The invention discloses a composite
lithium supplement material and a preparation method thereof, a positive
pole piece, a battery and an electric device. The composite
lithium supplement material comprises core-shell structure particles, each core-shell structure particle comprises an inner core and an outer shell
coating the outer surface of the inner core, and the outer shell comprises a
lithium supplement agent; the inner core comprises a
reducing agent, and the
reducing agent comprises at least one of elemental
sulfur, elemental
boron,
lithium sulfide,
sodium sulfide and
selenium disulfide. The lithium supplementing agent and the
reducing agent form the core-shell structure particles, so that the lithium supplementing efficiency is improved. Wherein the lithium supplementing agent serves as a shell, the reducing agent serves as a core, the reducing agent is placed in the lithium supplementing agent shell, it is guaranteed that the reducing agent can effectively react with the lithium supplementing agent, the
decomposition potential of the lithium supplementing agent is reduced, meanwhile, the reducing agent can be combined with anions in the lithium supplementing agent, stable salt is generated, and gas is avoided. And moreover, the reducing agent is coated by the lithium supplementing agent, so that
side reaction caused by direct contact between the reducing agent and the
electrolyte can be avoided.