Westlake University Breaks Practical Barriers with Anode-Free Batteries, Paving the Way for a Future Without Power Banks

Since the advent of smartphones, users have been plagued by the constant fear of running out of battery. With increasingly powerful processors, larger screens, and even large-scale AI models running on devices, power consumption continues to rise, while advancements in battery technology lag behind. This “power gap” has made portable power banks an essential item in modern society. However, a breakthrough from a Chinese research institution could upend this norm. A team from Westlake University has published a paper in the scientific journal Nature, suggesting they have made a decisive step toward the practical application of next-generation “anode-free batteries.”

Technology to End the “Battery Anxiety” of the Smartphone Era In the era of feature phones, batteries could last a week. With smartphones, they deplete in just a few days. This shift has fundamentally changed our lives. From payments and navigation to work and communication, smartphones have become an extension of our hands—a “cybernetic limb.” Losing power on these devices is tantamount to being paralyzed in a digital world. Battery technology, however, has not evolved as rapidly as semiconductor technology under Moore’s Law. As a result, the chronic anxiety over battery life has become a common “condition” in modern society. The research results published in Nature by a team led by Jianhui Wang and Lei Liu from the School of Engineering at Westlake University hold the potential to address this issue at its root. At the core of their breakthrough is the resolution of the lifespan challenges associated with anode-free batteries, bringing them closer to practical application.

What Are Anode-Free Batteries?

A Paradigm Shift in Battery Design To understand anode-free batteries, it helps to simplify the structure of a battery. In common lithium-ion batteries, lithium ions move between the cathode and anode during charge and discharge cycles. The anode typically consists of materials like graphite or silicon-carbon, which serve as a “space” to stably store lithium ions. Anode-free batteries, on the other hand, completely eliminate the active materials in the anode. At the time of manufacturing, the anode side consists only of a thin copper foil current collector. During charging, lithium ions are directly deposited on this copper foil, and during discharging, they dissolve again. This represents the ultimate “subtractive” approach to battery design. By eliminating heavy and bulky materials like graphite, the saved space and weight can instead be used entirely for energy storage. This design drastically increases theoretical energy density. While conventional smartphone batteries have a volumetric energy density of about 800–900 Wh/L, anode-free batteries could reach 1668 Wh/L, with a gravimetric energy density of 508 Wh/kg. This could allow for much longer usage times with the same battery size.

The Curse of Dendrites: The Barrier to Practical Application Despite its high potential, anode-free batteries have faced clear barriers to practical use. The primary challenges have been posed by “dendrites” (dendritic crystals) and “dead lithium.” The smooth surface of the copper foil has low affinity for lithium, leading to uneven deposition of lithium ions during charging. This uneven distribution encourages the growth of tree-like crystals known as dendrites. Sharp dendrites can penetrate the separator inside the battery, causing internal short circuits and, in the worst cases, fire hazards. Furthermore, repeated charging and discharging cause the accumulation of “dead lithium,” which can no longer participate in reactions, leading to rapid degradation of the battery’s capacity. These issues have been the main obstacles preventing anode-free batteries from surviving more than a few dozen cycles.

Westlake University’s “Double Insurance” Approach The breakthrough by Westlake University’s team lies in their solution to the issues of dendrites and dead lithium through precise two-stage control. The core of their research combines two technical innovations: “in situ crystal seeding” and the design of a novel electrolyte. The first stage, “in situ crystal seeding,” involves a special pre-treatment process conducted after assembling the battery. By charging the battery briefly at a high current rate under low temperatures, a thin, uniform layer of lithium crystals is “seeded” on the surface of the copper foil. This process is akin to evenly sowing seeds on rough ground. Thanks to these “seeds,” lithium deposits more uniformly during subsequent regular charging, effectively suppressing the uncontrolled growth of dendrites at its root. However, merely initiating uniform deposition is not enough to ensure stability over hundreds of cycles. This is where the second key innovation comes into play: the design of a novel electrolyte system. The research team developed a new electrolyte composition combining specific lithium salts, fluorinated amide solvents, and lithium-replenishing additives. This electrolyte forms a stable, dense, lithium fluoride (LiF)-rich solid electrolyte interphase (SEI) layer on the surface of the lithium metal. This SEI layer acts as a “protective shell,” preventing undesirable side reactions between the electrolyte and lithium metal, and significantly reducing the formation of dead lithium. The first innovation ensures “orderly initiation of growth,” while the second supports “long-term stability.” This dual insurance mechanism has elevated the cycle life of anode-free batteries to practical levels.

Practical Results Beyond the Laboratory One of the industry’s greatest concerns is that batteries showing excellent performance in coin-cell sizes may deteriorate significantly when scaled up to actual product sizes. What makes the Westlake University team’s achievement particularly significant is their demonstration of practical performance using a large-capacity soft-pack battery (sample capacity: 2.7Ah). The performance data reported in the paper is impressive. A volumetric energy density of 1668 Wh/L and a gravimetric energy density of 508 Wh/kg far surpass the potential of current state-of-the-art smartphone batteries. In terms of cycle life, the battery achieved over 100 stable cycles with a 100% depth of discharge and 250 cycles with a more practical 80% depth of discharge. While these figures fall short of the over 1,000 cycles typical of current smartphone batteries, this achievement marks a groundbreaking step in advancing anode-free batteries from a “laboratory concept” to being “on the brink of industrialization.”

Expectations for Industrialization and Moves by Major Manufacturers Capital and industry players are quick to sense emerging technological trends. In the field of anode-free batteries, often referred to as the “ultimate next-generation battery,” major Chinese manufacturers are already making moves. CATL, the world’s largest battery manufacturer, has accumulated numerous patents related to anode-free metal batteries, alongside solid-state and condensed-state batteries. They are reportedly exploring the integration of anode-free approaches into next-generation sodium-ion battery systems and working on protective layer designs to suppress dendrites. Meanwhile, BYD has continuously published patents related to metallic lithium anode technologies, including methods that enhance the affinity of the current collector with lithium. The research results from Westlake University resonate with these industrial developments, providing a solid scientific foundation for the roadmap to practical anode-free batteries. From smartphones and wearable devices to electric vehicles, this technology has the potential to revolutionize mobile energy paradigms. The day when we no longer worry about battery life may not be far off.