正极材料LiAl_(0.08)Mn_(1.92)O_(4)单晶颗粒形貌演变及电化学性能  

Morphological evolution and electrochemical properties of cathode material LiAl_(0.08)Mn_(1.92)O_(4) single crystal particles

作　　者：朱琴 马姣 钱志慧 罗宇旭 郭昱娇 向明武 刘晓芳 宁平[2] 郭俊明 ZHU Qin;MA Jiao;QIAN Zhihui;LUO Yuxu;GUO Yujiao;XIANG Mingwu;LIU Xiaofang;NING Ping;GUO Junming(Key Laboratory of Green Chemical Materials in University of Yunnan Province,College of Chemistry and Environment,Yunnan Minzu University,Kunming 650500,China;Faculty of Environmental Science and Engineering,Kunming University of Science and Technology,Kunming 650093,China)

机构地区：[1]云南民族大学化学与环境学院,云南省高校绿色化学材料重点实验室,昆明650500 [2]昆明理工大学环境科学与工程学院,昆明650093

出　　处：《无机化学学报》2024年第8期1549-1562,共14页Chinese Journal of Inorganic Chemistry

基　　金：国家自然科学基金(No.51972282)资助。

摘　　要：联合元素掺杂和形貌调控策略,采用固相燃烧法和不同焙烧温度处理合成LiAl_(0.08)Mn_(1.92)O_(4)正极材料。实验结果表明,Al掺杂和焙烧温度的变化未改变LiMn_(2)O_(4)的相结构,随着温度的升高,结晶性增强,颗粒尺寸增大,其中焙烧温度650℃是形成截断八面体单晶颗粒形貌的关键温度,750℃是颗粒突然变大的突变温度。650℃优化焙烧温度下焙烧的LiAl_(0.08)Mn_(1.92)O_(4)形成了较完整的包含(111)、(110)和(100)晶面的截断八面体单晶颗粒形貌,表现出优良的电化学和动力学性能。在1C下其首次放电比容量为112.0 mAh·g^(-1),循环500次后容量保持率为72.9%,在5C和10C倍率下,其首次放电比容量可达到107.1和100.4 mAh·g^(-1),经2000次长循环后,容量保持率为52.2%和53.5%。并且具有最小氧化还原峰电位差(ΔE_(p2),循环前后分别为0.109和0.114 V)、最小电荷转移电阻(R_(ct),循环前后分别106.49和125.49Ω)及较大的锂离子扩散系数(D_(Li^(+))=1.72×10^(-16)cm^(2)·s^(-1)),表现出较好的电化学可逆性和较快的锂离子扩散速率。Al掺杂和单晶截断八面体颗粒形貌既有效抑制了LiMn_(2)O_(4)的Jahn-Teller畸变,又降低了Mn溶解,提高了材料的倍率性能和长循环寿命。Combined with the element doping and morphology controlling strategies,the LiAl_(0.08)Mn_(1.92)O_(4) cathode material was synthesized by solid-state combustion method and dealt with at different calcination temperatures(600,650,700,and 750℃).The experimental results showed that the phase structure of LiMn_(2)O_(4) was not changed by Al doping and the change of calcination temperature.With the increase in temperature,the crystallinity of the sample increased and the particle size enlarged.The calcination temperature of 650℃was the key temperature for the formation of truncated octahedral single crystal particle morphology,and 750℃was the abrupt temperature of the particles that suddenly became larger.The LiAl_(0.08)Mn_(1.92)O_(4) material with an optimized calcination temperature of 650℃formed a relatively complete truncated octahedral single crystal morphology particle containing(111),(110),and(100)crystal planes,and showed excellent electrochemical and kinetic performance.The initial discharge capacity was 112.0 mAh·g^(-1) at 1C,and the capacity retention rate was 72.9%after 500 cycles.The initial discharge capacities were 107.1 and 100.4 mAh·g^(-1) at 5C and 10C,and the capacity retention rates were 52.2%and 53.5%after 2000 cycles,respectively.It had the minimum redox peak potential difference(ΔEp2=0.109 and 0.114 V before and after cycling respectively),the minimum charge transfer resistance(Rct=106.49 and 125.49Ωbefore and after cycling respectively),and the large lithium-ion diffusion coefficient(D_(Li^(+))=1.72×10^(-16) cm^(2)·s^(-1)).The Al doping and single crystal truncated octahedral particle morphology not only effectively inhibited the Jahn Teller effect of LiMn_(2)O_(4) but also relieved the dissolution of Mn,and improved the rate performance and long cycle life of the materials.

关 键 词：尖晶石LiMn_(2)O_(4) AL掺杂 固相燃烧法 焙烧温度 形貌调控 截断八面体 

分 类 号：TM912[电气工程—电力电子与电力传动] O614.31[理学—无机化学]