Synthesis and Characterization of a Multication Doped Mn Spinel, LiNi(0.3)Cu(0.1)Fe(0.2)Mn(1.4)O(4), as 5 V Positive Electrode Material

[Image: see text] The suitability of multication doping to stabilize the disordered Fd3̅m structure in a spinel is reported here. In this work, LiNi(0.3)Cu(0.1)Fe(0.2)Mn(1.4)O(4) was synthesized via a sol–gel route at a calcination temperature of 850 °C. LiNi(0.3)Cu(0.1)Fe(0.2)Mn(1.4)O(4) is evaluated as positive electrode material in a voltage range between 3.5 and 5.3 V (vs Li(+)/Li) with an initial specific discharge capacity of 126 mAh g(–1) at a rate of C/2. This material shows good cycling stability with a capacity retention of 89% after 200 cycles and an excellent rate capability with the discharge capacity reaching 78 mAh g(–1) at a rate of 20C. In operando X-ray diffraction (XRD) measurements with a laboratory X-ray source between 3.5 and 5.3 V at a rate of C/10 reveal that the (de)lithiation occurs via a solid-solution mechanism where a local variation of lithium content is observed. A simplified estimation based on the in operando XRD analysis suggests that around 17–31 mAh g(–1) of discharge capacity in the first cycle is used for a reductive parasitic reaction, hindering a full lithiation of the positive electrode at the end of the first discharge.