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摘要: 以无烟煤为原料,以工业硅粉为催化剂进行催化石墨化,制备了具有不同微观结构的煤基石墨,分析了催化反应机制,并考察了所制备的煤基石墨作为锂离子电池负极的电化学性能,进行了结构与性能的相关性研究。结果表明:当催化剂质量分数为5%时,所得石墨(G-2800-5%)的微晶尺寸较大,有序度较高,石墨化度为91.5%。将其用作锂离子电池负极材料时,表现出较好的电化学特性,在0.1 A g−1电流密度下稳定可逆容量为369 mAh g−1,当电流密度增大至1 A g−1,依然保持了209 mAh g−1的容量,在0.2 A g−1电流密度下循环200次的容量保持率可达92.2%。G-2800-5%样品石墨结构有序度高,表面形成的SEI膜薄均匀且锂离子的不可逆损失少,因此,其综合电化学性能较好。Abstract: Several graphite samples with different microstructures were prepared from anthracite using industrial silicon powders as catalyst. The mechanism of the catalytic reaction and the electrochemical properties of the prepared coal-based graphite in lithium anodes were investigated. The correlation between the microstructure and the properties of the graphite is discussed. Results show that the sample with 5% silicon (G-2800-5%) has the best lithium storage. It has the well-developed graphitic structure with a degree of graphitization of 91.5% as determined from the interlayer spacing. When used as an anode material, a high reversible capacity of 369.0 mAh g−1 was achieved at 0.1 A g−1 and its reversible capacity was 209.0 mAh g−1 at a current density of 1 A g−1. It also exhibits good cycling stability with a capacity retention of 92.2% after 200 cycles at 0.2 A g−1. The highly developed graphite structure, which is favorable for the formation of a stable SEI and therefore reduces lithium ion loss, is responsible for the superior electrochemical performance.
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Key words:
- Anthracite /
- Catalytic graphitization /
- Lithium ion battery /
- Anode materials
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Table 1. Lattice parameters of samples
Sample d(002)/(nm) La/(nm) Lc/(nm) G ID/IG G-2800-0% 0.3364 95 43 89.5% 0.09 G-2800-5% 0.3361 136 47 91.5% 0.07 G-2800-10% 0.3363 105 45 89.5% 0.10 Table 2. Electrochemical performance of samples
Sample Initial
(mAh g−1)200th
(mAh g−1)0.1 A g−1
(mAh g−1)0.2 A g−1
(mAh g−1)0.5 A g−1
(mAh g−1)1 A g−1
(mAh g−1)G-2800-0% 320.1 287.9 341.2 321.3 282.5 186.8 G-2800-5% 393.7 325.6 369.0 353.2 305.9 209.0 G-2800-10% 345.7 267.7 346.7 327.4 287.0 208.2 Note: Initial means initial charge capacity. 200th means the capacity after 200 cycles. Table 3. Comparison of first charging performance of sample with other literatures
Sample Precursor Temperture
(°C)Catalyzer Initial charge
(mAh g−1)Ref. SG-2800 Anthracite 2800 − 379.1/0.1 C [28] GA Anthracite 2800 − 340.2/
37 mA g−1[13] GA Anthracite 2800 − 361.4/0.1 C [29] Anthracite Anthracite 1100 − 370.0/
30 mA g−1[12] TXG/2800 Anthracite 2800 − 299.0/0.2 C [10] TXG/La Anthracite 2800 La2O3 337.2/0.2 C [10] G-2800-5% Anthracite 2800 Si 393.7/0.1 A g−1 This work Table 4. AC impedance fitting parameters of the graphite samples
Sample RSEI (Ω) Rct (Ω) W(Ω) (10−6) G-2800-0% 68.4 0.23 809.1 G-2800-5% 33.5 0.12 714.4 G-2800-10% 72.3 0.05 845.2 -
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