Cathodes for lithium ion batteries: the benefits of using nanostructured materials

Abstract

As celas de íon lítio disponíveis comercialmente, as quais são as mais avançadas entre as baterias recarregáveis disponíveis até agora, empregam óxidos de metais de transição microcristalinos como catodos, os quais funcionam como matrizes de inserção de lítio. Em busca por uma melhor performance eletroquímica, o uso de nanomateriais no lugar dos materiais convencionais tem emergido como excelente alternativa. Nesta revisão nós apresentaremos uma breve introdução sobre as motivações de usar materiais nanoestruturados como catodos em baterias de íon-lítio. Para ilustrar tais vantagens apresentamos exemplos de pesquisas relacionadas com a preparação e dados eletroquímicos dos mais usados catodos em nanoescala, tais como LiCoO 2 , LiMn 2 O 4 , LiMnO 2 , LiV 2 O 5 e LiFePO 4 .Commercially available lithium ion cells, which are the most advanced among rechargeable batteries available so far, employ microcrystalline transition metal oxides as cathodes, which function as Li insertion hosts. In search for better electrochemical performance the use of nanomaterials in place of these conventional ones has emerged as excellent alternative. In this review we present a brief introduction about the motivations to use nanostructured materials as cathodes in lithium ion batteries. To illustrate such advantages we present some examples of research directed toward preparations and electrochemical data of the most used cathodes in nanoscale, such as LiCoO 2 , LiMn 2 O 4 , LiMnO 2 , LiV 2 O 5 e LiFePO 4 .Keywords: nanotechnology, lithium-ion battery, cathode, nanoparticles Initial RemarksSince Sony introduced its 18650 cell in 1990, 1 Li-ion batteries with excellent electrochemical performance have been manufactured and occupied a prime position in the market place 2 to power portable and non-portable devices. [3][4][5] The reason for this relevance is that compared to traditional rechargeable batteries such as, lead acid and Ni-Cd, the lithium-ion battery shows several advantages, such as lighter in weight, smaller in dimension and higher energy density. 1 Moreover, although capacity values may be similar to other rechargeable systems, voltages are approximately three times higher, affording higher energy. 1 In general, the commercial lithium-ion batteries use graphite-lithium composite, Li x C 6 , as anode, lithium cobalt oxide, LiCoO 2 , as cathode and a lithium-ion conducting electrolyte. When the cell is charged, lithium is extracted from the cathode and inserted at the anode. On discharge, the lithium ions are released by the anode and taken up again by the cathode (Figure 1).Owing to the importance of lithium ion batteries, these cells are still object of intense research to enhance their properties and characteristics. The searches focus on all aspects of these batteries, including improved anodes, 6-8 cathodes 9-17 and electrolytes. [18][19][20][21][22] However, most of these efforts are concentrated in new cathode materials, since the most used cathode material (LiCoO 2 ) is expensive and is somewhat toxic.The active catho...

Synthesis and Characterization of LiCoO2 from Different Precursors by Sol‑Gel Method

“…2,4 The investigation of the structural aspects of the material is a crucial issue to better understand the electrochemical properties of the LiCoO 2 compound. [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17] For example, the nature of the crystal, its size and shape, are directly related with its electrochemical characteristics. 2 The LiCoO 2 synthesized at low temperatures (LT), below 500 °C, presents a cubic spinel structure ( ), while the synthesis at high temperatures (HT) (above 500 °C), generates the rhombohedral structure with stratified layers ( ).…”

The Current Situation and Problems of Rechargeable Lithium Ion Batteries

“…The deposition of lithium metal within the battery causes a serious safety concern, which may lead to an explosion. To overcome this, Li 4 Ti 5 O 12 has been developed as an anode material and is already used in practice [32]. The charge and discharge curves of Li 4 Ti 5 O 12 in Fig.…”

“…Fig. (2) depicts the reactions at the electrodes of lithium ion batteries [4], where LiCoO 2 and graphite are used as materials for the cathode and anode, respectively. An electrolyte and separator must be placed between the anode and cathode, although they have been omitted in the figure for clarity.…”

In-Situ Versus Post-Synthetic Stabilization of Metal Oxide Nanoparticles

“…Within the last two decades, the synthesis and application of nanoparticles has evolved as one of the most active fields of research and development, promising solutions to some of humanity's most pressing needs in cases as diverse as cancer therapy, water purification, or energy storage (Duget et al, 2006;Bazito & Torresi, 2006;Centi & Perathoner, 2009;Feldmann & Goesmann, 2010;Goyal et al, 2011;Kim & van der Bruggen, 2010;Li et al, 2008;Moghimi et al, 2005;Prandeep & Anshup, 2009;Sanvicens & Pilar, 2008;Sides et al, 2002;Theron et al, 2007). Today, nanoparticles are predominantly being applied as particulate materials with enhanced properties as compared to the standard bulk material.…”