Large-scale synthesis of lithium- and manganese-rich materials with uniform thin-film Al2O3 coating for stable cathode cycling

Abstract

The lithium-and manganese-rich layered oxide (LMR) holds great promise as a cathode material for lithiumion battery (LIB) applications due to its high capacity, high voltage and low cost. Unfortunately, its poor initial Coulombic efficiency (ICE) and unstable electrode/electrolyte interface with continuous growth of the solid electrolyte interphase leads to high impedance and large overpotential. These effects cause severe capacity loss and safety issues. In this work, we have developed a novel approach to fabricate a stable LMR cathode with a uniform thin layer of aluminum oxide (Al 2 O 3 ) coated on the surface of the LMR particles. This synthesis approach uses the microemulsion method that is environment-friendly, cost-effective and can be easily scaled. Typically, an 8-nm layer of Al 2 O 3 is shown to be effective in stabilizing the electrode/electrolyte interface (enhanced ICE to 82.0% and moderate impedance increase over 200 cycles). Moreover, the phase transformation from layered to spinel is inhibited (96.3% average voltage retention) and thermal stability of the structure is significantly increased (heat release reduced by 72.4%). This study opens up a new avenue to address interface issues in LIB cathodes and prompts the practical applications of high capacity and voltage materials for high energy density batteries.

Challenges and Recent Advances in High Capacity Li‐Rich Cathode Materials for High Energy Density Lithium‐Ion Batteries

“…Surface Coating: To date, a number of materials, such as Al 2 O 3 , [112,144] AlF 3 , [145] Li 2 ZrO 3 , [146] spinel phase Li 4 Mn 5 O 12 , [109] SiO 2 , [147] Li−Ni−PO 4 , [148] etc., have been employed as surface coating materials and proved to be effective in maintaining the structural stability of the electrode/electrolyte interface, providing fast ion conduction and thus alleviating the voltage fading of the LRM cathode materials. Hu et al [91] used the hexagonal La 0.8 Sr 0.2 MnO 3−y (LSM) as a protective and phasecompatible surface layer to stabilize the LRM cathode material.…”

Cobalt‐Free Cathode Materials: Families and their Prospects

“…For example, as the LiPF 6 ‐based electrolyte is likely to decompose and form different species, such as HF, POF 3 and PF 5 , it is claimed that the trimethylsilyl (TMS) group can be utilized to scavenge residual lithium, especially LiOH, and the resultant compound assists the decomposition of PF 5 . [ 158 ] In addition to the removal of harmful species, the addition of 2% LiDFOB into a fluoroethylene carbonate/2,2,2‐trifluoroethyl methyl carbonate/hydrofluoroether (FEC/FEMC/HFE) electrolyte can produce an F‐rich and B‐rich in situ layer on the LiNiO 2 surface. Hence, even after repeated lattice expansion and contraction during long‐term cycling, this material can retain a high capacity of 80%.…”

Solid Polymer Electrolytes with High Conductivity and Transference Number of Li Ions for Li‐Based Rechargeable Batteries

“…Li‐based rechargeable batteries (LBRBs) are widely used in applications from consumer electronics, vehicles, large‐scale energy storage, and integrated power systems to telecommunication equipment and applications [ 1–4 ] because of their high energy density and excellent cycling life. [ 5,6 ] However, safety concerns related to the use of flammable organic liquid electrolytes hinders LBRBs further development. [ 7–10 ] To tackle these safety concerns, solid‐state electrolytes (SSEs) are being employed to replace the liquid electrolyte, enabling LBRBs with excellent safety.…”