Jie Zhao,Saifang Huang,Yuyan Zhao,Bing Wu,Haiqin Lin,Zixuan Chen,Yudong Zhang,Weiji Dai,Can Cui
Solid-state lithium metal batteries (SSLMBs) face critical challenges, including low ionic conductivity, unstable electrode–electrolyte interfaces, and lithium dendrite growth issues. To address these issues, we designed a PVDF-based composite electrolyte embedded with NiSe nanosheets (PVDF-NS). The two-dimensional NiSe facilitated the in situ formation of Li2Se at the interface, promoting dendrite suppression by enhancing Li+ transport (room-temperature ionic conductivity: 5.53 × 10–4 S·cm–1; transference number: 0.449) and constructing a stable SEI layer. Notably, PVDF-NS supported Li||Li symmetric cells demonstrated excellent stability for over 2000 h at 0.2 mA·cm–2. When paired with NCM811 cathodes, full cells demonstrated 86.3% capacity retention over 300 cycles at 2 C. Additionally, the electrolyte exhibited high oxidative stability (4.83 V vs Li+/Li) and retained a capacity of 65.6 mAh·g–1 at 5 C, underscoring its practical applicability. This interfacial engineering approach presents a scalable and effective route for developing durable, high-performance solid electrolytes for next-generation SSLMBs.
Jinbo Zhang,Yanxia Su,Zeran Ding,Yuqian Qiu,Chong Li,Yue Ma,Ningyu Zhang,Fei Xu,Hongqiang Wang
The unstable Na/electrolyte interface, plagued by Na dendrites and interface degradation, critically hinders solid-state Na batteries. We propose the design of thin poly(ethylene oxide) (PEO)-based composite polymer electrolytes with a stabilized solid electrolyte interphase (SEI). Incorporating SnF 2 into PEO and infusing the composite into an ultrathin polyethylene (PE) scaffold (PEO-xSnF 2 @PE) promotes a stable Na 15 Sn 4 /NaF-rich SEI that facilitates uniform Na⁺ deposition, while the PE layer ensures a thin yet mechanically robust structure. Consequently, the optimized composite polymer electrolyte, featuring an ultrathin 20 µm thickness, low areal density of 1.9 mg cm −2 , and ultrahigh tensile strength of 35 MPa, demonstrates exceptional dendrite-suppressing capability. Such synergistic effects enable Na symmetric cells employing PEO-4SnF 2 @PE to achieve ultralong cycling exceeding 10800 h (>1 year), alongside a critical current density of 1.0 mA cm −2 . Full cells paired with a Na 3 V 2 (PO 4 ) 3 cathode exhibit exceptional cycling stability, achieving 97.6% capacity retention over 500 cycles. This work demonstrates that combining SnF 2 functional additives with a flexible, high-strength supporting layer effectively mitigates interfacial instability and dendrite propagation in solid polymer electrolytes, offering new design principles for long-life solid-state sodium metal batteries.
Lithium (Li) as one of the most promising anode materials for the next-generation batteries was unfortunately plagued by the inevitable Li dendrite growth and the dynamically destroy/reconstruction of the unstable native solid electrolyte interphase (SEI) layer, which can severely affect the specific capacity and lifespan of lithium batteries, limiting the practical application of the Li anode. In this work, we designed a single ion conducting artificial polymer SEI layer on the surface of the Li anode. The fabricated SEI layer shows high ionic conductivity and lithium transference number, which is beneficial for inducing homogeneous Li deposition, effectively suppressing the nucleation and growth of dendrite. Moreover, the uniform and stable SEI layer with a well-designed network structure can availably protect the Li anode from directly contacting with the electrolyte, reducing the related side reactions and effectually limit the additional consumption of the active Li and electrolyte. The symmetric Li cells can cycle stably over 1200 h without short-circuit at the current/capacity densities of 1 (1 mAh/cm2) and 5 mA/cm2 (5 mAh/cm2). The assembled LiFePO4/LPEDV-Li cells exhibit high capacity retention up to 81.3% after 2400 cycles at the high rate of 8 C. Therefore, the designed artificial SEI layer with excellent properties presents a high application potential in stabilizing the Li anode.
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