Compositionally Graded Cathode Material with Long‐Term Cycling Stability for Electric Vehicles Application

Al is introduced into a compositionally graded cathode with average composition of Li[Ni0.61Co0.12Mn0.27]O2 (FCG61) whose Ni and Mn concentrations are designed to vary continuously within the cathode particle. The Al-substituted full concentration gradient (Al-FCG61) cathode is tested for 3000 cycles in a full-cell, mainly to gauge its viability for daily charge/discharge cycles during the service life of electric vehicles (≈10 years). The Al-substitution enables the Al-FCG61 cathode to maintain 84% of its initial capacity even after 3000 cycles. It is demonstrated that the Al-substitution strengthens the grain boundaries, substantiated by the mechanical strength data, thereby delaying the nucleation of microcracks at the phase boundaries which is shown to be the main reason for the cathode failure during long-term cycling. It also shows that the Al-substitution decreases the cation mixing and suppresses the deleterious formation of the secondary phase that likely initiates the microcracks. Unlike an NCA cathode, whose depth of discharge (DOD) must be limited to 60% for long-term cycling, the proposed Al-FCG61 cathode is cycled at 100% DOD for 3000 cycles to fully utilize its available capacity for maximum energy density and subsequent reduction in cost of the battery.

[1]  J. Shim,et al.  Electrochemical analysis for cycle performance and capacity fading of a lithium-ion battery cycled at elevated temperature , 2002 .

[2]  Hajime Arai,et al.  Electrochemical and thermal behavior of LiNi1-zMzO2 (M = Co, Mn, Ti) , 1997 .

[3]  Yang‐Kook Sun,et al.  Improvement of electrochemical and thermal properties of Li[Ni0.8Co0.1Mn0.1]O2 positive electrode materials by multiple metal (Al, Mg) substitution , 2009 .

[4]  Ki-Soo Lee,et al.  Structural and Electrochemical Properties of Layered Li [ Ni1 − 2x Co x Mn x ] O2 ( x = 0.1 – 0.3 ) Positive Electrode Materials for Li-Ion Batteries , 2007 .

[5]  M. Kinoshita,et al.  Comparison of the surface changes on cathode during long term storage testing of high energy density , 2011 .

[6]  D. Aurbach,et al.  Al Doping for Mitigating the Capacity Fading and Voltage Decay of Layered Li and Mn‐Rich Cathodes for Li‐Ion Batteries , 2016 .

[7]  Ilias Belharouak,et al.  High-energy cathode material for long-life and safe lithium batteries. , 2009, Nature materials.

[8]  T. Fuller,et al.  A Critical Review of Thermal Issues in Lithium-Ion Batteries , 2011 .

[9]  Yang‐Kook Sun,et al.  Synthesis and electrochemical properties of Li[Ni0.8Co0.1Mn0.1]O2 and Li[Ni0.8Co0.2]O2 via co-precipitation , 2006 .

[10]  Chong Seung Yoon,et al.  Nanostructured high-energy cathode materials for advanced lithium batteries. , 2012, Nature materials.

[11]  Xiqian Yu,et al.  Correlating Structural Changes and Gas Evolution during the Thermal Decomposition of Charged LixNi0.8Co0.15Al0.05O2 Cathode Materials , 2013 .

[12]  Peter Lamp,et al.  High-energy-density lithium-ion battery using a carbon-nanotube–Si composite anode and a compositionally graded Li[Ni0.85Co0.05Mn0.10]O2 cathode , 2016 .

[13]  Daniel P. Abraham,et al.  Surface changes on LiNi0.8Co0.2O2 particles during testing of high-power lithium-ion cells , 2002 .

[14]  Yang-Kook Sun,et al.  Synthesis and characterization of Li[(Ni0.8Co0.1Mn0.1)0.8(Ni0.5Mn0.5)0.2]O2 with the microscale core-shell structure as the positive electrode material for lithium batteries. , 2005, Journal of the American Chemical Society.

[15]  Chong Seung Yoon,et al.  Cathode Material with Nanorod Structure—An Application for Advanced High-Energy and Safe Lithium Batteries , 2013 .

[16]  Chong Seung Yoon,et al.  Advanced Concentration Gradient Cathode Material with Two‐Slope for High‐Energy and Safe Lithium Batteries , 2015 .

[17]  C. Yoon,et al.  Review—High-Capacity Li[Ni1-xCox/2Mnx/2]O2 (x = 0.1, 0.05, 0) Cathodes for Next-Generation Li-Ion Battery , 2015 .

[18]  Masahiro Kinoshita,et al.  Capacity fading of LiAlyNi1−x−yCoxO2 cathode for lithium-ion batteries during accelerated calendar and cycle life tests (effect of depth of discharge in charge–discharge cycling on the suppression of the micro-crack generation of LiAlyNi1−x−yCoxO2 particle) , 2014 .

[19]  Masahiro Kinoshita,et al.  Capacity fade of LiAlyNi1−x−yCoxO2 cathode for lithium-ion batteries during accelerated calendar and cycle life tests (surface analysis of LiAlyNi1−x−yCoxO2 cathode after cycle tests in restricted depth of discharge ranges) , 2014 .

[20]  Daniel P. Abraham,et al.  Observation of Microstructural Evolution in Li Battery Cathode Oxide Particles by In Situ Electron Microscopy , 2013 .

[21]  J. Dahn,et al.  Solid-State Synthesis as a Method for the Substitution of Al for Co in LiNi1 ∕ 3Mn1 ∕ 3Co ( 1 ∕ 3 − z ) Al z O2 , 2009 .

[22]  Robert Kostecki,et al.  Local-probe studies of degradation of composite LiNi{sub 0.8}Co{sub 0.15}Al{sub 0.05}O{sub 2} cathodes in high-power lithium-ion cells , 2004 .

[23]  A. Milewska,et al.  Structural, transport and electrochemical properties of LiNi1 − yCoyMn0.1O2 and Al, Mg and Cu-substituted LiNi0.65Co0.25Mn0.1O2 oxides , 2011 .

[24]  C. Fisher,et al.  Microstructural Changes in LiNi0.8Co0.15Al0.05O2 Positive Electrode Material during the First Cycle , 2011 .