In recent decades, lithium-ion batteries (LIBs) have commercially dominated the portable electronics market, and gradually evolved into the most encouraging market area for electric vehicles (EVs).

Thanks to a discharge capacity of over 300 mAh g-1, Li-rich Mn-based layered cathode materials have emerged as a promising resource for developing high-performance Li-ion batteries.

The Advanced Li-ion Battery Engineering Lab, led by Professor Liu Zhaoping at the Ningbo Institute of Materials Technology and Engineering (NIMTE) of the Chinese Academy of Sciences (CAS), has delved into Li-rich Mn-based layered cathode materials, yielding remarkable research progress.

In a study published in Materials Today, the researchers have tested the safety performance of Li-rich layered cathodes.

The analysis reveals that the thermal-runaway temperature of Li-rich Mn-based layered cathodes decreases as the Mn content increases.

Furthermore, high Mn content in Li-rich layered cathode materials contributes to a high discharge capacity, but leads to a reduction of thermal stability and an acceleration of oxygen release.

By virtue of these findings, a polymorphic composition was designed for Li-rich layered cathode material that can reach an excellent balance between the energy density and thermal stability.

The thermally stable polymorphic layered cathode materials [IMAGE: NIMTE]

In addition, the available capacity in a low Li-ion diffusion coefficient is sensitive to the change of grain sizes, ranging from micron-size, and submicron-size to nano-size, according to a study published in Energy Storage Materials.

Compared with submicron-sized and nano-sized Li-rich layered cathode materials, the materials with micron-sized grains show a superior crystallinity and a higher Li-ion diffusion coefficient.

However, the increased diffusion distance results in an extremely uneven Li-ion concentration distribution during the charge-discharge process. Consequently, the strain stress inside the grains accumulates, leading to an unsatisfied capacity retention and a rapid voltage decay.

This insight on the kinetic limitation of Li-ion diffusion in Li-rich layered oxides may shed light on the modification of Li-rich Mn-based layered cathode materials for high-performance LIBs.

The kinetic limitations of Li-ion diffusion in Li-rich layered oxides [IMAGE: NIMTE]

For more information, please contact:

Qiu Bao

E-mail: qiubao@nimte.ac.cn

Ningbo Institute of Materials Technology and Engineering (NIMTE),

Chinese Academy of Sciences

Source: Ningbo Institute of Materials Technology and Engineering (NIMTE),

Chinese Academy of Sciences