Formation of the Secondary Phase Domain by Multi-Cation Substitution for the Superior Electrochemical Performance of Spinel Cathodes for High-Voltage Li-Ion Batteries

Abstract

Disorder-structured spinel oxides are opening frontiers for high-capacity/high-voltage cathodes to meet the challenges of independence on cobalt-containing cathodes toward cheap and sustainable energy storage sources in Li-ion batteries (LIBs). In the present work, a series of Co-free materials: LiMn 2-x-y-z Ni x Fe y Al z O 4 (x = 0.8−0.5, y = 0.1−0.25, and z = 0.1−0.25) with spinel/rock salt disordered structures are reported. The refinement studies confirmed that the materials synthesized are of mixed phase, and the I 311 /I 400 peaks ratio confirms that the synthesized materials are stable enough for electrochemical applications. This article addresses the influence of the secondary phase on the electrochemical activity and the reduction of the Mn 3+ ratio to alleviate the Mn dissolution issue for bettered stability. The optimized LiMnNi 0.7 Fe 0.1 Al 0.2 O 4 is appraised as a cathode material in the voltage range between 3.5 and 5 V (vs. Li + /Li) with an initial discharge capacity of 148.7 mA h g −1 at a rate of 1 C. This material showed very good cycling stability with a capacity retention of 79.5% after 1000 cycles. The cyclic voltammetry studies showed that the material can be a potential candidate for 5 V applications.

Kinetically controlled synthesis of low-strain disordered micro–nano high voltage spinel cathodes with exposed {111} facets

“…2a). 44,45 And the calculated lattice parameter of LNMO-111 ( a = 8.1726 Å) is close to that of standard LNMO ( Fd 3̄ m , a = 8.172 Å) (Table S1†). 46 In the Fd 3̄ m space group structure, Li is located at position 8a and diffuses along the 8a-16c pathway.…”

Influence of the Crystal Plane Orientation in Enhancing the Electrochemical Performance of a Trication-Substituted Cathode for Li-Ion Batteries

“…The P 4332 space group is associated when the low-temperature synthesis conditions are employed, and the Fd 3̅ m space group is associated when the high-temperature synthesis conditions are employed . This Fd 3̅ m space group is also accompanied by rock salt impurity, which we have reported previously . In our case, the synthetic temperature is higher; therefore, the phase of the material belongs to the Fd 3̅ m space group through a cubic close-packed structure with the capability of intercalating one Li + ion into an anode per unit formula.…”

“…Alongside, to achieve electrochemical stability and extend the cycle life of the cathode materials during charge/discharge processes, lithium manganese oxide (LMO) cathodes have been substituted by Fe 3+ and Al 3+ ions into Mn 3+ sites. , Therefore, the combination of all of these metal ions in LMO cathodes will enhance the electrochemical performance by reducing the J–T effect and Mn 3+ ion dissolutions. The influence of Fe 3+ and Al 3+ in the material is discussed in our previously published work, where we reported dual-phase material . Therefore, our prime focus in the present work was to achieve pure phase material by substituting trications, and we have succeeded in synthesizing pure phase material.…”