The development of cathode materials represents the key bottleneck to further push the performance of current Li-ion batteries (LIB) beyond the commercial benchmark. Li-rich transition-metal-layered oxides (LRLOs) are a promising class of materials to use as high-capacity/high-potential positive electrodes in LIBs thanks to the large lithium content (e.g., ∼1.2 Li equiv per formula unit) and the exploitation of multiple redox couples (e.g., Mn4+/3+, Co4+/3+, Ni4+/3+/2+). In this work, we propose and demonstrate experimentally a Co-free overlithiated LRLO material with a limited nickel content, i.e., Li1.25Mn0.625Ni0.125O2. This LRLO is able to exchange reversibly an outstanding practical specific capacity at room temperature, i.e., 230 mAh g–1 at C/10 for almost 200 cycles, and can sustain high current rates, i.e., 118 mAh g–1 at 2C. This material has been successfully prepared by a facile solution combustion synthesis and characterized by scanning electron microscopy (SEM), X-ray photoemission spectroscopy (XPS), X-ray absorption near-edge spectroscopy (XANES), X-ray diffraction (XRD), and Raman techniques. Overall, our positive electrodes based on Li1.25Mn0.625Ni0.125O2 overlithiated Co-free LRLO is a step forward in the development of the materials for batteries with improved performance and better environmental fingerprint.

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Lithium-rich layered oxides (LRLOs) are opening unexplored frontiers for high-capacity/high-voltage positive electrodes in Li-ion batteries (LIBs) to meet the challenges of green and safe transportation as well as cheap and sustainable stationary energy storage from renewable sources. LRLOs exploit the extra lithiation provided by the Li 1.2 TM 0.8 O 2 stoichiometries (TM = a blend of transition metals with a moderate cobalt content) achievable by a layered structure to disclose specific capacities beyond 200–250 mA h g –1 and working potentials in the 3.4–3.8 V range versus Li. Here, we demonstrate an innovative paradigm to extend the LRLO concept. We have balanced the substitution of cobalt in the transition-metal layer of the lattice with aluminum and lithium, pushing the composition of LRLO to unexplored stoichiometries, that is, Li 1.2+ x (Mn,Ni,Co,Al) 0.8– x O 2−δ . The fine tuning of the composition of the metal blend results in an optimized layered material, that is, Li 1.28 Mn 0.54 Ni 0.13 Co 0.02 Al 0.03 O 2−δ , with outstanding electrochemical performance in full LIBs, improved environmental benignity, and reduced manufacturing costs compared to the state-of-the-art.