Surface Lattice Modulation through Chemical Delithiation toward a Stable Nickel-Rich Layered Oxide Cathode

Abstract

Nickel-rich layered oxides (NLOs) are considered as one of the most promising cathode materials for next-generation high-energy lithium-ion batteries (LIBs), yet their practical applications are currently challenged by the unsatisfactory cyclability and reliability owing to their inherent interfacial and structural instability. Herein, we demonstrate an approach to reverse the unstable nature of NLOs through surface solid reaction, by which the reconstructed surface lattice turns stable and robust against both side reactions and chemophysical breakdown, resulting in improved cycling performance. Specifically, conformal La(OH) 3 nanoshells are built with their thicknesses controlled at nanometer accuracy, which act as a Li + capturer and induce controlled reaction with the NLO surface lattices, thereby transforming the particle crust into an epitaxial layer with localized Ni/Li disordering, where lithium deficiency and nickel stabilization are both achieved by transforming oxidative Ni 3+ into stable Ni 2+ . An optimized balance between surface stabilization and charge transfer is demonstrated by a representative NLO material, namely, LiNi 0.83 Co 0.07 Mn 0.1 O 2 , whose surface engineering leads to a highly improved capacity retention and excellent rate capability with a strong capability to inhibit the crack of NLO particles. Our study highlights the importance of surface chemistry in determining chemical and structural behaviors and paves a research avenue in controlling the surface lattice for the stabilization of NLOs toward reliable high-energy LIBs.

Gradient Boracic Polyanion Doping-Derived Surface Lattice Modulation of High-Voltage Ni-Rich Layered Cathodes for High-Energy-Density Li-Ion Batteries

“…At the same time, this phenomenon is effectively suppressed due to the existence of the surface disorder phase, so as to ensure the stability of the structure and enhance the electrochemical performance of the material. As previously reported, ,,, the phase transformation in B-NCM is effectively inhibited because an appropriate amount of Ni 2+ migrates to the Li layer, which strengthens the lattice by the pillar effect.…”

“…30 In addition, Wan et al constructed a nanometer-accurate La(OH) 3 shell (as a Li + capture agent) to realize the conversion of oxidized Ni 3+ to stable Ni 2+ , thereby transforming the particle shell into an epitaxial layer with local Ni/Li disorder. 31 Another key role of doping with elements such as B, Nb, Mo, W, etc. is to regulate the morphology of the particle structure.…”

“…44 Meanwhile, the Ni 2p 3/2 peak of B-NCM is at 854.88 eV, which is slightly lower than the pristine peak (855.18 eV). The transfer to lower energy indicates a decrease in nickel−oxygen covalence and a decrease in the nickel valence of the transition metal; that is, more Ni 2+ appears on the surface of B-NCM than in the original, 31 as shown in Figure S10a,c. This coincides with the XRD results, with B-NCM exhibiting a higher Ni 2+ /Li + mixed value of 4.7 compared to 4.1 for the pristine (Table 1).…”

“…That is, Ni 2+ migrates from the transition metal slabs to the lithium slabs and forms a disordered phase structure on the surface of the particles as a nanoscale surface-pillaring layer . In addition, Wan et al constructed a nanometer-accurate La­(OH) 3 shell (as a Li + capture agent) to realize the conversion of oxidized Ni 3+ to stable Ni 2+ , thereby transforming the particle shell into an epitaxial layer with local Ni/Li disorder . Another key role of doping with elements such as B, Nb, Mo, W, etc.…”

The genesis and control of microcracks in nickel-rich cathode materials for lithium-ion batteries

“…Conductive materials such as LiAlF 4 , Li 2 MoO 4, and LiF 3 can not only protect the surface structure of cathodes but also improve the conductivity of NROs. 82–85 In the study conducted by Fan et al , 69 a sodium-super-ion-conductor-type (NASICON-type) Li 1.4 Y 0.4 Ti 1.6 (PO 4 ) 3 (LYTP) ion/electron conductive coating layer was applied on the surface of LiNi 0.88 Co 0.09 Mn 0.03 O 2 (SC-NCM88) particles, as illustrated on Fig. 11a.…”