Strategies to Avert Electrochemical Shock and Their Demonstration in Spinels

We demonstrate that extensive electrochemical shock–electrochemical cycling induced fracture–occurs due to coherency stresses arising from first order cubic-to-cubic phase transformations in the spinels LiMn[subscript 2]O[subscript 4] and LiMn[subscript 1.5]Ni[subscript 0.5]O[subscript 4]. Electrochemical shock occurs despite the isotropy of the shape changes in these materials. This electrochemical shock mechanism is strongly sensitive to particle size; for LiMn[subscript 2]O[subscript 4] and LiMn[subscript 1.5]Ni[subscript 0.5]O[subscript 4], fracture can be averted with particle sizes smaller than ~1 μm. As a further critical test of the proposed mechanism, iron-doping was used to induce continuous solid solubility of lithium in LiMn[subscript 1.5]Ni[subscript 0.5]O[subscript 4], and shown to virtually avert electrochemical shock, while having minimal impact on the electrode potential and capacity.United States. Dept. of Energy. Office of Basic Energy Sciences. Division of Materials Sciences and Engineering (Award DE-SC0002633)National Science Foundation (U.S.). Graduate Research Fellowshi