Electrochemically-induced amorphization in multicomponent spinel oxide Li-ion cell anodes: Non-equimolarity enables improved electrochemical performance

• Li storage within an in-situ-formed amorphous matrix characterized. • Design guidelines to induce amorphization in multicomponent spinels formulated. • Novel Zn 1.6 Co 0.1 Mg 0.1 Mn 0.1 Ni 0.1 SnO 4 conversion-alloying anode developed. • Excellent cycling stability of 96% after 200 cycles for micrometer-sized material. • Configurational entropy is not directly related to performance in Li-ion cells. Among alternative anodes for Li-ion cells, conversion-alloying materials (CAMs) stand out as promising solutions for improving energy and power densities of these devices. Unfortunately, they often suffer from large volume changes upon (de-)lithiation, a process deleterious to their cycling stability. To address this issue, this work proposes altering their electrochemical reaction mechanism by introducing reversible Li storage within a multicomponent amorphous matrix, previously identified for the selected high-entropy oxide (HEO) anode, but without the compromises associated with the high-entropy approach. To demonstrate the feasibility of the concept, a novel Zn 1.6 Co 0.1 Mg 0.1 Mn 0.1 Ni 0.1 SnO 4 CAM, designed to combine the benefits of both conventional and high-entropy counterparts, is obtained. Compared to micrometer-sized Zn 2 SnO 4 , the developed new material shows superior cycling stability (56 % vs. 96 % capacity retention, respectively, 200 mA g −1 , comparing 200th to 10th cycle) while simultaneously having higher specific capacities and lower operating voltages than the high-entropy Zn 0.44 Co 0.44 Mg 0.44 Mn 0.44 Ni 0.44 Sn 0.8 O 4 analog. Through comparative studies, it is directly proven that the performance optimum does not necessarily correlate with the configurational entropy maximum, a common notion for HEOs. These discoveries point to a new direction for further development of high-performance multicomponent anodes and redefine the role of configurational entropy in the electrochemistry of compositionally complex systems.