  Enhanced EV market penetration requires durability of the battery with high
energy throughput. For long-term cycle stability of silicon-graphite anode
capable of high energy density, the reversible redox reactions are crucial.
Here, we unveil intriguing electrochemical phenomena such as crosstalk of
lithium ion ($Li^{+}$) between silicon and graphite, $Li^{+}$ accumulation in
silicon, and capacity depression of graphite under high pressure, which
engender the irreversible redox reactions. Active material properties, i.e. the
size of silicon and the hardness of graphite, silicon-graphite anode, are
modified based on the unveiled results to enhance the reaction homogeneity and
reduce subsequent degradation. Owing to the property change of the anode active
materials, silicon-graphite anode paired with high nickel cathode allows the
prismatic cell with 8.7 Ah to reach cycling performance over 750 cycles with
volumetric energy density of 665 $Whl^{-1}$, which is corresponding to 800
$Whl^{-1}$ in the prismatic cell with 87 Ah. Finally, the cycling performance
can be tailored by the design of electrode regulating $Li^{+}$ crosstalk. Our
findings provide electrochemical insights into degradation mechanisms and a
promising direction on the progressive improvement of materials and the design
of electrodes in silicon-graphite anode.
