【摘要】 本文通过溶胶凝胶法成功制备了尖晶石型LiMn_2-xSi_xO₄(x<1,用Si⁴⁺替代尖晶石LiMn₂O₄中的Mn⁴⁺).制备的LiMn_2-xSi_xO₄由几纳米至200纳米的孔组成,比表面积为8.76m²g^-1.XRD和XPS的结果表明Si原子进入到晶格中.作为可充电锂离子电池的正极材料,充放电过程中LiMn_2-xSi_xO₄展现出了优异的结构可逆性及完整性.结果表明用Si⁴⁺替代尖晶石LiMn₂O₄中的Mn⁴⁺能有效缓解由Jahn-Teller效应引起的相转变.尖晶石LiMn_2-xSi_xO₄在1.5 4.8V的电压窗口下,首次放电比容量为147mAhg^-1.51次循环后,比容量仅为88 mAhg^-1,容量保持率为60%.因此,需要进一步了解Si⁴⁺替代Mn⁴⁺的机理,从而提高其循环稳定性.更多还原

【Abstract】 Spinel LiMn_2-xSi_xO₄(x< 1,through substituting Mn⁴⁺ with Si⁴⁺ in cubic spinel LiMn₂O₄) was synthesized successfully by a facile sol-gel method.The as-prepared LiMn_2-xSi_xO₄ consisted of pores with large size distribution range from a few nanometers to over 200 nm and possessed specific surface area of 8.76 m²g^-1.Results of X-ray powder diffraction and X-ray photoelectron spectroscopy confirmed that Si atoms entered the host lattice.As a cathode material for rechargeable lithium-ion batteries,spinel LiMn_2-xSi_xO₄exhibited excellent structural reversibility and integrity during the charging-discharging process.The result indicated that substitution of Mn⁴⁺ by Si⁴⁺ in spinel LiMn₂O₄material effectively alleviated the phase transition caused by Jahn-Teller effect.The initial discharge capacity of the as-prepared spinel LiMn_2-xSi_xO₄ was 147 mA h g^-1 over the voltage range of 1.5-4.8 V.However,after 51 cycles,the specific capacity was 88 mA h g^-1 with capacity retention of 60%.More work is needed to understand the effects of substituting Mn⁴⁺ by Si⁴⁺ and to improve the cyclic stability.更多还原