Sn and Na Co‐doping to Suppress Voltage Decay of Li‐rich Layered Oxide. Issue 12 (22nd June 2021) - Hu, Yongyuan
Abstract: Li‐rich layered oxides (LLOs) as cathode materials are expected to be applied to advanced lithium‐ion batteries (LIBs) with great potential. However, the electrochemical instability and large voltage decay seriously restrict their development. In this work, a novel LLO cathode material (SN‐LLO) with Sn and Na co‐doping is fabricated through a co‐precipitation process with subsequent calcination, which exhibits enhanced electrochemical stability and suppressed voltage decay. Structural characterizations indicate that with the regulation of Na doping, the impurity Li2 SnO3 is inhibited and layered SN‐LLO solid solution with the 3 × 3 - R 30 ∘ arrangement of Sn in layers and stacking faults along c axis is obtained. DFT calculations demonstrate that the enhanced electrochemical stability results from the increase in the energy barrier of Mn migration in the slabs due to the steric effect of Sn. This study provides a rational design idea to improve the electrochemical stability of advanced Li‐rich layered oxides. Abstract : Stop the decay : The Sn and Na co‐doping Li‐rich layered oxide cathode material with well‐defined layered structure and characteristics of ordered solid solution exhibits enhanced electrochemical stability and suppressed voltage decay. The DFT calculations demonstrate that the steric effect of Sn immensely restricts the migration of transition metals in the slabs.