Manipulating the Local Electronic Structure in Li-Rich Layered Cathode Towards Superior Electrochemical Performance

Manipulating the local electronic structure is employed to address the capacity/voltage decay and poor rate capability of Li-rich layered cathodes (LLOs) via the dual-doping of Na+ and F- ions, as well as the regulation of Li+/Ni2+ intermixing and the content of Li-O-Li configuration. The designed cathode exhibits a high initial Coulombic efficiency of about 90%, large specific capacity of 296 mAh g(-1) and energy density of 1047 Wh kg(-1) at 0.2 C, and a superior rate capability of 222 mAh g(-1) at 5 C with a good capacity retention of 85.7% even after 500 cycles. And the operating voltage is increased without compromising the high-capacity advantage. Such improved electrochemical performances primarily result from the band shift of the TM 3d-O 2p and non-bonding O-2p to lower energy, which would decrease Li+, diffusion activation energy and increase oxygen vacancy forming energy, finally improving the Li+, diffusion kinetics and stabilizing lattice oxygen. Moreover, the increased Li-O-Li configuration in the Li2MnO3 phase via increasing the Mn concentration can increase the reversible capacity to offset the negative effect of inactive doping and Li+/Ni2+ intermixing. This strategy of modulating the local electronic structure of LLOs provides great potential to design high-energy-density Li-ion batteries.

Automated summary

The research successfully improved the performance of Li-rich layered cathodes by dual-doping Na+ and F- ions, and regulating Li+/Ni2+ intermixing and Li-O-Li configuration, leading to increased battery capacity and cycle life.