Role of zirconium dopant on the structure and high voltage electrochemical performances of LiNi 0.5 Co 0.2 Mn 0.3 O 2 cathode materials for lithium ion batteries

Enhanced Electrochemical Properties of Zr4+-doped Li1.20[Mn0.52Ni0.20Co0.08]O2 Cathode Material for Lithium-ion Battery at Elevated Temperature

“…In addition, the lowest irreversible capacity loss for the Li 1.20 [Mn 0.50 Zr 0.02 Ni 0.20 Co 0.08 ]O 2 sample has promoted the highest initial coulombic efficiency, which indicates that the Zr 4+ doping can restrain the release of oxygen from the Li 2 MnO 3 and decrease the irreversible capacity loss. Compared to the bonds break energy values for theΔ H ƒ 298 (Ni-O) = 391.6 kJ∙mol −1 , Δ H ƒ 298 (Co-O) = 368 kJ∙mol −1 and Δ H ƒ 298 (Mn-O) = 402 kJ∙mol −1 , the Zr-O delivers the higher bonds break energy value ofΔ H ƒ298(Zr-O) = 760 kJ mol −1 , therefore with the Zr 4+ doping, the oxygen release of the Zr 4+ -doped samples will face more resistance than the un-doped sample, subsequently the irreversible capacity loss has been suppressed 17 .

Figure 6Initial charge-discharge curves of the Li 1.20 [Mn 0.52− x Zr x Ni 0.20 Co 0.08 ]O 2 ( x  = 0, 0.01, 0.02, 0.03) samples in the voltage range of 2.0~4.8 V at 0.1 C rate.

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“…While the stronger total metal–oxygen bonding for the Zr 4+ -doped samples can contribute to stabilizing the structure of cathode during cycling, leading to the improved cycling performance. However, when the Zr 4+ doping content reaches to 0.03, the cycling performance of Li 1.20 [Mn 0.49 Zr 0.03 Ni 0.20 Co 0.08 ]O 2 is not as good as that of the Li 1.20 [Mn 0.50 Zr 0.02 Ni 0.20 Co 0.08 ]O 2 for that the inhomogeneity phase of the ZrO 2 existed in the compound can hinder the Li + intercalation/deintercalation from the cathode 17 .

Figure 10Cycling performance of the Li 1.20 [Mn 0.52− x Zr x Ni 0.20 Co 0.08 ]O 2 ( x  = 0, 0.01, 0.02, 0.03) at 0.5 C rate in the voltage range of 2.0~4.8 V at 45 °C.

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“…For example, when Zr 4+ was doped into the LiCoO 2 by using the ultrasonic spray pyrolysis method, the LiCo 0.99 Zr 0.01 O 2 delivered the discharge capacity of 108 mAh g −1 at 1 C in the voltage range of 3.0–4.2 V after 50 cycles, while the un-doped sample rapidly dropped down to 23 mAh g −1 at the same condition 16 . When the LiNi 0.5 Co 0.2 Mn 0.3 O 2 was doped modification with Zr 4+ by solid-state method reaction, the Li(Ni 0.5 Co 0.2 Mn 0.3 ) 0.09 Zr 0.01 O 2 demonstrated the much more enhanced rate capability than that of the LiNi 0.5 Co 0.2 Mn 0.3 O 2 by the suppression of electrode polarization 17 . While the radius of Zr 4+ (0.072 nm) is larger than those of Mn 4+ (0.053 nm), Ni 2+ (0.069 nm), Co 3+ (0.0685 nm) in the transition-metal layer, the Zr 4+ adulteration will expand the diffusion path of Li + insertion/extraction, leading to the improved electrochemical properties.…”

An Ostwald ripening route towards Ni-rich layered cathode material with cobalt-rich surface for lithium ion battery

“…In addition, these nickel-rich cathodes suffer from gradual capacity fading with cycling due to their structural instability, which is ascribed to the successive phase transitions from hexagonal 2 (H2) to hexagonal 3 (H3) phases when large amounts of Li + are extracted from the host structure [28][29][30][31][32][33]. To solve these problems, various approaches including structure tuning [34][35][36], substitution [37][38][39], and surface coating [40][41][42][43][44][45] have been proposed. Metal oxides such as Al 2 O 3 [46,47], ZrO 2 [48], MgO [49], have been studied as coating materials.…”

The Role of Zr Doping in Stabilizing Li[Ni0.6Co0.2Mn0.2]O2 as a Cathode Material for Lithium‐Ion Batteries

“…[10][11][12][13] The Li + /Ni 2 + cation mixingi sb elieved to be ak ey factor for the structural instability and phase transformation during the electrochemical cycling and it also leads to the high activationenergy barrierfor Li diffusion. [26][27][28][29][30][31][32][33][34][35][36] Among these, bulk doping has proved to be an effective method to enhancet he cycle and rate performance by stabilizing the structure and increasing the Li + diffusion rate. [26][27][28][29][30][31][32][33][34][35][36] Among these, bulk doping has proved to be an effective method to enhancet he cycle and rate performance by stabilizing the structure and increasing the Li + diffusion rate.…”