Plasma-enhanced atomic layer deposition of nickel and cobalt phosphate for lithium ion batteries. Issue 5 (18th January 2022)

• Record Type: Journal Article
• Authors: Henderick, Lowie; Blomme, Ruben; Minjauw, Matthias; Keukelier, Jonas; Meersschaut, Johan; Dendooven, Jolien; Vereecken, Philippe; Detavernier, Christophe
• Is Part Of: Dalton transactions. Volume 51:Issue 5(2022)
• Page Start: 2059
• Page End: 2067
• Publication Date: 2022-01-18
• Subjects: Chemistry, Inorganic -- Periodicals; Chemistry, Physical and theoretical -- Periodicals; Chemistry, Inorganic -- Periodicals; 546.05
• DOI: 10.1039/d1dt03417k
• Languages: English
• ISSNs: 1477-9226

Abstract

Abstract : Both a cobalt- and (novel) nickel phosphate deposited through a plasma-enhanced ALD process have been characterised as an LIB electrode. Abstract : A plasma-enhanced ALD process has been developed to deposit nickel phosphate. The process combines trimethylphosphate (TMP) plasma with oxygen plasma and nickelocene at a substrate temperature of 300 °C. Saturation at a growth per cycle of approximately 0.2 nm per cycle is observed for both the TMP plasma and nickelocene, while a continuous decrease in the growth per cycle is found for the oxygen plasma. From ERD, a stoichiometry of Ni3 (P0.8 O3.1 )2 is measured, but by adding additional oxygen plasma after nickelocene, the composition of Ni3 (P0.9 O3.7 )2 becomes even closer to stoichiometric Ni3 (PO4 )2 . The as-deposited layer resulting from the process without the additional oxygen plasma is amorphous but can be crystallized into Ni2 P or crystalline Ni3 (PO4 )2 by annealing under a hydrogen or helium atmosphere, respectively. The layer deposited with the additional oxygen plasma shows two X-ray diffraction peaks indicating the formation of crystalline Ni3 (PO4 )2 already during the deposition. The resulting PE-ALD deposited nickel phosphate layers were then electrochemically studied and compared to PE-ALD cobalt and iron phosphate. All phosphates need electrochemical activation at low potential first, after which reversible redox reactions are observed at a potential of approximately 2.5 V vs. Li + /Li. A relatively high capacity and good rate behavior are observed for both nickel and cobalt phosphate, which are thought to originate from either a conversion type reaction or an alloying reaction.