Recently, there has been news from major enterprises about solid-state batteries. Previously, the 150kwh battery package released by Ulay has achieved 360wh/kg energy density and its mileage has exceeded 1000 km. Ningde era BYD has also exposed its solid-state battery patents one after another, triggering social discussion.
Can solid-state batteries successfully replace the current lithium-ion batteries for large-scale industrialization? It is considered that we need to consider from three angles: energy density, safety performance, and battery cost.
The first is the energy density, which is one of the most important indicators to measure whether a power battery is good or not, because to a large extent, it determines the distance that a new energy vehicle can drive at a time. it also determines whether the model carried by the power battery can meet the daily needs of consumers. In fact, there are two common ways for the industry to improve the mileage of new energy vehicles: to increase the size of the power battery, and to increase the energy density of the battery. The former is to directly improve the overall quality of the cell, by making the volume larger to achieve the increase of electric capacity and the increase of mileage. However, this method has great limitations. The second is to improve the energy density of the battery itself, which is one of the most important goals in the power battery industry in recent years.
In the planning of power battery industry in China, the overall energy density of power battery is about 350-400WH in 2025. At present, the upper limit of theoretical energy density of traditional liquid lithium-ion battery is 350WHmax kg. The current liquid lithium-ion battery technology is trapped by the limitations of its own system, and it has been gradually difficult to keep up with the increasing energy density requirements, while solid-state battery itself has stronger electrochemical window compatibility. Its electrochemical stability window can reach more than 5V, which is higher than 4.2V of traditional liquid lithium ion batteries, which means that it can match higher performance cathode materials, and the use of metal lithium anode is also possible. Greatly increase the energy density of its theory. In the existing positive and negative material system, 300Wh/kg has a relatively high energy density, but the use of lithium metal anode can reach more than 500Wh/kg. The increase in energy density means that the volume and space utilization of new energy vehicles can also be effectively improved.
Second, security. According to the results of a previous survey conducted by the Shenzhen Consumer Commission, problems such as safety pressure and mileage anxiety of new energy vehicles have become the main reasons for consumers' refusal to buy. In recent years, with the substantial growth of the number of new energy vehicles in China, safety accidents occur frequently, and for a long time, liquid electrolytes are easy to leak or volatilize when they encounter shocks because of their flammability, which leads to safety accidents such as battery fire and explosion. On the other hand, solid-state batteries use non-flammable all-solid electrolytes instead of liquid electrolytes, which can avoid smoke, fire and explosion even after physical shocks. at the same time, the phenomenon of lithium dendrite has been restrained enough. the safety has been greatly improved.
Third, in terms of cost, as new energy vehicles are still a kind of consumer goods in nature, if we want to completely replace the status of fuel vehicles, except for the comprehensive performance such as mileage, safety performance should be flat or exceed, if the cost can not be better controlled, it is still difficult to carry out industrialization. Solid-state batteries do not need to use raw materials such as all-solid electrolytes, electrolytes, electrolyte salts, diaphragms and binders, which greatly simplify the battery construction steps, while some of the intermediate manufacturing processes, such as electrolyte injection and additional cooling system, can also be omitted. Data show that when the production capacity of solid-state batteries at the cell level reaches 20GWH, The cost reduction of solid-state batteries is very close to that of liquid lithium-ion batteries, which is 1.1 times that of liquid batteries. At the pack level, when the production capacity reaches 20GWH, the cost of solid-state batteries drops to 98 per cent of that of the liquid. However, after the gradual increase in capacity, the cost of solid-state batteries is expected to be lower than that of ordinary liquid lithium-ion batteries.
From the perspective of R & D progress, the development process of solid-state battery can be divided into three periods as a whole. The first period is 2018-2021, which is mainly the planning and research and development period of solid-state battery products. During this period, the products of the major battery manufacturers in the industry have gradually approached the theoretical energy density limit of traditional liquid lithium-ion batteries, and the industry as a whole is facing a period of transition. During this period, Traditional liquid lithium-ion batteries such as ternary iron lithium batteries still dominate the market. And then 2022-2025 is the application period, at this stage, models and products with solid or semi-solid batteries will gradually appear on the market, but because of their cost, they are expected to be more likely to be carried in high-end models, and the energy density at this stage will also exceed the theoretical limit of traditional liquid lithium-ion batteries. It is expected that the energy density will reach 300-500WH/KG. The third stage 2026-2040 solid-state battery market will usher in a mature period, this stage is expected to achieve technological breakthroughs, energy density breakthrough above 500WH/kg, large-scale commercial applications and mass production possible.
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