An investigation of Ni-Co-Mn oxides as anodes for Li⁺/Na⁺ ion batteries

Lithium-ion batteries (LIBs) and sodium-ion batteries (SIBs) represent a significant research hotspot in the field of rechargeable batteries. Conversion-type anodes have garnered considerable attention due to their dual lithium and sodium storage activities. Typically, conversion-type anode materials exhibit higher stability in LIB systems compared to SIB systems, attributed to the smaller radius of Li⁺ ions in comparison to Na⁺ ions. However, our synthesized microsphere-like (Ni_0.3Co_0.3Mn_0.4)₃O₄ material demonstrates enhanced stability in SIB systems compared to LIB systems. When employed as a SIB anode, the oxide electrode exhibits a sodiation capacity of 81 mAh g⁻¹ after 500 cycles at 0.2 A g⁻¹, with a retention rate of 65% compared to the capacity at the fifth cycle. Conversely, rapid capacity fading is observed in LIB systems. An explanation for this phenomenon is detailed as follows: sodiation primarily occurs on the material’s surface, given the challenging transport of Na⁺ ions. As a result, the sample experiences low stress in the SIB system. In contrast, complete lithiation induces substantial stress, leading to numerous cracks in the electrode, thereby compromising electric contact and resulting in a significant specific capacity attenuation in LIB systems. Furthermore, a stable Na⁺-ion full cell with (Ni_0.3Co_0.3Mn_0.4)₃O₄ as an anode and Na₃V₂(PO₄)₃ as a cathode is provided.