% after only 150 cycles at 65 °C and 1C. The long-term cycling behavior of the batteries is strongly affected by temperature, whereas it is negligibly affected by the discharge rate. The reversible lithium loss from the NCA cathode and structure decay of graphite–SiOx are responsible for the capacity loss of the battery. Many lithium alkyl carbonate (Li2CO3 and ROCO2Li), fluorophosphate (LixPOyFz and LixPFy), LiF, and oxygenated species are observed on the surface of graphite–SiOx due to the decomposition of the electrolyte at high temperatures. These species are deposited on the separator and thus block the pores and hinder ion transport; this results in a great increase of battery resistance and sudden loss of battery capacity.

  • Deterioration Mechanism of lini0 8co0 15al0 05o2 graphite siox power batteries under high temperature and discharge cycling conditions
    Journal of Materials Chemistry, 2018
    Co-Authors: Cheng Liu, Kun Qian, Danni Lei, Feiyu Kang
    Abstract:

    LiNi0.8Co0.15Al0.05O2 and graphite–SiOx composites have been considered as potential cathode and anode materials for next-generation batteries due to their high specific capacity. It is significant to illustrate the degradation Mechanism of NCA/graphite–SiOx power batteries under various conditions for their wide application. In this study, 10 A h NCA/graphite–SiOx power batteries were prepared and their Deterioration Mechanism at different temperatures (25 °C, 45 °C, and 65 °C) and discharge rates (1C and 3C) was systematically investigated. The results show that the batteries experienced 15.02% and 52.17% capacity loss after 400 cycles at 25 °C and 45 °C at 1C, respectively, and 21.94% after 400 cycles at a discharge rate of 3C. The capacity loss is as high as 79.93% after only 150 cycles at 65 °C and 1C. The long-term cycling behavior of the batteries is strongly affected by temperature, whereas it is negligibly affected by the discharge rate. The reversible lithium loss from the NCA cathode and structure decay of graphite–SiOx are responsible for the capacity loss of the battery. Many lithium alkyl carbonate (Li2CO3 and ROCO2Li), fluorophosphate (LixPOyFz and LixPFy), LiF, and oxygenated species are observed on the surface of graphite–SiOx due to the decomposition of the electrolyte at high temperatures. These species are deposited on the separator and thus block the pores and hinder ion transport; this results in a great increase of battery resistance and sudden loss of battery capacity.