Modified Coprecipitation Synthesis of Mesostructure-Controlled Li-Rich Layered Oxides for Minimizing Voltage Degradation

Modified carbonate coprecipitation synthesis without addition of chelating agent is introduced to obtain mesostructure-controlled Li-rich layered oxides. The designed mesostructure for target material Li_1.2Ni_0.2Mn_0.6O₂ has uniformly dispersed spherical secondary particles with size around 3 μm. These micrometer-sized particles consist of self-assembled crystallites with size of ∼150 nm. This unique design not only decreases the surface area compared with the sample with dispersive particles, but also increases overall structural mechanical stability compared with the sample with larger dense secondary particles as observed by transmission X-ray microscope. As a result, the voltage decay and capacity loss during long-term cycling have been minimized to a large extent. Our findings clearly demonstrate that mesostructure design of Li-rich layered oxides play a key role in optimizing this class of cathode materials. Surprisingly, the voltage fading issue can be partially mitigated by such an approach

Thermodynamics of Antisite Defects in Layered NMC Cathodes: Systematic Insights from High-Precision Powder Diffraction Analyses

While it is accepted that paired NiLi and LiNi antisite defects are present in the important family of NMC cathode materials with the general formula Li­(NixMnyCoz)­O2, their formation mechanism and influence on properties are not well understood due to the difficulty of accurately quantifying defects. In this work, novel high-precision powder diffraction methods have been used to elucidate the dependence of defect concentration on NMC composition. Formation energies for paired antisite defects (calculated under the assumption of equal state degeneracy) are observed to vary from about 320 to 160 meV, contradicting the constant defect formation energy that would be expected based on the previously proposed atomistic defect formation mechanism (size similarity of Ni2+ and Li+ cations). The present data support an alternative mechanism in which the equilibrium defect concentration is determined by the average size of transition-metal sites and thus suggest a new route by which chemical substitutions can be used to tune defect concentrations to optimal levels

Thermodynamics of Antisite Defects in Layered NMC Cathodes: Systematic Insights from High-Precision Powder Diffraction Analyses

While it is accepted that paired NiLi and LiNi antisite defects are present in the important family of NMC cathode materials with the general formula Li­(NixMnyCoz)­O2, their formation mechanism and influence on properties are not well understood due to the difficulty of accurately quantifying defects. In this work, novel high-precision powder diffraction methods have been used to elucidate the dependence of defect concentration on NMC composition. Formation energies for paired antisite defects (calculated under the assumption of equal state degeneracy) are observed to vary from about 320 to 160 meV, contradicting the constant defect formation energy that would be expected based on the previously proposed atomistic defect formation mechanism (size similarity of Ni2+ and Li+ cations). The present data support an alternative mechanism in which the equilibrium defect concentration is determined by the average size of transition-metal sites and thus suggest a new route by which chemical substitutions can be used to tune defect concentrations to optimal levels

Thermodynamics of Antisite Defects in Layered NMC Cathodes: Systematic Insights from High-Precision Powder Diffraction Analyses

While it is accepted that paired NiLi and LiNi antisite defects are present in the important family of NMC cathode materials with the general formula Li­(NixMnyCoz)­O2, their formation mechanism and influence on properties are not well understood due to the difficulty of accurately quantifying defects. In this work, novel high-precision powder diffraction methods have been used to elucidate the dependence of defect concentration on NMC composition. Formation energies for paired antisite defects (calculated under the assumption of equal state degeneracy) are observed to vary from about 320 to 160 meV, contradicting the constant defect formation energy that would be expected based on the previously proposed atomistic defect formation mechanism (size similarity of Ni2+ and Li+ cations). The present data support an alternative mechanism in which the equilibrium defect concentration is determined by the average size of transition-metal sites and thus suggest a new route by which chemical substitutions can be used to tune defect concentrations to optimal levels

Thermodynamics of Antisite Defects in Layered NMC Cathodes: Systematic Insights from High-Precision Powder Diffraction Analyses

While it is accepted that paired NiLi and LiNi antisite defects are present in the important family of NMC cathode materials with the general formula Li­(NixMnyCoz)­O2, their formation mechanism and influence on properties are not well understood due to the difficulty of accurately quantifying defects. In this work, novel high-precision powder diffraction methods have been used to elucidate the dependence of defect concentration on NMC composition. Formation energies for paired antisite defects (calculated under the assumption of equal state degeneracy) are observed to vary from about 320 to 160 meV, contradicting the constant defect formation energy that would be expected based on the previously proposed atomistic defect formation mechanism (size similarity of Ni2+ and Li+ cations). The present data support an alternative mechanism in which the equilibrium defect concentration is determined by the average size of transition-metal sites and thus suggest a new route by which chemical substitutions can be used to tune defect concentrations to optimal levels

Thermodynamics of Antisite Defects in Layered NMC Cathodes: Systematic Insights from High-Precision Powder Diffraction Analyses

While it is accepted that paired NiLi and LiNi antisite defects are present in the important family of NMC cathode materials with the general formula Li­(NixMnyCoz)­O2, their formation mechanism and influence on properties are not well understood due to the difficulty of accurately quantifying defects. In this work, novel high-precision powder diffraction methods have been used to elucidate the dependence of defect concentration on NMC composition. Formation energies for paired antisite defects (calculated under the assumption of equal state degeneracy) are observed to vary from about 320 to 160 meV, contradicting the constant defect formation energy that would be expected based on the previously proposed atomistic defect formation mechanism (size similarity of Ni2+ and Li+ cations). The present data support an alternative mechanism in which the equilibrium defect concentration is determined by the average size of transition-metal sites and thus suggest a new route by which chemical substitutions can be used to tune defect concentrations to optimal levels

Thermodynamics of Antisite Defects in Layered NMC Cathodes: Systematic Insights from High-Precision Powder Diffraction Analyses

While it is accepted that paired NiLi and LiNi antisite defects are present in the important family of NMC cathode materials with the general formula Li­(NixMnyCoz)­O2, their formation mechanism and influence on properties are not well understood due to the difficulty of accurately quantifying defects. In this work, novel high-precision powder diffraction methods have been used to elucidate the dependence of defect concentration on NMC composition. Formation energies for paired antisite defects (calculated under the assumption of equal state degeneracy) are observed to vary from about 320 to 160 meV, contradicting the constant defect formation energy that would be expected based on the previously proposed atomistic defect formation mechanism (size similarity of Ni2+ and Li+ cations). The present data support an alternative mechanism in which the equilibrium defect concentration is determined by the average size of transition-metal sites and thus suggest a new route by which chemical substitutions can be used to tune defect concentrations to optimal levels

Thermodynamics of Antisite Defects in Layered NMC Cathodes: Systematic Insights from High-Precision Powder Diffraction Analyses

While it is accepted that paired NiLi and LiNi antisite defects are present in the important family of NMC cathode materials with the general formula Li­(NixMnyCoz)­O2, their formation mechanism and influence on properties are not well understood due to the difficulty of accurately quantifying defects. In this work, novel high-precision powder diffraction methods have been used to elucidate the dependence of defect concentration on NMC composition. Formation energies for paired antisite defects (calculated under the assumption of equal state degeneracy) are observed to vary from about 320 to 160 meV, contradicting the constant defect formation energy that would be expected based on the previously proposed atomistic defect formation mechanism (size similarity of Ni2+ and Li+ cations). The present data support an alternative mechanism in which the equilibrium defect concentration is determined by the average size of transition-metal sites and thus suggest a new route by which chemical substitutions can be used to tune defect concentrations to optimal levels