文章信息/Info

Title:

Enhanced Electrochemical and Storage Properties of TiO2-Modified LiNi0.8Co0.1Mn0.1O2 Cathode

作者:

林桂仙; 韓博; 黃群; 張春曉; 韋偉峰

（中南大學(xué) 粉末冶金國家重點(diǎn)實(shí)驗(yàn)室，湖南 長沙 410083）

Author(s):

LIN Guixian;  HAN Bo;  HUANG Qun;  ZHANG Chunxiao;  WEI Weifeng

(State Key Laboratory of Powder Metallurgy, Central South University, Changsha, China)

關(guān)鍵詞:

高鎳系層狀三元氧化物; TiO2表面包覆; Ti4+體相摻雜; 循環(huán)穩(wěn)定性; 儲存性能

Keywords:

Ni-rich layered oxides;  TiO2 coating;  Ti4+ doping;  cycling stability;  storage property

文獻(xiàn)標(biāo)志碼:

A

摘要:

高鎳系層狀三元氧化物具有高比容量、高工作電壓等優(yōu)點(diǎn)，被認(rèn)為是最具有商業(yè)化前景的鋰離子電池正極材料之一。但是由于其表面穩(wěn)定性較差、易于發(fā)生一系列不可逆相變等問題，導(dǎo)致高鎳系層狀三元氧化物仍存在循環(huán)穩(wěn)定性及儲存性差等缺點(diǎn)，限制了其廣泛應(yīng)用。本實(shí)驗(yàn)采用簡單的濕化學(xué)法，對LiNi0.8Co0.1Mn0.1O2高鎳層狀氧化物表面進(jìn)行TiO2包覆改性，并通過800 ℃高溫復(fù)燒使部分Ti4+摻入LiNi0.8Co0.1Mn0.1O2的體相中，同時提高其循環(huán)穩(wěn)定性及儲存性能。受益于TiO2表面包覆及Ti4+體相摻雜的協(xié)同作用，改性后的LiNi0.8Co0.1Mn0.1O2表現(xiàn)出優(yōu)異的循環(huán)穩(wěn)定性，在2.8~4.3 V電壓區(qū)間內(nèi)，以2C（1C=200 mA·g-1）的電流密度循環(huán)100圈后容量保持率高達(dá)90.77%，而原始樣在相同條件下的容量保持率僅為80��38%。除此之外，在空氣中暴露30 d后，改性后的LiNi0.8Co0.1Mn0.1O2樣品仍具有86.12%新鮮樣品的初始放電比容量，100次循環(huán)后的容量保持率為85.31%，遠(yuǎn)遠(yuǎn)高于原始樣的對應(yīng)值（67.40%與68.02%）。借助CV、EIS、XPS、XRD、TEM等測試手段，對改性的原因進(jìn)行了詳細(xì)的分析。

Abstract:

Ni-rich layered oxides (NLOs) are widely considered as one class of commercially available cathodes for lithium-ion batteries (LIBs), mainly ascribed to their high specific capacities and working voltages. However, two major hurdles of NLOs for practical utilization are their inferior cycling stability and storage property, strongly deriving from the irreversible bulk phase transformations and detrimental surface degradation. Herein, we demonstrate a combination of TiO2 surface coating and Ti4+ bulk doping modification to improve the cyclability and storage property of LiNi0.8Co0.1Mn0.1O2 synchronously. The TiO2 coating layer is established by a simple hydrolytic process followed by a post�瞭reatment at 800 ℃ that leads to Ti4+ doping. Benefiting from the synergetic effects of chemical doping and surface coating, the TiO2�瞔oated LiNi0.8Co0.1Mn0.1O2 (811@TiO2) material exhibits superior cycling stability with 90��77% capacity retention after 100 cycles at 2C(1C=200 mA·g-1) between 2.8-4.3 V, while that of pristine (811-bare) is just 80.38%. Moreover, after 30 days of air exposure, the 811@TiO2 electrode still retains 86.12% of the initial reversible capacity delivered by the fresh one with 85.31% cycling capacity retention after 100 cycles at 2C, which are greater than the corresponding values of 67.40% and 68.02% for the 811-bare electrode respectively. Served with the analysis of CV,EIS,XPS,XRD,TEM, etc, the improved performances are exhibited and discussed in detail.