<p>Advanced lithium-ion batteries require fast-charging high-energy-density electrodes. Li- and Mn-rich layered positive electrodes can offer higher capacity (&gt;280 mAh g<sup>−1</sup>) and higher specific energy (&gt;1000 Wh kg<sup>−1</sup>) than Ni-rich chemistries, yet it is challenging to produce volumetric-energy-dense Li-rich single crystals. Another concern is the rate performance. Li-rich layered oxides have long been considered to have poor rate capability, not to mention their single-crystal version. Here we report high-rate single-crystal Li-rich layered oxides with fast rechargeability. 0.2 C-discharge capacity of 248 mAh g<sup>−1</sup>at 5 C fast-charging as well as 5 C fast-discharging capacity of 179 mAh g<sup>−1</sup> are demonstrated. We prove that the fast rechargeability can be resolved by a complex cation ordering of coherent layered-, cation mixed-, rock salt-, and spinel-type structure. The highly conductive and electrochemically active surface phases can buffer Li<sup>+</sup> concentration gradients and enable deeper bulk lithiation. The single-crystal morphology and redesigned surface phase ensure mechanical and structural stability over cycling, improving capacity retention to 94.5% over 150 cycles at 0.5 C-rate. This work uncovers the intrinsic high-rate performance of single-crystal Li-rich layered oxides and calls attention to think about the fast-charging potential of positive electrodes with coarse microstructure.</p>

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High-rate single-crystalline Li-rich layered oxide with diversified surface-phase cation ordering for Li-ion batteries

  • Jingxi Zhang,
  • Shile Chen,
  • Yuting Xia,
  • Ye Xiao,
  • Meicen Fan,
  • Rong-Ao Tong,
  • Zehui Liu,
  • Zhuoran Lv,
  • Yaqi Liao,
  • Moonsu Yoon,
  • Mengyuan Zhou,
  • Yanhao Dong,
  • Ju Li,
  • Chang-An Wang

摘要

Advanced lithium-ion batteries require fast-charging high-energy-density electrodes. Li- and Mn-rich layered positive electrodes can offer higher capacity (>280 mAh g−1) and higher specific energy (>1000 Wh kg−1) than Ni-rich chemistries, yet it is challenging to produce volumetric-energy-dense Li-rich single crystals. Another concern is the rate performance. Li-rich layered oxides have long been considered to have poor rate capability, not to mention their single-crystal version. Here we report high-rate single-crystal Li-rich layered oxides with fast rechargeability. 0.2 C-discharge capacity of 248 mAh g−1at 5 C fast-charging as well as 5 C fast-discharging capacity of 179 mAh g−1 are demonstrated. We prove that the fast rechargeability can be resolved by a complex cation ordering of coherent layered-, cation mixed-, rock salt-, and spinel-type structure. The highly conductive and electrochemically active surface phases can buffer Li+ concentration gradients and enable deeper bulk lithiation. The single-crystal morphology and redesigned surface phase ensure mechanical and structural stability over cycling, improving capacity retention to 94.5% over 150 cycles at 0.5 C-rate. This work uncovers the intrinsic high-rate performance of single-crystal Li-rich layered oxides and calls attention to think about the fast-charging potential of positive electrodes with coarse microstructure.