Structure and interfaces of compositionally graded Li(Ni, Mn)xOy cathodes on (111) Nb-doped SrTiO3

Core-shell Li(Ni, Mn)(x)O-y thin film has been deposited onto a (111) single-crystal Nb-doped SrTIO3 substrate by pulsed laser deposition. The thin film is similar to 350-400 nm thick with a similar to 60 nm-thick Ni-rich interface. The orientation relationship between the cubic Li(Ni, Mn)(2)O-4 spinet and distorted rhombohedral-layered Li(Ni, Mn)O-2 phases and the substrates are [1 1 2]( )(STO) parallel to[1 1 2]( Spinel) and ((1) over bar(1) over bar1)( STO) parallel to((1) over bar(1) over bar1) (Spinel); [112]( STO) parallel to[210] (LiNiO2) and ((1) over bar(1) over bar1) (STO )parallel to(00 (3) over bar)(LiNiO2) and [112]( Spinel); parallel to[210] (LiNiO2) and ((1) over bar(1) over bar1) (Spinel )parallel to( 00 (3) over bar ) (LiNiO2). The film-substrate interface is sharp, non-reactive and free of planar defects. The interfaces between spinel, rhombohedrallayered Li(Ni, Mn)O-2 and the order-disorder domains are coherent and diffused. As the spacing between octahedral cations in the spinel phase and in the Li(Ni, Mn)O-2 phase is different; these two phases could be distinguished by quantifying the spacings between two octahedrally located cations. The electro-chemical behaviour of the film is not likely to be optimum even with the intended phase composition and chemistry due to disordering in Li (Ni, Mn)O-2 and unsuitable orientation of the phases. Understanding such structural details is a precursor to tailor the electro-chemical activity in Li(Ni, Mn)(x)O-y.