Understanding the Synthesis Kinetics of Single‐Crystal Co‐Free Ni‐Rich Cathodes

Abstract

Non‐equilibrium kinetic intermediates are usually preferentially generated instead of thermodynamic stable phases in the solid‐state synthesis of layered oxides. Understanding the inherent complexity between thermodynamics and kinetics is important for designing high cationic ordering cathodes. Single‐crystal strategy is an effective way to solve the intrinsic chemo‐mechanical problems of Ni‐rich cathodes. However, the synthesis of high‐performance single‐crystal is very challenging. Herein, the kinetic reaction path and the formation mechanism of non‐equilibrium intermediates in the synthesis of single‐crystal Co‐free Ni‐rich were explored. We demonstrate that the formation of non‐equilibrium intermediate and the electrochemical‐thermo‐mechanical failure can be effectively inhibited by driving low‐temperature topotactic lithiation. This work provides a basis for designing high‐performance single‐crystal Ni‐rich layered oxides by regulating the defective structures.

Perspective on the Preparation Methods of Single Crystalline High Nickel Oxide Cathode Materials

“…A recent study elucidated the growth mechanism of SC‐LiNi 0.95 Mn 0.05 O 2 (SC‐NM9505) with the assistance of Li 2 SO 4 as the flux agent. [ 74 ] In the CHTS process without Li 2 SO 4 , the fusion and grain growth of precursor particles started at temperatures above the melting point of LiOH (475 °C). Before the melting of LiOH, precursor, and LiOH are both solid, leading to a sluggish diffusion of metal ions and hindering the reaction kinetics, leading to heavy Li/Ni mixing.…”

“…g) The formation mechanism of kinetic reaction pathway during synthesis of single-crystal Cofree Ni-rich oxides by molten salt method. Reproduced with permission [74]. Copyright 2023, Wiley-VCH.…”

Design of high‐performance and sustainable Co‐free Ni‐rich cathodes for next‐generation lithium‐ion batteries

“…Crystallization is usually slow and residual grain boundaries may be present, leading to degradation of electrochemical properties. 24,137,138 Recent studies have revealed that the molten salt synthesis method promotes the rapid formation of layered structures from precursors at lower calcination temperatures. The surface of the precursor becomes sub-stable due to the strong polarizing forces provided by the molten salt, facilitating the insertion of Li + into the layers of the precursor to form layered oxides and reducing the formation energy of the stabile layered structure.…”

“…[21][22][23] Notably, Ni-rich layered cathodes retain a great potential for commercialization due to their ability to produce Co-free materials. 15,[24][25][26] EVs will be powered primarily by LIBs. Consequently, the demand for power LIBs will be 10-20 times higher than it is now by 2030 (Figure 1A).…”

Recent progress in Co‐free, Ni‐rich cathode materials for lithium‐ion batteries

“…The most appropriate and successful strategies in recent years are the preparation of Co-free singlecrystal [52][53][54][55] or core-shell structures [56][57][58][59] and replacing the Co with other metal substitutions. 43,60 These approaches collectively aim to address the challenges associated with NCM cathodes and to improve electrochemical performance with good structural stability.…”