P2-type sodium layered oxide cathode(Na2/3Ni1/3Mn2/3O2,P2-NNMO)has attracted great attention as a promising cathode material for sodium ion batteries because of its high specific capacity.However,this material suffers from a rapid capacity fade during high-voltage cycling.Several mechanisms have been proposed to explain the capacity fade,including intragranular fracture caused by the P2-O2 phase tran-sion,surface structural change,and irreversible lattice oxygen release.Here we systematically investi-gated the morphological,structural,and chemical changes of P2-NNMO during high-voltage cycling using a variety of characterization techniques.It was found that the lattice distortion and crystal-plane buckling induced by the P2-O2 phase transition slowed down the Na-ion transport in the bulk and hin-dered the extraction of the Na ions.The sluggish kinetics was the main reason in reducing the accessible capacity while other interfacial degradation mechanisms played minor roles.Our results not only enabled a more complete understanding of the capacity-fading mechanism of P2-NNMO but also revealed the underlying correlations between lattice doping and the moderately improved cycle performance.

Meidan Jiang;Guannan Qian;Xiao-Zhen Liao;Zhouhong Ren;Qingyu Dong;Dechao Meng;Guijia Cui;Siqi Yuan;Sang-Jun Lee;Tian Qin;Xi Liu;Yanbin Shen;Yu-Shi He;Liwei Chen;Yijin Liu;Linsen Li;Zi-Feng Ma

Department of Chemical Engineering,Shanghai Electrochemical Energy Device Research Center(SEED),School of Chemistry and Chemical Engineering,Frontiers Science Center for Transformative Molecules,Shanghai Jiao Tong University,Shanghai 200240,China;Stanford Synchrotron Radiation Lightsource,SLAC National Accelerator Laboratory,Menlo Park,CA 94025,United States;In-Situ Center for Physical Sciences,School of Chemistry and Chemical Engineering,Shanghai Jiao Tong University,Shanghai 200240,China;Suzhou Institute of Nanotech and Nanobionics(SINANO),Chinese Academy of Sciences,Suzhou 215123,Jiangsu,China;Shanghai Jiao Tong University Sichuan Research Institute,Chengdu 610213,Sichuan,China

能源化学

[1]Meidan Jiang;Guannan Qian;Xiao-Zhen Liao;Zhouhong Ren;Qingyu Dong;Dechao Meng;Guijia Cui;Siqi Yuan;Sang-Jun Lee;Tian Qin;Xi Liu;Yanbin Shen;Yu-Shi He;Liwei Chen;Yijin Liu;Linsen Li;Zi-Feng Ma-.Revisiting the capacity-fading mechanism of P2-type sodium layered oxide cathode materials during high-voltage cycling)[J].能源化学,2022(06):16-25

NNMO

Revisiting,capacity,fading,P2,type,sodium,layered,oxide,cathode,materials,during,high,voltage,cycling,Na2,3Ni1,3Mn2,3O2,attracted,great,attention,promising,batteries,because,its,specific,However,this,suffers,from,rapid,fade,Several,mechanisms,have,been,proposed,explain,including,intragranular,fracture,caused,by,phase,sion,surface,structural,irreversible,lattice,oxygen,release,Here,systematically,investi,gated,morphological,chemical,changes,using,variety,characterization,techniques,It,was,found,that,distortion,crystal,plane,buckling,induced,transition,slowed,down,transport,bulk,hin,dered,extraction,sluggish,kinetics,main,reason,reducing,accessible,while,other,interfacial,degradation,played,minor,roles,Our,results,not,only,enabled,more,complete,understanding,but,also,revealed,underlying,correlations,between,doping,moderately,improved,cycle,performance

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