摘要
Lithium-rich manganese-based oxide(LRMO)cathode has emerged as a particularly promising candidate for achieving high energy densities in lithium-ion batteries due to its capability to access anion redox reactions at high voltage.The successful implementation of LRMO in energy storage systems is contingent upon the enhancement of their rate capabilities.However,the underlying relationship between high-rate cycling and electrode degradation for LRMO,particularly concerning structural evolution,still remains unclear.Benefiting from the high time resolution abilities of liquid-metal-jet operando twodimensional X-ray diffraction,it is observed that the Li_(2)MnO_(3)phase in LRMO is gradually activated accompanied by the emergence of oxygen vacancies during cycling at 1 C(1 C=250 mA/g).Consequently,the crystal lattice flexibility of LRMO is systematically enhanced,thereby preventing the collapse of the bulk structure.While,continuous release of oxygen during extended cycling results in deteriorations of the self-adjusting damping effect of the structure,ultimately leading to a decline in capacity.The findings of this study not only contribute to a more profound understanding of the structural changes of LRMOs at high rates,but also provide novel perspectives for the rational design of LRMOs with superior rate performances.
基金
financial supports from the National Natural Science Foundation of China(52372211,52371225 and 92472115)
the Guangdong Province Major Talent Introducing Program(2021QN020687)
the Shenzhen Basic Research Foundation(JCYJ20230807112503007)
the Guangdong Basic and Applied Basic Research Foundation(Grant No.2020A1515110176)。
