摘要
Layered Mn-based oxides are one of the promising cathode materials for potassium-ion batteries(KIBs)owing to their high theoretical capacities,abundant material supply,and simple synthesis method.However,the structural deterioration resulting from the Jahn-Teller effect of Mn ions hinders their further development in KIBs.Herein,a novel Mn-based layered oxide,K_(0.54)Mn_(0.78)Mg_(0.22)O_(2),is successfully designed and fabricated as KIBs cathode for the first time.It delivers smooth charging/discharging curves with high specific capacity of 132.4 mAh·g^(‒1)at 20 mA·g^(‒1)and good high-rate cycling stability with a capacity retention of 84%over 100 cycles at 200 mA·g^(‒1).Combining in-situ X-ray diffraction(XRD)and ex-situ X-ray photoelectron spectroscopy(XPS)analysis,the storage of K-ions by K_(0.54)Mn_(0.78)Mg_(0.22)O_(2)is revealed to be a solid-solution processes with reversible slip of the crystal lattice.The studies suggest that the rational doping of inactive Mg2+can effectively suppress the Jahn-Teller effect and provide outstanding structure stability.This work deepens the understanding of the structural evolution of Mn-based layered materials doped with inactive materials during de/potassiation processes.
基金
This work was supported by the National Natural Science Foundation of China(Nos.51972030 and 51772030)
the S&T Major Project of Inner Mongolia Autonomous Region in China(2020ZD0018)
Beijing Outstanding Young Scientists Program(BJJWZYJH01201910007023)
Guangdong Key Laboratory of Battery Safety(2019B121203008).
