Direct plasma phosphorization of Cu foam for Li ion batteries

Abstract

Phosphorus is a promising anode material for lithium ion batteries, while it suffers from poor electronic conductivity and large volume change during operation. These drawbacks can be effectively overcome by replacing P with Cu₃P, in which Cu serves as a conductive buffer. However, this strategy will cause significant capacity loss due to inclusion of inert Cu. In this work, we use plasma activated phosphorus vapor to deposit P on a Cu current collector, which converts the surface of the Cu into Cu₃P in situ. In this case, the P electrode is converted to a Cu₃P electrode without an external Cu source except for the current collector. The high chemical reactivity of plasma allows phosphorization at only 200 °C, leading to a monolithic electrode with excellent mechanical strength and free of any conductive additive and binder. The obtained electrode exhibits a high initial coulombic efficiency of >90%. The areal capacity is up to 2.3 mA h cm⁻² after 50 cycles at 3.2 mA cm⁻².