(1. 云南民族大學(xué) 生物基材料綠色制備技術(shù)國(guó)家地方聯(lián)合工程研究中心，昆明 650500；
2. 云南民族大學(xué) 云南省高校綠色化學(xué)材料重點(diǎn)實(shí)驗(yàn)室，昆明 650500)
摘 要: 采用液相無(wú)焰燃燒法制備單晶多面體LiLa0.02Mn1.98O4材料，通過(guò)X射線衍射(XRD)、場(chǎng)發(fā)射掃描電子顯微鏡(FESEM)和透射電子顯微鏡(TEM)等表征手段對(duì)材料的結(jié)構(gòu)和形貌進(jìn)行分析，并通過(guò)恒電流充放電、循環(huán)伏安(CV)、交流阻抗(EIS)等測(cè)試分析材料的電化學(xué)性能。結(jié)果表明：摻雜La3+沒有改變LiMn2O4的尖晶石結(jié)構(gòu)。在25 ℃、1C和5C倍率條件下，LiLa0.02Mn1.98O4初始放電比容量分別為112.7和94.5mA？h/g，循環(huán)500次后，LiLa0.02Mn1.98O4的容量保持率為64.42%和81.45%，而LiMn2O4樣品的容量保持率分別為53.69%和56.9%；特別是在10C高倍率下，LiMn2O4樣品的初始放電比容量?jī)H有44.7 mA？h/g，同樣條件下，LiLa0.02Mn1.98O4首次放電比容量達(dá)73.5 mA？h/g，循環(huán)500次后，容量保持率為81.09%。CV和EIS測(cè)試發(fā)現(xiàn)，摻雜后的材料有較好的循環(huán)可逆性，較大的鋰離子擴(kuò)散系數(shù)1.04×10-16 cm2/s，對(duì)循環(huán)2000次后的極片進(jìn)行分析，材料的晶體結(jié)構(gòu)和顆粒形貌基本沒有變化，適量的La摻雜能夠穩(wěn)定材料的晶體結(jié)構(gòu)，有效抑制Jahn-Teller，提高材料的循環(huán)性能。
關(guān)鍵字: 尖晶石型LiMn2O4；鑭摻雜；去頂角八面體；鋰離子電池；正極材料
（1. National and Local Joint Engineering Research Center for Green Preparation Technology of Biobased Materials, Yunnan Minzu University, Kunming 650500, China;
2. Key Laboratory of Green-chemistry Materials in University of Yunnan Province, Yunnan Minzu University, Kunming 650500, China）
Abstract:LiLa0.02Mn1.98O4 cathode material with a single crystal polyhedral morphology was prepared via a liquid flameless combustion method. The structure and morphology of the material were analyzed by X-ray diffraction (XRD), field emission scanning electron microscope (FESEM) and transmission electron microscope (TEM). The electrochemical performance was characterized by galvanostatic charge-discharge test, cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The results show that the LiLa0.02Mn1.98O4 do not change the spinel structure of LiMn2O4, it delivers the initial discharge capacity of 112.7 and 94.5 mA？h/g with high capacity retention rate of 61.42% and 81.45% than that of the 53.69% and 56.9% in LiMn2O4after 500 cycles at 1C and 5C under 25 ℃, respectively. Especially, at a high current rate of 10C, the initial specific discharge capacity of LiLa0.02Mn1.98O4 is 73.5 mA？h/g, however, the LiMn2O4 is only 44.7 mA？h/g. Passing 500 cycles, the capacity retention rate of LiLa0.02Mn1.98O4 still mantian 81.09%. The CV and EIS test results also show that the La-doped material has good cycle reversibility and a larger lithium ion diffusion coefficient (1.04×10-16 cm2/s). In addition, the crystal structure and particle morphology of the LiLa0.02Mn1.98O4 are basically unchanged after 2000 cycles, indicating the appropriate La doping can stabilize the crystal structure and effectively inhibit Jahn-Teller effect. Therefore, the cycle performance of the material is improved.
Key words: spinel LiMn2O4; La-doping; truncated octahedron; lithium-ion battery; cathode materials
