Surface Modification of LiCo&lt;sub&gt;1/3&lt;/sub&gt;Ni&lt;sub&gt;1/3&lt;/sub&gt;Mn&lt;sub&gt;1/3&lt;/sub&gt;O&lt;sub&gt;2&lt;/sub&gt; by TiO&lt;sub&gt;2&lt;/sub&gt;-Coating

Feng, Wu; 北京理工大学化工与环境学院, 国家高技术绿色材料发展中心

doi:10.3866/pku.whxb20090411

Cited by 4 publications

(1 citation statement)

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“…。而高镍正极材料也存在一些缺点，比如在充放电过程中，由于Ni 2+ 离子半径(r = 0.069 nm)和Li + 离子半径(r = 0.076 nm)相近，很容易导致镍离子向锂位迁移，造成锂镍混排(即"阳离子混排")，从而破坏高镍正极材料结构并诱发电化学性能衰减 [14][15][16]…”

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An Optimized Synthetic Process for the Substitution of Cobalt in Nickel-Rich Cathode Materials

Wu¹,

Li²,

Chen³

et al. 2020

Acta Physico Chimica Sinica

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High-performance rechargeable lithium ion batteries have been widely applied in electrochemical energy storage fields, such as, energy storage grids, portable electronic devices, and electric vehicles (EVs). However, the energy density of lithium ion batteries needs to be increased, and the cost of battery materials could be further reduced for wider commercial applications. An Ni-rich cathode, LiNixMnyCo1−x−yO2 (x>0.8), with high specific capacity is the most promising material for next-generation Li-ion batteries. LiNixMnyCo1−x−yO2 (x>0.8) contains three transition metal elements, Ni, Mn, and Co, respectively. The role of Ni 2+ is to provide high capacity for recharge The role of Mn 4+ is to stabilize the lattice structure during charging-discharging cycling. Crucially, the role of Co 3+ in Ni-rich materials is to improve the electrical conductivity and inhibit cation disorder in the lattice during electrochemical cycling. However, Co is both in shortage and expensive, which limits its worldwide commercial application. This work investigates substituting Co with other abundant and cheap transition metals. Transition metal ions Cr 3+ , Cd 2+ , and Zr 4+ can replace Co 3+ in Ni-rich cathode materials. LiNi0.8Cr0.1Mn0.1O2, LiNi0.8Cd0.1Mn0.1O2, and LiNi0.8Zr0.1Mn0.1O2 were synthesized by a co-precipitation method. Zr was found to be the best candidate for replacing Co in Ni-rich cathode materials. This study investigated Zr 4+ -doped Co-free Ni-rich materials. Initially, a carbonate coprecipitation process was used to synthesize Ni0.8Zr0.1Mn0.1CO3. This is due to that Zr 3+ /Zr 4+ ions are not precipitated in the strong alkali solution, and the pH during hydroxide co-precipitation and carbonate co-precipitation processes are approximately 11 and 8, respectively. Therefore, the carbonate co-precipitation synthesis method was chosen. Ni0.8Zr0.1Mn0.1CO3 was synthesized by carbonate co-precipitation at pH=7.6, 7.8, 8.0, and 8.2. After electrochemical analysis, pH=7.8 was identified as the optimal value. The next stage of the research involved completing an electrochemical performance comparison on two lithium sources. The following lithium sources were added to the precursor; LiOH•H2O, and a 1:1 mixture of LiOH•H2O and Li2CO3. The lithium source with the 1:1 mixture, exhibited better performance for the Ni-rich cathode, LiNi0.8Zr0.1Mn0.1O2. In this study, the ideal doping amount of Zr in Ni-rich materials was 0.05. In conclusion, by careful control of co-precipitation pH and Li source, the Zr doped cobalt free Ni-rich cathode LiNi0.85Mn0.1Zr0.05O2 delivered a discharge capacity of 179.9 mAh•g −1 at 0.2C. This was achieved between the voltage range of 2.75-4.3 V, with an 80 cycle capacity retention of 96.52%.

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