Ge-Regulated Ordered Phase in Pseudosphere-Structured LiNi_0.5Mn_1.5O₄ Spinel Effectively Inhibits Mn Dissolution

Due to the higher energy density, high thermal stability,and lowcost, LiNi0.5Mn1.5O4 (LNMO) spinel,with a large voltage operating window, has been one of the most promisingcathode materials for lithium-ion batteries (LIBs). However, the interfacialreaction between the cathode and electrolyte and the two-phase reactionwithin the bulk of LNMO would destroy the original structure and leadto capacity deterioration, posing a significant challenge. Therefore,the way to suppress the transition-metal (TM) dissolution in LNMOhas attracted much attention. However, the ordered/disordered phaseregulation by metal atom doping to prohibit TM dissolution has notbeen extensively explored. Herein, a Ge-doping strategy is proposedto adjust the ratio of disordered/ordered phases in LNMO, resultingin exceptional structural stability. For the modified spinel cathode,there is almost no voltage drop and the capacity retention is up to92.2% over 1000 cycles at 1C. These results demonstrate that incorporatingGe into LNMO forms a robust structure that effectively increases theamount of Mn4+ while blocking the diffusion of TM ions.In addition, Ge-doping also protects the bulk from further reactionswith electrolytes, significantly enhancing the interfacial stabilityand relieving voltage decay in cycling. This approach can also beapplied to design other high-stability cathodes through ordered/disorderedphase regulation. Thestrategy of Ge-doping regulating the phase ratio isused to stabilize Mn dissolution, greatly enhancing the cycling performanceof spinel cathode materials from 55.65 to 92.2% within 1000 cycles.