7 Application of Mössbauer Spectroscopy to Li-Ion and Na-Ion …
321
disassembled. In situ Mössbauer spectroscopy is of high interest for the characterization of lithiated and sodiated materials that are often air and moisture sensitive, but
also and above all, this technique provides information about the reactions taking
place in electrochemical cells. It should be noted that such reactions depend on
the experimental conditions such as the current imposed to the cell in galvanostatic
regime. While a high current usually enhances kinetic effects, a low current should
be used to approach thermodynamic equilibrium. This means that the experimental
protocol used for in situ measurements should be carefully defined. Finally, it is
worth noting that in situ experiments are not always needed to investigate reaction
mechanisms as shown in Sect. 7.6.4.
There are some restrictions in the application of Mössbauer spectroscopy to Li-ion
and Na-ion batteries. The number of isotopes that can be used with a conventional inlab Mössbauer technique (vs. synchrotron radiation-based Mössbauer spectroscopy)
is limited. Fortunately, many positive and negative electrode materials contain iron
and tin atoms, respectively, that are the most studied elements by Mössbauer spectroscopy. Both
57 Fe and
119 Sn isotopes can be considered for room temperature
investigations of Li-ion or Na-ion batteries. Other isotopes have been used such as
121 Sb [29] or
99 Ru [30] but these studies mainly focused on the characterization
of pristine electrode materials or ex situ measurements due to the required specific
experimental conditions. For electrode materials that do not contain any Mössbauer
isotopes, doping with a Mössbauer probe was also used as reported for Sn doped
TiO 2 [31] or Fe doped Li 2 Ti 3 O 7 [32].
This chapter primarily deals with the application of Mössbauer spectroscopy to
investigate electrochemical mechanisms in Li-ion and Na-ion batteries. This means
that the characterization of pristine electrode materials is not really considered here
although it is an important task for the optimization of these materials. However, this
aspect is similar to the well-documented applications of Mössbauer spectroscopy
in materials science and the methodology is not different for electrode materials.
Since this book is addressed to a large audience, some aspects of Li-ion batteries and
Mössbauer spectroscopy are first introduced to give the basic knowledge and the key
parameters for elucidating the electrochemical mechanisms in batteries.
This chapter covers general and specific aspects of Li-ion batteries and Mössbauer
spectroscopy. The main features of Li-ion batteries are given in Sect. 7.2, including
a presentation of the most commonly used electrode materials, the main types of
electrochemical reactions and some methods of characterization. Section 7.3 deals
with basic considerations on Mössbauer spectroscopy and is focused on electric and
magnetic hyperfine interactions that are at the origin of the Mössbauer parameters.
Some specific aspects of in situ Mössbauer measurements are also given. Finally, the
application of Mössbauer spectroscopy to the study of electrochemical reactions in
Li-ion and Na-ion batteries are illustrated by selected examples of insertion reactions
in Sect. 7.4, alloying reactions in Sect. 7.5 and conversion reactions in Sect. 7.6.
321
disassembled. In situ Mössbauer spectroscopy is of high interest for the characterization of lithiated and sodiated materials that are often air and moisture sensitive, but
also and above all, this technique provides information about the reactions taking
place in electrochemical cells. It should be noted that such reactions depend on
the experimental conditions such as the current imposed to the cell in galvanostatic
regime. While a high current usually enhances kinetic effects, a low current should
be used to approach thermodynamic equilibrium. This means that the experimental
protocol used for in situ measurements should be carefully defined. Finally, it is
worth noting that in situ experiments are not always needed to investigate reaction
mechanisms as shown in Sect. 7.6.4.
There are some restrictions in the application of Mössbauer spectroscopy to Li-ion
and Na-ion batteries. The number of isotopes that can be used with a conventional inlab Mössbauer technique (vs. synchrotron radiation-based Mössbauer spectroscopy)
is limited. Fortunately, many positive and negative electrode materials contain iron
and tin atoms, respectively, that are the most studied elements by Mössbauer spectroscopy. Both
57 Fe and
119 Sn isotopes can be considered for room temperature
investigations of Li-ion or Na-ion batteries. Other isotopes have been used such as
121 Sb [29] or
99 Ru [30] but these studies mainly focused on the characterization
of pristine electrode materials or ex situ measurements due to the required specific
experimental conditions. For electrode materials that do not contain any Mössbauer
isotopes, doping with a Mössbauer probe was also used as reported for Sn doped
TiO 2 [31] or Fe doped Li 2 Ti 3 O 7 [32].
This chapter primarily deals with the application of Mössbauer spectroscopy to
investigate electrochemical mechanisms in Li-ion and Na-ion batteries. This means
that the characterization of pristine electrode materials is not really considered here
although it is an important task for the optimization of these materials. However, this
aspect is similar to the well-documented applications of Mössbauer spectroscopy
in materials science and the methodology is not different for electrode materials.
Since this book is addressed to a large audience, some aspects of Li-ion batteries and
Mössbauer spectroscopy are first introduced to give the basic knowledge and the key
parameters for elucidating the electrochemical mechanisms in batteries.
This chapter covers general and specific aspects of Li-ion batteries and Mössbauer
spectroscopy. The main features of Li-ion batteries are given in Sect. 7.2, including
a presentation of the most commonly used electrode materials, the main types of
electrochemical reactions and some methods of characterization. Section 7.3 deals
with basic considerations on Mössbauer spectroscopy and is focused on electric and
magnetic hyperfine interactions that are at the origin of the Mössbauer parameters.
Some specific aspects of in situ Mössbauer measurements are also given. Finally, the
application of Mössbauer spectroscopy to the study of electrochemical reactions in
Li-ion and Na-ion batteries are illustrated by selected examples of insertion reactions
in Sect. 7.4, alloying reactions in Sect. 7.5 and conversion reactions in Sect. 7.6.