A hybrid-structured
Li[Ni0.9Co0.045Mn0.045Al0.01] (HS-NCMA90) cathode is proposed, in
which Li[Ni0.92Co0.04Mn0.03Al0.01]O2 forms the interior of the cathode
particle enclosed in a buffer layer of Li[Ni0.845Co0.067Mn0.078Al0.01]O2. The hybrid structure is compositionally partitioned into interior
and outer regions and develops radially aligned, size-refined primary
particles with a high aspect ratio. This optimized microstructure
enables the primary particles to contract uniformly and produces differential
states of stress that apply compressive stress to the particle interior,
thereby effectively suppressing the propagation of microcracks toward
the outer surface. The unique microstructure of the HS-NCMA90 cathode
markedly improves its cycling stability, which retains 84.7% of its
initial capacity after 1500 cycles. The proposed microstructurally
engineered cathode, with high mechanical stability and fracture toughness,
prolongs the service life of batteries with high energy densities.
The electrochemical and structural stabilities of a conventional Li[Ni0.90Co0.045Mn0.045Al0.01]O2 (NCMA90) cathode and a core–shell with concentration gradient cathode (CSG‐NCMA90) are evaluated by cycling the cathodes at different depths of discharge (DoDs). The CSG‐NCMA90 cathode consists of fine, elongated primary particles that are radially aligned from the center of a spherical secondary particle. This unique microstructure effectively suppresses microcrack formation and propagation in the highly charged state. Moreover, microstructural analysis through transmission electron microscopy reveals that the thin elongated primary particles, largely featuring (001) facets on their lateral sides, are tolerant of electrolyte attack, thus suppressing surface degradation. In a full cell, these microstructural features enable the CSG‐NCMA90 cathode to retain 90.7% of its initial capacity after 1000 cycles at 100% DoD. Unlike conventional Ni‐rich layered cathodes whose capacity should be restricted to ≈60–80% to ensure their long service life, the proposed CSG‐NCMA90 cathode can be cycled at full capacity, thus facilitating higher electrochemical performance and realizing the development of economical Li‐ion batteries.
Recharging capability of Ni-rich layered cathodes deteriorates rapidly upon cycling mainly from mechanical instability caused by removing a large amount of Li ions from the host structure. Through multi-stage microstructural...
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.