A multiscale investigation elucidating the structural complexities and electrochemical properties of layered–layered composite cathode materials synthesized at low temperatures

Abstract

0.5Li2MnO3·0.5LiCoO2 composite cathodes prepared using various heating and cooling rates under 600 °C reveal different microstructural characteristics that significantly impact their structural stability and electrochemical properties.

Impacts of Mg doping on the structural properties and degradation mechanisms of a Li and Mn rich layered oxide cathode for lithium-ion batteries

“…Our previous reports illustrated that the domain size of the Li 2 MnO 3 phase has significant influence on the electrochemical properties of composite-based Li- and Mn-rich layered oxide cathode materials. Varying Li 2 MnO 3 domain sizes can alter Li 2 MnO 3 activation, largely affecting the degree of transition from a layered to a spinel structure during electrochemical cycling 30 , 32 , 33 . From our experimental results, the domain sizes of Li 2 MnO 3 -like and LiCoO 2 -like phases are strongly related to the Mg content.…”

“…This indicates that the activation of Li 2 MnO 3 to form a LiMnO 2 phase can induce a spinel-like phase transition during cycling. Previous reports revealed that the degree of Li 2 MnO 3 activation is largely determined by the Li 2 MnO 3 domain size and current rate 33 , 42 , 43 . A small Li 2 MnO 3 domain size and low current rate could facilitate activation of the Li 2 MnO 3 phase and subsequently cause a large initial irreversible capacity and a spinel-like phase transition, leading to poor cyclability.…”

Impacts of Mg doping on the Structural Properties and Degradation Mechanisms of a Li and Mn Rich Layered Oxide Cathode for Lithium-ion Batteries

“…Our previous reports illustrated that the domain size Li 2 MnO 3 phase has signi cant in uence on the electrochemical properties of composite-based Li-and Mn-rich layered oxide cathode materials. Varying Li 2 MnO 3 domain sizes can alter Li 2 MnO 3 activation, largely affecting the degree of structural transition from a layered to a spinel structure during electrochemical cycling 30,32,33 . From the experimental results, the domain sizes of affected the electrochemical properties of the prepared materials, is seen in the electrochemical results.…”

“…This indicates that the activation of Li 2 MnO 3 to form an LiMnO 2 phase can induce a spinel-like phase transition during cycling. Previous reports revealed that the degree of Li 2 MnO 3 activation was largely determined by the Li 2 MnO 3 domain size and current rate 33,42,43 . A small Li 2 MnO 3 domain size and low current rate could facilitate activation of the Li 2 MnO 3 phase and subsequently cause a large initial irreversible capacity and a spinel-like phase transition, leading to poor cyclability.…”

“…This is because the cathodes with smaller Li respectively. Undoped cathode (Li 1.2 Mn 0.4 Co 0.4 O 2 ) shows a small oxidation peak at 2.0 V, corresponding to spinel-like phase features 33 . Furthermore, the Mg-doped cathode with low Mn content (Li 1.2 Mn 0.38 Mg 0.02 Co 0.4 O 2 ) reveals a shift of the reduction peak at 2.8 V to a lower voltage of around 2.5 V, indicating that the cathode exhibits a spinel-like phase evolution during electrochemical cycling [44][45][46] .…”