Atomic Layer Deposition of Nitrogen-Doped Al Phosphate Coatings for Li-Ion Battery Applications

Abstract

In situ nitrogen doping of aluminum phosphate has been investigated in two dierent plasma enhanced atomic layer deposition (PE-ALD) processes. The rst method consisted of the combination of trimethyl phosphate plasma (TMP*) with a nitrogen plasma and trimethyl aluminum (TMA), i.e. TMP* -N 2 * -TMA. The second method replaces TMP* with a diethylphosphoramidate plasma (i.e. DEPA* -N 2 * -TMA), of which the amine group could further aid nitrogen doping and/or eliminate the need for a nitrogen plasma step. 1At a substrate temperature of 320 • C, the TMP*-based process showed saturated growth (0.8 nm/cycle) of a nitrogen doped (approximately 8 at.%) Al phosphate, while the process using DEPA* showed a similar amount of nitrogen but a signicantly higher growth rate (1.4 nm/cycle). In the latter case, nitrogen doping could also be achieved without the nitrogen plasma, but this leads to a high level of carbon contamination.Both lms were amorphous as-deposited, while X-ray diraction peaks related to AlPO 4 appeared after annealing in a He atmosphere. For high coating thickness (> 2 nm), a signicant increase in the Li-ion transmittance was found after nitrogen doping, although the coating has to be electrochemically activated.At lower thickness scales, such activation was not needed and nitrogen doping was found to double the eective transversal electronic conductivity. For the eective transversal ionic conductivity, no conclusive dierence was found. When a lithium nickel manganese cobalt oxide (NMC) powder is coated with one ALD cycle of N-doped Al phosphate, the rate capability and the energy eciency of the electrode improves.

Plasma-enhanced atomic layer deposition of nickel and cobalt phosphate for lithium ion batteries

“…[14][15][16][17] In this regard, various metal phosphates have, for example, already been proven to be very promising towards improving the final electrode's performance. [18][19][20] However, the study of thin films in general also offers a unique way to create model systems to gain a fundamental insight into a broad range of applications. In that way, the study of nickel phosphate through ALD can be of interest in various research fields.…”

Improvement of the Electrochemical Performance of LiNi0.8Co0.1Mn0.1O2 via Atomic Layer Deposition of Lithium-Rich Zirconium Phosphate Coatings

“…Table shows the previous attempts to use metal phosphate M x PO y coatings (where M is Li, Al, Ca, Fe, Mn, Mg, or Zr) to improve the performance of layered oxide cathode materials. Many of these phosphate ACEIs exhibit poor ionic and electronic conductivity, which results in increased electrode polarization upon cycling . Xin et al showed that lithium-containing species introduced into the ACEI can enhance the lithium-ion diffusivity. , For instance, coatings such as LiZr 2 (PO 4 ) 3 , LiAlF 4 , or Li 2 TiO 3 on NMC were reported to improve capacity retention upon prolonged cycling. − Park et al synthesized a zirconium phosphate ACEI on NMC via wet chemical treatment using zirconium nitrate (ZrO­(NO 3 ) 2 ·4H 2 O) and diammonium phosphate ((NH 4 ) 2 HPO 4 ) as precursors .…”

Effect of TiOx Surface Modification on the Electrochemical Performances of Ni-Rich (NMC-622) Cathode Material for Lithium-Ion Batteries

“…Numerous metal oxides such as Al 2 O 3 , , MgO, and TiO 2 , have been used as coating materials to enhance the electrochemical performances of electrode materials. Also, fluorides (AlF 3 ) and phosphates (AlPO­(N)) were successfully deposited by ALD and improved the electrochemical performance of a number of positive electrode materials. However, several of them show poor ionic and electronic conductivities, thereby compromising the electrode’s rate capability …”