Multilayer Battery Anode Structure for Fast Charging and Cycle Stability

The anode active material is divided into multiple layers with different compositions and functions. The first layer (close to current collector) uses carbon-based materials for stability and conductivity, while the second layer (outer layer) uses silicon-based materials for high capacity. This segmentation allows each layer to optimize its properties without compromising the other, resolving the contradiction between stability and power.

The patent creates a composite anode structure combining carbon-based materials (graphite, hard carbon, soft carbon) with silicon-based materials (amorphous silicon, crystalline silicon, silicon oxides). The carbon layer provides structural stability and electrical conductivity, while the silicon layer provides high lithium storage capacity. This composite approach enables simultaneous improvement of cycle-life stability and output properties.

The carbon-based first layer acts as a protective cushion for the silicon-based second layer. During charging-discharging cycles, the silicon layer undergoes significant volume expansion and contraction, which can cause mechanical damage. The carbon layer absorbs these mechanical stresses and prevents direct damage to the silicon particles, enabling the high-capacity silicon material to maintain its structural integrity over many cycles.

The carbon-based first layer functions as a flexible protective shell surrounding the silicon-based active material. This shell accommodates the volume changes of silicon during lithiation and delithiation processes, preventing particle cracking and maintaining electrical contact. The flexible carbon matrix allows the silicon to expand and contract without mechanical failure.