Capacity–Retention Balance Determines Single-Crystal Payoff in Ni-Rich Cathodes

Single crystallization is widely pursued to mitigate structural degradation in Ni-rich layered cathodes, yet its practical value remains difficult to define because improved durability can be accompanied by kinetic limitations and an initial-capacity penalty. Here, we establish a literature-derived quantitative framework that converts this long-standing trade-off into a measurable payoff criterion. Directly comparable polycrystalline–single-crystal cathode pairs from 12 datasets and 42 test contexts were evaluated through logarithmic response ratios describing initial-capacity, retention, and end-of-test capacity effects. Single-crystal cathodes showed higher retention in 67% of comparisons but higher initial capacity in only 19%, while 64% ultimately achieved a higher end-of-test capacity. These results identify compensation between early capacity sacrifice and durability gain as the central determinant of single-crystal benefit. Cross-dataset analysis further shows that this payoff is condition-dependent. The resulting break-even framework shifts single crystallization from a qualitative stability preference to a quantitative materials selection principle and offers a broader strategy for evaluating energy-storage materials in which long-term durability is gained at the expense of initial performance.