Amorphous LiCoO2-based Positive Electrode Active Materials with Good Formability for All-Solid-State Rechargeable Batteries

Abstract

Amorphous LiCoO2-based positive electrode materials are synthesized by a mechanical milling technique. As a lithium oxy-acid, Li2SO4, Li3PO4, Li3BO3, Li2CO3, and LiNO3 are selected and milled with LiCoO2. XRD patterns indicate that reaction between LiCoO2 and these lithium oxy-acids proceeds. Amorphization mainly occurs, and several broad peaks attributable to cubic LiCoO2 are observed in all the samples. These amorphous active materials show mixed conductivities of electron and lithium ion. All-solid-state cells using the prepared amorphous active materials and the Li2.9B0.9S0.1O3.1 glass-ceramic electrolyte are fabricated and their charge-discharge properties are examined. The cells with only the 80LiCoO2·20Li2SO4 (mol%) and the 80LiCoO2·20Li3PO4 active materials function as secondary batteries. This is because higher lithium ionic conductivities are obtained in the 80LiCoO2·20Li2SO4 and 80LiCoO2·20Li3PO4 active materials than in the others. The largest capacity is obtained in the cell with the 80LiCoO2·20Li2SO4 active material because of its good formability and high lithium ionic conductivity. In addition, the cell with the 80LiCoO2·20Li2SO4 positive electrode active material shows the better cycle and rate performance than that with the crystalline LiCoO2. It is noted that the amorphization with lithium oxy-acids is a promising technique for achieving a novel active material with better electrochemical performance.

Amorphous Ni‐Rich Li(Ni1−x−yMnxCoy)O2–Li2SO4 Positive Electrode Materials for Bulk‐Type All‐Oxide Solid‐State Batteries

“…[23] Similar results was obtained in the composite electrode using the corresponding amorphous materials although there is difference in the morphology of the crystalline particles between LiCoO 2 and NMC532. In our previous report, the composite electrode using amorphous LiCoO 2 -Li 2 SO 4 showed better performance than that using crystalline LiCoO 2 .…”

“…[22,23] Commercially available crystalline NMC materials such as NMC811, NMC532, and NMC333 and LiNiO 2 were used as starting materials. [22,23] Commercially available crystalline NMC materials such as NMC811, NMC532, and NMC333 and LiNiO 2 were used as starting materials.…”

“…Over the past decades, many types of solid electrolytes with high conductivities have been discovered. [22][23][24] The obtained amorphous LiCoO 2 -Li 2 SO 4 positive electrode material exhibited the best charge-discharge performance. [18] In addition, there are advantages in the use of amorphous materials to achieve higher capacities and better cycle characteristics owing to the open and random structures.…”

“…Some of the sulfidebased electrolytes exhibit extremely high conductivities (higher than 10 −2 S cm −1 ) at room temperature, higher than those of www.advmatinterfaces.de corresponding crystals. [23] The amorphous Li 1.2 Co 0.8 S 0.2 O 2.4 (80LiCoO 2 ·20Li 2 SO 4 (mol%)) active material exhibited a good formability as those of ductile electrolytes such as the Li 2.9 B 0.9 S 0.1 O 3.1 glass electrolyte. [19][20][21] Recently, we have developed amorphous LiCoO 2 -based positive electrode active materials with various lithium oxyacids for all-solid-state batteries.…”

“…[19][20][21] Recently, we have developed amorphous LiCoO 2 -based positive electrode active materials with various lithium oxyacids for all-solid-state batteries. [22][23][24] The obtained amorphous LiCoO 2 -Li 2 SO 4 positive electrode material exhibited the best charge-discharge performance. [23] The amorphous Li 1.2 Co 0.8 S 0.2 O 2.4 (80LiCoO 2 ·20Li 2 SO 4 (mol%)) active material exhibited a good formability as those of ductile electrolytes such as the Li 2.9 B 0.9 S 0.1 O 3.1 glass electrolyte.…”