In this study, Li(Ni1/3Mn1/3Co1/3)O2 (NMC333) and Li(Ni0.5Mn0.3Co0.2)O2 (NMC532) have been subjec... more In this study, Li(Ni1/3Mn1/3Co1/3)O2 (NMC333) and Li(Ni0.5Mn0.3Co0.2)O2 (NMC532) have been subjected to a phosphoric acid (H3PO4) solution treatment to form a thin Li3PO4 coating on their surfaces. The Li3PO4 coating formed is found to be very potent in enhancing the specific capacity of the first discharge as well as the rate capability and capacity retention in the subsequent charge/discharge cycles for both NMC333 and NMC532. The specific capacity of the first discharge for NMC532 has been increased drastically from ∼160 mA h g−1 for pristine NMC532 to ∼250 mA h g−1 for Li3PO4-coated counterpart at 0.1C and such a large capacity enhancement is retained throughout the subsequent cycles at 1C. The final specific capacity of Li3PO4-coated NMC532 is 187 mA h g−1 after 100 cycles at 1C, whereas the corresponding value of pristine NMC532 is only 50 mA h g−1. The rate capability has also been improved significantly with Li3PO4-coated NMC532 exhibiting ∼150 mA h g−1 capacity at 6C while pristine NMC532 showing zero capacity. Similar improvements have also been achieved with NMC333. These results demonstrate that the H3PO4 treatment is a facile and general method to improve the electrochemical properties of NMCs with different compositions and can be utilized for practical applications.
Li3BN2 is a known lithium ion conductor and has been predicted lately to be a high capacity catho... more Li3BN2 is a known lithium ion conductor and has been predicted lately to be a high capacity cathode for Li-ion batteries (Németh, 2014) [4]. In this study, we have investigated the synthesis of Li3BN2 through reactions between Li3N and h-BN powders. Effects of the reaction temperature, holding time and reaction atmosphere on the formation of Li3BN2 have been evaluated. Rietveld refinement of X-ray diffraction patterns of all powders has been performed to quantify the percentage of each phase. The results show that both the reaction temperature and holding time affect strongly the percentage of Li3BN2 in the reaction product. Furthermore, a trace amount of oxygen in the reaction atmosphere can negatively impact the purity of the reaction product because of the high affinity of Li3BN2 towards oxidation.
Li3BN2 is a known lithium ion conductor and has been predicted lately to be a high capacity catho... more Li3BN2 is a known lithium ion conductor and has been predicted lately to be a high capacity cathode for Li-ion batteries (J. Chem. Phys., 141, 054711, 2014). In this study, we have investigated the synthesis of Li3BN2 through liquid-solid and solid-solid reactions between Li3N and h-BN. Effects of the reaction temperature, holding time and reaction atmosphere on the formation of Li3BN2 have been evaluated. Rietveld refinement of X-ray diffraction patterns of all powders has been performed to quantify the percentage of each phase. The results show that both the reaction temperature and holding time affect strongly the percentage of Li3BN2 in the reaction product. Furthermore, a trace amount of oxygen in the reaction atmosphere can negatively impact the purity of the reaction product because of the high affinity of the reactants and products to oxidation.
In this study, Li(Ni1/3Mn1/3Co1/3)O2 (NMC333) and Li(Ni0.5Mn0.3Co0.2)O2 (NMC532) have been subjec... more In this study, Li(Ni1/3Mn1/3Co1/3)O2 (NMC333) and Li(Ni0.5Mn0.3Co0.2)O2 (NMC532) have been subjected to a phosphoric acid (H3PO4) solution treatment to form a thin Li3PO4 coating on their surfaces. The Li3PO4 coating formed is found to be very potent in enhancing the specific capacity of the first discharge as well as the rate capability and capacity retention in the subsequent charge/discharge cycles for both NMC333 and NMC532. The specific capacity of the first discharge for NMC532 has been increased drastically from ∼160 mA h g−1 for pristine NMC532 to ∼250 mA h g−1 for Li3PO4-coated counterpart at 0.1C and such a large capacity enhancement is retained throughout the subsequent cycles at 1C. The final specific capacity of Li3PO4-coated NMC532 is 187 mA h g−1 after 100 cycles at 1C, whereas the corresponding value of pristine NMC532 is only 50 mA h g−1. The rate capability has also been improved significantly with Li3PO4-coated NMC532 exhibiting ∼150 mA h g−1 capacity at 6C while pristine NMC532 showing zero capacity. Similar improvements have also been achieved with NMC333. These results demonstrate that the H3PO4 treatment is a facile and general method to improve the electrochemical properties of NMCs with different compositions and can be utilized for practical applications.
Li3BN2 is a known lithium ion conductor and has been predicted lately to be a high capacity catho... more Li3BN2 is a known lithium ion conductor and has been predicted lately to be a high capacity cathode for Li-ion batteries (Németh, 2014) [4]. In this study, we have investigated the synthesis of Li3BN2 through reactions between Li3N and h-BN powders. Effects of the reaction temperature, holding time and reaction atmosphere on the formation of Li3BN2 have been evaluated. Rietveld refinement of X-ray diffraction patterns of all powders has been performed to quantify the percentage of each phase. The results show that both the reaction temperature and holding time affect strongly the percentage of Li3BN2 in the reaction product. Furthermore, a trace amount of oxygen in the reaction atmosphere can negatively impact the purity of the reaction product because of the high affinity of Li3BN2 towards oxidation.
Li3BN2 is a known lithium ion conductor and has been predicted lately to be a high capacity catho... more Li3BN2 is a known lithium ion conductor and has been predicted lately to be a high capacity cathode for Li-ion batteries (J. Chem. Phys., 141, 054711, 2014). In this study, we have investigated the synthesis of Li3BN2 through liquid-solid and solid-solid reactions between Li3N and h-BN. Effects of the reaction temperature, holding time and reaction atmosphere on the formation of Li3BN2 have been evaluated. Rietveld refinement of X-ray diffraction patterns of all powders has been performed to quantify the percentage of each phase. The results show that both the reaction temperature and holding time affect strongly the percentage of Li3BN2 in the reaction product. Furthermore, a trace amount of oxygen in the reaction atmosphere can negatively impact the purity of the reaction product because of the high affinity of the reactants and products to oxidation.
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