posted on 2023-12-22, 15:33authored byTae Young Kim, Susung Yun, Jin Ah Chae, Hee Joong Kim, U Hyeok Choi
For
the development of high-energy-density lithium metal batteries
(LMBs), we designed nanohybrid gel polymer electrolytes (NGPEs). In
NGPEs, vinyl-functionalized mesoporous silica nanoparticles (VMSNs,
as reinforcement fillers) are integrated with cross-linkable poly(ethylene
glycol) (PEG) oligomers and an ionic species mixture of ionic liquid
and Li salt via a UV curing process. Two types of mesoporous silica
nanoparticles with and without vinyl groups (VMSN vs MSN) are synthesized
via the surface grafting method and used to prepare NGPE-VMSN and
NGPE-MSN, where the corresponding silica nanoparticles are chemically
and physically dispersed into the PEG network, respectively. The hybrid
PEG network-derived NGPEs with mesoporous silica nanoparticles show
attractive electrolyte properties, i.e., high shear storage modulus
(G′ = 1.1 × 106 Pa), high
ionic conductivity (σdc = 1 × 10–4 S cm–1), and wide electrochemical stability window
(ESW ∼ 4.5 V), at room temperature. The resultant NGPE in the
Li|Li cell also shows long-term cyclic stability without short-circuiting
over 1000 h under 0.1 mA cm–2, suggesting the NGPE’s
effectiveness in dendrite inhibition. Furthermore, the LiFePO4|NGPE|Li full cell presents a high specific capacity of 124
mAh g–1 at 0.5C and stable cycling performances
with 100% capacity retention and 99.5% Coulombic efficiency after
190 cycles at 25 °C. The NGPE demonstrates a simple design principle
for replacing liquid electrolytes with solid-state electrolytes, allowing
for a perfect complex between inorganic silica nanoparticles and organic
PEG gel network through vinyl bonds on the MSN surface and PEG terminal
group for high-energy-density LMBs.