Eliminating the “Dead By‐Product” Effect Realizes Powerful Vanadium‐Based Zinc‐Ion Batteries: An Overlooked Case

The accumulation of inactive by-products caused by the parasitic side reaction on cathode side is an overlooked question leading to performance degradation of zinc-ion batteries. In this research, taking the MnV₂O₄ as a model, an amorphous carbon interphase is proposed as a pre-implanted cathode-electrolyte interphase (CEI) to design ultrafast-kinetics MnV₂O₄@C cathode. It is noted that such CEI integrates hydrophobic and conductive characteristics, contributing to dissolution shielding, continuous interfacial conductive channel, and thus preventing inactive by-product accumulation on the cathode interface. Unexpectedly, such electrode shows superior storage performance at a wide temperature range of -20-55 °C. It can deliver a specific capacity of 253.3 mAh g^-1 at the high current density of 10 A g^-1 even after 8000 cycles. Moreover, a high specific capacity of 393.8 mAh g^-1 (0.1 A g^-1) can be retained after 300 cycles at 55 °C, as well as 205.1 mAh g^-1 at the condition of -20 °C and 5 A g^-1. Beyond that, flexible solid-state zinc-ion batteries based on MnV₂O₄@C cathode with excellent wide temperature performance are demonstrated. This work highlights the importance of eliminating the dead by-product effect to design advanced cathode materials for zinc-ion batteries.