Lithium–silicon batteries are lithium-ion batteries that employ a silicon-based anode and lithium ions as the charge carriers. Silicon-based materials, generally, have a much larger specific energy capacity: for example, 3600 mAh/g for pristine silicon. The standard anode material graphite is limited to a maximum theoretical capacity of 372 mAh/g for the fully lithiated state LiC6.
Silicon's vast volume change (approximately 400% based on crystallographic densities) when lithium is inserted, along with high reactivity in the charged state, are obstacles to commercializing this type of anode. Commercial battery anodes may have small amounts of silicon, boosting their performance slightly. The amounts are closely held trade secrets, limited as of 2018 to, at most, 10% of the anode. Lithium-silicon batteries also include cell configurations where silicon is in compounds that may, at low voltage, store lithium by a displacement reaction, including silicon oxycarbide, silicon monoxide, or silicon nitride.
History The first laboratory experiments with lithium-silicon materials took place in the early to mid-1970s.
Silicon-graphite composite electrodes Silicon carbon composite anodes were first reported in 2002 by Yoshio. Studies of these composite materials have shown that the capacities are a weighted average of the two end members (graphite and silicon). On cycling, electronic isolation of the silicon particles tends to occur with the capacity falling off to the capacity of the graphite component. This effect has been tempered using alternative synthetic methodologies or morphologies that can be created to help maintain contact with the current collector. This has been identified in studies involving grown silicon nanowires chemically bonded to the metal current collector by alloy formation. Sample production of batteries using a silicon nanowire-graphite composite electrode were produced by Amprius in 2014, which claims to have sold several hundred thousand of these batteries as of 2014.
In 2016, Stanford University researchers presented a method of encapsulating silicon microparticles in a graphene shell, which confines fractured particles and also acts as a stable solid electrolyte interphase layer. These microparticles reached an energy density of 3,300 mAh/g.
As of 2018, products by startups Sila Nanotechnologies, Global Graphene Group, Enovix, Enevate, Group14 Technologies, Paraclete Energy, and others were undergoing tests by battery manufacturers, car companies, and consumer-electronics companies. BMW announced plans to incorporate Sila technology by 2023 and increase battery-pack capacity by 10–15%. As of 2021, Enovix was the first company to ship finished silicon anode batteries to end customers. In September 2021, Sila announced that it had begun shipping its first product and that it had been incorporated in Whoop 4.0.
Group14 Technologies has patented a silicon-carbon composite SCC55, which enables 50% more in fully lithiated volumetric energy density than graphite used in conventional lithium-ion battery anodes. SCC55 has been tested and validated by battery manufacturers Farasis and StoreDot, the latter of which found that SCC55 could be charged to 80% capacity in 10 minutes. In May 2022, Porsche AG announced plans to produce lithium-silicon battery cells with Group14's technology in Germany in 2024 to help power their new electric vehicles. Group14 plans to use Porsche's funding to accelerate the development of their second U.S. factory to supply a minimum of 600,000 EVs annually. In January 2024, Group14 announced that through its partnership with Amperex Technology Limited, they had over 1 million smartphones in China (Honor) using its technology.
In 2015, Tesla CEO Elon Musk claimed that silicon in Model S batteries increased the car's range by 6%. On September 22, 2020, Tesla revealed its plans for gradually increasing the amounts of silicon in its future batteries, focusing on the anodes. Tesla's approach is to encapsulate the silicon particles with an elastic, ion-permeable coating. In this way, the silicon-swelling concern is accommodated, thereby enabling the desired increase in battery capacity to be achieved. Overall battery life expectancy is expected to remain unimpacted by this change. The reason for the gradual (instead of sudden) increases in silicon usage is to enable testing and confirmation of the stepwise changes.Tesla Inc. Fox, Eva.
Alternatively, a study has shown the possibility of increasing the silicon oxide content to 90% using graphene nanotubes, also known as single-wall carbon nanotubes, which create long, flexible, conductive, strong nanobridges between silicon particles and hold them together during charge/discharge cycles.
Use On June 29, 2026, Chinese Honor released the X80 Pro Max mobile phone with a Si/C Li-Po 11000 mAh battery and a near-normal weight of 203 g (7.16 oz).
