6.2 Lithium Batteries and Lithium-Ion Batteries
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capacity of only 260 mAh/g and an irreversible specific capacity of more than
100 mAh/g. The flake graphite interplanar spacing (d002) is 0.335 nm, which is
mainly 2H + 3R crystal surface ranking structure, that is, the graphite layers are
arranged in two orders of ABAB…. and ABCABC… Flake graphite with more than
99% carbon has reversible charge/discharge capacity of 300–350 mAh/g. Since the
graphite pitch (d002 = 0.34 nm) is smaller than the interlaminar spacing (d002 =
0.37 nm) of the lithium-interlayer compound Li-GIC, the graphite layer spacing
during charge/discharge process changes and the graphite layer is easily peeled off
and powdered. Also accompanied by the phenomenon of lithium and organic solvents
co-embedded in the graphite layer, will affect the battery cycle performance. Therefore, people have studied other graphite materials, such as modified graphite and
graphitized carbon fiber.
Soft Carbon
Soft carbon, which is easily graphitized carbon and the amorphous carbon can be
graphitized at 2500 °C or higher. The soft carbon has low crystallinity (i.e., graphitization degree), small crystal grain size, large interplanar spacing (d002), and good
compatibility with the electrolyte, but the first charge and discharge have higher irreversible capacity and lower output voltage There is no apparent charge and discharge
plateau potential. Common soft carbons include petroleum coke, needle coke, carbon
fiber, and carbon microspheres.
Hard Carbon
Hard carbon refers to hardly graphitized carbon and is a pyrolytic carbon of a
high molecular polymer. This kind of carbon is also hard to graphitize at a high
temperature of 2500 °C or higher. Common hard carbons are resinous carbon (such
as phenolic resin, epoxy resin, polycaprolactone PFA-C, etc.), organic polymer
pyrolytic carbon (PVA, PVC, PVDF, PAN, etc.), carbon black (acetylene black).
Among them, Polycarbonate resin carbon PFA-C, Japan Sony Corporation has been
used as the lithium-ion batteries anode material. The capacity of PFA-C is up to
400 mAh/g, and the PFA-C crystal plane spacing (d002) is suitable. This facilitates
the insertion of lithium without causing significant expansion of the structure and has
a good charge–discharge cycle performance. Another type of hard carbon material
is polyacene (PAS), an amorphous semiconductor material obtained by pyrolysis of
phenolic resin at a temperature below 800 °C. Its capacity is about 800 mAh/g and
the interplanar spacing is 0.37–0.40 nm, which is favorable for lithium intercalation
and deintercalation resulting in good cycle performance.
Tin-Based Materials
Although most of the anode material is a carbon-based material; the low
charge/discharge capacity and initial charge–discharge efficiency, and insufficient
embedding of organic solvents, other non-carbon materials with high specific
capacity have been developed. One of them is tin-based materials. Japan was the
first country to study tin-based anode materials. Companies such as Sanyo Electric,
Matsushita Electric, and Coats have conducted research in succession. Tin-based
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capacity of only 260 mAh/g and an irreversible specific capacity of more than
100 mAh/g. The flake graphite interplanar spacing (d002) is 0.335 nm, which is
mainly 2H + 3R crystal surface ranking structure, that is, the graphite layers are
arranged in two orders of ABAB…. and ABCABC… Flake graphite with more than
99% carbon has reversible charge/discharge capacity of 300–350 mAh/g. Since the
graphite pitch (d002 = 0.34 nm) is smaller than the interlaminar spacing (d002 =
0.37 nm) of the lithium-interlayer compound Li-GIC, the graphite layer spacing
during charge/discharge process changes and the graphite layer is easily peeled off
and powdered. Also accompanied by the phenomenon of lithium and organic solvents
co-embedded in the graphite layer, will affect the battery cycle performance. Therefore, people have studied other graphite materials, such as modified graphite and
graphitized carbon fiber.
Soft Carbon
Soft carbon, which is easily graphitized carbon and the amorphous carbon can be
graphitized at 2500 °C or higher. The soft carbon has low crystallinity (i.e., graphitization degree), small crystal grain size, large interplanar spacing (d002), and good
compatibility with the electrolyte, but the first charge and discharge have higher irreversible capacity and lower output voltage There is no apparent charge and discharge
plateau potential. Common soft carbons include petroleum coke, needle coke, carbon
fiber, and carbon microspheres.
Hard Carbon
Hard carbon refers to hardly graphitized carbon and is a pyrolytic carbon of a
high molecular polymer. This kind of carbon is also hard to graphitize at a high
temperature of 2500 °C or higher. Common hard carbons are resinous carbon (such
as phenolic resin, epoxy resin, polycaprolactone PFA-C, etc.), organic polymer
pyrolytic carbon (PVA, PVC, PVDF, PAN, etc.), carbon black (acetylene black).
Among them, Polycarbonate resin carbon PFA-C, Japan Sony Corporation has been
used as the lithium-ion batteries anode material. The capacity of PFA-C is up to
400 mAh/g, and the PFA-C crystal plane spacing (d002) is suitable. This facilitates
the insertion of lithium without causing significant expansion of the structure and has
a good charge–discharge cycle performance. Another type of hard carbon material
is polyacene (PAS), an amorphous semiconductor material obtained by pyrolysis of
phenolic resin at a temperature below 800 °C. Its capacity is about 800 mAh/g and
the interplanar spacing is 0.37–0.40 nm, which is favorable for lithium intercalation
and deintercalation resulting in good cycle performance.
Tin-Based Materials
Although most of the anode material is a carbon-based material; the low
charge/discharge capacity and initial charge–discharge efficiency, and insufficient
embedding of organic solvents, other non-carbon materials with high specific
capacity have been developed. One of them is tin-based materials. Japan was the
first country to study tin-based anode materials. Companies such as Sanyo Electric,
Matsushita Electric, and Coats have conducted research in succession. Tin-based