Ni‐rich layered LiNixCoyMn1−x−yO2 (LNCM) with Ni content over >90% is considered as a promising lithium ion battery (LIB) cathode, attributed by its low cost and high practical capacity. However, ...Ni‐rich LNCM inevitably suffers rapid capacity fading at a high state of charge due to the mechanochemical breakdown; in particular, the microcrack formation has been regarded as one of the main culprits for Ni‐rich layered cathode failure. To address these issues, Ni‐rich layered cathodes with a textured microstructure are developed by phosphorous and boron doping. Attributed by the textured morphology, both phosphorous‐ and boron‐doped cathodes suppress microcrack formation and show enhanced cycle stability compared to the undoped cathode. However, there exists a meaningful capacity retention difference between the doped cathodes. By adapting the various analysis techniques, it is shown that the boron‐doped Ni‐rich layered cathode displays better cycle stability not only by its ability to suppress microcracks during cycling but also by its primary particle morphology that is reluctant to oxygen evolution. The present work reveals that not only restraint of particle cracks but also suppression of oxygen release by developing the oxygen stable facets is important for further improvements in state‐of‐the‐art Li ion battery Ni‐rich layered cathode materials.
Herein, the effect of boron doping on oxygen stability in LiNi0.92Co0.04Mn0.04O2 (LNCM) lithium ion battery cathodes is systematically investigated using various measurements. The boron‐doped LNCM produces the textured microstructure with more oxygen stabilized facets, thus not only aiding in restraining the particle cracks but also effectively suppressing the oxygen evolution to improve the cycle stability.
Full text
Available for:
BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Phosphorus‐rich 6‐MnP4 nanoparticles are synthesized via high energy mechanical milling (HEMM) and their electrochemical properties as an anode for lithium‐ion batteries (LIBs) and sodium‐ion ...batteries (SIBs) are investigated focusing on the electrochemical activity and reaction mechanism. The 6‐MnP4 nanoparticles with a triclinic structure (P‐1) are successfully synthesized by HEMM and they are composed of 5 to 20 nm‐sized crystallites. During the lithiation process, the MnP4 phase undertakes the sequential alloying (MnP4 + 7 Li+ + 7 e− → Li7MnP4) and conversion (Li7MnP4 + 5 Li+ + 5 e− → Mn0 + 4 Li3P) reactions. On the other hand, the MnP4 nanoparticles are directly converted to Mn0 and Na3P without the formation of an intermediate Na–Mn–P alloy phase during sodiation process. The MnP4 electrode shows high initial discharge and charge capacity (1876 and 1615 mAh g−1 for LIBs, and 1234 and 1028 mAh g−1 for SIBs) and high initial Coulombic efficiency (86% for LIBs and 83% for SIBs), indicating a promising candidate for high capacity anodes. In addition, the long‐term cyclability and high rate capability of MnP4 can be further improved through the formation of MnP4/graphene nanocomposites and vanadium substituted Mn0.75V0.25P4 solid solutions.
Phosphorus‐rich MnP4 nanoparticles are introduced as high capacity anodes for both lithium‐ion batteries (LIBs) and sodium‐ion batteries (SIBs). The MnP4 electrode shows a high electrochemical activity and a reversible capacity of 1615 and 1028 mAh g–1 respectively, with high initial coulombic efficiency of 86% and 83% for both LIBs and SIBs respectively, indicating a promising candidate for high capacity anodes.
Full text
Available for:
FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
NCM‐based lithium layered oxides (LiNi1–x–yCoxMnyO2) have become prevalent cathode materials in state‐of‐the‐art lithium‐ion batteries. Higher energy densities can be achieved in these materials by ...systematically increasing the nickel content; however, this approach commonly results in inferior cycle stability. The poor cycle retention of high‐nickel NCM cathodes is generally attributed to chemo‐mechanical degradation (e.g., intergranular microcracks), vulnerability to oxygen‐gas evolution, and the accompanying rocksalt phase formation via cation mixing. Herein, the feasibility of doping strategies is examined to mitigate these issues and effective dopants for high‐nickel NCM cathodes are theoretically identified through a stepwise pruning process based on density functional theory calculations. Specifically, a sequential three‐step screening process is conducted for 38 potential dopants to scrutinize their effectiveness in mitigating chemo‐mechanical lattice stress, oxygen evolution, and cation mixing at charged states. Using this process, promising dopant species are selected rationally and a silicon‐doped LiNi0.92Co0.04Mn0.04O2 cathode is synthesized, which exhibits suppressed lattice expansion/contraction, fewer intergranular microcracks, and reduced rocksalt formation on the surface compared with its undoped counterpart, leading to superior electrochemical performance. Moreover, a comprehensive map of dopants regarding their potential applicability is presented, providing rational guidance for an effective doping strategy for high‐nickel NCM cathodes.
