## 1 Introduction  
Nowadays, lithium-ion batteries (LIB) are the fastest developing energy storage systems, and have widespread application in mobile phones, laptops, electric vehicles, etc. [1; 2; 3]. However, the commercial graphite anode material has a limited theoretical capacity of 372 mAh g\({}^{-1}\), which cannot meet the energy density requirements in certain applications [4; 5]. Various studies have been carried out to find new high energy density materials, such as Sn- [6; 7] or Si-based anodes [8; 9; 10], and transition metal oxides [11; 12]. Among these, Si-based material is considered as a promising candidate owing to its high theoretical capacity of 4200 mAh g\({}^{-1}\)[13; 14]. At present, the main challenge is the enormous volumetric change of the Si during the cycle process, leading to structural failure and pulverization [15; 16], and the low electronic conductivity of silicon also induces severe irreversible capacity loss. At present, research has mainly focused on finding new Si-based structures to solve the problems of the volumetric changes. The utility of nanoparticles, nanosheets, nanohollows, nanowires, and nano-core-shells has been studied as well [17; 18; 19; 20; 21]. Among them, silicon/carbon composites are regarded as effective structures to alleviate the volumetric changes of the silicon. In them, the silicon acts as the active material to provide lithium storage capacity, and the carbon material acts as a buffer to resist the volumetric changes of silicon during the cycle process. In addition, the drastic capacity fading of the Si-based anode corresponds to the solid electrolyte interphase (SEI) films repeatedly formed during the cycles. It has been proved that the surrounding carbon material avoids direct contact between the silicon and the electrolyte, preventing repeated SEI formation [22; 23; 24]. To develop a high-performance anode material, [PERSON] et al. [25] synthesized a Si/carbon/graphite composite, and the Si nanoparticles were encapsulated by the carbonized coal-tar pitch and attached to the surface of graphite; the amorphous carbon layer avoided the direct contact between the Si nanoparticles and electrolyte and alleviated the volumetric changes of the Si nanoparticles during the cycles. The specific capacity of the composite was 712 mAh g\({}^{-1}\) at a current density of 130 mA g\({}^{-1}\), with a capacity retention of 80% after 100 cycles [25]. [PERSON] et al. [26] proposed a sandwich-structured silicon nanoparticle/hollow graphite fiber/carbon-coated composite. In this work, the volume expansion of the Si nanoparticles was effectively controlled by the new sandwich-structure, and the specific capacity of the composite was maintained at 910.1 mA h g\({}^{-1}\) after the 50 th cycle. Most silicon-carbon nanocomposites are embedded structures and are prepared by high-temperature pyrolysis of carbon materials, in which the Si nanoparticles are encapsulated by amorphous carbon layers to resists the volumetric change and enhance electrode conductivity. However, the further improvement of the electrochemical performance is limited by the non-uniform thickness of carbon coating and serious agglomeration of Si nanoparticles [27, 28]. Moreover, the complex process, reagent pollution, and high cost make it difficult for industrialization. Recently, plasma technology has been introduced to prepare silicon-carbon nanocomposites due to the rapid synthesis process without expensive materials or toxic reagents. However, the traditional plasma technology for the preparation of silicon-carbon nanocomposite is inadequate to achieve mass production. Herein we proposed a novel plasma process with a magnetron plasma generator, in which the addition of magnetic force increases the volume and density of the plasma reaction region and reduces energy consumption. Thus, it lays a good foundation for mass production.