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Production of Ultrahigh-Purity of Electrode Active Materials
from Spent Lithium-ion Batteries Using Thermal Pyrolysis
Coupled with Ultrafine Particle Gravity Separation Technology
Ruiting Zhan, Tinu-Ololade Folayan, and Lei Pan
Michigan Technological University, Houghton, MI, USA
ABSTRACT: The challenge associated with the state-of-the-art lithium-ion battery recycling is the difficulty
of achieving 90% separation efficiency between recycled electrode materials from spent Li-ion batteries for the
downstream reuse and refinery. In this work, a new process has been developed to separate mixed electrode
active materials recycled from both new and spent Li-ion batteries. This process is based on thermal pyrolysis to
remove contained organic binders and followed by ultrafine centrifugal gravity separation method that separates
the two electrode active materials based on the density difference. Result showed that for the black mass sample
recycled from new and spent Li-ion batteries, the grade of cathode active materials in the concentrate product
reached 93% after one rougher stage and further reached 98% after additional cleaner stages. The loss of cathode
active materials in the waste product stream was attributed to the presence of PVDF binders within cathode
agglomerate particles which consequently reduced the difference in densities between cathode agglomerate
particles and individual anode particles. In the absence of PVDF binders by a thermal pyrolysis process, the
grade of cathode active material in the concentrate product reached over 99.1% and the yield of recycled
cathode materials reached 95% or above. The present work demonstrates a new method in separating electrode
active materials from spent Li-ion batteries and producing high-purity recycled cathode materials and recycled
anode materials.
BACKGROUND
Lithium-ion batteries (LIBs) are energy storage devices that
are used in many products in our daily life, including con-
sumer electronics, power tools, energy storage, and electric
vehicles (EVs). For the last few years, the global production
volume of LIBs has grown substantially and is expected to
grow at a double-digit rate for years to come. It is expected
that the global LIB production volume will increase to
1,447 GWh in 2025 (Curry, 2017). Compared with
competing technologies, LIBs exhibit several advantages,
including high energy density, low self-discharge rate, and
long cycling life (Armand &Tarascon, 2008 Larcher &
Tarascon, 2014 Tarascon &Armand, 2001). On the other
hand, LIBs have limited service life (Marano et al., 2009
Sarre et al., 2004 Wood et al., 2011). After reaching their
end of user life in EVs, LIBs are to be reused and recycled
(Bernardes et al., 2004 Gaines, 2014). Some spent Li-ion
batteries from end-of-life (EOL) vehicles may be reused
in energy storage applications (Li et al., 2015 Liao et al.,
2017). For those EV batteries that are not suitable for a
second use or reaching the end of their life cycle, appropri-
ate disposal and recycling is required (Ordoñez et al., 2016
Wang et al., 2012).
Recycling of Li-ion battery has been devoted to a
recovery of all components from LIBs (Gaines, 2018). LIBs
comprise many valuable battery components, and these
Production of Ultrahigh-Purity of Electrode Active Materials
from Spent Lithium-ion Batteries Using Thermal Pyrolysis
Coupled with Ultrafine Particle Gravity Separation Technology
Ruiting Zhan, Tinu-Ololade Folayan, and Lei Pan
Michigan Technological University, Houghton, MI, USA
ABSTRACT: The challenge associated with the state-of-the-art lithium-ion battery recycling is the difficulty
of achieving 90% separation efficiency between recycled electrode materials from spent Li-ion batteries for the
downstream reuse and refinery. In this work, a new process has been developed to separate mixed electrode
active materials recycled from both new and spent Li-ion batteries. This process is based on thermal pyrolysis to
remove contained organic binders and followed by ultrafine centrifugal gravity separation method that separates
the two electrode active materials based on the density difference. Result showed that for the black mass sample
recycled from new and spent Li-ion batteries, the grade of cathode active materials in the concentrate product
reached 93% after one rougher stage and further reached 98% after additional cleaner stages. The loss of cathode
active materials in the waste product stream was attributed to the presence of PVDF binders within cathode
agglomerate particles which consequently reduced the difference in densities between cathode agglomerate
particles and individual anode particles. In the absence of PVDF binders by a thermal pyrolysis process, the
grade of cathode active material in the concentrate product reached over 99.1% and the yield of recycled
cathode materials reached 95% or above. The present work demonstrates a new method in separating electrode
active materials from spent Li-ion batteries and producing high-purity recycled cathode materials and recycled
anode materials.
BACKGROUND
Lithium-ion batteries (LIBs) are energy storage devices that
are used in many products in our daily life, including con-
sumer electronics, power tools, energy storage, and electric
vehicles (EVs). For the last few years, the global production
volume of LIBs has grown substantially and is expected to
grow at a double-digit rate for years to come. It is expected
that the global LIB production volume will increase to
1,447 GWh in 2025 (Curry, 2017). Compared with
competing technologies, LIBs exhibit several advantages,
including high energy density, low self-discharge rate, and
long cycling life (Armand &Tarascon, 2008 Larcher &
Tarascon, 2014 Tarascon &Armand, 2001). On the other
hand, LIBs have limited service life (Marano et al., 2009
Sarre et al., 2004 Wood et al., 2011). After reaching their
end of user life in EVs, LIBs are to be reused and recycled
(Bernardes et al., 2004 Gaines, 2014). Some spent Li-ion
batteries from end-of-life (EOL) vehicles may be reused
in energy storage applications (Li et al., 2015 Liao et al.,
2017). For those EV batteries that are not suitable for a
second use or reaching the end of their life cycle, appropri-
ate disposal and recycling is required (Ordoñez et al., 2016
Wang et al., 2012).
Recycling of Li-ion battery has been devoted to a
recovery of all components from LIBs (Gaines, 2018). LIBs
comprise many valuable battery components, and these