Chen Xi, Lv Yingying, Shang Mingwei, Niu Junjie
Department of Materials Science and Engineering, CEAS , University of Wisconsin-Milwaukee , Milwaukee , Wisconsin 53211 , United States.
ACS Appl Mater Interfaces. 2019 Jun 19;11(24):21584-21592. doi: 10.1021/acsami.9b05364. Epub 2019 Jun 11.
Lithium metal as an anode in lithium-ion batteries is attracting more attention because of the high gravimetric/volumetric energy density and low electrochemical potential. However, the irreversible Li plating/striping can reduce the cycling capability and very possibly introduce dendrite growth, thus leading to a series of issues such as infinite volume change, low Coulombic efficiency, and uncontrollable solid electrolyte interphase. Here, we report a novel, single-side Li-infused carbon fiber fabric (LiCFF) with a controllable, minimized Li loading, which shows a highly reversible plating/stripping with an extremely low overpotential of less than 30 mV (Li foil: >1.0 V over 50 cycles) upon >3000 cycles (6000 and 2000 h) at 1 and 3 mA/cm in symmetric cells, respectively. With a high areal capacity up to 10 mA h/cm and a high current density of 10 mA/cm, the cell still shows a minimum overpotential of 150-175 mV after 250 cycles (500 h). Full-cell batteries using the LiCFF as "all-in-one" anodes without the additional slurry-making process and nickel-manganese-cobalt oxide (NMC) as cathodes exhibit an improved capacity retention when compared with Li foil: 32% at 0.5 C and 119% at 1.0 C capacity improved after 100 cycles. In parallel, the mossy/dendritic Li on the LiCFF was largely suppressed, which was confirmed using in situ observations of Li plating/striping in a capillary cell. The excellent electronic conductivity of the carbon fabric leads to small contact/transfer resistances of 3.4/3.8 Ω (Li foil: 4.1/44.4 Ω), enabling a drastically lowered energy barrier for Li nucleation/growth. Thus, a uniform current distribution results in forming a homogeneous Li layer instead of forming dendrites. The current LiCFF as the anode with controllable Li (n/p ratio), improved cycling stability, mitigated dendrite formation, and flexibility displays promising applications in versatile Li-metal batteries such as Li-NMC, Li-S, and Li-O.
锂金属作为锂离子电池的阳极，因其高重量/体积能量密度和低电化学势而备受关注。然而，不可逆的锂镀层/脱层会降低电池的循环性能，并极有可能引发枝晶生长，进而导致一系列问题，如无限的体积变化、低库仑效率以及不可控的固体电解质界面。在此，我们报道了一种新型的单面锂注入碳纤维织物（LiCFF），其锂负载量可控且最小化，在对称电池中，分别以1 mA/cm²和3 mA/cm²的电流密度进行超过3000次循环（6000小时和2000小时）时，显示出高度可逆的镀层/脱层，过电位极低，小于30 mV（锂箔：在50次循环中超过1.0 V）。在面积容量高达10 mA h/cm²和电流密度为10 mA/cm²的情况下，该电池在250次循环（500小时）后仍显示出最低过电位为150 - 175 mV。使用LiCFF作为“一体化”阳极且无需额外制浆工艺、以镍锰钴氧化物（NMC）作为阴极的全电池，与锂箔相比，在100次循环后容量保持率有所提高：在0.5 C时提高了32%，在1.0 C时提高了119%。同时，LiCFF上的苔藓状/枝晶状锂得到了极大抑制，这在毛细管电池中对锂镀层/脱层的原位观察中得到了证实。碳纤维织物优异的电子导电性导致其接触/转移电阻较小，为3.4/3.8 Ω（锂箔：4.1/44.4 Ω），从而大幅降低了锂成核/生长的能垒。因此，均匀的电流分布导致形成均匀的锂层，而不是形成枝晶。当前的LiCFF作为阳极，具有可控的锂（n/p比）、改善的循环稳定性、减轻的枝晶形成以及柔韧性，在诸如锂 - NMC、锂 - S和锂 - O等多种锂金属电池中显示出广阔的应用前景。
