An electrolyte for a lithium-ion battery, a lithium-ion battery, a battery module, a battery pack, and an apparatus are provided. The electrolyte includes an organic solvent, an electrolyte lithium salt dissolved in the organic solvent, and an additive, where the additive is a compound represented by following formula I. The electrolyte can inhibit generation of lithium dendrites in the lithium-ion battery, improve cycle performance of the battery, and also improve flame retardancy of the battery, thereby effectively resolving defects in the existing technology.