Specific capacity A crystalline silicon anode has a theoretical specific capacity of 3600 mAh/g, approximately ten times that of commonly used graphite anodes (limited to 372 mAh/g). Each silicon atom can bind up to 3.75 lithium atoms in its fully lithiated state (), compared to one lithium atom per 6 carbon atoms for the fully lithiated graphite ().
+ Specific capacity and volume change for some anode materials (given in their lithiated state). Anode material Specific capacity (mAh/g) Volume change 3862 - 372 10% 990 252% 2235 178% 3600 320%
Silicon swelling The lattice distance between silicon atoms multiplies as it accommodates lithium ions (lithiation), reaching 320% of the original volume. The expansion causes large anisotropic stresses to occur within the electrode material, fracturing and crumbling the silicon material and detachment from the current collector. Prototypical lithium-silicon batteries lose most of their capacity in as few as 10 charge-discharge cycles. A solution to the capacity and stability issues posed by the significant volume expansion upon lithiation is critical to the success of silicon anodes.
Because the volume expansion and contraction properties of nanoparticles differ greatly from the bulk material, silicon nanostructures have been investigated as a potential solution. While they have a higher percentage of surface atoms than bulk silicon particles, the increased reactivity may be controlled by encasement, coatings, or other methods that limit surface—electrolyte contact. One method identified by researchers has used silicon nanowires on a conductive substrate for an anode, and found that the nanowire morphology creates direct current pathways to help increase power density and decreases disruption from volume change. However, the large volume change of the nanowires can still pose a fading problem.
Other studies examined the potential of silicon nanoparticles. Anodes that use silicon nanoparticles may overcome the price and scale barriers of nanowire batteries, while offering more mechanical stability over cycling compared to other silicon electrodes. Typically, these anodes add carbon as a conductive additive and a binder for increased mechanical stability. However, this geometry does not fully solve the issue of large volume expansion upon lithiation, exposing the battery to increased risk of capacity loss from inaccessible nanoparticles after cycle-induced cracking and stress.
Another nanoparticle approach is to use a conducting polymer matrix as both the binder and the polymer electrolyte for nanoparticle batteries. One study examined a three-dimensional conducting polymer and hydrogel network to encase and allow for ionic transport to the electrochemically active silicon nanoparticles. The framework resulted in a marked improvement in electrode stability, with over 90% capacity retention after 5,000 cycles. Other methods to accomplish similar outcomes include utilizing slurry coating techniques, which are inline with presently used electrode creation methodologies.
Self-healing polymer binders for silicon anodes In 2013, Stanford researchers developed a self-healing polymer binder to improve the cycling stability of silicon microparticle (SiMP) anodes in lithium-ion batteries. Silicon, with a theoretical specific capacity of ~3,600 mAh/g — nearly 10 times that of graphite — suffers from rapid capacity loss due to ~300% volumetric expansion during lithiation, causing electrode cracking and electrical disconnection.
The binder, a randomly branched hydrogen-bonding polymer, autonomously repairs cracks formed during cycling, maintaining mechanical and electrical integrity. This approach enabled SiMP anodes to achieve a cycle life over 90 cycles at 80% capacity retention — more than 10 times longer than conventional polyvinylidene fluoride (PVDF) binders, which drop below 80% capacity within 9 cycles. The self-healing electrode maintained a high specific capacity of ~3,000 mAh/g and demonstrated stable Coulombic efficiency above 98% after initial cycles, marking advancements toward scalable, high-energy, long-lifetime battery technology using silicon-based anodes in combination with self-healing polymers.
Charged silicon reactivity Besides the well recognized problems associated with large volume expansion, for example cracking the SEI layer, a second well recognized issue involves the reactivity of the charged materials. Since charged silicon is a lithium silicide, its salt-like structure is built from a combination of silicon (-4) Zintl anions and lithium cations. These silicide anions are highly reduced and display high reactivity with the electrolyte components that is charge compensated locally by reduction of the solvents. Recent work by Han, et al., has identified an in-situ coating synthesis method that eliminates the redox activity of the surface and limits the reactions that can take place with the solvents. Although it does not affect the issues associated with volume expansion, it has been seen with Mg cation based coatings to increase the cycle life and capacity significantly in a manner similar to the film forming additive fluoroethylene carbonate (FEC).
Solid electrolyte interphase layer