Although the doping strategy in high‐nickel NCM materials is a simple and effective method to improve the electrochemical performance, a dopant selection map revealing the unique properties of the dopant has not been presented yet. Here, a systematic stepwise pruning process combined with experimental validation is applied, and a dopant selection map is proposed, offering adequate guidance on doping strategies for high‐nickel NCM cathode materials.
Full text
Available for:
FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
SnO2–Fe2O3–C triple-shell hollow nano-spheres are fabricated by combining the template-based sol–gel coating technique and hydrothermal method, and their electrochemical performance as an anode for ...lithium ion batteries (LIBs) is investigated, particularly focusing on their structural stability and long term cyclability. To accomplish this, same-sized SnO2 solid spheres, Fe2O3 solid spheres, SnO2–Fe2O3 solid spheres, SnO2–Fe2O3–C solid spheres, SnO2 hollow spheres and SnO2–Fe2O3 hollow spheres are prepared in a similar manner and their cyclic performances are compared. It is found that the as-synthesized 80 nm-sized SnO2–Fe2O3-C hollow sphere electrode exhibits an extraordinary reversible capacity (1100 mA h g−1 after 100 cycles at 200 mA g−1) and excellent long cycle stability (475 mA h g−1 after 1000 cycles at 2000 mA g−1), which are attributed to the Fe-enhanced reversibility of the Li2O reduction reaction, high electrical conductivity, high Li+ ion mobility, and structural stability of the carbon-coated triple-shell hollow spheres.
In the pandemic era, the development of high‐performance indoor air quality monitoring sensors has become more critical than ever. NO2 is one of the most toxic gases in daily life, which induces ...severe respiratory diseases. Thus, the real‐time monitoring of low concentrations of NO2 is highly required. Herein, a visible light‐driven ultrasensitive and selective chemoresistive NO2 sensor is presented based on sulfur‐doped SnO2 nanoparticles. Sulfur‐doped SnO2 nanoparticles are synthesized by incorporating l‐cysteine as a sulfur doping agent, which also increases the surface area. The cationic and anionic doping of sulfur induces the formation of intermediate states in the band gap, highly contributing to the substantial enhancement of gas sensing performance under visible light illumination. Extraordinary gas sensing performances such as the gas response of 418 to 5 ppm of NO2 and a detection limit of 0.9 ppt are achieved under blue light illumination. Even under red light illumination, sulfur‐doped SnO2 nanoparticles exhibit stable gas sensing. The endurance to humidity and long‐term stability of the sensor are outstanding, which amplify the capability as an indoor air quality monitoring sensor. Overall, this study suggests an innovative strategy for developing the next generation of electronic noses.
A strategy for ultrasensitive and selective detection of NO2 based on S‐doped SnO2 nanoparticles by visible light illumination is suggested. Cationic and anionic sulfur doping improve the surface area and light absorption. The gas sensing performance at room temperature is significantly improved by S doping and visible light illumination.
Full text
Available for:
BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
The realization of high performance Ni-rich layered cathodes remains a challenge because of the multiple degradation factors that concurrently operate during battery cycling. In particular, depletion ...of oxygen charge and consequent lattice-oxygen instability at deep charge state accelerate the subsequent chemomechanical degradation mechanisms. Among the proposed methodologies, doping has proven to be effective in enhancing the cathode cycle life by stabilizing the layered structure. Herein, we achieved the electrochemically stabilized Ni-rich LiNi
0.92
Co
0.04
Mn
0.04
O
2
through Zr doping, resulting in a 15% increase of the capacity retention after 100 cycles. In-depth investigations are conducted to unveil the effects of Zr doping on the layered cathode, and in particular, the critical role of Zr doping on the lattice oxygen stability is systematically studied. By combining state-of-the-art magnetometer characterization, X-ray analysis, and first-principles calculation, we reveal that Zr doping positively contributes the to lattice oxygen stability by alleviating the oxygen charge loss at deep charge, thereby improving the cathode electrochemical reversibility. Our findings provide an insight into the Zr doping mechanism and help to design Ni-rich layered oxides for future applications.
