6.3 The Theory and Research Progress of Sodium-Ion Batteries
153
6.3.2.5 Non-metallic Single Anode Materials
I. Red phosphorus
Compared with Sn and Sb, in addition to the larger volume expansion problem of
red phosphorus, there is a problem that the red phosphorus conductivity is too low,
so most researchers mainly combine red phosphorus with carbon (PC) or other. The
metal composite forms an alloy (PM) to enhance its cyclic stability. The alloys that
have been studied so far include Zn−Ge−P, Ge−P, Fe−P, CoP, and Sn−P. The
P–C compound mainly combines P with graphene, carbon nanotubes or other carbon
matrices to enhance the conductivity of the material.
II. Phosphorene
Phosphorene is a new type of two-dimensional material with only one or several
layers of black phosphorus, which has a wrinkled layered structure. Common preparation methods include mechanical peeling, liquid phase peeling, and chemical vapor
deposition. Sun et al. first used phosphorene as a sodium storage anode material,
sandwich structure of phosphorene and graphene composites at 50 mA/g, and the
first week charging capacity was as high as 2440 mAh/g, and the capacity retention
rate was 83% after 100 cycles. The authors believe that after reducing the number
of black phosphorus layers to form phosphorene, the layer spacing increases, which
is conducive to the diffusion of sodium ions between layers, and graphene provides
a fast channel for the transmission of electrons, which makes the sandwich structure of phosphorene-graphene composites have good electrochemical properties.
Recently, Huang et al. used electrochemical cation embedding to prepare phosphorene as a sodium storage anode material. The preparation method is simple and
rapid, and the number of phosphorene layers can be controlled by adjusting the
voltage. The phosphene produced by this method had a specific charge capacity of
1968 mAh/g at 100 mA/g, remaining 60.5% after 50 cycles. At present, the application of phosphene in sodium-ion battery is less, and it needs further exploration. At
the same time, the application of phosphorene also provides new ideas for developing
the new high-performance materials.
The specific capacity of P is much higher than that of Sb- and Sn-based materials.
It has a stable circulation for over 1000 cycles while maintaining a high specific
capacity. However, P has certain toxicity and flammability. At the same time, its
reduced product, Na 3 P, will be easily hydrolyzed. Burning and toxic PH 3 gas, which
limits the application of P in sodium-ion batteries.
6.3.2.6 Organic Anode Material
As shown in Fig. 6.8, only the following two types of free radical anode materials
have been reported (Suga et al. 2009). The theoretical specific capacity of Polymer 1
is 59 mAh/g. Considering that a certain amount of cross-linking agent is added during
the polymerization process, and its theoretical specific capacity is only 42 mAh/g.
153
6.3.2.5 Non-metallic Single Anode Materials
I. Red phosphorus
Compared with Sn and Sb, in addition to the larger volume expansion problem of
red phosphorus, there is a problem that the red phosphorus conductivity is too low,
so most researchers mainly combine red phosphorus with carbon (PC) or other. The
metal composite forms an alloy (PM) to enhance its cyclic stability. The alloys that
have been studied so far include Zn−Ge−P, Ge−P, Fe−P, CoP, and Sn−P. The
P–C compound mainly combines P with graphene, carbon nanotubes or other carbon
matrices to enhance the conductivity of the material.
II. Phosphorene
Phosphorene is a new type of two-dimensional material with only one or several
layers of black phosphorus, which has a wrinkled layered structure. Common preparation methods include mechanical peeling, liquid phase peeling, and chemical vapor
deposition. Sun et al. first used phosphorene as a sodium storage anode material,
sandwich structure of phosphorene and graphene composites at 50 mA/g, and the
first week charging capacity was as high as 2440 mAh/g, and the capacity retention
rate was 83% after 100 cycles. The authors believe that after reducing the number
of black phosphorus layers to form phosphorene, the layer spacing increases, which
is conducive to the diffusion of sodium ions between layers, and graphene provides
a fast channel for the transmission of electrons, which makes the sandwich structure of phosphorene-graphene composites have good electrochemical properties.
Recently, Huang et al. used electrochemical cation embedding to prepare phosphorene as a sodium storage anode material. The preparation method is simple and
rapid, and the number of phosphorene layers can be controlled by adjusting the
voltage. The phosphene produced by this method had a specific charge capacity of
1968 mAh/g at 100 mA/g, remaining 60.5% after 50 cycles. At present, the application of phosphene in sodium-ion battery is less, and it needs further exploration. At
the same time, the application of phosphorene also provides new ideas for developing
the new high-performance materials.
The specific capacity of P is much higher than that of Sb- and Sn-based materials.
It has a stable circulation for over 1000 cycles while maintaining a high specific
capacity. However, P has certain toxicity and flammability. At the same time, its
reduced product, Na 3 P, will be easily hydrolyzed. Burning and toxic PH 3 gas, which
limits the application of P in sodium-ion batteries.
6.3.2.6 Organic Anode Material
As shown in Fig. 6.8, only the following two types of free radical anode materials
have been reported (Suga et al. 2009). The theoretical specific capacity of Polymer 1
is 59 mAh/g. Considering that a certain amount of cross-linking agent is added during
the polymerization process, and its theoretical specific capacity is only 42 mAh/g.