Viability of all-solid-state lithium metal battery coupled with oxide solid-state electrolyte and high-capacity cathode

Owing to the utilization of lithium metal as anode with the ultrahigh theoretical capacity density of 3860 mA h g^(-1)and oxide-based ceramic solid-state electrolytes(SE),e.g.,garnet-type Li7La_(3)Zr_(2)O_(12)(LLZO),all-state-state lithium metal batteries(ASLMBs)have been widely accepted as the promising alternatives for providing the satisfactory energy density and safety.However,its applications are still challenged by plenty of technical and scientific issues.In this contribution,the co-sintering temperature at 500℃is proved as a compromise method to fabricate the composite cathode with structural integrity and declined capacity fading of LiNi_(0.5)Co_(0.2)Mn_(0.3)O_(2)(NCM).On the other hand,it tends to form weaker grain boundary(GB)inside polycrystalline LLZO at inadequate sintering temperature for LLZO,which can induce the intergranular failure of SE during the growth of Li filament inside the unavoidable defect on the interface of SE.Therefore,increasing the strength of GB,refining the grain to 0.4μm,and precluding the interfacial defect are suggested to postpone the electro-chemo-mechanical failure of SE with weak GB.Moreover,the advanced sintering techniques to lower the co-sintering temperature for both NCM-LLZO composite cathode and LLZO SE can be posted out to realize the viability of state-of-the-art ASLMBs with higher energy density as well as the guaranteed safety.

Reinforced interface endows the lithium anode with stable cycle at high-temperature of 80℃

Embracing ultrahigh theoretical capacity of 3860 mA h g^(-1)and the lowest reduction potential of-3.04 V(versus standard hydrogen electrode),lithium(Li) is considered as the "holy grail" material for pursuing higher energy density,of which application has been challenged due to the unstable interface caused by the non-uniform electrodeposition as well as high chemical activity.Operating at higher temperature can be recommended to uniform electrodeposition of Li metal.Nevertheless,the intrinsic side-reaction between Li metal anode and electrolyte is inevitably aggravated and thus fosters the failure of Li metal anode rapidly with uneven electrodeposition.Here,a kind of temperature-tolerated ionic liquid(1-methyl-3-ethylimidazole bis(fluorosulfo nyl)imide/lithium bis(trifluoromethylsulfo nyl)imide,EF/LT)based electrolyte that matrixed with poly(vinylidene fluoride-hexafluoropropylene) was designed to maintain the interfacial stabilization of Li metal due to the weak interfacial reaction and uniform electrodeposition at high temperature of 80℃.It is the matter that the 660-h cycle with lower polarization is achieved with EF/LT-based electrolyte at temperature of 80 ℃ and the full cell embraces outstanding cyclic performance,without capacity fading within 100 cycles.Delighting,a door for practical application of Li metal anode for higher energy density as the carbon neutrality progresses in the blooming human society has been opened gradually.

Electro-chemo-mechanical design of polymer matrix in composited LiNi_(0.8)Co_(0.1)Mn_(0.1)O_(2) cathode endows solid-state batteries with superior performance

Nickel-rich LiNi_(0.8)Co_(0.1)Mn_(0.1)O_(2)(NCM811) cathode material has been widely concerned due to its high voltage,high specific capacity and excellent rate performance,which is considered as one of the most promising cathode materials for the next generation of high-energy-density solid-state lithium batteries.However,serious electro-chemo-mechanical degradation of Nickel-rich cathode during cycling,especially at a high voltage(over 4.5 V),constrains their large-scale application.Here,using the multiphysical simulation,highly-conductive polymer matrix with spontaneous stress-buffering effect was uncovered theoretically for reinforcing the electrochemical performance of composited NCM81 1 cathode through the visualization of uniform concentration distribution of Li-ion coupled with improved stress field inside NCM811 cathode.Thereupon,polyacrylonitrile(PAN) and soft polyvinylidene fluoride(PVDF) were selected as the polymer matrix to fabricate the composited NCM811 cathode(PVDFPAN@NCM811) for improving the electrochemical performance of the solid-state NMC811|Li full cells,which can maintain high capacity over 146.2 mA h g^(-1)after 200 cycles at a high voltage of 4.5 V.Suggestively,designing a multifunctional polymer matrix with high ionic conductivity and mechanical property can buffer the stress and maintain the integrity of the structure,which can be regarded as the door-opening avenue to realize the high electrochemical performance of Ni-rich cathode for solidstate batteries.

通过原位表面掺杂实现稳定金属锂负极的晶体定向沉积

锂金属由于其高理论比容量(3860 mA g^-1)而被认为是最具潜力的高能量密度锂电池用负极材料.然而,锂枝晶的不可控生长和金属锂对电解液的高反应活性严重阻碍了其实际应用.区别于以往广泛使用的电解液优化或界面修饰工艺,本文采用一种原位铈掺杂的策略,从根本上改变了锂金属的电沉积行为.通过锂电极表面的原位铈掺杂促进锂在电化学过程中沿[200]方向优先沉积,显著降低金属锂的表面能.光谱、形貌和电化学测试等结果证明,原位铈掺杂大大降低了锂电极对电解液的反应活性,使得电极在沉积/脱出过程中具有无枝晶形貌.采用这种策略装配的对称电池中,锂电极具有低腐蚀电流密度,甚至在贫液条件下循环寿命也得到显著提升.采用铈掺杂锂负极的锂-钴酸锂全电池可稳定循环300周,库伦效率和循环寿命得到明显提高.本工作为金属锂负极在高能量密度电池中的实用化研究提供了一种具有启发性的策略.