高亲锂性的Ti3C2Tx-MXene锚定在柔性炭泡沫骨架上用于无枝晶锂金属负极

Highly lithiophilic Ti3C2Tx-Mxene anchored on a flexible carbon foam scaffold as the basis for a dendrite-free lithium metal anode

  • 摘要: 不理想的枝晶生长、不稳定的固体电解质界面以及循环过程中锂金属体积的无限变化等问题极大地限制了锂金属电池的实际应用。作者设计了亲锂Ti3C2Tx-MXene修饰的炭泡沫(Ti3C2Tx-MX@CF)来调节锂的成核行为,有效缓解锂金属负极的体积变化,获得了高稳定的锂金属电池。其中,三维的CF骨架具有较高的比表面积,不仅降低了局部电流密度来避免浓度极化,而且为缓解循环过程中的体积膨胀提供了足够的空间。更重要的是,丰富的官能团赋予了Ti3C2Tx-MX优异的亲锂性,能够有效的降低锂成核过电位,引导锂均匀沉积而不形成锂枝晶,并使负极表面的界面保持稳定。因此,组装的Li-Ti3C2Tx-MX@CF对称电池在电流密度为4 mA cm−2,容量为1 mAh cm−2时,表现出超过2400 h的良好循环稳定性,过电位低至9 mV。此外,Li-Ti3C2Tx-MX@CF||NCM111全电池在1 C下循环330圈后仍能提供129.6 mAh g−1的容量,表明Ti3C2Tx-MX对构建稳定的锂金属负极具有重要意义。

     

    Abstract: We report the fabrication of a lithiophilic Ti3C2Tx MXene-modified carbon foam (Ti3C2Tx-MX@CF) for the production of highly-stable LMBs that regulates Li nucleation behavior and reduces the volume change of a lithium metal anode (LMA). The 3D CF skeleton with a high specific surface area not only reduces the local current density to avoiding concentrated polarization, but also provides enough space to absorb the volume expansion during cycling. The excellent lithiophilicity of Ti3C2Tx-MX produced by its abundant functional groups reduces the Li nucleation overpotential, guides uniform Li deposition without the formation of Li dendrites, and maintains a stable SEI on the anode surface. Consequently, a Li infiltrated Ti3C2Tx-MX@CF symmetrical cell has an excellent cycling stability for more than 2 400 h with a low overpotential of 9 mV at a current density of 4 mA cm−2 and has a capacity of 1 mA h cm−2. Furthermore, a Li- Ti3C2Tx-MX@CF||NCM111 full cell has a capacity of 129.6 mA h g−1 even after 330 cycles at 1 C, demonstrating the advantage of this method in constructing stable LMAs.

     

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