### NaTiSi2O6/C复合材料用于锂离子电池负极材料

• 收稿日期:2019-12-10 录用日期:2020-01-07 发布日期:2020-01-13
• 通讯作者: 王丛笑,夏永姚 E-mail:cxwang@fudan.edu.cn;yyxia@fudan.edu.cn
• 基金资助:
国家自然科学基金会(21875045);国家重点研发项目(2016YFB0901500)

### NaTiSi2O6/C Composite as a Novel Anode Material for Lithium-Ion Batteries

Kun Liu, Yao Liu, Haifeng Zhu, Xiaoli Dong, Yonggang Wang, Congxiao Wang(), Yongyao Xia()

• Received:2019-12-10 Accepted:2020-01-07 Published:2020-01-13
• Contact: Congxiao Wang,Yongyao Xia E-mail:cxwang@fudan.edu.cn;yyxia@fudan.edu.cn
• Supported by:
the National Natural Science Foundation of China(21875045);the National Key Research and Development Program of China(2016YFB0901500)

Abstract:

The development of human society and the continuously emerging environmental problems call for cleaner energy resources. Lithium-ion batteries, since their commercialization in the early 1990s, have been an important power source of mobile phones, laptops as well as other portable electronic devices. Their advantages include environment-friendliness, light weight, and no memory effect compared with lead-acid or nickel-cadmium batteries. Electrode materials play an important role in the performance of lithium-ion batteries. The traditional commercial anode material, graphite, has a theoretical specific capacity of 372 mAh·g-1 and working potential close to 0 V (vs Li+/Li), making it prone to the formation of lithium dendrite, which may cause short circuit especially when large current is applied. Another commercial anode material Li4Ti5O12, which also undergoes an intercalation reaction during lithiation process, has a theoretical specific capacity of 175 mAh·g-1 along with three lithium-ion intercalations per formula unit. This is relatively small, and it has a relatively high working potential of 1.55 V (vs Li+/Li), which reduces its output voltage and specific energy when assembled in full battery. To overcome the shortcomings mentioned above, it is essential to search for new anode materials that are low-cost, environment-friendly, and easy to synthesize. Silicate materials have gained widespread attention owing to their low cost and facile synthesis. Herein, we report for the first time a novel titanosilicate, NaTiSi2O6, synthesized by sol-gel and solid sintering. It is isostructural to pyroxene jadeite NaAlSi2O6, belonging to monoclinic crystal system with a space group of C2/c. By in situ pyrolysis and carbonization of glucose, nanosized NaTiSi2O6 mixed with carbon was successfully obtained with a specific surface area of 132 m2·g-1, calculated according to the Brunauer–Emmett–Teller formula. The specific charge/discharge capacity in the first cycle at current density of 0.1 A·g-1 is 266.6 mAh·g-1 and 542.9 mAh·g-1, respectively, with an initial coulombic efficiency of 49.1%. After 100 cycles, it retains a specific charge capacity of 224.1 mAh·g-1, corresponding to a capacity retention rate of 84.1%. The average working potential of NaTiSi2O6 is 1.2–1.3 V (vs Li+/Li), slightly lower than that of Li4Ti5O12. The reaction mechanism while charging and discharging was determined by in situ X-ray diffraction test as well as selected area electron diffraction. The results showed that NaTiSi2O6 undergoes an intercalation reaction during lithiation process, with two lithium-ion intercalations per formula unit. This makes NaTiSi2O6 a new member of the silicate anode material family, and may provide insights into the development of new silicate electrode materials in the future.

MSC2000:

• O646