文章信息/Info

Title:

Enhanced Electrochemical Performance of Zinc Phosphate Coated Ni-Rich LiNi0.8Co0.1Mn0.1O2 Cathode for Li-Ion Battery

文章編號(hào):

1674-3962(2021)07-0553-08

作者:

王禎濤; 顧虹; 王娟

（西安建筑科技大學(xué) 西安市清潔能源重點(diǎn)實(shí)驗(yàn)室，陜西 西安 710016）

Author(s):

WANG Zhentao; GU Hong; WANG Juan

(Xi’an Key Laboratory of Clean Energy，Xi’an University of Architecture and Technology，Xi’an 710016， China)

關(guān)鍵詞:

Li+電池; 富鎳正極材料;  Zn3(PO4)2包覆改性; 循環(huán)性能; 倍率性能

Keywords:

Lithium ion battery;  Ni-rich cathode material;  Zn3(PO4)2 coating modification;  cycle performance;  rate performance

分類(lèi)號(hào):

TM912

DOI:

10.7502/j.issn.1674-3962.202005031

文獻(xiàn)標(biāo)志碼:

A

摘要:

富鎳正極材料LiNi0.8Co0.1Mn0.1O2(NCM811)具有低成本、可逆容量大等優(yōu)勢(shì)，是一種受到廣泛研究的、極具商業(yè)化應(yīng)用潛力的正極材料。然而高的鎳含量會(huì)使電極表面結(jié)構(gòu)不穩(wěn)定性加劇，晶面間距降低，從而導(dǎo)致較差的循環(huán)性能與倍率性能。在采用共沉淀法制備純樣NCM811正極材料基礎(chǔ)上，采用聚乙烯吡咯烷酮（PVP）輔助磷酸鋅（Zn3(PO4)2）包覆NCM811正極材料，XRD圖譜表明，ZnO添加量（質(zhì)量分?jǐn)?shù)）3%時(shí)的改性樣品（NCM2）的I(003)/I(104)值最大，c/a值較純樣的大，具有較低的Li+/Ni2+混排程度。同時(shí)，Zn2+進(jìn)入電極材料表面晶格，使晶面間距擴(kuò)大，（003）平面內(nèi)原子散射能力提升。X射線光電子能譜（XPS）、掃描電鏡（SEM）及能譜（EDS）等表征結(jié)果表明，Zn3(PO4)2均勻包覆在正極材料顆粒表面。NCM2在0.1C電流密度下進(jìn)行100次循環(huán)后的容量為191 mAh·g-1，容量保持率為92%，而未改性樣品的容量保持率為87%。在5C電流密度下NCM2放電比容量比純樣高43%。循環(huán)伏安曲線和電化學(xué)阻抗譜結(jié)果表明，改性后正極材料電化學(xué)極化降低且Li+擴(kuò)散速率提高，提升了正極材料的循環(huán)性能和倍率性能。

Abstract:

Nickel-rich cathode material LiNi0.8Co0.1Mn0.1O2 (NCM811) has the advantages of low cost and large reversible capacity, so it has great potential for commercial application and becomes a hot spot for extensive research of new energy materials. However, high nickel content of Ni-rich cathode materials leads to increased surface structural instability and reduced interplanar spacing, as a result the cathode material shows poor cycle performance and rate performance in the commercial application. Based on the preparation of pure NCM811 by coprecipitation method, PVP (polyvinylpyrrolidone) assisted zinc phosphate coating NCM811 cathode material were synthesized. XRD patterns indicate that I(003)/I(104) of the coated sample with 3% ZnO addition (mass fraction, named NCM2) is the largest, and its c/a is bigger than that of the pristine, which means NCM2 has a lower degree of Li+/Ni2+ mixing. At the same time, zinc ion insertion improves the atomic scattering ability in the (003) plane. X-ray photoelectron spectroscopy（XPS）, scanning electron microscope（SEM）, energy dispersive spectrometer（EDS）results show zinc phosphate is uniformly coated on the particle surface of cathode materials. The capacity of NCM2 after 100 cycles at the current density of 0.1C is 191 mAh·g-1, and the capacity retention rate is 92%, however, the capacity retention rate of the pure sample is 87%. At 5C current density, the discharge capacity of NCM2 is 43% higher than that of the pure sample. The cyclic voltammetry（CV）and electrochemical impedance spectroscopy（EIS）test results show that the electrochemical polarization of the cathode material decreases and the lithium ion diffusion rate increases after coating, As a result, the cycle performance and the rate performance of zinc phosphate coated NCM811 cathode material are improved.