Effect of Nb5+ charge neutralization substitution on the electrochemical performance of lithium-rich layered oxides
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The effect of the Nb5+ substitution with a charge-compensated strategy in lithium-rich layered oxides (LLOs) Li1.2Ni0.13+xCo0.13-xMn0.54-xNbxO2 (x = 0, 0.01, 0.02, and 0.03) has been investigated systematically. A hydroxide co-precipitation method followed by a high-temperature solid-state reaction is adopted in the synthesis process. Structural characterization confirms that the low dose substituting of Nb5+ in the layered structures forms a solid solution, and the samples show low cation mixing and enlarged Li+-diffusing channels, which imply favorable high-rate capability. The initial charge/discharge measurements suggest that the oxygen loss from the network during the delithiation process has been suppressed by the substitution of Nb5+ due to the formation of robust Nb–O bonds and a decrease in TM-O (TMs are transition metals) covalence. Moreover, these Nb–O bonds contribute to the stabilization of the crystalline framework, resulting in an excellent cycle stability with a mitigated voltage decay.
KeywordsLithium-rich layered oxides Niobium substitution Voltage decay
This work is financially supported by the National Natural Science Foundation of China (Grant 51572024) and the Science and Technology Project of the State Grid Corporation of China (Grant DG71-16-025).
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