Crystallographic-Site-Specific Structural Engineering Enables Extraordinary Electrochemical Performance of High-Voltage LiNi_0.5 Mn_1.5 O₄ Spinel Cathodes for Lithium-Ion Batteries.

Abstract

The development of reliable and safe high-energy-density lithium-ion batteries is hindered by the structural instability of cathode materials during cycling, arising as a result of detrimental phase transformations occurring at high operating voltages alongside the loss of active materials induced by transition metal dissolution. Originating from the fundamental structure/function relation of battery materials, the authors purposefully perform crystallographic-site-specific structural engineering on electrode material structure, using the high-voltage LiNi_0.5 Mn_1.5 O₄ (LNMO) cathode as a representative, which directly addresses the root source of structural instability of the Fd <math xmlns="http://www.w3.org/1998/Math/MathML"><mover><mn>3</mn> <mo>¯</mo></mover> </math> m structure. By employing Sb as a dopant to modify the specific issue-involved 16c and 16d sites simultaneously, the authors successfully transform the detrimental two-phase reaction occurring at high-voltage into a preferential solid-solution reaction and significantly suppress the loss of Mn from the LNMO structure. The modified LNMO material delivers an impressive 99% of its theoretical specific capacity at 1 C, and maintains 87.6% and 72.4% of initial capacity after 1500 and 3000 cycles, respectively. The issue-tracing site-specific structural tailoring demonstrated for this material will facilitate the rapid development of high-energy-density materials for lithium-ion batteries.