The suppression of oxygen oxidation is proposed as the critical origin of Zr doping on LiNi
0.92
Co
0.04
Mn
0.04
O
2
layered oxide LIB cathode material.
The nucleation and growth behavior of Cu nanoparticles during thermal heating of Cu(II) complex inks for printed Cu metallization were investigated, particularly focusing on the effects of the amine ...concentration on the microstructure evolution and electrical conductivity. Herein, the dual effects of hexylamine as a reducing agent dissociating the carboxyl group from the precursor and a capping agent hindering the subsequent growth of Cu nuclei were confirmed. On the basis of such dual effects of amine, the sufficient complexation of the Cu(II) precursor with a high amine concentration in the ink led to the single-route growth of Cu nanoparticles during thermal heating, which resulted in the dense film with a narrow particle size distribution exhibiting a high electrical conductivity. The electrical conductivity of the film could be further enhanced by a reducing atmosphere with formic acid. Significantly, the understanding of the ink chemistry and the nucleation and growth kinetics in the metal ion complex or metal–organic decomposition (MOD) ink can provide the design rules for the formulation of the solution-type inks to control the microstructure of printed metallization.
Full text
Available for:
IJS, KILJ, NUK, PNG, UL, UM
Tin phosphide (Sn4P3) has emerged as an anode for sodium ion batteries (SIBs) due to its high reversible capacity and low redox potential. Sn4P3 shows a synergistic Na-storage reaction to form ...Na15Sn4 and Na3P, but suffers from large volume expansion and Sn aggregation during the Na+ insertion–extraction resulting in poor cycle stability. Sn4P3 has also been considered a promising anode material for lithium ion batteries (LIBs), but very limited studies have been performed. Herein, core–shell Sn4P3–C (carbon) composite nanospheres are fabricated by carbonization/reduction and phosphorization of SnO2–GCP (glucose-derived, carbon-rich polysaccharide) nanospheres. The size of Sn4P3–C nanospheres is controlled to optimize their electrochemical performance as long-term stable anodes for SIBs and LIBs. Among them, the 140 nm-sized Sn4P3–C nanosphere electrode exhibits high reversible capacity, high rate capability, and ultra-long cycle stability as an anode for both SIBs and LIBs, delivering a high capacity of 420 mA h g−1 after 2000 cycles (SIBs) and 440 mA h g−1 after 500 cycles (LIBs) at a high current density of 2000 mA g−1. Hence, the Sn4P3–C nanospheres can be considered as a promising anode material for next generation SIBs and LIBs.
Silicon (Si) is a promising anode candidate for next generation lithium ion batteries (LIBs) due to its high theoretical specific capacity, low discharge potential, and abundance in nature. However, ...the large volume change during the lithiation/delithiation process causes pulverization and electrical connectivity loss. To resolve the issues associated with Si anodes, composites with graphene or its derivatives have been extensively studied, and a conformal graphitic carbon coating with well-defined internal void spaces is reported to be very effective to improve the cycle life and coulombic efficiency of Si anodes. Here, we develop a method to encapsulate Si nanoparticles with nano-porous N-doped graphitic carbon through Fe 3+ -mediated polymerization of dopamine, followed by subsequent carbonization and acid treatment and investigate their electrochemical performance as an anode for LIBs. Indeed, the as-synthesized 50 nm-sized Si nanoparticles with a graphitic carbon shell of 10 nm thickness exhibit excellent high rate capability and long cycle stability, delivering a high capacity of 1056 mA h g −1 after 800 cycles at a high current density of 2000 mA g −1 , which is attributed to the high electrical conductivity, high Li + ion mobility, and structural stability of nano-pore embedded, N-doped graphitic carbon coated Si (PGC@Si). For the feasibility of practical use, a full cell consisting of the as-synthesized PGC@Si anode and commercially available LiNi 0.6 Co 0.2 O 2 (NCM) cathode is assembled and its electrochemical performance is examined.
Meso-porous Si-coated carbon nanotube （CNT） composite powders were prepared by combining a sol-gel method and the magnesiothermic reduction process. Meso-porous Si-coated CNT electrodes exhibit ...excellent cycle and rate performances as anodes in Li-ion batteries （LIBs）, which can be attributed to the efficient accommodation of volume change from meso-porous Si structure and the enhanced electrical conductivity from CNT core. This simple synthesis and subsequent reduction process provide a scalable route for the large-scale production of Si-C composite nanostructures, which can be utilized in a variety of applications, such as in photocatalysis, photoelectrochemical cells （PECs）, and LIBs.
Full text
Available for:
EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
PDF
