摘要
High-voltage LiCoO_(2)(LCO)offers a prelude to breaking the bottleneck of the energy density of lithium-ion batteries,however,LiCoO_(2)is subject to serious structural and interfacial degradation above voltages>4.55 V(vs.Li/Li^(+)).Herein,an in-situ Li_(6.25)La_(3)Zr_(2)A_(l0.25)O_(12)(LLZAO)layer is constructed on the LCO surface to achieve operating voltage at 4.6 V.The detailed characterizations(ex-situ XRD,ex-situ Raman,DFT,etc.)reveal that the LLZAO layer greatly enhances Li+conductivity attributed to the ionconducting layer on the surface/interface,and closely combines with LiCoO_(2)particle to ensure stable cathode/electrolyte interface,thus suppressing the highly reactive Co^(4+)and O^(-)triggered surface side reactions at high-voltage.Moreover,the introduction of La^(3+)/Zr^(4+)/Al^(3+)with a larger ionic radius(La^(3+)/Zr^(4+)are larger than Co^(3+))and weaker electronegativity(La/Zr/Al are weaker than Co)into Co^(3+)sites readjusts the electron cloud density between Co–O–Li,which reinforces the Co–O bond and widens the band-center gap of Co 3d and O 2p,thus restraining the detrimental phase transition(from H3 to H1-3 phase)and the formation of Co_(3)O_(4)spinel phase(attributed to lattice oxygen release),subsequently alleviating the particle cracking and structural collapse during repeated Li^(+)de/intercalation.Therefore,after 100 cycles at 3.0–4.6 V,LCO@1.0LLZAO exhibits a superior discharge capacity of 188.5 m A h g^(-1),with a capacity retention of 85.1%.The above research has brought about meaningful guidance for the evolution of cathode materials with high voltage.
基金
supported by the Chongzuo Science and Technology Program Project Fund(No.FA20210713)。
作者简介
Corresponding author:Yunjiao Li,E-mailaddress:yunjiao_li@csu.edu.cn。
