Improved cycling stability of conversion and alloying anodes through the use of nanomaterials

• In order to meet the growing need for portable energy storage future batteries need to provide improved energydensities. One major problem lies in the current use of intercalation based electrode materials which are typicallylimited to storing one lithium ion per formula unit. Improved energy storage can be achieved through the use ofconversion and alloying reactions where it is possible to store multiple lithium ions per formula unit. Eventhough impressive energy densities can be obtained through the use of conversion and alloying anode materials,only surpassed by the use of lithium metal itself, these systems are typically plagued by capacity fading duringcycling. The origin is generally ascribed to irreversible reactions with the electrolyte amplified by major volumeexpansion, causing the growth of a solid electrolyte interphase (i.e. SEI). One promising strategy to address thisissue is through the use of nanosized electrode materials (e.g. Si nanoparticles), as it has been shown thatnanoparticles and nanowires show better cycling stability than their bulk counterparts [1, 2]. Large particles (i.emicrometer sized) form cracks during cycling as opposed to smaller particles (i.e. < 150 nm) [3]. Even thoughthe use of nanoparticles can reduce crack formation and the accompanied SEI growth, capacity fading is stillobserved for these systems. Our work has focused on studying freestanding nanostructured conversion materials(e.g. Cu2O nanowires), which offer in depth analyses of the conversion reactions without disturbance frombinders or conducting additives. Contrary to previous understanding nanosized Cu2O thin films and multilayerednanostructures show an increase in capacity during cycling [4, 5]. This behaviour is caused by improvedaccess to the entire material when using the nanomaterials. The system has also shown improved performanceduring cycling likely caused by electrochemical milling of the particles thereby consistently reducing the particlesize and thus allowing more of the material to be accessible. With the successful use of nanosized conversionmaterials our research is now focused on addressing the stability problems of alloying materials by studying theeffect of nanomaterials.References1. A. Magasinski, et al.. Nat. Mater., 2010. 22: p. 353-3582.2 C.K. Chan, et al.. Nat. Nanotechnol., 2008. 3: p. 31-353.3 X. H. Liu, et al.. Adv. En. Mater., 2012. 2: p. 722-7414.4 D. Rehnlund, et al.. J. Mat. Chem. A., 2014. 2: p. 9574-95865.5 D. Rehnlund, et al.. Nanoscale, 2015. 7: p. 13591-13604

Ämnesord

NATURVETENSKAP  -- Kemi -- Oorganisk kemi (hsv//swe)

NATURAL SCIENCES  -- Chemical Sciences -- Inorganic Chemistry (hsv//eng)

Nyckelord

lithium

batteries

alloy forming

conversion

nanostructures

anodes

stability

Kemi med inriktning mot oorganisk kemi

Chemistry with specialization in Inorganic Chemistry

Publikations- och innehållstyp

vet (ämneskategori)

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